玛湖凹陷及周缘二叠系超压分布特征及成因研究  

Pressure distribution characteristics and overpressure genesis of the Permian formation in Mahu Sag and surrounding areas

作　　者：张泽[1,2] 常健 单祥[3] 李晨星 郭华军 彭博 徐甲博 黄越 Zhang Ze;Chang Jian;Shan Xiang;Li Chenxing;Guo Huajun;Peng Bo;Xu Jiabo;Huang Yue(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249;College of Geosciences,China University of Petroleum,Beijing 102249;PetroChina Hangzhou Research Institute of Geology,Hangzhou 310023)

机构地区：[1]中国石油大学(北京)油气资源与工程全国重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249 [3]中国石油杭州地质研究院,杭州310023

出　　处：《地质科学》2024年第5期1229-1244,共16页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国石油天然气股份有限公司“十四五”基础性前瞻性重大科技项目(编号:2021DJ0202,2021DJ0108);中国石油天然气股份有限公司科技专项(编号:2023ZZ24-01)资助。

摘　　要：最新钻井显示玛湖凹陷二叠系碎屑岩层普遍存在超压,但超压分布不明且超压主控因素研究相对薄弱。本文旨在分析玛湖凹陷地区二叠系异常压力纵向和平面的分布规律,明确异常压力的主控因素,阐述超压形成机制,揭示超压与油气分布之间的联系。利用65口井的79个实测压力数据、钻井泥浆密度以及测井曲线资料等,采用测井曲线分析法、Bowers法和密度—声波速度交会图法,运用平衡深度法和Eaton法预测压力,在此基础上结合超压发育的地质环境综合讨论了其形成的主要原因。玛湖凹陷地区异常压力存在于三叠系白碱滩组及以下地层,下部地层压力逐渐增大,垂向上压力具有单一结构特征。下乌尔禾组异常压力由乌夏断裂带向东南方向逐渐增大,在达巴松凸起压力系数最高达2.0。烃源岩的生烃增压效应是形成玛湖凹陷地区超压的重要因素,玛南斜坡的下乌尔禾组及中拐凸起的上乌尔禾组为不均衡压实和生烃增压复合成因,而风城组为构造挤压与生烃增压复合成因,达巴松凸起下乌尔禾组为流体膨胀和压力传导成因。由于玛湖凹陷西斜坡区断裂发育,构造挤压造成的超压已散失,仅留下具有构造挤压形成的测井曲线的超压响应特征,现今的超压还是以生烃增压为主,产生的超压为油气运移提供动力;构造活动产生的断裂作为油气运移和压力传导的路径,影响了该地区的异常压力大小与油气的垂向分布。Recent drilling examples have revealed the widespread existence of overpressure in the Permian clastic rock layers of the Mahu Sag,but the distribution of overpressure remains unclear and the research on the main controlling factors of overpressure are relatively weak.This paper aims to analyze the vertical and horizontal distribution patterns of abnormal pressure in the Permian of the Mahu Sag,clarify the main controlling factors of abnormal pressure,elaborate the formation mechanism of overpressure,and reveal the relationship between overpressure and oil and gas distribution.Using 79 measured pressure data from 65 wells,drilling mud density and well logging curve data,this study employed well logging curve analysis,Bowers method,and density-acoustic velocity crossplot method to predict pressure using the equilibrium depth method and Eaton method.Based on these predictions,the main reasons for the formation of overpressure were comprehensively discussed in combination with the geological environment of overpressure development.Abnormal pressure in the Mahu Sag exists in the Triassic Baijiantan Formation and underlying strata,with gradually increasing pressure in the lower strata and a single structural characteristic vertically.The abnormal pressure in the Lower Wuerhe Formation gradually increases from the Wuxia Fault Zone to the southeast direction,reaching a maximum pressure coefficient of 2.0 in the Dabasong Bulge.The hydrocarbon generation and pressure increase effect of source rocks is an important factor in the formation of overpressure in the Mahu Sag.The Lower Wuerhe Formation in the Manan slope and the Upper Wuerhe Formation in the Zhongguai Bulge are caused by a combination of unbalanced compaction and hydrocarbon generation pressure increase,while the Fengcheng Formation is caused by a combination of tectonic compression and hydrocarbon generation pressure increase.The Lower Wuerhe Formation in the Dabasong Bulge is caused by fluid expansion and pressure conduction.Due to the development of faults in

关 键 词：玛湖凹陷 二叠系 地层压力分布 超压成因 压力预测 

分 类 号：TE122[石油与天然气工程—油气勘探]