Geochemical Characters of the Tight Sandstone Gas from Xujiahe Formation in Yuanba Gas Field and Its Gas Source
详细信息
- 责任者：Yin Feng (Exploration Southern Company ; SINOPEC ; Chengdu 610041 ; China) ; Liu Ruobing
- 刊名：Natural Gas Geoscience
- 出版年：2013
- 卷期：24(3)
- 关键词：气藏 ; gas reservoirs ; 四川盆地 ; Sichuan Basin
- 页码：p.621-627
- 图表：5 illus., 3 tables, 25 refs.
- 分类号：1003
- issnNo：ISSN1672-1926
- isbnNo：CN62-1177/TE
摘要
Unconventional oil and gas reservoirs are those that cannot use conventional methods and technical means for exploration and development under current economic and technological conditions.The gas reservoirs of Xujiahe Formation in Yuanba Gas Field belong to tight sandstone gas reservoirs.Geochemical data of 20gas samples from 14wells of Xujiahe Formation are analyzed for main gas component,gas dryness coefficient and so on in the Yuanba Gas Field.The tight sandstone gas of Xujiahe Formation in Yuanba Gas Field is dominated by methane with content up to 98.39%.The dryness coefficient is basically more than 0.97for the dry gas with high thermal maturity.δ13C1values of gas samples in the study area are lower than-30‰,while the majority of the samples is characterized by positive carbon isotope series.In addition to the biogenic origin,the Xujiahe tight sandstone gas mainly consists of self-sourced coal-derived gas and other-sourced oil-associated gas.Secondary alteration has greater influences on oil-associated gases.Gas samples in the study area normally have R/Ra values varying from 0.01to 0.02.The crust origin helium indicates that tight sandstone gas reservoirs of the study area are mainly located in the tectonically stable area.The widely distributed coal series and dark muddy rocks in the Xujiahe Formation are the main source of coal-associated alkane gas.Part of the tight sandstone gas in the Xujiahe Formation is oil-derived alkane gas,therefore it infers that its existence may be from the underlying strata of the Upper Permian Longtan Formation.
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