Overview of Geomechanical Properties of Bakken Formation in Williston Basin, North Dakota

摘要

This paper summarizes the collected geomechanical properties of the Bakken Formation screened from 4000+ wells in North Dakota's portion of the Williston Basin. Contents f all the geomechanical parameters are rather scattered, and they are not correlated with the depth and location directly. The orientation of the maximum horizontal principal stress, determined using anelastic strain recovery method, acoustic anisotropy velocity method, and induced tensile fractures in oriented cores and well walls, is N30°E to N70°E in the Bakken formation. In addition, the fracture gradient, estimated with laboratory tests, ranges from 0.75 to 0.85 psi/ft. The vertical stress (overburden) is the maximum principal stress. The stress conditions are favorable for normal faulting, and the ratios among three principal stresses, i.e. the vertical, the maximum horizontal and the minimum horizontal stresses are 1:0.95-0.85:0.85-0.75.