丽水凹陷幔源CO_(2)充注对油气成藏的影响  

Influence of mantle-source CO_(2) charging on hydrocarbon accumulation in Lishui Sag

作　　者：马文睿 MA Wenrui(Research Institute of Shanghai Branch of CNOOC(China)Limited,Shanghai 200338,China)

机构地区：[1]中海石油(中国)有限公司上海分公司研究院,上海200338

出　　处：《复杂油气藏》2023年第3期282-288,共7页Complex Hydrocarbon Reservoirs

基　　金：中海油“七年行动计划”课题(CNOOC-KJ 135 ZDXM39 SH02)。

摘　　要：丽水凹陷勘探中发现了许多圈闭含CO_(2),同位素分析显示以幔源无机成因为主。凹陷深大断裂附近未发现含CO_(2)气藏,而已发现CO_(2)气藏周边均有岩浆活动发育,故认为丽水凹陷幔源CO_(2)运聚与岩浆幕式活动必然存在联系。因此,油气勘探中为规避风险需开展岩浆活动期次与油气成藏期分析、关注岩浆活动区与圈闭距离、识别CO_(2)的断裂-砂体运移通道与圈闭的空间接触关系等。结合丽水凹陷烃源岩生排烃关键期和圈闭分布分析,认为烃源岩生烃高峰(56 Ma)后的第Ⅲ期(23.03 Ma)岩浆活动带来的幔源无机CO_(2)充注对油气藏可能具有占位和破坏作用,位于岩浆体纵向上直接与其搭接或与岩浆岩通过断裂间接搭连的圈闭含CO_(2)风险高。该研究结果对丽水凹陷油气勘探具有指导意义。During the exploration of the Lishui Sag,many traps containing CO_(2) were found,and isotopic analysis showed that mantlesource inorganic genesis was dominant.No CO_(2)-bearing gas reservoirs were found near the deep fault of the depression,but magmatic activities were found around the CO_(2) gas reservoir,so it is believed that there must be a relationship between the mantle-derived CO_(2) migration and accumulation and the magmatic episodic activities in the Lishui Sag.Therefore,to avoid risks in oil and gas exploration,it is necessary to carry out the analysis of the magmatic activity stage and hydrocarbon accumulation stage,pay attention to the distance between magmatic activity areas and traps,and identify the spatial contact relationship between CO_(2) fault-sand migration channels and traps.Combined with the analysis of the key period of hydrocarbon generation and expulsion of source rocks and the distribution of trap in the Lishui Sag,it is concluded that mantle-derived inorganic CO_(2) injection brought by magmatic activities in the third period(23.03Ma)after the peak of hydrocarbon generation(56Ma)may have an occupying and destructive effect on the reservoirs.The traps located in the longitudinal direction of magma bodies that are either directly connected to them or indirectly connected to them by fracture have a high risk of containing CO_(2).The research results are of guiding significance for oil and gas exploration in the Lishui Sag.

关 键 词：幔源CO_(2) 岩浆幕式活动 断裂-砂体运移通道 丽水凹陷 

分 类 号：TE132[石油与天然气工程—油气勘探]