渤南洼陷页岩生烃组分动力学分析及其对页岩油气勘探的意义

Kinetic analysis of hydrocarbon generation components in shales from the Bonan sub-Sag and its significance for hydrocarbon exploration

蒋启贵 申宝剑 仰云峰 李志明 马媛媛 钱门辉

Jiang Qigui Shen Baojian Yang Yunfeng Li Zhiming Ma Yuanyuan Qian Menhui

中国石化油气成藏重点实验室, 江苏无锡 214151 2. 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

SINOPEC Key Laboratory of Hydrocarbon Accumulation, Wuxi, Jiangsu 214151, China 2. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

中国东部古近系页岩层系烃源岩有机质类型较好,成烃生物以浮游藻为主,主要为Ⅰ型有机质。利用热解色谱仪对Ⅰ型有机质进行了烃源岩生烃组分动力学分析,并结合热史外推地质过程,对渤南洼陷烃源岩层段页岩油气生成潜力、组分及含油饱和度进行了研究。渤南洼陷沙三中亚段烃源岩层系轻烃及重烃生烃转化率分别为31.1%和43.8%,已进入主生油期,如排烃不畅,则层系油饱和指数为273.24,有一定的页岩油潜能,但油质重,不利于页岩油开发;沙三下亚段(沙四上亚段)烃源岩层系轻烃及重烃生烃转化率分别为73%和83.5%,原油已大量生成,甲烷生烃转化率为33.2%,已进入大量生成甲烷阶段,湿气生烃转化率为58.1%,是生成湿气的高峰,如排烃不畅,则层系油饱和指数达571.17,且油气并存,弹性驱动力强,是页岩油开发重要目标区;沙四中及下亚段,生油已结束,是甲烷生成高峰期,如排烃效率低,已生成的原油将会裂解,除非形成超压体系,此时烃源岩层系主要是以气为主,应以页岩气勘探开发为主。

The Paleogene shales in the East China contain Type I organic matter comprised mainly of planktonic algae. A kinetic analysis of the hydrocarbon generation of this source rock was made using a pyrolysis-gas chromatograph. The hydrocarbon generation potential, composition and oil saturation of shales in the Bonan sub-Sag were studied in the context of the thermal history of the Shahejie Formation. The hydrocarbon conversion rates of light and heavy hydrocarbons in source rocks in the middle section of the third member of Shahejie Formation (Es3) are 31.1% and 43.8%, respectively, indicating the oil generation period. The oil saturation index might reach 273.24 mg/g, showing some shale oil potential. However, the oil is too heavy for exploitation. The lower section of Es3 (and the upper section of Es4) has a high oil saturation up to 571.17 mg/g and a high elastic force with coexisting oil and gas, and hence is an excellent target for shale oil exploitation. The middle and lower sections of Es4 arrived at the peak of methane generation. Any residual oil would have been cracked. Shale gas should be the main exploration focus unless an overpressure system developed.

国家重点基础研究计划(973计划)项目(2014CB239101)资助。

https://doi.org/10.11781/sysydz201602231