This document provides information about seismic refraction methods used in geophysical exploration. It discusses how seismic refraction works, how the tests are conducted by placing geophones along a line and recording seismic waves generated by a hammer or explosive source. It explains how the travel times of the seismic waves through different subsurface layers are used to calculate layer velocities and thicknesses. Applications of the method include determining subsurface geological structures and properties for purposes like engineering, mining, and hydrocarbon exploration.
This document defines groundwater as water present beneath the Earth's surface, within soil pores and fractures in rock formations. An aquifer is a unit of rock or sediment that yields usable water. The water table marks the depth where pores and fractures become fully saturated. Groundwater is extracted via wells for agriculture, municipal, and industrial uses. Its study is called hydrogeology. Springs form when aquifers fill to the point of overflowing onto land. Pumping a well creates a cone of depression in the water table or pressure levels around the well. The size of this cone depends on factors like the pumping rate, aquifer properties, storage, and thickness.
Geophysical exploration uses physical methods to measure subsurface properties without sampling. It includes passive methods that measure natural fields like gravity and magnetism, and active methods using artificial sources like seismic surveys. Seismic surveys involve generating seismic waves, including faster P-waves and slower S-waves, from sources like explosions. These waves travel through and reflect off subsurface interfaces to reveal information about geological structures and detect hydrocarbon deposits like oil and gas. Geophysical surveys are a low-cost exploration technique used to find new reserves and guide further exploration activities.
Este documento describe los procesos de transporte y sedimentación de partículas en corrientes de agua. Explica que las partículas pueden transportarse en solución, suspensión o por carga de fondo, y que la abrasión y selección hidráulica causan cambios en su tamaño y distribución. Luego detalla cómo el tamaño de la partícula afecta el método de transporte y cómo la velocidad de la corriente determina si las partículas se mantienen en suspensión o se depositan.
The importance of geohazards for safety, rig/well integrity & drilling. It includes real incidents & worst case scenarios. Pressure concepts, seismic and diagrams are utilized to explain given examples.
It includes the definition, properties, classification of groundwater with appropriate examples and figures in details. It also deals about the formation of groundwater. The properties of aquifers (all of 7) are described here in details with figures and mathematical terms.
This presentation discusses porosity, which is the ratio of pore volume to bulk volume of a rock. Porosity is denoted by φ and expressed as a percentage. The document defines porosity and outlines factors that affect it such as particle shape, packing, sorting, and cementation. It describes two main types of porosity: primary porosity formed during deposition and secondary porosity developed after. Porosity is further divided into total, effective, micro, meso, and macro categories based on pore size. Methods for determining porosity include direct measurement of bulk and material volumes or comparing saturated and dried sample weights.
Groundwater is water located beneath the Earth's surface that saturates pores and fractures in rock and soil. It is the largest supply of fresh water available for human use. Groundwater occurs naturally and is replenished through precipitation, though the amount that can be accessed through wells varies significantly between locations. It is stored in porous geologic formations called aquifers and can be confined by layers of impermeable rock. Wells are constructed to access groundwater from aquifers, with casing, screens, grout and gravel packs used to properly construct the well. Groundwater can become contaminated if wells are improperly built or toxic materials leak into the ground near a well.
This document discusses slope stability analysis. It begins with introductions and objectives, then describes types of slope failures such as plane, wedge, toppling and rotational. Factors affecting slope stability and variables to consider in design are outlined. Methods of slope stability analysis including limit equilibrium methods and factor of safety calculations are explained. A case study of a landslide in Nigeria is presented, with soil testing and modeling using Slope/W software yielding a factor of safety near 1, indicating incipient failure. The document concludes with recommendations for further slope stability assessments.
This document defines groundwater as water present beneath the Earth's surface, within soil pores and fractures in rock formations. An aquifer is a unit of rock or sediment that yields usable water. The water table marks the depth where pores and fractures become fully saturated. Groundwater is extracted via wells for agriculture, municipal, and industrial uses. Its study is called hydrogeology. Springs form when aquifers fill to the point of overflowing onto land. Pumping a well creates a cone of depression in the water table or pressure levels around the well. The size of this cone depends on factors like the pumping rate, aquifer properties, storage, and thickness.
Geophysical exploration uses physical methods to measure subsurface properties without sampling. It includes passive methods that measure natural fields like gravity and magnetism, and active methods using artificial sources like seismic surveys. Seismic surveys involve generating seismic waves, including faster P-waves and slower S-waves, from sources like explosions. These waves travel through and reflect off subsurface interfaces to reveal information about geological structures and detect hydrocarbon deposits like oil and gas. Geophysical surveys are a low-cost exploration technique used to find new reserves and guide further exploration activities.
Este documento describe los procesos de transporte y sedimentación de partículas en corrientes de agua. Explica que las partículas pueden transportarse en solución, suspensión o por carga de fondo, y que la abrasión y selección hidráulica causan cambios en su tamaño y distribución. Luego detalla cómo el tamaño de la partícula afecta el método de transporte y cómo la velocidad de la corriente determina si las partículas se mantienen en suspensión o se depositan.
The importance of geohazards for safety, rig/well integrity & drilling. It includes real incidents & worst case scenarios. Pressure concepts, seismic and diagrams are utilized to explain given examples.
It includes the definition, properties, classification of groundwater with appropriate examples and figures in details. It also deals about the formation of groundwater. The properties of aquifers (all of 7) are described here in details with figures and mathematical terms.
This presentation discusses porosity, which is the ratio of pore volume to bulk volume of a rock. Porosity is denoted by φ and expressed as a percentage. The document defines porosity and outlines factors that affect it such as particle shape, packing, sorting, and cementation. It describes two main types of porosity: primary porosity formed during deposition and secondary porosity developed after. Porosity is further divided into total, effective, micro, meso, and macro categories based on pore size. Methods for determining porosity include direct measurement of bulk and material volumes or comparing saturated and dried sample weights.
Groundwater is water located beneath the Earth's surface that saturates pores and fractures in rock and soil. It is the largest supply of fresh water available for human use. Groundwater occurs naturally and is replenished through precipitation, though the amount that can be accessed through wells varies significantly between locations. It is stored in porous geologic formations called aquifers and can be confined by layers of impermeable rock. Wells are constructed to access groundwater from aquifers, with casing, screens, grout and gravel packs used to properly construct the well. Groundwater can become contaminated if wells are improperly built or toxic materials leak into the ground near a well.
This document discusses slope stability analysis. It begins with introductions and objectives, then describes types of slope failures such as plane, wedge, toppling and rotational. Factors affecting slope stability and variables to consider in design are outlined. Methods of slope stability analysis including limit equilibrium methods and factor of safety calculations are explained. A case study of a landslide in Nigeria is presented, with soil testing and modeling using Slope/W software yielding a factor of safety near 1, indicating incipient failure. The document concludes with recommendations for further slope stability assessments.
This document discusses groundwater hydrology. It defines groundwater and describes the zones of saturation and aeration below the surface. It then explains various hydrologic concepts like the water table, soil water, and capillary fringe. It also defines different zones within an aquifer like unconfined and confined, and describes their properties. Key concepts like porosity, permeability, transmissibility, and Darcy's law are summarized. Finally, it briefly discusses Dupuit's assumptions and pumping tests.
The document discusses subsurface exploration, which involves determining the soil layers and properties beneath a proposed structure. It describes the various phases of a soil investigation: collecting existing information, conducting site visits, preliminary exploration including some boreholes, detailed exploration with more boreholes and laboratory/in-situ testing, and reporting findings. Guidelines are provided for borehole depth, spacing, and number based on factors like structure type and loads, soil variability, and cost. Common subsurface exploration methods include test pits, hand augers, mechanical augers, shell and auger borings, percussion borings, wash borings, rotary borings, and diamond core drilling.
2D MASW ANALYSIS FOR GEOTECHNICAL ENGINEERINGAli Osman Öncel
This document describes a study that used seismic refraction and multi-channel analysis of surface waves (MASW) to investigate near-surface shear wave velocities at a site in Egypt. Seismic refraction was used to determine P-wave velocities down to depths of 30 m. MASW was used to determine 1D and 2D shear wave velocity profiles by analyzing Rayleigh surface wave dispersion. Shear wave velocities obtained from MASW were used to evaluate site response and classify the site according to standard site classifications. The study area consists of Quaternary deposits overlying Tertiary sedimentary rocks. P-wave and MASW surveys were conducted along multiple profiles using geophones and a seismograph to
The document lists the group members and registration numbers for a presentation on geotechnical investigation. It includes an outline of the presentation topics which are an introduction to soil exploration, investigation phases, exploration methods, soil sampling, amount of exploration needed, in-situ tests, planning an investigation, and records/reports. The key topics to be covered are the purpose of soil exploration, direct and indirect exploration methods such as test pits and boreholes, sampling disturbed and undisturbed soil samples, and planning the exploration program.
Groundwater is saturated rock and soil below the land surface. It is an important source of water for many uses. Water flows through the subsurface based on hydraulic head, which considers both pressure and elevation. It moves more quickly through permeable materials like sandstone. While groundwater is generally safe, the document warns about potential contaminants. The majority of groundwater is used directly by humans or indirectly by discharging into streams.
This document provides an overview of well logging techniques. It introduces well logging and describes the borehole environment. It then outlines the main types of well logging as electrical, radioactivity, sonic, and miscellaneous. The document focuses on electrical well logging, describing the resistivity, self-potential, and induction methods. For resistivity logging, it explains tools such as normal/lateral logs, micrologs, laterologs, microlaterologs, and proximity logs. It also discusses using resistivity to determine saturation, flushed zones, and mud filtrate invasion profiles.
Electrofacies a guided machine learning for practice of geomodellingPetro Teach
• Goal: to bring consistency to facies logs thus enhancing the
workflows, integration of data, and quality of reservoir modeling
• Premise: Facies logs are typically not tuned optimally to the
hierarchical geomodeling workflows
This document discusses groundwater, including:
- Groundwater is water found beneath the Earth's surface, filling spaces in rock and sediment. It is a major source of water supply.
- Groundwater originates from precipitation that infiltrates underground. It moves through the hydrologic cycle and is stored in aquifers.
- Aquifers are permeable rock formations that can supply significant water to wells and springs. Properties like porosity and permeability determine how much water rock can hold and transmit.
- Permeability is a property of porous rocks that measures their ability to transmit fluids. Higher permeability means fluids can flow more easily through the rock.
- Darcy's law states that for laminar flow through a permeable medium, the flow rate is proportional to the permeability of the medium and the pressure gradient, and inversely proportional to the fluid viscosity.
- There are different units used to measure and describe permeability, including darcies and millidarcies. Permeability is a key parameter in evaluating reservoir performance and fluid flow.
The document discusses hydraulic conductivity, which measures the ability of a material like soil or rock to transmit fluids through pores and fractures under an applied hydraulic gradient. It describes hydraulic conductivity as being important for calculating groundwater movement rates and outlines experimental and empirical methods for determining it in the field or laboratory, such as constant head tests, falling head tests, or correlations with soil properties. Hydraulic conductivity is the constant in Darcy's Law and is defined as the volume of water that will move through a porous medium per unit time under a unit hydraulic gradient through a unit area measured perpendicular to flow.
This document provides an overview of geophysics and its various applications. It discusses how geophysics studies the physics of the Earth and its atmosphere. Key methods described include seismic reflection and refraction techniques to map subsurface structures. These methods make use of the travel times of seismic waves to determine depths and detect features like faults and folds. The document also outlines how geophysics has various applications in mineral and oil/gas exploration to locate deposits and structures below the surface using physical property measurements.
1) A pumping test was conducted where a well was pumped at 2500 m3/day and drawdowns were measured in an observation well 60 m away at various times.
2) The transmissivity and storativity of the confined aquifer were estimated using the Theis and Cooper-Jacob methods in AquiferTest software by analyzing the linear relationship between the logarithm of time and drawdown.
3) The accuracy of the aquifer parameter estimates depends on maintaining a constant pumping rate and measuring drawdowns at appropriate time intervals in multiple observation wells.
1. The document discusses methods for calculating net-to-gross (NTG) ratios in heterolithic sequences with thin interbedded sands and shales at resolutions below conventional well log scale.
2. It presents thought experiments comparing binary and continuous NTG calculations, showing that continuous NTG is required to accurately capture NTG values when upscaling between core, log, and reservoir scales.
3. Various methods are proposed for determining continuous NTG, including cross-plots using additional logging data, modeling the effects of dispersed and laminated clays, and using NMR logging to partition porosity at the pore scale.
Este documento resume los conceptos clave relacionados con las plataformas petrolíferas costa afuera. Explica que estas plataformas se utilizan para extraer petróleo y gas natural del subsuelo marino, y describe los diferentes tipos de plataformas, métodos de perforación, ubicaciones geográficas clave y etapas del proceso de producción. También aborda temas como los sistemas FPSO, partes de una plataforma, proyectos a nivel mundial, regulaciones y posibles daños ambientales.
The document discusses various topics related to hydrologic cycles and groundwater including:
1) The water cycle is driven by energy from the sun and involves evaporation, transpiration, condensation, precipitation, and runoff.
2) Groundwater occurs below the ground surface in voids and fractures in rocks and soil based on porosity and permeability.
3) Aquifers are underground areas that store and transmit groundwater while aquicludes and aquitards have low permeability and transmit water slowly or not at all.
4) Different rock types like sedimentary, igneous, and metamorphic rocks can serve as aquifers depending on their porosity and permeability.
Schlumberger - Drilling and Measurement Segment - Internship PresentationZorays Solar Pakistan
I learnt about all the Drilling and Measurement equipment and procedures. During the internship period, I had to survey few technical modules which were specific to Drilling and Measurment segment, which included
• an introduction to Drilling & Measurment segment and its core services
• interpretation of Direction & Inclination terminologies
• learning of Telemetry procedures and working of Measurement While Drilling tools
• understanding of Surface System structure.
The Fullbore Formation MicroImager (FMI) instrument provides high resolution images of bedding and fractures in borehole walls. It uses electrical resistivity contrasts to image features around the borehole at vertical resolutions of 5 mm. FMI data is processed using Schlumberger software to correct speed, equalize histograms, and enhance images. FMI can be used for structural analysis, reservoir characterization of natural fractures and porosity, thin bed detection, and other applications. It images features like dips, fractures, vugs, laminations, and other sedimentological structures.
This document discusses various geophysical well logging methods used to delineate aquifers and estimate water quality, including resistivity, spontaneous potential, radioactivity, neutron, temperature, and fluid resistivity logging. Resistivity logging measures the resistivity of formations and can help determine lithology, porosity, and fluid salinity. Spontaneous potential logging indicates bed boundaries and distinguishes shale from permeable rocks. Radioactivity logging uses natural gamma rays or gamma-gamma techniques to identify lithology and determine porosity. Neutron logging measures hydrogen content to estimate porosity and moisture levels. Temperature and fluid resistivity logging provide additional information about groundwater. These geophysical logs provide critical subsurface data for groundwater exploration and management.
This document discusses resistivity logs and how they are used to analyze borehole formations. Resistivity is measured in ohms per meter and depends on factors like water volume, temperature, and salinity. Resistivity logs can determine hydrocarbon versus water-bearing zones and indicate permeable zones. The Archie equation relates resistivity to water saturation and uses constants determined by rock type. Different resistivity tools like electrode and induction logs measure resistivity at varying depths around the borehole to analyze fluid content and identify zones.
This document provides an overview of fracture characterisation from borehole image logs. It discusses how fractures of different sizes, apertures, and mineral infills can be imaged using various borehole tools. Direct measurements that can be taken from images include fracture location, orientation, morphology, continuity and apparent aperture. Fracture descriptions should be ground-truthed with core data. The impact of fractures on reservoir performance can be both positive and negative. Analysis of fracture image data involves displaying and separating fractures into sets, analyzing factors like density and spacing, and developing a conceptual fracture model.
1) Seismic reflection is a method of exploration based on measuring the response of seismic waves (sounds) introduced into the ground and then reflected or refracted along differences in soil layers or rock boundaries.
2) Seismic reflection measures the time it takes for an acoustic impulse to travel from the sound source, reflect off geological formation boundaries, and return to the surface at a geophone.
3) Reflections from a geological horizon are similar to an echo at the face of a cliff or ravine. Seismic reflection is widely used for oil exploration, determining earthquake sources, and detecting soil layer structures.
Seismic surveys use explosions or vibrations at shot points to generate seismic waves that reflect off subsurface structures and are detected at receiving points. The time it takes for reflections or refractions of the waves to reach the detectors are recorded in seismograms. Denser rocks are found at greater depths, so reflected waves arrive first at close distances while refracted waves through denser layers arrive first at longer distances. Interpreting the depths and structures penetrated by the seismic waves depends on the shot-detector distances and the densities of the underground strata. Seismic profiles are cross-sectional drawings created from the survey results to visualize subsurface structures.
This document discusses groundwater hydrology. It defines groundwater and describes the zones of saturation and aeration below the surface. It then explains various hydrologic concepts like the water table, soil water, and capillary fringe. It also defines different zones within an aquifer like unconfined and confined, and describes their properties. Key concepts like porosity, permeability, transmissibility, and Darcy's law are summarized. Finally, it briefly discusses Dupuit's assumptions and pumping tests.
The document discusses subsurface exploration, which involves determining the soil layers and properties beneath a proposed structure. It describes the various phases of a soil investigation: collecting existing information, conducting site visits, preliminary exploration including some boreholes, detailed exploration with more boreholes and laboratory/in-situ testing, and reporting findings. Guidelines are provided for borehole depth, spacing, and number based on factors like structure type and loads, soil variability, and cost. Common subsurface exploration methods include test pits, hand augers, mechanical augers, shell and auger borings, percussion borings, wash borings, rotary borings, and diamond core drilling.
2D MASW ANALYSIS FOR GEOTECHNICAL ENGINEERINGAli Osman Öncel
This document describes a study that used seismic refraction and multi-channel analysis of surface waves (MASW) to investigate near-surface shear wave velocities at a site in Egypt. Seismic refraction was used to determine P-wave velocities down to depths of 30 m. MASW was used to determine 1D and 2D shear wave velocity profiles by analyzing Rayleigh surface wave dispersion. Shear wave velocities obtained from MASW were used to evaluate site response and classify the site according to standard site classifications. The study area consists of Quaternary deposits overlying Tertiary sedimentary rocks. P-wave and MASW surveys were conducted along multiple profiles using geophones and a seismograph to
The document lists the group members and registration numbers for a presentation on geotechnical investigation. It includes an outline of the presentation topics which are an introduction to soil exploration, investigation phases, exploration methods, soil sampling, amount of exploration needed, in-situ tests, planning an investigation, and records/reports. The key topics to be covered are the purpose of soil exploration, direct and indirect exploration methods such as test pits and boreholes, sampling disturbed and undisturbed soil samples, and planning the exploration program.
Groundwater is saturated rock and soil below the land surface. It is an important source of water for many uses. Water flows through the subsurface based on hydraulic head, which considers both pressure and elevation. It moves more quickly through permeable materials like sandstone. While groundwater is generally safe, the document warns about potential contaminants. The majority of groundwater is used directly by humans or indirectly by discharging into streams.
This document provides an overview of well logging techniques. It introduces well logging and describes the borehole environment. It then outlines the main types of well logging as electrical, radioactivity, sonic, and miscellaneous. The document focuses on electrical well logging, describing the resistivity, self-potential, and induction methods. For resistivity logging, it explains tools such as normal/lateral logs, micrologs, laterologs, microlaterologs, and proximity logs. It also discusses using resistivity to determine saturation, flushed zones, and mud filtrate invasion profiles.
Electrofacies a guided machine learning for practice of geomodellingPetro Teach
• Goal: to bring consistency to facies logs thus enhancing the
workflows, integration of data, and quality of reservoir modeling
• Premise: Facies logs are typically not tuned optimally to the
hierarchical geomodeling workflows
This document discusses groundwater, including:
- Groundwater is water found beneath the Earth's surface, filling spaces in rock and sediment. It is a major source of water supply.
- Groundwater originates from precipitation that infiltrates underground. It moves through the hydrologic cycle and is stored in aquifers.
- Aquifers are permeable rock formations that can supply significant water to wells and springs. Properties like porosity and permeability determine how much water rock can hold and transmit.
- Permeability is a property of porous rocks that measures their ability to transmit fluids. Higher permeability means fluids can flow more easily through the rock.
- Darcy's law states that for laminar flow through a permeable medium, the flow rate is proportional to the permeability of the medium and the pressure gradient, and inversely proportional to the fluid viscosity.
- There are different units used to measure and describe permeability, including darcies and millidarcies. Permeability is a key parameter in evaluating reservoir performance and fluid flow.
The document discusses hydraulic conductivity, which measures the ability of a material like soil or rock to transmit fluids through pores and fractures under an applied hydraulic gradient. It describes hydraulic conductivity as being important for calculating groundwater movement rates and outlines experimental and empirical methods for determining it in the field or laboratory, such as constant head tests, falling head tests, or correlations with soil properties. Hydraulic conductivity is the constant in Darcy's Law and is defined as the volume of water that will move through a porous medium per unit time under a unit hydraulic gradient through a unit area measured perpendicular to flow.
This document provides an overview of geophysics and its various applications. It discusses how geophysics studies the physics of the Earth and its atmosphere. Key methods described include seismic reflection and refraction techniques to map subsurface structures. These methods make use of the travel times of seismic waves to determine depths and detect features like faults and folds. The document also outlines how geophysics has various applications in mineral and oil/gas exploration to locate deposits and structures below the surface using physical property measurements.
1) A pumping test was conducted where a well was pumped at 2500 m3/day and drawdowns were measured in an observation well 60 m away at various times.
2) The transmissivity and storativity of the confined aquifer were estimated using the Theis and Cooper-Jacob methods in AquiferTest software by analyzing the linear relationship between the logarithm of time and drawdown.
3) The accuracy of the aquifer parameter estimates depends on maintaining a constant pumping rate and measuring drawdowns at appropriate time intervals in multiple observation wells.
1. The document discusses methods for calculating net-to-gross (NTG) ratios in heterolithic sequences with thin interbedded sands and shales at resolutions below conventional well log scale.
2. It presents thought experiments comparing binary and continuous NTG calculations, showing that continuous NTG is required to accurately capture NTG values when upscaling between core, log, and reservoir scales.
3. Various methods are proposed for determining continuous NTG, including cross-plots using additional logging data, modeling the effects of dispersed and laminated clays, and using NMR logging to partition porosity at the pore scale.
Este documento resume los conceptos clave relacionados con las plataformas petrolíferas costa afuera. Explica que estas plataformas se utilizan para extraer petróleo y gas natural del subsuelo marino, y describe los diferentes tipos de plataformas, métodos de perforación, ubicaciones geográficas clave y etapas del proceso de producción. También aborda temas como los sistemas FPSO, partes de una plataforma, proyectos a nivel mundial, regulaciones y posibles daños ambientales.
The document discusses various topics related to hydrologic cycles and groundwater including:
1) The water cycle is driven by energy from the sun and involves evaporation, transpiration, condensation, precipitation, and runoff.
2) Groundwater occurs below the ground surface in voids and fractures in rocks and soil based on porosity and permeability.
3) Aquifers are underground areas that store and transmit groundwater while aquicludes and aquitards have low permeability and transmit water slowly or not at all.
4) Different rock types like sedimentary, igneous, and metamorphic rocks can serve as aquifers depending on their porosity and permeability.
Schlumberger - Drilling and Measurement Segment - Internship PresentationZorays Solar Pakistan
I learnt about all the Drilling and Measurement equipment and procedures. During the internship period, I had to survey few technical modules which were specific to Drilling and Measurment segment, which included
• an introduction to Drilling & Measurment segment and its core services
• interpretation of Direction & Inclination terminologies
• learning of Telemetry procedures and working of Measurement While Drilling tools
• understanding of Surface System structure.
The Fullbore Formation MicroImager (FMI) instrument provides high resolution images of bedding and fractures in borehole walls. It uses electrical resistivity contrasts to image features around the borehole at vertical resolutions of 5 mm. FMI data is processed using Schlumberger software to correct speed, equalize histograms, and enhance images. FMI can be used for structural analysis, reservoir characterization of natural fractures and porosity, thin bed detection, and other applications. It images features like dips, fractures, vugs, laminations, and other sedimentological structures.
This document discusses various geophysical well logging methods used to delineate aquifers and estimate water quality, including resistivity, spontaneous potential, radioactivity, neutron, temperature, and fluid resistivity logging. Resistivity logging measures the resistivity of formations and can help determine lithology, porosity, and fluid salinity. Spontaneous potential logging indicates bed boundaries and distinguishes shale from permeable rocks. Radioactivity logging uses natural gamma rays or gamma-gamma techniques to identify lithology and determine porosity. Neutron logging measures hydrogen content to estimate porosity and moisture levels. Temperature and fluid resistivity logging provide additional information about groundwater. These geophysical logs provide critical subsurface data for groundwater exploration and management.
This document discusses resistivity logs and how they are used to analyze borehole formations. Resistivity is measured in ohms per meter and depends on factors like water volume, temperature, and salinity. Resistivity logs can determine hydrocarbon versus water-bearing zones and indicate permeable zones. The Archie equation relates resistivity to water saturation and uses constants determined by rock type. Different resistivity tools like electrode and induction logs measure resistivity at varying depths around the borehole to analyze fluid content and identify zones.
This document provides an overview of fracture characterisation from borehole image logs. It discusses how fractures of different sizes, apertures, and mineral infills can be imaged using various borehole tools. Direct measurements that can be taken from images include fracture location, orientation, morphology, continuity and apparent aperture. Fracture descriptions should be ground-truthed with core data. The impact of fractures on reservoir performance can be both positive and negative. Analysis of fracture image data involves displaying and separating fractures into sets, analyzing factors like density and spacing, and developing a conceptual fracture model.
1) Seismic reflection is a method of exploration based on measuring the response of seismic waves (sounds) introduced into the ground and then reflected or refracted along differences in soil layers or rock boundaries.
2) Seismic reflection measures the time it takes for an acoustic impulse to travel from the sound source, reflect off geological formation boundaries, and return to the surface at a geophone.
3) Reflections from a geological horizon are similar to an echo at the face of a cliff or ravine. Seismic reflection is widely used for oil exploration, determining earthquake sources, and detecting soil layer structures.
Seismic surveys use explosions or vibrations at shot points to generate seismic waves that reflect off subsurface structures and are detected at receiving points. The time it takes for reflections or refractions of the waves to reach the detectors are recorded in seismograms. Denser rocks are found at greater depths, so reflected waves arrive first at close distances while refracted waves through denser layers arrive first at longer distances. Interpreting the depths and structures penetrated by the seismic waves depends on the shot-detector distances and the densities of the underground strata. Seismic profiles are cross-sectional drawings created from the survey results to visualize subsurface structures.
Exploration and Exploitation Groundwater From Journal and MaterialsMartheana Kencanawati
This document discusses various methods for exploring and exploiting groundwater resources, including surface exploration techniques like remote sensing, geophysical methods, and geological mapping, as well as subsurface techniques like test drilling and geophysical well logging. It provides details on specific surface geophysical methods like electrical resistivity, seismic refraction and reflection, and gravitational surveys. Subsurface techniques covered include well construction, borehole geophysical logging tools for measuring resistivity, spontaneous potential, natural gamma radiation, neutron porosity, temperature, and borehole diameter. The document emphasizes integrating multiple exploration techniques to better understand subsurface geology and locate groundwater.
Geophysical Methods of Hydrocarbon ExplorationM.T.H Group
This document provides an overview of geophysical methods used for hydrocarbon exploration, specifically focusing on seismic surveying. It describes how seismic surveying works, including generating sound waves at shot points and measuring the travel time of reflections to determine subsurface rock densities and structures. Gravity and magnetic methods are also discussed briefly as tools used in the pre-drilling phase to locate salt domes and reefs, while seismic surveying is described as the most widely used method and applicable to both exploration and development phases.
This document discusses seismic surveying methods used in geophysical exploration. It describes how seismic waves are generated artificially and recorded to map subsurface structures and lithologies. The main methods discussed are 2D and 3D seismic surveys. 2D surveys involve collecting seismic data along widely spaced lines, while 3D surveys acquire closely-spaced data to generate high-resolution 3D images of the subsurface. The document outlines the objectives, preparation, data acquisition, and interpretation of seismic data to infer the presence of oil and gas reservoirs.
This document compares methods for determining subsurface shear-wave velocity, which is important for seismic hazard assessment. It analyzes data from seismic cone penetration tests (SCPT), spectral analysis of surface waves (SASW), continuous surface wave system (CSWS), and microtremors in the Victoria, Canada area. The peak frequencies determined from SCPT measurements generally agree well with microtremor measurements, as both sample to similar depths. Surface wave methods like SASW and CSWS have more limited depth penetration and thus microtremor frequencies are sometimes lower. Combining microtremors with invasive or active non-invasive methods provides the best characterization of site response.
Seismic methods use seismic waves created by impacts on the surface to map underground structures. The waves travel through underground layers and are reflected or refracted at boundaries between different materials. Analysis of the travel times and velocities of the waves allows determining the depth and type of geological layers. Seismic reflection techniques involve creating waves at shot points and recording them with receivers at different offsets to generate common midpoint gathers. Processing the gathers yields a seismic section that images layer boundaries like an echo sounder. Seismic refraction uses refracted head waves along interfaces to build a shallow velocity model for near-surface layers. Both methods together provide structural and physical characterization of underground features like buried valleys.
This document discusses seismic stratigraphy, which uses seismic data to extract stratigraphic information about subsurface rock layers. It defines seismic waves and methods, including refraction and reflection. Reflection seismic is more commonly used to identify structures like folds and faults beneath the surface. Key parameters for interpretation are reflection configuration, continuity, amplitude, frequency, and interval velocity. Depositional environments are also identified based on their relationship to the wave base.
The sonic log measures the travel time of elastic waves through rock formations and can be used to derive porosity. It uses a transmitter and receiver to measure pulse travel times. Faster travel times indicate higher porosity as pores allow faster fluid-filled wave propagation than solid rock. The sonic log provides information to support seismic calibration and tie well measurements to seismic data. It can also be used to calculate porosity values when combined with density and neutron logs.
Seismic Refraction Test
Subsurface investigation by seismic refraction
Seismic Data Analysis
Seismic refraction instrumental set up and operation
P-waves velocity ranges for different strata
Geologists and geophysicists work together using various methods like collecting rock samples, studying rock properties, and surveying magnetic and gravity fields to understand the geology of an area. This informs decisions about whether to drill exploratory wells. Petroleum exploration uses direct observations of natural oil seeps. It also uses geological mapping and analysis of subsurface data from wells. Geophysical methods measure gravity, magnetic, and seismic readings to identify underground structures that may indicate oil and gas reservoirs. Together, these techniques provide information to evaluate a site's potential for commercial petroleum deposits.
This document provides information about earthquake engineering. It begins with definitions of key earthquake terminology. It then discusses the causes of earthquakes, challenges with earthquake forecasting, seismic zones in India, and factors that affect earthquake magnitude and intensity. The document outlines principles for planning earthquake-resistant buildings and describes seismic construction aspects, repair of damaged structures, and Indian building codes for earthquake design.
This document discusses various subsurface mapping techniques used in seismic interpretation, including:
- Seismic picking, fault interpretation, contouring, time structure mapping, velocity modeling, and depth conversion to analyze seismic data.
- Tools for basic seismic mapping including workstations to access large volumes of 2D and 3D seismic data.
- Methods for well tie, structural interpretation, 3D visualization, and attribute analysis of seismic volumes.
- Creating structure contour maps, depth structure maps, and 3D structural models from seismic horizon picks and velocity modeling.
- Using attributes like coherency to enhance fault and feature imaging at the limit of seismic resolution.
- Analyzing sequences, unconformities,
Geophysical prospecting uses physical methods to study the structure of the Earth's crust and locate minerals and ores. It involves collecting data using geophysical methods like seismic, gravitational, magnetic, electrical, and electromagnetic surveys. Seismic methods are commonly used in exploration. They involve generating seismic waves using sources like sledgehammers and analyzing the reflected and refracted waves detected by receivers to characterize subsurface layers and locate resources based on their elastic properties. Proper data acquisition, processing to reduce noise, and geological interpretation of processed seismic data are required to build an accurate model of the subsurface.
Seismic surveys use seismic waves to image the subsurface. There are two main types: refraction surveys use refracted waves to determine shallow layer velocities, while reflection surveys use reflected waves to image deeper geological structures and boundaries between rock layers. Reflection surveys require more receivers and sources to adequately image the subsurface, making the data acquisition and processing more complex but able to image deeper targets compared to refraction surveys.
REVIEW OF RECENT EARTHQUAKES IN THE LIGHT OF PLATE TECTONICS AND SEISMIC RISK...Johana Sharmin
This slide represents the knowledge of tectonic plates related problems and massive earthquakes affecting our lives. Here also I accumulated the relationship between geomorphological and plate tectonic aspects in Bangladesh.
Archaeological and groundwater investigationsZaidoon Taha
This document discusses the use of seismic methods for archaeological and groundwater investigations. It provides examples of how seismic reflection and refraction surveys can be used to map subsurface structures and locate buried archaeological remains or water sources. Specifically, it describes 3D seismic acquisition techniques that provide ultra-high resolution for shallow investigations. Case studies demonstrate how seismic imaging can detect a buried shipwreck and Roman dyke. The document also discusses applications of seismic methods for groundwater exploration, such as locating aquifers and fractured zones.
Seismic waves can be reflected or refracted and are used to interpret subsurface geology. Reflection geometry uses the arrival times of waves to interpret subsurface features. For example, reflection along a horizontal reflector results in a hyperbolic travel time curve. Seismic source-well drilling (SSWD) uses reflected seismic waves to locate reservoirs before drilling and address problems like leaks during production by using relief wells. It provides advantages over wireline methods by enabling borehole seismic measurements while drilling.
Similar to presentacion en la terminacion de pozos petroleros con respecto a la terminacion y estimulacion (20)
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
VARIABLE FREQUENCY DRIVE. VFDs are widely used in industrial applications for...PIMR BHOPAL
Variable frequency drive .A Variable Frequency Drive (VFD) is an electronic device used to control the speed and torque of an electric motor by varying the frequency and voltage of its power supply. VFDs are widely used in industrial applications for motor control, providing significant energy savings and precise motor operation.
Software Engineering and Project Management - Introduction, Modeling Concepts...Prakhyath Rai
Introduction, Modeling Concepts and Class Modeling: What is Object orientation? What is OO development? OO Themes; Evidence for usefulness of OO development; OO modeling history. Modeling
as Design technique: Modeling, abstraction, The Three models. Class Modeling: Object and Class Concept, Link and associations concepts, Generalization and Inheritance, A sample class model, Navigation of class models, and UML diagrams
Building the Analysis Models: Requirement Analysis, Analysis Model Approaches, Data modeling Concepts, Object Oriented Analysis, Scenario-Based Modeling, Flow-Oriented Modeling, class Based Modeling, Creating a Behavioral Model.
Software Engineering and Project Management - Software Testing + Agile Method...Prakhyath Rai
Software Testing: A Strategic Approach to Software Testing, Strategic Issues, Test Strategies for Conventional Software, Test Strategies for Object -Oriented Software, Validation Testing, System Testing, The Art of Debugging.
Agile Methodology: Before Agile – Waterfall, Agile Development.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Design and optimization of ion propulsion dronebjmsejournal
Electric propulsion technology is widely used in many kinds of vehicles in recent years, and aircrafts are no exception. Technically, UAVs are electrically propelled but tend to produce a significant amount of noise and vibrations. Ion propulsion technology for drones is a potential solution to this problem. Ion propulsion technology is proven to be feasible in the earth’s atmosphere. The study presented in this article shows the design of EHD thrusters and power supply for ion propulsion drones along with performance optimization of high-voltage power supply for endurance in earth’s atmosphere.
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Gas agency management system project report.pdfKamal Acharya
The project entitled "Gas Agency" is done to make the manual process easier by making it a computerized system for billing and maintaining stock. The Gas Agencies get the order request through phone calls or by personal from their customers and deliver the gas cylinders to their address based on their demand and previous delivery date. This process is made computerized and the customer's name, address and stock details are stored in a database. Based on this the billing for a customer is made simple and easier, since a customer order for gas can be accepted only after completing a certain period from the previous delivery. This can be calculated and billed easily through this. There are two types of delivery like domestic purpose use delivery and commercial purpose use delivery. The bill rate and capacity differs for both. This can be easily maintained and charged accordingly.
AI for Legal Research with applications, toolsmahaffeycheryld
AI applications in legal research include rapid document analysis, case law review, and statute interpretation. AI-powered tools can sift through vast legal databases to find relevant precedents and citations, enhancing research accuracy and speed. They assist in legal writing by drafting and proofreading documents. Predictive analytics help foresee case outcomes based on historical data, aiding in strategic decision-making. AI also automates routine tasks like contract review and due diligence, freeing up lawyers to focus on complex legal issues. These applications make legal research more efficient, cost-effective, and accessible.
Digital Twins Computer Networking Paper Presentation.pptxaryanpankaj78
A Digital Twin in computer networking is a virtual representation of a physical network, used to simulate, analyze, and optimize network performance and reliability. It leverages real-time data to enhance network management, predict issues, and improve decision-making processes.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
2. TURNO FIN DE SEMANA
9no Semestre
Act1Bloque1
Presentación Refracción y
Reflexión Sísmica
DOCENTE: Dr. Boris Chako Tchamabe
ALUMNO: Carlos Arturo Chávez Rosado.
Exploración
Geofísica
3. • Los métodos sísmicos se enmarcan dentro de los métodos
indirectos, es decir, dentro de aquellos que se realizan sin
necesidad de alterar el terreno y que por lo tanto tampoco
permiten la observación directa de este.
• Actualmente la sísmica de refracción es el método sismico
mas empleado para el análisis de los terrenos, el otro
método existente conocido sísmica de reflexión suele
utilizarse solo en investigaciones a gran profundidad como
por ejemplo en técnicas petroleras
4. Sísmica por Refracción
• La sísmica de refracción es una técnica que se encuadra
dentro de los métodos de exploración geofísica y estudia la
propagación en el terreno de ondas sísmicas producidas
artificialmente, estableciendo su relación con la configuración
geológica del subsuelo. Es un meotod muy útil para la
investigación de la estructura geológica, las propiedades del
terreno, problemas de circulación, asi como el estudio de
capas aluviales.
5. • Este es un método sísmico
muy empleado y consiste en
realizar perfiles longitudinales
con sensores, geófonos,
espaciados entre si en una
distancia permitida. La energía
se libera al disparo mediante
el golpeo con un martillo o la
utilización de explosivos, es
registrada en sensores y
almacenada en un sismógrafo,
6. • La profundidad normal de la investigación oscila entre 10 a 20 m
con la posibilidad de alcanzar profanidades del orden de 100 a
200 m en determinados casos muy favorables. De una forma
general, la profundidad explorada esta comprendida entre el 20 y
40% de la distancia que separa el emisor del receptor.
• Produciendo un impacto mecánico, se propagan en el subsuelo
ondas sísmicas con velocidad diferentes según los terrenos
atravesados. Esta velocidad de las ondas sísmicas depende
esencialmente de la capacidad de las capas consideradas. La
refracción sísmica saca partido de este fenómeno.
7. • En la mayoría de los casos, para el subsuelo próximo, las capas
presentan velocidades crecientes con la profundidad. Se admite
que la onda de choque se propaga en línea recta en un terreno
dado, no cambiando nunca la dirección, excepto cuando penetran
un terreno diferente.
8. Descripción del método
• En la zona de exploración se produce una serie de mini-explosiones
que son recibidas en pequeños aparatos denominados GEÓFONOS,
los que calculan la velocidad de transmisión de las ondas
perturbadoras y a través de una tabla correlativa se determina el
tipo de suelo. Para esto se disponen en superficie una serie de
sensores (geófonos) en línea recta a distancias conocidas, formando
lo que se conoce como tendido sísmico o línea de refracción. A una
distancia conocida del extremo del tendido, en el punto de disparo,
se generan ondas sísmicas con la ayuda de un martillo o por la
detonación de explosivos, las cuales inducen vibraciones en el
terreno que se propagan por el subsuelo y que son detectadas por
cada uno de los sensores en el tendido
9. • Los registros de cada sensor tienen información de la
respuesta del terreno en función del tiempo y son conocidos
como sismogramas. Estas trazas son analizadas en la
refracción sísmica para obtener el tiempo de llegada de las
primeras ondas de cuerpo, tanto onda P como también las
llegadas de la onda S, a cada sensor desde el punto de
disparo. El análisis e interpretación de estos datos permite
calcular las velocidades longitudinales (Vp [m/s]), además de
la determinación de los refractores que se pueden asociar a
interfaces de los materiales del subsuelo en profundidad lo
que a su vez se puede interpretar litológicamente
10. • El método de refracción
sísmica se basa en:
o a) Según la naturaleza del
terreno varía la transmisión –
velocidad de propagación- de
las ondas elásticas.
o b) Los contactos entre los
estratos con diferente velocidad
de transmisión de las ondas
sísmicas, definen superficies de
separación donde las ondas
experimentan fenómenos de
refracción. Esto permitirá
determinar la profundidad a la
que aparecen nuevas capas
11. Realización del Ensayo
• En el terreno a estudiar se realizan perfiles longitudinales
sobre los que se colocan sensores espaciados entre sí una
distancia conocida y generalmente regular. Estos sensores
que se denominan geófonos llevan incorporados sismógrafos
para registrar el movimiento y se pinchan sobre la tierra firme.
• Desde algunos puntos significativos del perfil se realiza un
disparo, habitualmente mediante golpeo con un martillo de
8kg o usando explosivos, y el impulso de éste llega a los
sensores provocando una perturbación que se registra en el
sismógrafo.
12. • La longitud de los perfiles suele situarse habitualmente entre 25
y 100m, con separación entre geófonos que no suele exceder los
5m, con objeto de garantizar el detalle de la investigación. Los
puntos de golpeo suelen ser como mínimo tres en cada perfil,
situados al inicio, mitad y final de éste. Si los perfiles exceden de
longitudes de 60m, el número de puntos de golpeo es
habitualmente de cinco. • La medida de los tiempos de llegada
de las ondas elásticas a los geófonos proporciona el valor de la
velocidad de propagación y el espesor de los distintos materiales
atravesados
13. • Cada punto alcanzado por una onda se puede considerar como
centro emisor de ondas secundarias, habrá una onda secundaria
que llegará a un punto de la superficie y será registrada por uno de
los geófonos.
• Se mide el tiempo transcurrido entre el momento del disparo y la
llegada de la primera perturbación a cada geófono. Las primeras en
llegar son las ondas directas, sin embargo a partir de un punto
(distancia crítica) llegan primero las ondas refractadas, es decir, las que
circulan por los niveles inferiores del subsuelo. La mayor distancia
recorrida por estas ondas es compensada por la mayor velocidad
14. Cálculos
• Se puede observar gráficamente la exploración geofísica por el método
sísmico de refracción
• Sobre un gráfico de coordenadas (Fig. 4 y 5), se colocan en las
abscisas las distancias entre el punto emisor y el geófono, y en las
ordenadas los tiempos medidos, seobtiene una Curva Democrónica,
que normalmente está formada por segmentos de rectas
correspondientes a las distintas capas del subsuelo.
15. • Estos segmentos tienen una gradiente inversamente proporcional
a la velocidad del medio considerado, pudiendo por este
concepto, obtenerse las velocidades buscadas.
• En la gráfica anterior se observa se podrá observar la forma de
determinar la altura H del suelo hasta la roca basal.
16. • El Espesor de los diferentes estratos, se puede calcular con la
siguiente expresión:
Donde:
• H= Espesor de cada estrato
• X=distancia horizontal correspondiente al cambio de velocidad en
la Curva Democrónica.
• V1 y V2 = velocidades de propagación en las diferentes capas de
suelo
𝐻 =
𝑥
2
𝑉2 − 𝑉1
𝑉2 + 𝑉1
17. • Cuando en el gráfico aparecen tres o más velocidades
correspondientes a diferentes estratos, la expresión para
estimar el espesor de los estratos inferiores es usualmente
resuelta con la ayuda de ábacos o, para una primera
aproximación se puede utilizar las siguientes expresiones:
• O también:
𝐻2 =
𝑥2
2
𝑉3 − 𝑉2
𝑉3 + 𝑉2
+ 0.85 = 𝑥1
𝐻2 − 𝐻1 =
𝑥2 − 𝑥1
2
𝑉3 − 𝑉2
𝑉3 + 𝑉2
18. Prospección por refraccion
• La mayor aplicación del método es explorar el subsuelo con
fines geotécnicos o mineros
• a profundidades entre 0 y 100 m .
• Es efectivo para delimitar la interfase entre medios elásticos
con un fuerte contraste de velocidad (mayor que 2:1), tal
como el que existe entre el basamento de roca inalterada y el
material de recubrimiento constituido por aluvión o por roca
meteorizada. No suele ser de utilidad para delimitar estratos
sedimentarios entre si.
19. VSP
• El VSP (Vertical Seismic Profile) o perfil sísmico vertical
• se tiene una fuente sísmica en la superficie con varios detectores
fijos en un pozo.
• Se obtienen registros sísmicos, similares a los de reflexión, para
varias distancias de la fuente al pozo, con los que se construye un
sección sísmica de su entorno.
• Las principales aplicaciones del VSP son: diferenciar entre
reflexiones primarias y múltiples, medir velocidades de onda
compresional y de corte y ayudar en la conversión de tiempo a
profundidad de las secciones sísmicas de reflexión. Este método
aprovecha ondas directas y ondas reflejadas.
20. WST
• El WST (Well Seismic Tool) o tiros de verificación, es una técnica
en la que se tiene un fuente sísmica fija en superficie y una
sonda (WST) con un receptor dentro del pozo.
• Para una profundidad dada de la sonda, se obtiene un registro
sísmico en el cual se mide el tiempo de viaje de las ondas
primarias desde la fuente hasta el receptor.
• El procedimiento se repite para varias profundidades de la
sonda. Sus principales aplicaciones son obtener la función de
conversión de tiempo a profundidad para las secciones sísmicas
de reflexión y calibrar los registros sónicos.
21. Registro sónico
• En esta técnica se utiliza una herramienta de pozo, la cual contiene un emisor
de ondas sísmicas y un par de receptores a distancias fijas del emisor. La
herramienta se introduce por el pozo y a intervalos regulares de profundidad
(por ejemplo 1 pie) se mide el tiempo de tránsito de una señal sísmica desde
el emisor hasta los receptores.
• Esta es una onda cónica producida por refracción crítica en la formación
geológica. El inverso de ese tiempo de tránsito representa la velocidad de
propagación de las ondas sísmicas en el subsuelo a la profundidad donde se
efectuó la medición. El método se caracteriza por su alta resolución para
delimitar estratos y tiene extensa utilidad en estudios de petrofísica,
estratigrafía, producción de yacimientos y correlación de secciones sísmicas
con las formaciones geológicas.
• Es catalogado como un método de testificación petrofísica de pozo como los
registros eléctricos, neutrónicos, gamma ray, SP.
22. Downhole
• Este método es similar al WST, la diferencia estriba en que las aplicaciones
del downhole están más enfocadas a la Geotecnia, las profundidades son
someras (0-100 m) y usualmente se utilizan sondas con detectores de tres
componentes vectoriales: una vertical y dos horizontales en direcciones
ortogonales.
• Se registran las ondas P y S típicamente a intervalos de profundidad de 1
pie. Su finalidad es obtener los parámetros elásticos dinámicos como
función de la profundidad en el entorno del pozo.
23. Crosshole
• Esta técnica para objetivos geotécnicos requiere la perforación de al
menos dos pozos de igual profundidad, preferiblemente tres pozos
alineados, con una separación de unos 3 a 8 m . Igual que en el downhole,
se utiliza una sonda que detecta tres componentes vectoriales de las
ondas sísmicas; la diferencia está en que la fuente no permanece fija en
superficie, sino que se coloca a la misma profundidad que la sonda en un
pozo adyacente.
24. Tomografía
• Al igual que el crosshole requiere la perforación de dos o tres pozos alineados.
También se colocan detectores en uno o dos pozos y la fuente en el tercero. La
variante es que se toman registros de todas las combinaciones posibles de
profundidades de fuentes y detectores.
• De esta forma el subsuelo entre los pozos es atravesado por numerosas y
diferentes trayectorias fuente-receptor, lo cual permite plantear sistemas de
ecuaciones para calcular la distribución de velocidades y calidad de la roca.
25. Aplicaciones del método de prospección por
refracción
• · Obtener perfiles del espesor de sedimentos hasta el basamento
en una cuenca sedimentaria
• · Localizar fallas, paleocauces, zonas de fracturas en el
basamento rocoso somero.
• · Obtener un perfil de espesores y velocidades hasta la roca
fresca, diferenciando suelo, roca meteorizada, roca submeteorizada
y roca inalterada.
• · Calcular volumen de material explotable principalmente en minas
de arena, caliza, oro de aluvión, ocre, caolín.
• · Determinar la continuidad de estratos acuíferos
• · Calcular los tiempos de tránsito de las ondas a través de las
capas de baja velocidad cercanas a la superficie, para corrección
estática de campo en prospección por reflexión.
26. • Recopilación de información y planificación
• En esta etapa se obtienen todos los datos disponibles relevantes
sobre la zona de prospección, ello incluye:
• · mapas e informes de geología de superficie
• · registros e informes geofísicos previos
• · registros e informes de perforaciones geotécnicas
• · informes de pozos de agua
• · mapas topográficos
• · fotografías aéreas
27. • En base al objetivo de la prospección y la información disponible se diseñan los parámetros de
adquisición, en los que se
• cuentan:
• · rumbo de las líneas sísmicas
• · número de líneas sísmicas
• · distancia entre líneas
• · distancia entre tendidos
• · distancia entre receptores
• · distancia fuente-primer receptor
• · duración de registro
• · intervalo de muestreo
• · tipo de fuente sísmica
• · si la fuente son explosivos: profundidad de hueco y cantidad de explosivo
28. Procedimiento de adquisición
• Se ubican las líneas sobre el terreno de acuerdo a los mapas y se abren las picas o
rebaja la vegetación para facilitar el
• movimiento de equipo, cables, detectores, etc.
• · Se clavan estacas en los sitios donde estarán ubicados los detectores y las fuentes
• · Se efectúa un perfil topográfico de las líneas sísmicas sino se dispone de uno adecuado
a partir de los mapas. Suele ser
• suficiente un perfil de nivelación, con valores de cota en los puntos donde estarán
situados las fuentes y los detectores.
• · Se abren los hoyos para las cargas sísmicas en caso de utilizarse explosivos como
fuente de energía.
• · Se extiende el cable de detectores para el primer tendido de la línea sísmica. Cada
toma eléctrica del cable debe caer en
• la estaca que señala la ubicación de un detector.
29. • Se clavan los detectores en el terreno (geófonos). Luego se conectan a
la toma o conexión eléctrica del cable de
• detectores, que lleva la señal al sismógrafo.
• · Se conecta el cable de detectores al sismógrafo.
• · Se verifica desde el sismógrafo que no existan cortocircuitos en el
cable de detectores o circuitos abiertos por geófonos
• estropeados o no conectados. Se verifica el nivel de ruido ambiental.
• · Se colocan las ganancias y filtros adecuados en cada canal del
sismógrafo
• · Se entierran las cargas sísmicas en los puntos fuentes del tendido.
• · Se efectúa la explosión de la carga en uno de los extremos del
tendido y se registran las ondas. Estas quedan almacenadas
• provisionalmente en la memoria electrónica del sismógrafo
30. • Se acomodan las amplitudes de cada traza registrada para facilitar
posteriormente la lectura de los tiempos de primera
• llegada de las ondas
• · Se graban en un medio permanente las trazas. Esto puede ser en
papel, disquete o cinta magnética.
• · Se borra el registro de la memoria del sismógrafo
• · Se efectúa la explosión en el otro punto fuente del tendido y se
repite de forma similar el proceso de registro y grabación
• · Se mueve el cable de detectores y el sismógrafo a la posición del
segundo tendido. Se sacan los detectores de su
• posición actual y se colocan en los puntos de recepción del segundo
tendido, repitiendo el proceso seguido en el primer
• tendido. Esta rutina se extiende a tendidos y líneas sucesivas.
31. Procesamiento
• El procesamiento manual involucra:
• · Leer los tiempos de primeras llegadas en los registros
• · Representar estos tiempos en gráficos tiempo-distancia (dromocrónicas)
• · Agrupar los puntos por alineaciones (ramas) de primeras llegadas. Debe existir una
rama por cada estrato, siempre que
• no ocurran inversiones de velocidad o que las capas sean muy delgadas. La primera rama
debe corresponder a los
• tiempos de llegada de la onda directa y las demás corresponderán a ondas cónicas
provenientes de refractores cada vez
• más profundos.
• · Determinar las pendientes de cada rama, así como los tiempos de intersección de las
rectas de ajuste de cada rama con
• el eje del tiempo. También se pueden determinar el tiempo total y las distancias de cruce
entre ramas.
• · Calcular las velocidades y espesores de cada estrato.
32. Resultados del Ensayo
• La velocidad de transmisión de ondas sísmicas es un
buen indicador de las características geotécnicas de los
materiales. Los resultados obtenidos son las
velocidades de propagación de las ondas de los medios
encontrados, así como los espesores.
• Por comparación con tipos de referencia, es posible
tener una idea de su naturaleza geológica.A medida que
los materiales se degradan y aumenta el grado de
alteración, la velocidad disminuye.
33. • Además proporciona óptimos resultados a la hora de determinar la profundidad del
nivel freático, ya que dicho nivel constituye un refractor muy característico con
velocidad de propagación de 1500m/s (velocidad de propagación del sonido en el
agua).
• No existe una normativa al respecto pero sí se puede encontrar ejemplos de
caracterización del terreno atendiendo a la velocidad de propagación de las ondas
elásticas.
• A continuación se puede leer la siguiente tabla que muestra la correlación existente
entre el tipo de suelo y la velocidad de transmisión de las ondas sísmicas.
34. INTERVALO APROXIMADO DE LA VELOCIDAD DE ONDA LONGITUDINAL PARA
DIVERSOS TIPOS DE MATERIALES REPRESENTATIVOS
MATERIAL VELOCIDAD (m/seg)
Suelo 170 – 500
Arcilla 1000 – 2800
Arcilla Arenosa 975 – 1100
Arcilla Arenosa Cementada 1160 – 1280
Limo 760
Arena Seca 300
Arena Húmeda 610 – 1830
Aluvión 550 – 1000
Aluvión Profundo 1100 – 2360
Depósito Glacial 490 – 1700
Dunas 500
Arenisca 2400 – 4000
Caliza 3000 – 5700
Granito 4000 – 5600
Roca Ígnea de Basamento (BASAL) 5500 - 6600
35. Limitaciones
• Para que exista refracción de las ondas, la velocidad de
propagación de estas debe ser estrictamente creciente
con la profundidad. En el caso de suelos con capas
intermedias de menor velocidad el método no las
visualizará (capa ciega).
• Requiere disponer de zonas con suficiente extensión, ya
que la longitud del tendido en superficie está
directamente relacionada con la profundidad de
investigación que se alcance
36. • Dicha profundidad está condicionada
por el tipo de fuente activa empleada
(entre otros factores como se mencionó
anteriormente). Es así, como mediante
el uso de martillo se puede alcanzar
una profundidad del orden de 30-50
metros.
37. Consideraciones
• La precisión del método requiere el uso de un
levantamiento topográfico de detalle.
• Se considera que las ondas longitudinales se propagan
a velocidades constantes en cada estrato para cada
tendido sísmico (spread), que es la unidad básica de
interpretación.
• Si la longitud del perfil supera la extensión de un spread,
se debe considerar un traslape de geófonos para no
perder información de los rayos.
38. • El contraste de velocidad entre estratos y el espesor de éstos, debe ser
suficientemente alto para que queden representados con claridad en las curvas
camino-tiempo.
• Una fuerte humedad crea generalmente corto circuitos en los aparatos alterando
las medidas.
• El hielo modifica las velocidades falseando los resultados.
• Una fuente de vibraciones próxima (viento violento en los árboles, paso de
trenes, circulación de maquinaria pesada), provocando también ondas parásitas
que pueden también alterar las medidas.
• Si es un terreno de alta velocidad, que se encuentra sobre otro de velocidad
más débil, este último no puede ser prospectado, puesto que la onda profunda
en ningún caso alcanzará la onda superficial.
40. El método sísmico de reflexión se basa en las reflexiones del
frente de ondas sísmico sobre las distintas interfases del
subsuelo.
• Las reflexiones son detectadas por los receptores (geófonos)
que se ubican en superficie y que están alineados con la
fuente emisora.
el dispositivo experimental soporta que se esté operando en
"corto ángulo"; asegurando así la obtención de reflexiones y,
distinguiéndose de la sísmica de refracción o de "gran
ángulo".
41. • número de disparos
mayor y se aumenta
la cantidad de
geófonos
• Se suman todos los
resultados de los
disparos, se orden en
puntos reflectores
comunes CMP
42.
43. • Las trazas de un mismo CMP se suman y se obtiene un la traza
de un CMP
• El conjunto de todos los cmp se le llama sección sísmica de
reflexión
44. procesamiento
• Una vez obtenidos
los registros de
campo
• Transformada de
Fourier que en
sísmica permite
pasar del dominio
del tiempo al
dominio de la
frecuencia
45.
46. Interpretación
• Debería contarse con sísmica de pozos o información alguna
relacionada con el área.
• Existen tantas interpretaciones como interpretes hay
• La certeza de los datos sera mejor si se cuenta con mas datos
u otro tipo de geofisica asociada
47. Interfaces reflectores
1. Representan impedancia acústica
2. Debe tenerse cuidado con el ruido
3. En las cuencas sedimentarias los reflectores tienden a seguir líneas de
tiempo geológico,
4. La continuidad lateral mayor o menor será resultante de cuán estables
lateralmente sean las condiciones sedimentarias en un tiempo geológico
dado
5. Los contrastes verticales, a su vez, serán indicativos de los cambios en las
condiciones de depositación a través del tiempo
6. Los reflectores pueden corresponder a unidades de roca con fuerte
contraste
48. Etapas de la Interpretación Sísmica Estructural
• Evaluación geológica general:
• Resulta de vital importancia determinar la posible existencia
de un control estructural en los procesos sedimentarios.
49. Correlación regional de
pozos:
• Delimitación de bloques principales y correlación de niveles
guía o marcadores (markers) regionales, donde se define la
posición exacta de las fallas
• Confección de cortes (cross-sections) regionales
(longitudinales y transversales a las principales estructuras
reconocidas en el área).
50. Correlación estratigráfica de pozos:
• Elección de bloques a estudiar y secuencias a interpretar
mediante correlación estratigráfica:
• Confección de cortes estructurales cruzados a escala
conveniente
• Cortes estratigráficos de detalle
• Diagramas estratigráficos de paneles
51. Interpretación sísmica:
• partir del punto con mejores datos de correlación sísmico-
geológica
• elegir dos o tres reflectores continuos
• se van interpretando las fallas,
52.
53. Engaños Sísmicos (Pitfalls):
• las imágenes sísmicas que se perciben no son cortes
geológicos, ni los isócronos mapas estructurales, sino sólo
aproximaciones a éstos
• puede tenerse problemas significativos si ésta no ha sido
migrada,
• la sísmica no puede ver nada que se aproxime a la vertical.