Judgement of natural gas resource and accumulation analysis of the second member of Xujiahe Formation in Xiaoquan-Xinchang-Hexingchang area of West Sichuan depression
Online published: 2011-08-20
The analysis of natural gas composition and carbon isotope of the second member ofUpper Triassic Xujiahe Formation in Xiaoquan-Xinchang-Hexingchang area ofWest Sichuan depression indicates that the natural gas is hybrid origin consisting of coaliferous gas and oil-cracked gas. It has three sources:①source rock ofMaantang and Xiaotangzi Formation, humic-sapropelic organic material generated oil and gas and then the oil cracked into gas under high temperature;②source rock within the second member of Xujiahe Formation, gas-generated mainly, self-generating and self-reserving; ③source rock within the third member of Xujiahe Formation, which did few contributions to the gas accumulation of the second member of Xujiahe Formation. By analyzing the dynamic relationship between gas charging history and the rock-tightening evolution, the gas reservoir of the second member of Xujiahe Formation is judged as a typical “subsequent tight sand gas” reservoir, whose accumulation process conformed to the specific mode of “early accumulation-seal up-late activation”.
Key words: diagenetic facies; diagenesis; Chang6 oil reservoir set; OrdosBasin
LUO Junmei , LUO Shunshe , CHEN Xiaojun , ZHU Junqiang . Judgement of natural gas resource and accumulation analysis of the second member of Xujiahe Formation in Xiaoquan-Xinchang-Hexingchang area of West Sichuan depression[J]. Lithologic Reservoirs, 2011 , 23(4) : 100 -105 . DOI: 10.3969/j.issn.1673-8926.2011.04.018
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