Potentials of low permeability gas in intracratonic basin: Insights from sedimentary facies of the Shan1 Member in the Su6‐Zhao42 Block of the Sulige gas field, Ordos Basin

Abstract

The Sulige gas field is a typical low permeability gas field with multi‐thin layer of pay zones. The upper member of the Shanxi Formation (Shan1) is the primary productive layer of the Su6‐Zhao42 area, located in the north‐west of the Shanbei Slope of the Sulige gas field. The Shan1 Member could be divided into 3 tiny sequences by coring and well logging data. On the basis of sedimentary sequence analysis, the sedimentary environment and facies are studied combined with lithological information, logging data, and sampling. This paper summarizes the characteristics and distribution of the sedimentary facies of the Shan1 Member in the Su6‐Zhao42 area. During the deposition of the Shan1 Member, this area developed a meandering river sedimentary facies, which can be subdivided into meandering riverbed, river floodplain, and abandoned channel subfacies. The sedimentary facies of meandering river in the Shan1 Member are characterized by point bars, crevasse splays, floodplains, flood swamps, and abandoned channels. The sedimentary facies bands extend roughly east‐west parallel to the meandering river. It is indicated that the sand bodies deposited in river channel have better physical conditions and larger thickness for gas accumulation based on the analysis of physical characteristics and seismic attributes. The effective reservoir, being controlled by the sedimentary facies belt, distributes along a NE–SW trending belt where is the favourable area for the gas reservoir.