Luo Xia; Sun Fenjin; Shao Mingli; Wang Zhihong; Zeng Fuying; Zhao Zehui; Xia Li and He Feng
, 2009, 36(3): 1718-0.
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The composition and carbon isotope composition of about 150 natural gas samples reveals that natural gases of deep strata in Songliao Basin are derived from multiple sources and the coal-formed gases are widely distributed in the basin. Several gas fields show features of coal-formed gas or contain coal-formed gases, with δ13C2 being larger than -28‰ and δ13CMCC6 being larger than -22‰, such as Shengping gas field in the north of the basin, Xiaohelong and Xiaochengzi gas fields in the south. Organic matter of source rocks in the deep strata is dominantly Type Ⅲ, with a small portion of Type Ⅱ. The average TOC of source rocks in the Shahezi (K1sh) Formation is 1.99%. Sedimentary facies studies of single wells, which penetrated coals of the Shahezi Formation, indicate that these coals are developed in peat swamps of deltaic plain, depressions between fan deltas, coastal shallow lakes, flooding plain etc, and structures are mainly distributed in the boundary of fault depressions, especially in their slope, some in the center of lakes.