川东南涪陵地区凉高山组湖相页岩生烃潜力评价

Evaluation of Hydrocarbon Generation Potential of Lacustrine Shale of Lianggaoshan Formation in Fuling Area, Southeastern Sichuan

李斌 吉鑫 彭军 张昆 魏祥峰

LIBin JIXin PENGJun ZHANGKun WEIXiangfeng

西南石油大学地球科学与技术学院, 四川 成都 610500 油气藏地质及开发工程全国重点实验室·西南石油大学, 四川 成都 610500 中国石化勘探分公司, 四川 成都 610041

School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China National Key Laboratory of Oil and Gas Reservoir Geology and Exploration, Southwest Petroleum University, Chengdu, Sichuan 610500, China Exploration Company, SINOPEC, Chengdu, Sichuan 610041, China

为查明川东南涪陵地区凉高山组湖相页岩的生烃潜力，对该区10余口页岩含油井段400余件凉高山组岩样开展了地球化学测试分析，结果表明，凉二下亚段、凉一上亚段有机质丰度最高，总有机碳含量平均值分别为1.57%和0.81%；岩石热解生烃潜量为2.63~5.59 mg/g，干酪根类型以II、II型为主；湖相泥页岩镜质体反射率在0.98%~1.46%，处于成熟-高成熟演化阶段。基于凉高山组湖相有机质的地化特征，采用体积动力学原理建立了3种不同干酪根的生烃动力学模型，恢复了涪陵地区凉高山组泥页岩的生排烃史和生烃量。模拟结果表明，涪陵地区凉高山组泥页岩生烃转化率为65.0%~98.2%；生烃演化过程具有“单峰”特征，最大产烃率为5.15~18.50 mg/（g·Ma）；单位生烃总量为（63.0~144.0）×10 t。烃源岩生烃潜力受沉积环境控制，从滨湖-浅湖-半深湖，生烃转化率、最大产烃率和生烃总量呈现逐渐增加的趋势，其中，半深湖相泥页岩是涪陵地区最优质的烃源岩，其主要分布于TL7-YX1-TY1井区，是该区最有利的陆相页岩油富集区。

In order to ascertain the hydrocarbon generation potential of the lacustrine shale of Lianggaoshan Formation in Fuling Area of southeastern Sichuan, geochemical test and analyses were done to more than 400 samples of Lianggaoshan Formation from more than 10 oil-bearing shale wells in this area. The research results show that Lower Liang-2 Member and Upper Liang-1 Member have the highest abundance of organic matter, with average TOC contents of 1.57% and 0.81% respectively, the hydrocarbon generation potential (S+S) of rock pyrolysis is 2.63~5.59 mg/g, and the major type of kerogen are II and II. The reflectivity of the vitrinite of lacustrine shale is between 0.98% and 1.46%, which has the characteristics of mature to highly mature evolution. Based on the geochemical characteristics of the lacustrine organic matter in Lianggaoshan Formation, three different kerogen hydrocarbon generation kinetic models were established with reference to the principle of volume dynamics, which effectively restored the hydrocarbon generation and expulsion history of the mud shale in Lianggaoshan Formation in Fuling Area. The simulation results show that the hydrocarbon generation conversion rate of the mud shale of Lianggaoshan Formation in Fuling Area is 65.0%~98.2%, the hydrocarbon generation evolution process has a “single peak” characteristic, and the maximum hydrocarbon production rate is 5.15~18.50 mg/(g·Ma). The total hydrocarbon generation volume is 630 000 to 1 440 000 t. The hydrocarbon generation potential of source rocks is controlled by the sedimentary environment: from lake-side lakes to shallow lakes to semi-deep lakes, the hydrocarbon generation conversion rate, the maximum hydrocarbon production rate and the total amount of hydrocarbon generation show a gradual increase trend, of which semi-deep lake facies shale is the highest quality source rock in Fuling Area, which is mostly distributed in the area of TL7–YX1–TY1, and is the most favorable continental shale oil enrichment area in this area.

10.11885/j.issn.1674-5086.2021.11.29.02