The worlds premier DFN software

www.fracman.com © Golder Associates Inc, 2015

Golder Houston Breakfast Series – Jan 2015

Improving Oil Production: Understanding Natural, Induced, and Reactivated Fractures

Bill Dershowitz, Technical Director FracMan Technology Group fracman@golder.com

Golder Associates – Geomechanics and Environment

Golder – Mining, Oil and Gas, and Environment

FIRL 3%

Land Development 9%

Manufacturing 8%

Mining 36%

Oil & Gas 20%

Power 7%

Transportation 9%

Waste Management 5%

Water Resources 1%

Other 2%

Percentage of Global Revenues by Client Sector

FIRL

Land Development

Manufacturing

Mining

Oil & Gas

Power

Transportation

Waste Management

Water Resources

Other

Unconventional Oil and Gas Project Lifecycle

Appraisal Exploration Development Production

Asset Retirement

Resource Evaluation

Seismic, Drilling &

Stimulation

Vertical/ Horizontal Drilling &

Stimulation

Production, Workover & Enhanced Recovery

Restoration &

Closure

Reservoir Engineering/FracMan Stakeholder Mapping and Consultation

Planning and Permitting

Environmental Monitoring and Compliance

Reclamation Golder

Services &

Solutions

Remediation

Play Selection &

Siting

Pre-Development

Due Diligence

Integrated Water Management and Planning

Pipeline & Infrastructure Design & Engineering

Geotechnical Engineering

4

Golder Unconventional Oil and Gas Services

Wednesday, January 28, 2015

Some of Golder’s Fractured Reservoir Projects Over the Past 20 Years

Unconventional Reservoir Experience

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Barnett Haynesville Eagle Ford Permian Bakken Appalachian Marcellus Niobrara Mesaverde Monterey Woodford Wolfcamp Horn River Grosmont La Vaca Muerte

Morocco Poland Russia Australia Kuwait (Najmah & Makhul)

FracMan® Discrete Fracture Network Modelling

Explicitly represent discrete fractures in 3D Space

Build a model of key fracture geometry, mechanical properties, storage and permeability

Transform geological, geotechnical and well testing data into quantitative parameters to describe fracture network

Generation of Geologically Realistic DFN models based on parameters derived from field data

Stochastic process allowing probabilistic assessment to be carried out

Provides direct data to geomechanical simulators

DFN Model

DFN models can be used directly or

upscaled to equivalent properties

.

Formation Analysis &

Geo-Modelling

Geo- mechanics

Seismic Analysis & Geophysics

Dynamic Analysis & simulation

Advanced seismic processing Unique VSP processing & imaging Micro-seismic monitoring and

analysis

Hydraulic fracturing Critical stress analysis Sanding issues Wellbore stability Subsidence

Data analysis, integration & synthesis Conceptual model development DFN & Petrel model building DFN Volumetrics

Interpretation of dynamic data Multi-porosity Flow Simulation Calibration of DFN models Reservoir simulation

FracMan Carbonate and Unconventional Reservoir Analyses

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Natural Fractures Matter!

Few natural fractures HF defines drainage

Natural fractures but most are healed

HF essential for opening up healed fractures and increasing drainage

Persistent, open, natural fractures

HF may not greatly increase production in all wells or stages

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Eagle Ford

Utica

Hydraulic Fracture Geometry

• What is the interaction between hydraulic fractures and • in situ stress field

(local and regional) ? • pre-existing natural

fractures and faults ? • Geomechanical units

and their heterogeneity (both vertical and lateral) ? All these questions relate to discrete features and

heterogeneities. Can we rely on a simple continuum solution ?

σhmin

σhmax

Induced Hydrofracs, Inflated Natural Fractures, and Hydrosheared Natural Fractures

Stress grid: Sigma 3 direction shown

Identify fractures that are connected to the perf zone and whose state of stress is such that they will take fluid and/or pressure

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(c) Golder Associates Inc. 2014

Field Development Issues Addressed by DFN Hydraulic Fracture Modeling

With a DFN model we can address the following field development issues:

Landing depth Well spacing Lateral length Stage spacing Vertical drainage contribution Well sequencing Geologic differences within the lease area Completions optimization EUR

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Hydroshearing

Hydroshearing: microseismic events are simulated and assigned to fractures which are sheared and critically stressed beyond inflated fractures due to pressure diffusion.

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Plan View

Hydraulic Fractures & Natural Fractures Scenarios

TYPE A: Hydraulic fracture propagation provides the only flow pathway to the well TYPE B: Hydraulic fracture propagation provides the primary flow pathway to the

well, but is supplemented by fractures that are critical stressed by frac fluids (esp. rough fractures)

TYPE C: Frac fluid “leakoff” to natural fractures is extensive, and production is through a combined network defined by the hydraulic fracture and natural fractures (or perhaps by the natural fractures alone!)

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Do these have unique signatures?

Type A – Hydrofracs Provide only Flow

Implies that Gas/Oil Storage is Exclusively in Rock Matrix Classic “1-D” Linear Flow Signature from Rock Matrix to

Fracture Typical Reservoir – Some parts of Barnett

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Well

Hydraulic Fractures

Pressure Response

Type B – Hydrofracs and Natural Fractures Provide Flow and Storage

Natural fracture - particularly those reactivated by fracing can provide both flow and storage

More extensive, higher dimension network delivering gas to the well – not necessarily linear flow!

Natural fractures can dramatically increase tributary drainage volume of each well – increasing both IP and EUR

Or.. Rapid decline as natural fractures are depleted Typical Reservoir – Fayetteville

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Well

Natural Fractures

Pressure Response

Hydraulic Fractures

Type C – Natural and Reactivated Natural Fractures Dominate Production

Hydraulic Fractures primarily provide connection to and enhancement of pre-existing natural fracture network

Low apparent hydraulic efficiency of fracing, as frac-fluid is diverted to natural fracture

Wide, diffuse microseismic response Flow dimension depends on geometry of natural

fracture network – 1D, 2D, or 3D ! Dynamic stress effects can be very important Typical Reservoir – Appalachian Basin

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“Leakoff” from Hydrofrac to Natural Fractures

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0

1000

2000

3000

4000

5000

6000

0 2 4 6 8 10 12 14 16 18

psi

Square Root Time

0500

100015002000250030003500400045005000

1 10 100 1000

psi

Time, seconds

3D DFN Model and Hydraulic Fracturing Simulation

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Induced Hydraulic Fracture

Propped Natural Fractures

Stimulated Natural Fractures

Discrete Fracture Network (DFN)

Simulated Microseismic Events

FracMan Discrete Fracture Network Workflow

Propped Natural Fractures

Hydrosheared Natural Fractures

Induced Hydraulic Fractures and Stimulated Natural Fractures

Hydraulic fracture (HF) initiates at the well in the direction of σHmax

Natural fractures intersected by the HF are checked for dilation criterion:

Dilatable fracture = fracture pore pressure > fracture

normal stress

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Induced Hydraulic Fracture

Volume of the stimulated fractures is solved in time steps and is determined by the: elastic properties of the rock; in situ stress regime; internal fracture pore pressure

At each time step a fraction of slurry is pumped to the HF, as the HF grows the intersected natural fractures are checked for their injection possibility

Movie of Hydraulic Fracturing – Induced Fractures and Stimulated Natural Fractures

Inflated Natural and induced fractures

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Induced hydraulic fractures

Inflated Natural Fractures

Simulated and Measured Microseismic

Microseismic point is generated for each element having a critical stress, which can be used to compare with observed microseismic data

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Simulated Microseismic

Simulated Microseismic with hydraulic and reactivated natural fractures

Measured Microseismic

Simulated and Measured Microseismic

Production from Stimulated Natural Fractures DFN Dual Porosity Dynamic Simulation

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Tributary Drainage to well is a combination of induced, inflated, and hydrosheared natural fractures

Rock Drainage Concepts

Reservoir volumetric reports, including EUR, Stimulated Reservoir Volume (SRV) or Tributary Drainage Volume (TDV).

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FVFRFSNTGSRVEUR matrixoil /∗∗∗∗= φ

Tributary Drainage Volume (TDV) Fractures Contributing to Flow and their Connected Rock Matrix

Stimulated Reservoir Volume (SRV) Microseismic Cloud

Induced Fractures, Inflated Natural Fractures, and Hydrosheared Natural Fractures

1/28/2015

(c) Golder Associates Inc. 2015

77

Induced hydraulic fractures only

Induced hydraulic fractures and inflated natural fractures

Hydrosheared natural fractures

Stress Shadow Effects in Zipper Fracing Comparison

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Overlapping Zones

Stress Shadow Effect No Stress Shadow Effect

Grid Stiffness Increase due to Frac inflation

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DFN Dual Porosity Match to Well Test (Early Time)

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Hydraulic Fractures with 350 Feet Well Spacing

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Hydraulic Fractures with 500 Feet Well Spacing

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Hydraulic Fractures with 650 Feet Well Spacing

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Pressure Derivatives

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500ft 350ft

650ft

Designing Completions and Well Spacing Using FracMan DFN 3D Dynamic Simulation

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Pressure Map – 350 Feet Well Spacing

Pressure Map – 500 Feet Well Spacing

Pressure Map – 650 Feet Well Spacing

Perspective view – fractures can be seen in 3D

Natural Conductive Fractures – Appalacian Basin Gas Shale Example

Rich Data Set Conventional

microseismics Image logging Flow logging using %

natural gas in the drilling returns from quadrupole mass spectrometer

Tracer testing Tomographic Fracture

Imaging (TFI)

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Drilling Gas Monitoring and Production Log

PLT (Green) Natural Gas Returns (Red)

Tomographic Fracture Imaging (TFI)™

Method of Global Geophysical Services Passive seismic method Employs surface arrays imaging responses of both artificial and natural

fractures Total trace energy mapped by voxels and summed over periods ranging

from minutes to hours

TFI Shows Affected Volume Larger than That Shown by Conventional Microseismics

Conventional Microseismics

3 miles

Tracer Responses

3 miles

All Conductive Fractures

•Hydrofracs

•Conductive Fractures in Well

•TFI Lineaments

•Stochastic TFI Lineaments

3 miles

Pressure From Production

108 second ~ 1100 days

Increasing Permeability

Natural Fractures Matter Appalachian Basin Case Study

1. The most successful wells can be expected where stress concentrations ensure large hydraulic fractures. This can be determined by geomechanical modeling of faults, stratigraphy, and topography

2. Orientation of horizontal wells should be adjusted to local stress conditions

3. Reactivated natural fractures frequently contribute to production, such that higher natural fracture intensity can be an indication of better well locations

Reactivated Natural Fractures and Hydraulic Fractures

Reactivated Natural Fractures and Hydraulic Fractures

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FracMan Discrete Fracture Network Workflow