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Principal Stress Orientations and Relative Magnitudes in Unconventional Oil and Gas Basins, Western Cordillera and Central and Eastern U.S.A.

Abstract

Over the past four years, we have compiled >450 orientations of the maximum horizontal stress (SHmax) in the central and eastern USA. We have also mapped the relative principal stress magnitudes, revealing systematic changes in faulting regime across the continent.

The northeastern USA and southeastern Canada are characterized by reverse and reverse-/strike-slip faulting, with SHmax oriented ENE-WSW to NE-SW. The faulting regime is more extensional southward and westward, which profoundly affects operations in the Utica and Marcellus plays of the Appalachian Basin. Horizontal hydrofracs are expected in northeastern areas, where reverse faulting is active, but vertical hydrofracs are expected to the southwest, where strike-slip faulting is active.

In much of Oklahoma, including the SCOOP and STACK plays, SHmax is ~E-W. We observe a transition northward from strike-slip/reverse in southwest Oklahoma, strike-slip in central Oklahoma, normal/strike-slip in north-central Oklahoma, and normal faulting in southern Kansas. The Denver-Julesberg Basin to the northwest experiences normal/strike-slip faulting, but SHmax rotates broadly clockwise northward from SW-NE in southern Colorado to NW-SE in southeast Wyoming, and then again to NE-SW in the Williston Basin of western North Dakota.

The faulting regime also becomes more extensional southward from southern Oklahoma, with normal/strike-slip faulting and ~NNE-SSW SHmax directions in the central and southern Fort Worth Basin. Sedimentary rocks along the Gulf Coastal Plain, including most of the Eagle Ford and Haynesville areas, experience predominantly normal faulting, with SHmax sub-parallel to the coastline. In the eastern Permian Basin of west Texas and southeast New Mexico, and also the Raton Basin in southeast Colorado and northwest New Mexico, SHmax is ~E-W and normal/strike-slip faulting is active. However, a rapid transition occurs westward to normal faulting and N-S SHmax, reflecting the influence of Rio Grande Rift extension. SHmax regains a large E-W component outside of this extensional area, including the Uinta-Piceance, Green River, and Wind River basins of the Colorado Plateau and central Rocky Mountains. Finally, in the Basin and Range Province between central Utah and eastern California, the faulting regime becomes extensional again and SHmax is NNE-SSW. Together, these remarkable but coherent variations in the stress field provide operators with exceptional power for predicting the fractures that will be active during stimulation.