Geomechanical Interpretation of a ‘Simul-Frac' in Bakken Shale

Chen, Mian; Li, Qinghui; Jin, Yan

For the purpose of eliminating human being's footprint and improving construction efficiency, more wells are getting drilled from the same pad, various stimulation patterns and techniques are being tested in search of the optimum approach to hydraulic fracture treatment. ‘simul-frac' is a process where two horizontal wells are stimulated simultaneously with large hydraulic fracture treatments. It is an efficient approach to generating economic production from gas and oil shales such as the Bakken Shale formation in North Dakota. This approach may provide similar fluid volumes and fracturing energy input to the formation at each individual stage and so provides a very interesting geomechanical situation, where essentially similar perturbations are applied in succession to the Earth. Using acoustic emission observations made on recently laboratory scale hydraulic fracturing tests, we consider an idealized fracture model, whereby all perforations accept fluid equally and consider the cumulative geomechanical effect of the ‘simul-frac' using a microscopic damage mechanics considering the interaction between different lateral hydraulic fractures in the Bakken Shale blocks. From the tests we concluded that the geomechanical situation between different hydraulic fractures changed slightly which could not affect a long distance away from fracture tips, but could change in-situ stress intensity and fracture propagating direction before two fractures interacting and could get fracture complexity index much higher. We review the observed acoustic events in the light of the damage factor and stress intensity factor and ask whether the simple model can be rejected by the observations.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013