鄂尔多斯盆地杭锦旗地区二叠系地层水地球化学特征和来源

Geochemical characteristics and source of Permian formation water in Hangjinqi area, Ordos Basin

赵永强 倪春华 吴小奇 朱建辉 刘光祥 王付斌 贾会冲 张威 齐荣 安川

ZHAO Yongqiang NI Chunhua WU Xiaoqi ZHU Jianhui LIU Guangxiang WANG Fubin JIA Huichong ZHANG Wei QI Rong AN Chuan

中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126 中国石化 油气成藏重点实验室, 江苏 无锡 214126 中国石化 石油勘探开发研究院, 北京 102206 中国石化 华北油气分公司 油气勘探管理部, 郑州 450006 中国石化 华北油气分公司 勘探开发研究院, 郑州 450006

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China SINOPEC Key Laboratory of Hydrocarbon Accumulation, Wuxi, Jiangsu 214126, China Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 102206, China Department of Oil and Gas Exploration Management, SINOPEC North China Branch, Zhengzhou, Henan 450006, China Research Institute of Exploration and Development, SINOPEC North China Branch, Zhengzhou, Henan 450006, China

杭锦旗地区二叠系是近年来鄂尔多斯盆地重要的天然气增储上产领域之一，其气水关系复杂，目前对该区地层水成因和来源的研究较为薄弱。通过对杭锦旗地区二叠系地层水样品开展常量组分、微量元素和氢、氧同位素分析，揭示地球化学特征对地层水来源的指示意义。杭锦旗地区二叠系地层水主体为CaCl2型，泊尔江海子断裂以北和以南地区地层水矿化度平均分别为52.1 g/L和41.9 g/L；不同类型水化学特征参数均指示了地层封闭性较好，地层水在埋藏过程中经历了较强的浓缩变质作用，天然气保存条件较好；地层水主体为蒸发浓缩后的陆相地层水，地层中发生了斜长石的钠长石化作用和胶结物的白云岩化作用；地层水氢、氧同位素值主体分别介于-81‰~-75‰和-12.1‰~-8.8‰，水岩相互作用整体明显弱于苏里格气田。受晚白垩世以来区域性抬升过程中凝析水混入、地表水沿断裂渗入等因素影响，少数地层水样品具有偏低的氢同位素值。

The Permian stratum in Hangjinqi area is one of the important fields to increase gas reserves and outputs in the Ordos Basin in recent years. The studies of the origin and source of formation water are still insufficient due to the complexity of relationship between gas and formation water. Based on the analysis of major components, trace elements, as well as hydrogen and oxygen isotopes, the indication of geochemical characteristics for the source of formation water is then revealed. The Permian formation water in Hangjinqi area is mainly of CaCl2 type, and the average total dissolved solids (TDS) of formation water to the north and south of the Borjianghaizi fault are 52.1 and 41.9 g/L, respectively. Different water chemical parameters indicate favorable formation sealing conditions, and the formation water has experienced strong concentrated metamorphism with beneficial preservation conditions for natural gas. The formation water is mainly terrigenous one after evaporation and concentration, and the stratum has experienced albitization of plagioclase and dolomitization of cements. The δD and δ18O values of the formation water are mainly in the ranges of -81‰ to -75‰ and -12.1‰ to -8.8‰, respectively, suggesting weaker water-rock interaction than that in the Sulige gas field. Due to the mixing of condensate water in regional uplift since the Late Cretaceous or the seepage of surface water along faults, a small number of formation water samples display more negative δD values.

国家自然科学基金项目 42172149;国家自然科学基金项目 41872122;国家科技重大专项 2016ZX05002-006

https://doi.org/10.11781/sysydz202202279