AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Hydraulic Fracture and Natural Fracture Simulation for Improved Shale Gas Development
(1) FracMan Technology Group, Golder Associates Inc, Redmond, WA.
(2) Devon Energy, Oklahoma City, OK.
(3) Golder Associates UK Ltd, Belfast, United Kingdom.
This paper describes a discrete fracture approach for assessment and exploitation of unconventional gas plays. The strategy depends on the evaluation of a localized, well trajectory specific tributary drainage volume, which considers the combined effect of hydraulic and natural fractures.
The developed methodology includes (1) the prediction of the in situ stress (2) geomechanical modeling of hydraulic fracture stimulation and (3) a scalable DFN approach enabling rapid assessment of large numbers of hydraulic fracture configurations.
Using a geomechanical FE/DE technique, a prediction of the in situ stress conditions in locations where exploration wells may not exist has been made. The models have utilized a stepped approach and have considered specific geometry (major faults and stratigraphical boundaries) and rock properties surrounding the reservoir. The models have allowed local variations in stress and strain across faults to be assessed, and have provided a means for assessing data between wells to unexplored locations.
Reservoir-scale assessment of the in situ stress has provided initial condition for a range of well-scale models investigating hydraulic fracture stimulation. These geomechanical hydraulic fracture configurations have been supplemented using a scalable DFN based simulation approach. This has permitted several thousand hydraulic fracture configurations to be rapidly assessed for varying configurations. Both of these approaches use key physical representations, including intact rock strength, natural fracture response, the insitu stress, and the fluid injection conditions.
The result obtained from these simulations allows better understanding of different injection strategies and insight into how the physical quantities of stress, displacement, and fluid pressure inter-relate.
Unconventional gas is present at many locations around the globe. These sources exist in a variety of forms, including shale gas, coal bed methane and tight gas. Prediction and understanding of hydraulic fracture stimulation is critical to facilitating enhanced unconventional gas production.