Much is now made about “Stress Shadows” and their impact on hydraulic fracturing - particularly in multi-stage horizontal laterals commonly used in Unconventionals. Unfortunately, there is no standard definition of Stress Shadows and, as a result, there is much confusion over what they are and aren’t, and, most importantly, why they can have a significant impact on hydraulic fracturing operations. The goal of this presentation will be to address this confusion and more fully explain Stress Shadows and their impact. The creation of hydraulic fracture width during a stimulation generates a change in the stress field, which alters all three principal stresses as well as tip shear stresses. These stress changes are the Stress Shadows. As hydraulic fracture propagation is often controlled by the stress field, Stress Shadows may change the propagation path for subsequent hydraulic fractures or, as seen in cluster fracturing, propagation may be impeded completely. The presence of natural fractures and weakness planes can also affect, and be affected by, Stress Shadows. At the hydraulic fracture tip, shear stresses are generated that offer the potential to shear and open closed natural fractures and weak planes – and if opened, it may be possible to stimulate them. Equally important, behind the hydraulic fracture tip Stress Shadows increase the magnitude of all three principal stresses, which tends to close weakness planes making them more difficult to stimulate. Because of these effects and others, understanding and designing for the impact of Stress Shadows is often critical for stimulation optimization.
Stress analysis is the essence that is needed while planning exploration, drilling and development operations in oil and gas industries. Proper knowledge of Geomechanics will help us to reduce the risk of failure as well as provide a better picture of stresses inside the earth. From Hydrofracturing to directional drilling, stresses play their parts.
DAMAGE ISSUES IMPACTING THE PRODUCTIVITY OF TIGHT GAS PRODUCING FORMATIONS; Formation Damage; Fracturing/Refracturing; Hydraulically Fractured; Tight Gas Reservoir; Economic Tight Gas Reservoir Production
Stress analysis is the essence that is needed while planning exploration, drilling and development operations in oil and gas industries. Proper knowledge of Geomechanics will help us to reduce the risk of failure as well as provide a better picture of stresses inside the earth. From Hydrofracturing to directional drilling, stresses play their parts.
DAMAGE ISSUES IMPACTING THE PRODUCTIVITY OF TIGHT GAS PRODUCING FORMATIONS; Formation Damage; Fracturing/Refracturing; Hydraulically Fractured; Tight Gas Reservoir; Economic Tight Gas Reservoir Production
The extensive slide-pack starts with introducing physics and basics on geomechanics. A lot of stress and rock strength concepts are explored. Then it moves on to explain the importance of the discipline for drilling, injection, sanding. Apart from giving theory to understand more difficult content that follow, it throws in practical application and prepares good ground for further study of geomechanical literature.
Briefly explaining the basics of Pore Pressure Fracture Gradient (PPFG) plot & its role in planning, drilling & decision making. Please, refer to my "Formation pressure" upload for more details on pressure concepts.
Apresentação de Victor Manuel Salazar Araque, da Computer Modelling Group, durante o evento promovido pelo Sistema FIEB, Fundamentos da Exploração e Produção de Não Convencionais: a Experiência Canadense.
That is my presentation for my grad research about reservoir geomechanics, hope you find it useful, and my source book was reservoir geomechanics for prof Mark Zoback, soon the PDF copy will be available as well.
Much is now made about “Stress Shadows” and their impact on hydraulic fracturing - particularly in multi-stage horizontal laterals commonly used in Unconventionals. Unfortunately, there is no standard definition of Stress Shadows and, as a result, there is much confusion over what they are and aren’t, and, most importantly, why they can have a significant impact on hydraulic fracturing operations. The goal of this presentation will be to address this confusion and more fully explain Stress Shadows and their impact. The creation of hydraulic fracture width during a stimulation generates a change in the stress field, which alters all three principal stresses as well as tip shear stresses. These stress changes are the Stress Shadows. As hydraulic fracture propagation is often controlled by the stress field, Stress Shadows may change the propagation path for subsequent hydraulic fractures or, as seen in cluster fracturing, propagation may be impeded completely. The presence of natural fractures and weakness planes can also affect, and be affected by, Stress Shadows. At the hydraulic fracture tip, shear stresses are generated that offer the potential to shear and open closed natural fractures and weak planes – and if opened, it may be possible to stimulate them. Equally important, behind the hydraulic fracture tip Stress Shadows increase the magnitude of all three principal stresses, which tends to close weakness planes making them more difficult to stimulate. Because of these effects and others, understanding and designing for the impact of Stress Shadows is often critical for stimulation optimization.
The extensive slide-pack starts with introducing physics and basics on geomechanics. A lot of stress and rock strength concepts are explored. Then it moves on to explain the importance of the discipline for drilling, injection, sanding. Apart from giving theory to understand more difficult content that follow, it throws in practical application and prepares good ground for further study of geomechanical literature.
Briefly explaining the basics of Pore Pressure Fracture Gradient (PPFG) plot & its role in planning, drilling & decision making. Please, refer to my "Formation pressure" upload for more details on pressure concepts.
Apresentação de Victor Manuel Salazar Araque, da Computer Modelling Group, durante o evento promovido pelo Sistema FIEB, Fundamentos da Exploração e Produção de Não Convencionais: a Experiência Canadense.
That is my presentation for my grad research about reservoir geomechanics, hope you find it useful, and my source book was reservoir geomechanics for prof Mark Zoback, soon the PDF copy will be available as well.
Much is now made about “Stress Shadows” and their impact on hydraulic fracturing - particularly in multi-stage horizontal laterals commonly used in Unconventionals. Unfortunately, there is no standard definition of Stress Shadows and, as a result, there is much confusion over what they are and aren’t, and, most importantly, why they can have a significant impact on hydraulic fracturing operations. The goal of this presentation will be to address this confusion and more fully explain Stress Shadows and their impact. The creation of hydraulic fracture width during a stimulation generates a change in the stress field, which alters all three principal stresses as well as tip shear stresses. These stress changes are the Stress Shadows. As hydraulic fracture propagation is often controlled by the stress field, Stress Shadows may change the propagation path for subsequent hydraulic fractures or, as seen in cluster fracturing, propagation may be impeded completely. The presence of natural fractures and weakness planes can also affect, and be affected by, Stress Shadows. At the hydraulic fracture tip, shear stresses are generated that offer the potential to shear and open closed natural fractures and weak planes – and if opened, it may be possible to stimulate them. Equally important, behind the hydraulic fracture tip Stress Shadows increase the magnitude of all three principal stresses, which tends to close weakness planes making them more difficult to stimulate. Because of these effects and others, understanding and designing for the impact of Stress Shadows is often critical for stimulation optimization.
The slam induced loads on two-dimensional bodies have been studied by applying an explicit
finite element code which is based on a multi-material arbitrary Lagrangian-Eulerian
formulation and penalty coupling method. This work focuses on the assessment of total
vertical slamming force, pressure distributions at different time instances and pressure
histories on the wetted surfaces of typical rigid bodies. Meanwhile, the simulation technique
involved in the two-dimensional slamming problem is discussed through related parameter
study.
Slide deck used during the SPE Live broadcast on 19 August 2020 with guest Doug Peacock, 2010-11 SPE Distinguished Lecturer and currently a Technical Director for GaffneyCline.
WATCH VIDEO: https://youtu.be/ykJhFkNUXqc
TRAINING COURSE: http://go.spe.org/peacockSPELIVE
The unitization process has evolved over the years and is now well established throughout the world with many countries having legislation for unitization.
Although there are generic agreements, each unitization agreement is unique and requires a wide range of issues to be considered.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
Heap Sort (SS).ppt FOR ENGINEERING GRADUATES, BCA, MCA, MTECH, BSC STUDENTS
Stress Shadows: How and Why They Can Affect Hydraulic Fracturing in Both Conventional and Unconventional Plays
1. Stress Shadows:
How and Why They Affect
Hydraulic Fracturing in
Unconventional Shale Plays
Neal Nagel, Ph.D.
Chief Engineer, Oilfield Geomechanics LLC (OFG)
2. Presentation Outline
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
2
April 2015
I. The Geomechanics of Hydraulic Fracturing
II. Stress Changes from a Single Hydraulic Fracture
III. Stress Changes from Multi-Stage Hydraulic
Fractures and the Potential for Fracture Rotation
IV. Stress Shadows and Cluster Fracturing
V. Stress Shadows and Naturally Fractured Shales
VI. Hydraulic Fracturing and Tip Shear Stresses
VII. Stress Shadows and Multi-Well Completions
VIII.Conclusions
3. Geomechanics and Hydraulic Fractures
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
3
April 2015
For Hydraulic Fracturing:
e=s/E
Where: w =Fracture width (deformation)
L =Fracture half-length
Dp=Net pressure
x =Distance from wellbore
2
1)( x
E
pL
xw
D
Generalized Hooke’s Law:
(basic geomechanics)
Where: e=Strain (DL/L)=normalized deformation
s=Stress (Force/Area)
E=Young’s modulus (Stiffness)
E
σε
Basic geomechanics says
that, for an elastic
material, deformation is
proportional to stress
divided by stiffness.
In hydraulic fracturing,
fracture width
(deformation) is
proportional to the net
pressure (stressing the
formation) divided by
stiffness.
But….
4. Geomechanics and Hydraulic Fractures
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
4
April 2015
Generalized Hooke’s Law:
(basic geomechanics)
s=E/e es E
For Hydraulic Fracturing:
)(xwE s
Increasingnormalized
distancefromfracture
face
½ Fracture
NormalizedStress
Just as stress causes deformation,
deformation (i.e., fracture width)
causes a change in the stress field.
This was shown as early as 1946 by
Sneddon and others.
5. “Stress Shadows”: Single Hydr. Fracture
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
5
April 2015
The generation of
fracture width causes a
change in the stress
field. Here, the
simulated increase in
the minimum horizontal
stress (DShmin) – often
called the “Stress
Shadow” – is shown in
cutaway view.
6. Stress Shadow Basics
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
6
April 2015
Just as hydraulic fracture width varies laterally and vertically, so does the
magnitude and shape of the change in Shmin (Stress Shadow).
7. DShmin ~f(height) – Single Stage
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
7
April 2015
The magnitude and depth of the change in Shmin into the formation is
controlled by width - f(net pressure) - and height (PKN-type fracture).
8. Stress Shadows DShmin
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
8
April 2015
Unfortunately, the common perception that the “Stress Shadow” is just a
change in Shmin is incorrect as all the principal stresses may change.
Furthermore, shear stresses are generated as well.
9. Stress Changes Around a Hydr. Fracture
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
9
April 2015
From original stresses (A), a fracture
with small net pressure (B) shifts all
principal stresses higher. If the net
pressure is high enough (C), Shmin
and Shmax may reverse.
10. Stress Shadows from Dual Hydr. Fractures
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
10
April 2015
When multiple hydraulic fractures are generated from a single
horizontal as shown, the Stress Shadows interact and combine.
11. Shmin Profiles – Dual Hydr. Fractures
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
April 2015
11
At close fracture spacing (A), there is
combining of the change in Shmin for
all heights. As the spacing increases
(B), the combined increase is smaller
until (C) there minimal stress
interaction between fractures.
12. Stress Shadows from Dual Hydr. Fractures
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
12
April 2015
When multiple hydraulic fractures are generated from a single horizontal, the
Stress Shadows interact and combine; however, timing does play a role as
shown.
13. Stress Shadows Along the Wellbore
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
13
April 2015
Along the horizontal wellbore, the increase in Shmin will be determined by
frac spacing and net pressure. For variable frac spacing (planned or not), the
change in Shmin will be highly variable.
14. Stress Shadows: ISIP Field Data
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
14
April 2015
It is difficult to get direct stress measurements along a horizontal, so ISIP is
used as a reasonable analog. As shown, field ISIP data clearly confirm the
generation of an increase in Shmin from toe to heel.
15. On Potential Hydraulic Fracture Rotation
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
15
April 2015
Owing to the nature of hydraulic
energy, hydraulic fractures propagate
towards the path of least resistance.
As the Stress Shadow from a hydraulic
fracture causes a variable change in
stress (above), subsequent fractures
will tend to grow away from the 1st
(right).
16. Frac Rotation - Field Evidence
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
16
April 2015
Under certain
conditions, the stress
shadow will cause
fracture rotation.
What is the
significance for MS
evaluations??
This case from the
Vaca Muerta suggests
fracture rotation after
the 4th frac stage (S4)
17. Stress Shadows and Cluster Fracturing
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
17
April 2015
Because of the prohibitive cost of pumping into each perforation cluster,
multiple clusters are used per frac stage. If/when there is equal wellbore flow
diversion, the Stress Shadow greatly influences hydraulic fracture growth.
18. Stress Shadows and Cluster Fracturing
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
18
April 2015
“Limited Entry” is a concept by which the number and size of perforation is
varied in order to achieve flow diversion within the wellbore. As shown, flow
diversion (w/o LE is no diversion) significantly affects hydraulic fracture
propagation from 3 and 4 cluster stages.
19. Stress Shadows and Shale Plays
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
19
April 2015
As presented, the Stress Shadow responds to fracture width, which is a
function of net pressure. Net pressure is related to the resistance to fracture
propagation – as net pressure gets smaller, so does the Stress Shadow.
20. Stress Shadows and Natural Fractures
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
20
April 2015
When the natural fracture pattern is
extensive and conductive, its
orientation may dominate the flow of
fluids during a hydraulic fracture
stimulation (left).
For a dominate natural
fracture system not aligned
with the stress field (right,
above), the generated Stress
Shadow (far right) becomes
highly complex.
21. Hydraulic Fractures and Shear Stresses
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
21
April 2015
Hydraulic fractures also generate significant shear stresses along their
leading edge; however, the dominate orientation of the shear stresses
changes depending upon position along the edge.
22. Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
22
April 2015
Tip Shear Area and Nat. Frac. Orientation
Because of the influence
of natural fracture friction
and the stress normal to
it, some orientations of
natural fractures are
more prone to slip due to
hydraulic fracture tip
shear stresses.
As shown, as natural
fracture orientation varies
from parallel (0°) to
perpendicular (90°) to the
fracture, the amount of
rock sheared changes.
23. DShmin Contours Ahead of the Tip
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
23
April 2015
Most hydraulic fractures
propagate in tension,
which means at the tip
the earth compressive
stresses must be
overcome.
Ahead of the actual
fracture, the compressive
stresses are reduced –
which becomes an easier
propagation path for
approaching hydraulic
fractures.
24. Tip Movement for Overlapping HFs
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
24
April 2015
The inset shows
hydraulic fractures
propagating from
parallel wellbores in a
Zipper configuration.
The plot shows the tip
position as a function of
injection time.
Initially, the fractures propagate inwards and outwards uniformly; however,
at time T1 the tips sense the reduce stress region and accelerate towards
each other. Then, at T2, the inner tips stop and all propagation is outwards
due to Stress Shadows.
26. Conclusions and Comments
Stress Shadows & Hydraulic Fracturing - Nagel SPE DL
26
April 2015
• Stress Shadows are a real and easily explained geomechanical
effect of hydraulic fracturing.
• Colloquially, Stress Shadows are considered to be the change in
Shmin; however, Stress Shadows include the change in SHmax and
Sv as well as tip shear stresses.
• When hydraulic fractures are closely spaced, the increase in Shmin
is additive.
• Because the change in Shmin is not simply planar, hydraulic
fracture rotation is possible (particularly with high net pressures).
• Shear stresses are generated along the edge of a hydraulic
fracture, which may serve to shear local natural fractures.
• Multi-well Stress Shadows are very complex and not easily
predicted.
27. Primary funding is provided by
The SPE Foundation through member donations
and a contribution from Offshore Europe
The Society is grateful to those companies that allow their
professionals to serve as lecturers
Additional support provided by AIME
Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dlApril 2015