oilfield geomechanics (ofg) services...oilfield geomechanics llc ofg geomechanics services for the...

OilField Geomechanics (OFG) Services

Geomechanical Services for the Oil&Gas Industry

August 2014

OilField Geomechanics LLC

OFG Geomechanics Services for the Oil&Gas Industry2

OilField Geomechanics, OFG, is an independent geomechanics consulting company.

OFG can be your third party experienced advisor, part of your team, providing the geomechanics expertise needed to tackle challenges from exploration to abandonment – whether for conventional or unconventional developments.

OFG can deliver turn key geomechanics projects for oil and gas applications.

OFG Geomechanics Services


Ne

ar W

ellb

ore

• 1D Geomech. Models -Stresses, PP, Mech. prop.

• Wellbore Stability evaluations

• Conventional and Unconventional HF Design & Optimization

• BHS / Drilling –conventional, salt/sub-salt, HPHT

• Sand Production

• Casing Deformation

• Cuttings Reinjection

• Pre-Salt/Sub-Salt Analysis

Sect

or

and

Re

serv

oir

Sc

ale

• 3D Geomech. Models

• Reservoir Compaction / Subsidence - effects in the overburden

• Coupled Flow / Stress-Strain Evaluations

• Multistage - Multi-well HF Evaluations

• Fault Seal / Reactivation Analysis

• Integrated Fractured Reservoir Characterization

• Integrated Unconventional Reservoir Analysis

3D GEOMECHANICAL MODELS


3D Geomechanical Model


Stratigraphic

horizons, reservoir

Eclipse layering and

near-reservoir faults

North Sea HP/HT Case

3D Geomechanical Model -Horizons and Faults


Gulf of Mexico Carbonate Case

A 3D geomechanical model can be used to

evaluate an entire range of production or

injection schemes and determine the stress

changes within the reservoir or along faults

(as shown here).

The critical issues for fault modeling include

stress magnitude changes and rotations (as

shown in this figure of principal stress

tensors) as well as fault movement.

3D Geomechanical Model Results


GEOMODEL (e.g. PETREL)

3D Geomechanical Model

Reservoir Simuator(i.e. ECLIPSE, STARS, Psim, etc)

One-way or two-way iterative coupling between the reservoir simulator and the geomechanics simulator (HTM coupling)

Model imported into a

geomechanics

simulator

Coupling Flow and Geomechanics


THREE-DIMENSIONAL

GEOMECHANICAL MODEL

FRACTURE DISCRETE MODEL

AT FIELD SCALE

Calibrated for intensity, geometry

and hydraulic properties of

fractures, and scaled to the dual

porosity model.

Including faults and stratigraphic

layers from surface to underburden,

calibrated with well and core data.

3D Geomechanical Model + DFN


Critically Stressed Fractures

Fracturas en KS


HYDRAULIC FRACTURING FOR UNCONVENTIONALS


Unconventional Play Scenarios


HF=Hydraulic Fracture NF=Natural Fractures/weakness planes

Critical Issues in Unconventionals


Presence of the resource (TOC, maturity…..);

Presence of natural fractures and/or weak planes (free surface to

be converted to flow area) and their connectivity and hydro-

mechanical properties;

Fluid pressure and fluid type – high pressures favor the stimulation

of nat. fractures as the effective stresses are low and less shear is

needed for stimulation and can the fluid pressure be increased in

the nearby wells;

Influence of stresses and mechanical properties on HF

geometry and SRV – some conditions are more favorable than

others; and

Influence of operational parameters/design, well landing and

spacing on HF geometry and SRV.

Our Approach - Geomechanics is Key


Characterization - multidisciplinary

Geomechanical Models - OFG uses models that

incorporate the right physics of coupled geomechanics

and fluid flow, including the natural fractures to represent

rock mass failure, changes in the shape of HFs with

multiple stages, changes in ISIP (stress shadows) and its

effect on the natural fractures.

Calibration - The field data (microseismics, injection

pressures, PLTs, tracers and ultimately production)

together with the models help us understand and

quantify the effects of geomechanical, reservoir,

geological and operational parameters on the stimulation

efficiency (increased SRV) and optimization strategies

Summary of Services for HF


Resource Characterization Support• Geomechanical assessment (stress, pore pressure, and rock mechanical properties - 1D or

3D sector models).

• Design of Data Acquisition Program

Geomechanical Evaluation of Microseismic Data• Numerical geomechanical simulations of synthetic microseismicity

Hydraulic Fracture Stimulation Design and Optimization• DFIT/FET/Mini-frac design and interpretation

• Evaluation and optimization of operational parameters (rates, volumes, etc.)

• Evaluation and optimization of stage spacing-stress shadows

• Post-frac analyses

• Simulation history-matching to field MS data and injection data

Multi-Stage/Multi-Well Completions Design and Optimization• Stage spacing/Cluster evaluation and optimization

• Evaluation and optimization of multi-well stimulation strategies (Simul-Frac, Zipper-Frac, etc)

• Evaluation and optimization of well placement and orientation

Upscaling of Propped/Stimulated Volume for Flow Simulations• Single porosity, Directional permeability, Double porosity/double permeability models

Applications Examples - DFN


DEM Model - DFN


Perspective View (core only) X-Section View

Outer Boundary Domain

Core DFN Domain

• The DFN was populated in an inner core domain.

• An outer boundary domain, extended twice of the size of the inner core domain, was used to decrease the boundary effects.

Sparse DFN @15 min Injection


Stim. DFN

HF

Plan view contours of pore pressure

distribution

Shmin

SHmax

Inj. Pt.

Plotting

planeHF plane

Dense DFN @15 min Injection


Stim. DFN

HF

Plan view contours of pore pressure

distribution

Shmin

SHmax

Inj. Pt.

Plotting

planeHF plane

Horizontal

wellbore

Effect of Injection Rate


• Injection rate ↓; ratio of stimulated DFN area to HF area ↑.

• Injection rate ↓; leakoff ratio ↑.

• Dense DFN was more sensitive to the change of injection rate.

Sparse

Dense

(+30%

)

Sparse

Dense

(+20%)

Decrease

Q

Influence of Fracture Network


• The Dense DFN had as much as a 5.2 x DFN stimulated area to HF area....

• The Dense DFN had as much as 70% of the fluid go to stimulate the DFN....

2.9

:1

1.8

:1

Influence of Fracture Network


Sparse DFN Dense DFN

Pre

ssu

reM

S E

ven

ts

Plan view (at injection pt) of pressure & MS events

Inj. Pt.

Inj. Pt.HF Trace HF Trace

Sparse vs. Dense DFN– HF Width


Sparse DFN Dense DFN

X-section view (at injection pt) of HF aperture

Proppant Transport?????

Injection pt Injection pt

Effect of Initial Pressure and Stress Ratio


Shmin/Shmax=30/30 MPa Shmin/Shmax=30/33 MPa

(e) Invaded fracture length: 2220.7m (f) Invaded fracture length: 2914.2m

Stimulated

length increases

with:

- initial

pressure

(lower

effective

stress); and

- in-situ stress

ratio.

Effect of Initial Pressure and Stress Ratio


Shmin/Shmax=30/30 MPa Shmin/Shmax=30/33 MPa

(e) Wet events: 799; Dry events: 366 (e) Wet events: 724; Dry events: 121

MS wet events

increase with:

- initial pressure

(lower effective

stress); and

- in-situ stress

ratio.

MS dry events

significant

increase with

pressure but

decrease with

stress ratio.

Pressure

changes

Fracture

Aperture

Changes

Directional Perm Changes

Scaling for Flow Analysis


Stress Shadows: ISIP Field Data


Frac Rotation - Field Evidence


ISIP

Under certain conditions, the

stress shadow will cause fracture

rotation.

What is the significance for MS

evaluations??

- 50 psi

- 20 psi

- 30 psi

- 40 psi

- 10 psi

Stress Shadows


Shmin ~f(Height) – One stage


H=40m

H=60m

H=80m

wellbore

HF

lo

ca

tio

n

Shmin – Two Stages, Sp=56m


wellboreH

F l

oc

ati

on

DShmin: 12 Stages - Irregular Spacing


Wellbore Length

ToeHeel

900

800

700

600

500

400

300

200

100

HF

lo

ca

tio

n

Zipper Fracs - Overlapping HFs


Shmin (29 to 34 MPa) Sxy Shear (0 to 5 MPa)W

ell

bo

re#

1

Planview at injection point

We

llb

ore

#2

We

llb

ore

#1

We

llb

ore

#2

++

+

++

+

50m

HF Trace

Integrated Unconventional Evaluations

34

Static Model (TOC, Petroph: Poro,

perm, reservgeometry,

structures, seismic attrib, elast. seismic

inversion)

Geological Model (Natural fracs, weak

planes, intensity, open/closed,

mineralization)

Geomech. Model(Stresses, Pore Press,

Mech. Properties matrix and fractures)

DFN Realizations – Stat. Model –

(seismic, logs, cores, outcrops) Upscalingof Hyd. properties

RESERVOIR CHARACT.

‘Sweet’ Spots,Well Location,

Landing Location

STIMULATIONModeling,

CompletionDesign and

Optimization

Shale Play & DFN Scenarios

(construct HF models)

HF Modeling & Hist. Match (pressure, MS and prelim flow area

from product.)

HF Geometry and Improved SRV (HF +

Nat. fractures)

Multiwell HF -Zipper Fracs

(designs to max. flow area)

Flow Area Optimization

(parametric analysis: rate, fluid, proppant)

Stress Shadows (opt. stage spacing,

near-wellbore effects)

Most Likely Reservoir

Parameters + # stages, well length

Production History Matching (post-frac,

few days, months, years). Use improved

SRV

Model of Well/Multi-well/

Reserv. (single/ double poro-perm)

Optimum Well Spacing & Landing

LocationForecast Scenarios

Exploitation Plan (NPV, etc.)

FLOW SIMULATIONProduction

Optimization

Reserv. Eng.

Coupling @ specific

times

Upscaling of Propped Flow Area

(HF & Stimul. Nat Fracs) to Double

Poro/Perm Model

Pressure Saturations Flow Area

OFG Relevant Publications


1. Nagel, N.B., Sheibani, F., Lee, BT., Agharazi, A., Zhang, F., 2014, “Fully-Coupled Numerical Evaluations of Mulitwell Completion

Schemes: The Critical Role of In-Situ Pressure Changes and Well Configuration”, SPE Paper 168581 presented at the SPE

Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 4-6 February.

2. Nagel, N.B., Zhang, F., Sanchez-Nagel, M., Lee, BT., Agharazi A., 2013, “Stress Shadow Evaluations for Completion Design in

Unconventional Plays”, SPE Paper 167128 presented at the SPE Unconventional Resources Conference-Canada, Calgary, Alberta, 5-7

November.

3. Zhang, F., Nagel, N.B., Sanchez-Nagel, M., Lee, BT., Agharazi, A., 2013, “The Critical Role of In-Situ Pressure on Natural Fracture

Shear and Hydraulic Fracturing-Induced Microseismicity Generation”, SPE Paper 167130 presented at the SPE Unconventional

Resources Conference-Canada, Calgary, Alberta, 5-7 November.

4. Agharazi, A., Lee, BT., Nagel, N.B., Zhang, F., and Sanchez-Nagel, M., 2013 “Tip-Effect Microseismicity – Numerically Evaluating the

Geomechanical Causes for Focal Mechanisms and Microseismicity Magnitude at the Tip of a Propagating Hydraulic Fracture”,

SPE Paper 167129 presented at the SPE Unconventional Resources Conference-Canada, Calgary, Alberta, 5-7 November.

5. Nagel, N.B., F. Zhang, M. Sanchez-Nagel and B. Lee, 2013, "Evaluation of Stress Changes Due to Multi-Stage Hydraulic Fracturing -

Consideration of Field Results", presented at Rock Mechanics for Resources, Energy and Environment, Eurock13, the ISRM

International Symposium, Wroclaw, Poland, 21-26 September.

6. Garcia, X., N.B. Nagel, F. Zhang, M. Sanchez-Nagel and B. Lee, 2013, "Revisiting Vertical Hydraulic Fracture Propagation Through

Layered Formations - A Numerical Evaluation", Paper ARMA 13-203 presented at 47th US Rock Mechanics/Geomechanics

Symposium, San Francisco, CA, USA, 23-26 June.

7. Rios, A.M., G. Gutierrez, N.B. Nagel, F. Zhang, M. Sanchez-Nagel and B. Lee, 2013, "Stress Shadow Evaluations for Chicontepec -

Evaluating New Completion Options", Paper ARMA 13-200 presented at 47th US Rock Mechanics/Geomechanics Symposium, San

Francisco, CA, USA, 23-26 June.

8. Zhang, F., N.B. Nagel, B. Lee and M. Sanchez-Nagel, 2013, "The Influence of Fracture Network Connectivity on Hydraulic Fracture

Effectiveness and Microseismcity Generation", Paper ARMA 13-199 presented at 47th US Rock Mechanics/Geomechanics

Symposium, San Francisco, CA, USA, 23-26 June.

9. Zhang, F., N.B. Nagel, X. Garcia, B. Lee and M. Sanchez-Nagel, 2013, "Fracture Network Connectivity - A Key To Hydraulic

Fracturing Effectiveness and Microseismcity Generation", presented at ISRM International Conference for Effective and Sustainable

Hydraulic Fracturing, Brisbane, Australia, 20-22 May.

10. Nagel, N.B., F. Zhang, M. Sanchez-Nagel, X. Garcia, and B. Lee, 2013, "Quantitative Evaluation of Completion Techniques on

Influencing Shale Fracture Complexity", presented at ISRM International Conference for Effective and Sustainable Hydraulic Fracturing,

Brisbane, Australia, 20-22 May.



11. Savitski, A. A., M. Lin, A. Riahi, B. Damjanac and N.B. Nagel, 2013, "Explicit Modeling of Hydraulic Fracture

Propagation in Fractured Shales", in International Petroleum Technology Conference, Beijing, China.

12. Nagel, N.B., M. Sanchez-Nagel, F. Zhang, X. Garcia, and B. Lee, 2013, “Coupled Numerical Evaluations of the

Geomechanical Interactions Between a Hydrualic Fracture Stimulation and a Natural Fracture System in Shale

Formations”, Rock Mechanics and Rock Engineering, DOI 10.1007/s00603-013-0391-x

13. Pettitt, W.S., M. Pierce, B. Damjanac, J. Hazzard, L. Lorig, C. Fairhurst, M. Sanchez-Nagel, N.B. Nagel, J. Reyes-Montes, J.

Andrews and R.P. Young, 2012, "Combining Microseismic Imaging and Hydrofractur Numerial Simulations", Paper

ARMA 12-554 presented at the 46th U.S. Rock Mechanics Symposium, Chicago, Illinois, USA.

14. Pettitt, W.S., B. Damjanac, J. Hazzard, Y. Han, M. Sanchez-Nagel, N.B. Nagel, J. Reyes-Montes and R.P. Young, 2012,

"Engineering Hydraulic Treatment of Existing Fracture Networks", Paper SPE 160019 presented at the SPE Annual

Technical Conference and Exhibition, San Antonio, Texas, USA.

15. Nagel, N.B., M. Sanchez-Nagel, X. Garcia, and B. Lee, 2012, “Understanding "SRV": A Numerical Investigation of

"Wet" vs. "Dry" Microseismicity During Hydraulic Fracturing”, Paper SPE 159791 presented the SPE Annual Technical

Conference and Exhibition held in San Antonio, Texas, USA, 8-10 October.

16. Nagel, N.B., M. Sanchez-Nagel, X. Garcia, and B. Lee, 2012, “A Numerical Evaluation of the Geomechanical

Interactions Between a Hydraulic Fracture Stimulation and a Natural Fracture System”, ARMA 12-287 presented at

the 46th Rock Mechanics / Geomechanics Symposium, Chicago, Illinois, 24-27 June.

17. Nagel, N.B., X. Garcia, B. Lee, and M. Sanchez-Nagel, 2012, “Hydraulic Fracturing Optimization for Unconventional

Reservoirs - The Critical Role of the Mechanical Properties of the Natural Fracture Network", Paper SPE 161934

presented at the SPE Canadian Unconventional Resources Conference, Calgary, Alberta, Canada, 30 October - 1

November.

18. Nagel, N., M. Sanchez-Nagel, and BT Lee, 2012, "Gas Shale Hydraulic Fracturing: A Numerical Evaluation of the

Effect of Geomechanical Parameters", Paper SPE 152192 presented at the SPE Hydraulic Fracturing Technology

Conference and Exhibition, The Woodlands, Texas, USA, 6-8 February.

19. Pettitt, W.S., M. Pierce, B. Damjanac, J. Hazzard, L. Lorig, C. Fairhurst, I. Gil, M. Sanchez-Nagel, N.B. Nagel, J. Reyes-

Montes R.P. Young, 2011, "Fracture Network Engineering for Hydraulic Fracturing", The Leading Edge, 30(8), pp844-

853.



20. Nagel, N., I. Gil, M. Sanchez-Nagel, and B. Damjanac, 2011, “Simulating Hydraulic Fracturing in Real Fractured Rock –

Overcoming the Limits of Pseudo3D Models”, Paper SPE 140480 presented at the SPE Hydraulic Fracturing Technology

Conference and Exhibition, The Woodlands, Texas, USA, 24-26 January.

21. Nagel, N., B. Damjanac, X. Garcia, and M. Sanchez-Nagel, 2011, "Discrete Element Hydraulic Fracture Modeling -

Evaluating Changes in Natural Fracture Aperture and Transmissivity", Paper SPE 148957 presented at the Canadian

Unconventional Resources Conference, Calgary, Alberta, Canada, 15-17 November.

22. Nagel, N. and M. Sanchez-Nagel, 2011, “Stress Shadowing and Microseismic Events: A Numerical Evaluation”, Paper

SPE 147363 presented at the SPE Annual Technical Conference and Exhibition, Denver, Colorado, USA, 30 October-2

November.

23. Gil, I., N.B. Nagel, M. Sanchez-Nagel, and B. Damjanac, 2011, "The Effect of Operational Parameters on Hydraulic

Fracture Propagation in Naturally Fractured Reservoirs - Getting Control of the Fracture Optimization Process",

Paper ARMA 11-391 presented at ARMA 45th U.S. Rock Mechanics/Geomechanics Symposium, San Francisco, California,

USA.

24. Damjanac, B., I. Gil, M. Pierce, M. Sanchez-Nagel, A. Van As, and J. McLennan, 2010, “A New Approach to Hydraulic

Fracturing Modeling in Naturally Fractured Reservoirs", Paper ARMA 10-400 presented at ARMA 44th U.S. Rock

Mechanics/5th US-Canadian Rock Mechanics Symposium, Salt Lake City, UT, USA, June 27-30.


Contact Info:

Marisela Sanchez-Nagel, Ph.D.

President, OilField Geomechanics LLC

Neal Nagel, Ph.D.

Chief Engineer, OilField Geomechanics LLC

24200 Southwest Freeway, Suite 402 #293

Rosenberg, Texas 77471

[email protected]

[email protected]

www.ofgeomech.com

Office: 832-327-9566

http://www.itascahouston.com/

OFG - OilField Geomechanics


Thanks for your interest in OFG

www.ofgeomech.com

oilfield geomechanics (ofg) services...oilfield geomechanics llc ofg geomechanics services for the...

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