Author(s)

Rulang Wang^1,2, Feng Qin³, Nianfa Yang^1*, Yun Zhou¹

¹State Key Laboratory of Petroleum Resources and Prospecting, College of Geosciences, China University of Petroleum, Beijing, China.
²Zhejiang Mercantile Exchange, Zhoushan, China.
³Exploration and Development Research Institute, Shengli Oilfield Company, SINOPEC, Dongying, China.

Pull-apart basins are faulting and folding zones with high intensity of fractures that strongly affect the production in unconventional shale gas. While most observations of pull-apart basins were from surface mapping or laboratory experiments, we investigated a nascent pull-apart basin in the subsurface. We characterized a nascent pull-apart basin along the strike-slip fault within the Woodford Shale by using seismic attributes analyses, including coherence, dip-azimuth, and curvature. The results indicate a 32 km long, N-S striking strike-slip fault that displays a distinct but young pull-apart basin, which is ~1.6 km by 3.2 km in size and is bounded by two quasi-circular faults. The curvature attribute map reveals two quasi-circular folds, which depart from the main strike-slip fault at ~25°, resulting in an elliptical basin. Inside the basin, a series of echelon quasi-circular normal faults step into the bottom of the basin with ~80 m of total subsidence. We propose that the controls of the shape of pull-apart basin are the brittleness of the shale, and we suggest proper seismic attributes as a useful tool for investigating high fracture intensity in the subsurface for hydrofracturing and horizontal drilling within the shale.

Pull-Apart Basin, Seismic Attributes, Analog Model, Fractures, Shale Gas

Wang, R. , Qin, F. , Yang, N. and Zhou, Y. (2023) Analysis of a Pull-Apart Basin and Its Associated Fractures in the Woodford Shale, Central Oklahoma. Open Journal of Geology, 13, 276-286. doi: 10.4236/ojg.2023.134013.