莺歌海盆地乐东10区CO包裹体特征及其流体充注史

Fluid charging history in Ledong 10 area, Yinggehai Basin, revealed by CO inclusion characteristics

税蕾蕾 郭来源 徐新德 黄向胜 黄合庭 陈书伟 宋修章

SHUI Leilei GUO Laiyuan XU Xinde HUANG Xiangsheng HUANG Heting CHEN Shuwei SONG Xiuzhang

中海油能源发展股份有限公司 工程技术公司 中海油实验中心, 天津 300452 浙江一龙环保科技有限公司, 杭州 310051 中海石油(中国)有限公司 海南分公司, 海口 570312

CNOOC Central Laboratory, Drilling & Production Co., CNOOC Energy Technology & Services Ltd., Tianjin 300452, China Zhejiang Yilong Environmental Protection Technology Co., Ltd., Hangzhou, Zhejiang 310051, China Hainan Branch of CNOOC Ltd., Haikou, Hainan 570312, China

莺歌海盆地新生界富含天然气，近年来在盆地中深层勘探取得了突破；而乐东10区气田的发现，引起了对非底辟构造的中深层岩性气藏天然气运移成藏问题的关注。乐东10区块中新统黄流组天然气藏富含CO2，为了查明CO2在天然气藏中的运移特征和期次，以包裹体岩相学为前提，结合激光拉曼光谱分析对其进行了研究。该区包裹体主要包括盐水包裹体、二氧化碳包裹体、气相甲烷包裹体、混合气包裹体、含混合气的盐水溶液包裹体五种类型。使用激光拉曼分析和显微测温技术，定量分析了CO2包裹体的均一温度和密度等参数；结合CO2流体包裹体捕获条件、沉积特征、埋藏史以及CO2同位素值，认为该区CO2为两期幕式充注：第一期为1.4~0.9 Ma充注的高密度无机成因CO2；第二期为0.7~0.4 Ma充注的中密度无机成因CO2。

The Cenozoic strata of Yinggehai Basin is rich in natural gas, and exploration breakthroughs have been achieved in the middle and deep strata of the basin in recent years. The discovery of gas fields in the Ledong 10 area had attracted concerning for the migration and accumulation of natural gas in lithologic reservoirs in the middle and deep strata of nondiapir structures. The natural gas reservoir in the Miocene Huangliu Formation in the Ledong 10 block appeared to have a high content of CO2. The characteristics and periods of CO2 migration to natural gas reservoirs were discussed by the approaches including Laser Raman spectroscopy and combined with inclusion petrographic observation. Five types of fluid inclusions were classified, including brine inclusions, CO2 inclusions, gas-phase CH4 inclusions, gas-mixed inclusions and gas-mixed brine inclusions. According to the homogenization temperature and density of CO2 inclusions measured by Laser Raman and microthermometry analysis, and combined with the estimation of the capture conditions of CO2 inclusions, sedimentary characteristics, burial history as well as isotopic composition of CO2, two-stage filling mode for CO2 gas reservoirs was then concluded. The first stage was high-density inorganic-origin CO2 charged between 1.4-0.9 Ma; the second stage was medium-density inorganic CO2 charged between 0.7-0.4 Ma.

广东省软科学研究计划项目 2018B030323028

https://doi.org/10.11781/sysydz202105835