An integrated well-pattern optimization strategy to unlock continental tight gas reservoir in China

The successful technology in development the tight gas reservoir in North America—a combination of long horizontal drilling and multi-stages hydraulic fracturing—has poor adaptability for the tight gas reservoir in China, where the tight gas reservoirs are mostly deposited on the background of continental geological setting with thin formation thickness, low lateral continuity and poor permeability. In this work, an integrated well-pattern optimization frame in adaption to the geological setting of Ordos basin is systematically proposed. In this frame, the strong heterogeneity, horizontal sand continuity, multi-layers sand matching, as well as ground surface environment are all adequately considered. The field application of the frame to a pilot region in Yan’an gas field, a typical continental tight gas reservoir in Ordos basin, shows a very good response, which demonstrates the superiority of the proposed frame. The results show that the strong heterogeneity, low horizontal sand continuity, and multi-layers sand matching compel the well spacing to be non-uniform, well pattern to be irregular and well type to be diverse, respectively, meanwhile, the complex ground surface environment gives constraints on the drilling operations. Through this frame, the world-class challenging tight gas reservoir in Ordos basin is successfully unlocked and maximized, which can be taken as a good reference for the development of similar types of tight gas reservoirs in the world.