Application of integrated formation evaluation and three-dimensional modeling in shale gas prospect identification

Abstract

Identifying the shale gas prospect is crucial for gas extraction from suchreservoirs. Junggar Basin (in Northwest China) is widely considered tohave high potential as a shale gas resource, and the Jurassic, the mostsignificant gas source strata, is considered as prospective for shale gasexploration and development. This study evaluated the Lower JurassicBadaowan Formation shale gas potential combined with geochemical,geological, and well logging data, and built a three-dimensional (3D)model to exhibit favorable shale gas prospects. In addition, methane sorption capacity was tested for verifying the prospects. The Badaowan shalehad an average total organic carbon (TOC) content of 1.30 wt. % andvitrinite reflectance (Ro) ranging from 0.47% to 0.81% with dominatedtype III organic matter (OM). X-ray diffraction (XRD) analyses showedthat mineral composition of Badaowan shale was fairly homogeneous anddominated by clay and brittle minerals. 67 wells were used to identifyprospective shale intervals and to delineate the area of prospects. Consequently, three Badaowan shale gas prospects in the Junggar Basin wereidentified: the northwestern margin prospect, eastern Central Depressionprospect and Wulungu Depression prospect. The middle interval of thenorthwestern margin prospect was considered to be the most favorableexploration target benefitted by wide distribution and high lateral continuity. Generally, methane sorption capacity of the Badaowan shale wascomparable to that of the typical gas shales with similar TOC content,showing a feasible gas potential.