东海西湖凹陷地温场及其对烃源岩的作用

GEOTHERMAL FIELD AND ITS EFFECT ON SOURCE ROCK IN THE XIHU SAG, THE EAST CHINA SEA BASIN

仝志刚 贺清 何仕斌 杨树春 熊斌辉 郝建荣

Tong Zhigang He Qing He Shibin Yang Shuchun Xiong Binhui Hao Jianrong

中国地质大学, 能源学院, 北京, 100083 2. 中海石油(中国)有限公司 北京研究中心, 北京, 100027

Energy College, China University of Geosciences, Beijing 100083, China 2. Research Center, China National Offshore Oil Corporation, Beijing 100027, China

针对海上盆地钻井资料少的特点,利用地温与地层深度或岩石圈底界深度的相关性,把钻井地热研究结果外推到无井区域,建立了东海西湖凹陷的区域地温场,并分析其对烃源岩的作用。研究表明,凹陷北部和南部现今平均地温梯度较高,凹陷中部相对较低;平湖组烃源岩的热演化程度凹陷北部高于南部。尽管目前的储量发现集中在凹陷的西南部,但更要重视凹陷北部的勘探潜力。平湖组烃源岩的主要排烃期为30~10 Ma。西湖凹陷大构造、小油气藏的现象,可能是保存条件差,也可能是油气充注量不足造成的,加强圈闭形成期与烃源岩排烃期的匹配关系研究是下一步勘探取得突破的关键。

Extrapolating the geothermal analysis results of wells into the area without well on the corre-lativity between the temperature and the formation depth or the bottom of the lithosphere,this paper made the geothermal model of all the Xihu Sag in the East China Sea Basin,and analyzed its effect on the Pinghu Formation source rock.The result shows that the geothermal gradient in the northern and southern area is high.The maturity of the Pinghu Formation in the northern area is more than the one in the southern area.In despite of the reserves found in the southwest of the Xihu Sag,the explore potential of the northern area must be emphasized.Most of the hydrocarbon expelled from the Pinghu Formation during 30～10 Ma.The fact that the traps are large,but their hydrocarbon filling degree is little in the Xihu Sag,is the result of the absence of the preservation or the insufficient hydrocarbon charge.The study on the duration relationship between the trap formed and the hydrocarbon expelled is the key to find more reserves in the future in the Xihu Sag.

国家重大专项(2008ZX05023-01)

https://doi.org/10.11781/sysydz200905466