Characteristics and Hydrocarbon Generation Potential for Source Rock of Carboniferous Shiqiantan Formation in Shiqiantan Depression, Eastern Junggar Basin

The source rock of Shiqiantan formation is a main hydrocarbon−generation bed of the carboniferous for Shiqiantan depression in Junggar basin. Based on the detailed investigation on spatial distribution of formation,the newly found Shuangjingzi geological trench section, Shiqian 1 well, Shiqian 2 well and Qian 1 well can be selected for systematic organic geochemistry analysis and testing of total organic carbon, pyrolysis, group composition, organic macerals, vitrinite reflectance, and chromatogram−mass spectrometry of saturated hydrocarbon for source rock samples, the results show that the source rock of the Shiqiantan formation is a set of typical bay lagoon deposits, which is mainly distributed in the Shiqiantan depressionin with northwest−southeast direction. Besides, the local thickness is huge, even up to 370 m. The center of sediment thickness is located in the southeastern corner. The organic rich strata are mainly concentrated in the lower part of formation, and the upper part comes second. The overall organic matter content is relatively high, and can reach the good grade or above, the main type of organic matter is II₂-III, and has entered the high mature gas generation stage. It is concluded that the source rock of carboniferous Shiqiantan formation is characertized by good hydrocarbon generation condition and can provide sufficient resources for Shiqiantan depression.