四川盆地梓潼凹陷烃源岩与天然气地球化学特征

Geochemical characteristics of source rocks and natural gas in Zitong Sag, Sichuan Basin

董军 王鹏 袁东山 任青松 王顺玉 李斌

Dong Jun Wang Peng Yuan Dongshan Ren Qingsong Wang Shunyu Li Bin

成都理工大学 能源学院, 成都 610059 2. 中国石化 西南油气分公司 勘探开发研究院, 成都 610041 3. 西南石油大学 地球科学与技术学院, 成都 610500

College of Energy Resources, Chengdu University of Technology, Chengdu, Sichuan 610059, China 2. Exploration & Development Institute of SINOPEC Southwest Oil & Gas Company, Chengdu, Sichuan 610041, China 3. School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China

通过对四川盆地梓潼凹陷烃源岩发育特征及天然气地球化学特征的研究,探讨了该区天然气基本特征及成因类型。研究区烃源岩主要发育于须家河组一段、三段与五段,其中须家河组三段烃源岩厚度最大。烃源岩TOC含量普遍大于1.0%,有机质类型主要为腐殖型,有机质成熟度以成熟、高成熟为主,并已进入大量生烃阶段,生烃强度大于30×108m3/km2,良好的烃源岩条件是研究区天然气聚集成藏的物质基础。研究区干气与湿气同时存在,九龙山、剑门、魏城、白龙场等地区主要为干气,而中坝、老关庙等地区主要为湿气,文兴场、柘坝场、丰谷、绵阳等地区干气与湿气均存在。研究区天然气主要为热成因煤型气,来自该区须家河组烃源岩,仅九龙山地区为油型气,主要来自下伏海相烃源岩。

The characteristics and genetic types of natural gas in the Zitong Sag of the Sichuan Basin have been studied according to the development and geochemical features of source rocks. The hydrocarbon source rocks in the study area mainly located in the first, third and fifth members of the Xujiahe Formation, among which the third member is the thickest. The TOC content of the source rocks is generally greater than 1.0%. Organic matter is of humic type, usually mature or highly mature. A large amount of hydrocarbon has been generated, and the generation intensity is greater than 3×109 m3/km2. Favorable source rock conditions enhance the accumulation of natural gas in the study area. Both dry gas and wet gas have been found. In the Jiulongshan, Jianmen, Weicheng and Bailongchang areas, dry gas is dominant. In the Zhongba and Laoguanmiao areas, wet gas is common. In the Wenxingchang, Zhebachang, Fenggu and Mianyang areas, both dry gas and wet gas exist. The natural gas in the study area is mainly thermogenic coal gas originating from the Xujiahe Formation. Oil type gas exists only in the Jiulongshan area, and is sourced from the underlying marine source rocks.

国家科技重大专项课题(2011ZX05002-004-001)资助.

https://doi.org/10.11781/sysydz201503367