## Fracture Growth in Layered and

Discontinuous Media

Norm Warpinski© 2011 Halliburton. All Rights Reserved. 2 

## Fracture growth in complex media
 Extensive research into affects of important parameters  In situ stresses  Material properties  Interfaces  Layering  Fracture toughness  Heterogeneities DOE/GRI M-Site core through

Mounds Drill Cuttings Injection Experiment© 2011 Halliburton. All Rights Reserved. 3 

## Hydraulic Fracture Growth

 In Situ Stress  Dominant factor in controlling hydraulic fracture growth  Mineback tests showing fracture termination at high stress layer DOE Mineback results showing effects of in situ stress contrasts© 2011 Halliburton. All Rights Reserved. 4 

## Fracture Height Growth  In situ stress  Example equilibrium calculation  Requires:  Stress  Pressure  Fracture toughness



###  In general, more complex equations are used  Modulus  Layers 1 – stress in reservoir 2 – stress in bounding layers P – pressure in fracture H – fracture height h – reservoir thickness Simonson et al., SPE, 1978© 2011 Halliburton. All Rights Reserved. 5 

## Modeling fracture growth
 Calibrated models using diagnostics Verify data and behavior  Example in the Bossier sandstone in East Texas Griffen et al., SPE 84489© 2011 Halliburton. All Rights Reserved. 6 

## Fracture Height Growth
 Modulus variations  Limited effect due to influence on width Van Eekelen formulation

 Interfacial effect  Fracture toughness behavior at interfaces  Not observed in field Mineback example showing behavior of fracture at a material property interface© 2011 Halliburton. All Rights Reserved. 7 

## Fracture Height Growth  Fracture toughness  Generally assumed to have a small effect  Relatively low fracture toughness for rocks  Potential for scale effects that might constrain growth (Shlyapobersky)

Equation for calculating stress intensity factor, Rice (in Fracture, Liebowitz, 1968) Data from DOE Multiwell experiment in Piceance basin, Colorado© 2011 Halliburton. All Rights Reserved. 8 

## Fracture Height Growth  Composite layering 

###  Mineback photos suggest a wide variety of mechanisms are interplaying  Fracture diagnostics have shown the same behavior  Microseismic  Downhole tiltmeters© 2011 Halliburton. All Rights Reserved. 9 

## Fracture Height Growth
 Observed layering effects at DOE/GRI M-Site  Microseismic and downhole tiltmeter measurements of fracture height  In situ stress measurements Treatment pressure© 2011 Halliburton. All Rights Reserved. 10 

## Discontinuities  Fracture growth across discontinuities in the rock mass has been extensively 

### studied  Depends upon  Stress  Material properties  Angle of approach 

###  Models  Mineback  Laborataory Propagation Cement Fracture

Jeffrey & Zhang, 2009, SPE 119351 DOE mineback tests© 2011 Halliburton. All Rights Reserved. 11 

## Discontinuities  Fracture behavior as influenced by a wide range of discontinuities have been observed in minebacks and other tests  Faults  Cleats Coal DOE mineback tests

Bureau of Mines Report 9083, Diamond & Oyler

, SPE 22395, Diamond CBM Symposium 11/87, Lambert SPE 15258© 2011 Halliburton. All Rights Reserved. 12 

## Hydraulic Fracture Growth
 Summary  Hydraulic fractures influenced by heterogeneities within the reservoir  Any change in properties/uniformity  In situ stress is the dominant influence  Large stress contrasts contain fractures  Layering and interfaces result in inefficient growth  Models available to simulate/mimic behavior