4 radio wave propagation over the earthSolo Hermelin
Describes the Electromagnetic Wave Propagation over the Earth Surface. Please send comments to solo.hermelin@gmail.com.
For more presentations on different subjects pleade visit my website at http://www,solohermelin.com.
This presentation is in the Radar folder.
This presentation gives basic details about refraction and its effects on the environment. The contents involved in this ppt are the refraction defintion in general, refraction in a glass slab.
4 radio wave propagation over the earthSolo Hermelin
Describes the Electromagnetic Wave Propagation over the Earth Surface. Please send comments to solo.hermelin@gmail.com.
For more presentations on different subjects pleade visit my website at http://www,solohermelin.com.
This presentation is in the Radar folder.
This presentation gives basic details about refraction and its effects on the environment. The contents involved in this ppt are the refraction defintion in general, refraction in a glass slab.
A high-resolution 3D seismic velocity model of the 2010 Mw 8.8 Maule, Chile e...Stephen Hicks
Knowledge of the spatial distribution of seismic properties within an earthquake rupture zone is essential to our understanding of rupture mechanics. Following the Maule earthquake, there was an international collaborative effort to deploy a dense network of seismic instruments in order to record the aftershock sequence; this means a large dataset is available to perform seismic velocity tomography in the area of the rupture zone. Since most co-seismic slip occurred in the offshore region, it is important to interpret the velocity structure of the marine forearc and the underlying oceanic crust. However, since many aftershocks are located offshore, and thus outside of the land network, both the offshore velocity structure and the location of these aftershocks are inherently poorly resolved. During the period July - December 2010, The National Taiwan Ocean University and The University of Liverpool each deployed ocean-bottom seismometer (OBS) networks in the northern and southern ends of the rupture zone, respectively, comprising a total of 43 stations. We use a catalogue of ~500 seismic events recorded at both land and OBS stations, containing ~60000 hand-picked P- and S-wave travel-times. We use a staggered 1D inversion scheme, which initially incorporates a separate velocity model for the marine forearc in order to form better hypocentral locations for the offshore events. Based on previous estimates for slab geometry, we find that the location of offshore seismicity is more tightly constrained along and above the interface. Taking these improved locations into account, we then re-invert for a new 1D model with station corrections. We present a 3D local earthquake tomography model based on manually-picked arrival times. The incorporation of OBS picks into the inversion elucidates better both the up-dip geometry of the subducting plate and the structure of the marine forearc. Beneath the low vp marine forearc (vp < 6.0 km/s), at depths of 7-15 km, we infer the presence of a high velocity structure (vp > 7.0 km/s); the upper interface of which dips at 10-15°, interpreted as the top of the downgoing oceanic crust. These first-order features are in accordance with results from previous active source studies in the region. We continue to analyse the nature and geometry of velocity anomalies along and around the megathrust, and their relation to rupture models and aftershock distribution.
Filtering in seismic data processing? How filtering help to suppress noises. Haseeb Ahmed
To enhance the signal-Noise ratio different techniques are used to remove the noises.
Types of Seismic Filtering:
1- Frequency Filtering.
2- Inverse Filtering (Deconvolution).
3- Velocity Filtering.
The Top Skills That Can Get You Hired in 2017LinkedIn
We analyzed all the recruiting activity on LinkedIn this year and identified the Top Skills employers seek. Starting Oct 24, learn these skills and much more for free during the Week of Learning.
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Time-Frequency Attenuation of Swell Noise on Seismic Data from Offshore Centr...iosrjce
Diversity of noise types with different characteristics makesseparation of signal and noise a
challenging process.Swell noiseusually contaminates tracesand it is characterized by high amplitude and low
frequencies and affects only a limited band offrequencies.This work presents how FX projection filter (FXEDIT
code) processing approach was used to attenuate swell noise on dataset from a marine seismic survey
offshoreCentral Niger-Delta, Nigeria, which shows as an effective amplitude preserving and robust tool that
gives better results compared to many other conventional filtering algorithms.With this processing approach
and working side-by-side with the shot gather and the RMS windows; the results achieved are reliable and
satisfactory by giving clearer images for reservoir characterization. The level of swell noise attenuation after
this approach greatly increased the confidence to use the data for subsequent processing steps.
Andrea D’Alpaos finally talked about tidal networks, their formation, their shapes, their similarity or dissimilarity from river networks. All of it in a blend of equations, analysis in the field and lab experiments.
Wave-Current Interaction Model on an Exponential Profileijceronline
We develop a model that approximates the exponential depth, which exhibits the behavior of linear depth particularly in the surf zone. The main effect of the present exponential depth is found in the shoaling zone, where the depth remains finite. The basic description and the outcome is essentially rip currents where in the surf zone the wave behavior is the same as found in the linear depth case. In the shoaling zone the present exponential depth exhibits the hypergeometric functions.
A study of the dissipation and tracer dispersion in a submesoscale eddy field...
Basalt Presentation
1. 10/30/2016Prepared By Yassir 1
OUT LINES:
Challenge Of Basalt In Seismic Resolution.
Reflection and Transmission in Basalt.
Review of Rawat Old 2D Data.
Technique used for better imaging sub –basalt.
Proposed Parameters Test for New 2D Project.
2. Challenge Of Basalt In Seismic Resolution
Objective:
The objectives of this presentation is to
reflect the influences of the basalt in the
seismic data .
Introduction:
Basalt layers usually have a complex
structure with thin layers and large
velocity and density differences. and
scatter the seismic energy of conventional
seismic reflection system so that becomes
difficult to obtain information on deeper
Reflectors.
High frequencies are scattered more than
low frequencies. and may display a
positive velocity gradient. In general, it is
not difficult to map the top of a basalt
layer because it is a strong reflector. But
multiples from the bottom and top of the
basalt generally mask sub-basalt reflected
waves.
10/30/2016Prepared By Yassir 2
VolcanicGeometries
• Advantage Of Basalt In seismic Data:
• Volcanic rocks may form lateral seal or
migration barriers providing positive impact
on the petroleum system, Non preamble
volcanic can seal the top of reservoir or they
can build migration barrier for fluids on its
way from the source rock into the trap.
3. Line SD01-062
Line SD01-047
• The high impedance contrast between
sedimentary and basaltic rocks directly
influences the reflection and transmission of
waves. If a wave encounters an interface
between a sedimentary layer and a basalt,
most of the energy will be reflected back and
less energy will be transmitted through the
interface. The top of a basalt sequence will
have a high reflectivity and therefore will
transmit less energy through it. An incident
P-wave will produce reflected P- and S-
modes also beyond the critical angle, but the
transmission of a P-wave down into the
high-velocity layer will stop at this point and
only S-wave energy will travel further down.
Reflection and Transmission in Basalt
10/30/2016Prepared By Yassir 3
4. Basalts have velocities and densities much higher than the
surrounding and interbedded sediments. Forming strong
seismic reflectors.
Ingeneral ,interflow materialspossessverylowdensities(1.5
– 2.5 g/cm³) and P- wave velocities (1 – 2km/s) (Bergman
1997).Thelavaflowsthemselveshaveinternalstructurewhich
can be detected on most well logs. Each flow consists of an
inner core . And a top and a bottom margin. Where
approximately 25% of the flow thickness is defined as top
marginand5%asbottommargin.Thesemarginsbuildduring
the cooling and degassing of the Lava flow and show an
increased velocity gradient to – wards the flow core. Cerney
and Carlson (1999) studied the basalts drilled at south east
Greeland margin and concluded that P- wave velocity
controlledbytheporosityoftheinternalbasaltzones.Fromthe
flowtopthevelocitiesincreasefromabout2-3km/stoaround
5–6.5km/sintheinterioranddegreaserapidlyagaintowards
thebasaltbase(Planke.1994:ShipboardScientificParty.1994).
10/30/2016Prepared By Yassir 4
5. • FMI result is reflect there is high
resistivity, low ROP zones were
interpreted as igneous rocks and
they covered part of the Northern
Sub-basin.
• The effect of these igneous bodies
on the petroleum system of the
area is poorly known.
Volcanic Interpretation for the Drilled
Well
Top Volcanic
Bottom Volcanic
10/30/2016Prepared By Yassir 5
6. Review of Rawat Old 2D Data
RPOC was re-processed two 2D lines from
the northern Basin to improve target image
within the volcanic Rocks (Basalt).
There are some improvement at top of
volcanic compare to the bottom due to
acquisition parameters limitation such as
fold and dipping angle (far offset).
10/30/2016Prepared By Yassir 6
Dip line sd01-
046
BA
10. S.Int R.Int Charge
Size
T.
Station
Max.Offse
t
Fold
Coverag
e
50 m 25 m 2 Kg 280 3487.5 70
S.Int R.Int Charge
Size
T. Station Max.Offset Fold
Coverage
125 m 25 m 12 Kg 248 2312.5 25
2001 2009
Dip Line
Probability Of Improving Data Quality with dynamite crew
10/30/2016Prepared By Yassir 10
11. 10/30/2016Prepared By Yassir 11
S.Int R.Int Charge
Size
T. Station Max.Offset Fold
Coverage
125 m 25 m 12 Kg 248 2312.5 25
S.Int R.Int Charge
Size
T.
Station
Max.Offse
t
Fold
Coverag
e
50 m 25 m 2 Kg 280 3487.5 70
Probability Of Improving Data Quality with dynamite crew
Strike Line
12. Technique used for better imaging sub –basalt
WideAngle
Technique used for better
imaging sub –basalt:
Wide –angle (long offset)
seismic surveys to avoid
scattering problem to some
extent , usually give results
related only to large scale
interval velocity of the
basalt.
The Use of Broad Band
contain low frequency
seismic waves may avoid
the scattering problem of
thin layering and lateral
heterogeneous and may
provide the basis for
reflection energy to
penetrate through the
basalt (Gatliff et al.1984
10/30/2016Prepared By Yassir 12
Long offset to improve S/N and NMO resolution and to
allow processing of most critical reflections.
13. Low FrequencyHigh FrequencyImpedance
Sediments Volcanic
Technique used for better imaging sub –basalt
Low Frequency
The basalt lead to filter and scattered most of the High Frequency and reflected as
multiples layers.
10/30/2016Prepared By Yassir 13
18. Ground Equipment has used for Low frequency
Micro Electro Mechanical System (MEMS) is
advanced geophone use for low frequency and it
is accelerometers that work below their resonant
frequency ,while coiled geophone are
velocimeters that work above their resonant
frequency .This different provides the two types
of sensor with quite different dimensions and
specification.
Ground motion can be measured as
displacement, velocity and acceleration. A mass/
spring assembly used for these measurement.
The essential benefit of MEMS accelerometers
is broadband linear amplitude and phase
response that may extend from 0 DC to 800Hz
within ±1% in amplitude and ±20 µs in time.
MEMS resonant frequency is far above the
seismic band (1 kHz).
This makes it possible to record frequencies
below 10 Hz without attenuation, including the
direct current related to gravity acceleration.
The gravity vector provides useful reference for
sensitivity calibration and tilt measurement (3C
sensor).
10/30/2016Prepared By Yassir 18
19. Comparison BetweenAnalog and Digital Geophone
10/30/2016Prepared By Yassir 19
Linear phase and amplitude response compared
between MEMS and 10HZ Geophone.
Comparison in the velocity domain of electric
noise of geophone with one of digital sensor
unit with MEMS.
20. No. No.Holes Hole Depth Holes
Patterns
Charge
Size
T. Charge
Size
1 1 12 m 12.5m 4 Kg 4 Kg
2 2 12 m 8 - 12.5 – 8 m 3 kg 6 Kg
2 2 9 m 8 - 12.5 – 8 m 3 kg 6 Kg
4 3 9 m 8 – 8 – 8 m 2 kg 6 Kg
5 4 6 m 4 – 4 – 4 – 4 m 2 kg 8 Kg
Proposed Source Parameters Test
As far as we are looking for broad band frequency rather than strong energy which could be
lead to increase source generate Noise and ground Roll amount. Deep hole with reasonable
charge size is recommended.
2D Geometry:
Total Live Channels:420
Receiver Interval: 25
Source Interval: 50
Fold Coverage:105
Max Offset: 5250 m
10/30/2016Prepared By Yassir 20
21. Propose test will carry out
with using double geophones
string for better sampling and
n ambient noise attenuation.
Proposed 2D Lines (300 Km)
10/30/2016Prepared By Yassir 21
22. 10/30/2016Prepared By Yassir 22
Fold Plot shows
the effects of
mute function on
CMP across the
survey
The Diagram shows the
strike line azimuth and
Bin or CMP distribution