黄河口凹陷古近系地层结构新认识与勘探潜力评价  

Insights of Paleogene stratigraphic structure and evaluation of exploration potential of Huanghekou Sag

作　　者：王改卫 张海义 郭轩 王孝辕 汪晶 WANG Gaiwei;ZHANG Haiyi;GUO Xuan;WANG Xiaoyuan;WANG Jing(Bohai Oilfield Research Institute,Tianjin Branch,CNOOC China Company Limited,Tianjin City,300459,China)

机构地区：[1]中海石油(中国)有限公司天津分公司渤海石油研究院,天津300459

出　　处：《油气地质与采收率》2020年第5期1-12,共12页Petroleum Geology and Recovery Efficiency

基　　金：“十三五”国家科技重大专项“渤海海域勘探新领域及关键技术研究”(2016ZX05024-003);“十三五”全国油气资源评价项目“中海油矿权区油气资源评价”(2017YQZYPJ0109)。

摘　　要：黄河口凹陷位于渤海湾盆地济阳坳陷东北部,由于缺乏完整的三维地震资料,且局部三维地震资料中深层成像条件差,难以进行全区对比,导致研究区存在中深层凹陷结构认识不清、古近系地层划分归属全区认识不统一、孔店组―沙四段地层厚度及平面展布特征与围区存在较大差异等问题。在中浅层持续勘探过程中发现油气资源规模与上报储量不匹配、缺乏勘探接力层系等问题,严重制约勘探进程。为此,利用研究区全新的三维大连片地震数据,结合新钻井岩性、古生物、锆石、同位素测年等资料,开展古近系区域地层对比及演化规律研究。落实各级不整合面归属,调整孔店组―沙四段与沙三段的分界,明确新生界底界。调整后,沙三段底界最大下移深度达900 m,新生界底界最大下移深度达2300 m,并新增一套勘探层系。地层结构新认识明确了黄河口凹陷箕状结构特征,落实了孔店组―沙四段展布规律。根据新认识对研究区油气资源规模进行重新计算,新增油气资源量7.4×10^8 t,解决了油气资源规模与上报储量不匹配的矛盾。通过拓展中深层勘探层系,在孔店组落实一批具有较大勘探潜力的有利构造圈闭。Huanghekou Sag is located in the northeast of Jiyang Depression in Bohai Bay Basin.Due to the lack of unified 3D seismic data and poor quality of regional mid-deep seismic imaging in 3D seismic data,it is difficult to carry out the whole area correlation and results in many problems,such as unclear recognition of mid-deep sag structure,inconsistent understanding of the division of the Paleogene strata in the whole area,serious difference of the strata thickness and their distribution regularity of Kongdian Formation-the fourth member of Shahejie Formation(Ek-Es4)with the surrounding area.In the process of continuous exploration in mid-shallow strata,problems such as the mismatch between the hydrocarbon resources and the reported reserves and the lack of new exploration strata have severely restricted the exploration process.To this end,the new three-dimensional contiguous seismic data are used and the lithology,paleontology,zircon,isotopic dating and other data of new drilled wells in the study area,etc.are integrated to study the regional stratigraphic correlation and evolution of Paleogene.The attribution of unconformities at all levels are defined,the interface between Es3 and Ek-Es4 is adjusted,and the Cenozoic bottom surface is recognized.After the adjustment,the bottom surface of the Es3 has been move downward by 900 m,the bottom surface of the Cenozoic has been move downward by 2300 m,and new exploration strata of Ek-Es4 has been found.According to the new understanding of the stratigraphic structure,Huanghekou Sag is defined with a dustpan style and the distribution characteristics of Ek-Es4 has been clarified.The scale of hydrocarbon resources in the study area is recalculated with an increase of 740 million tons,and the contradiction between resource and reserves reported has been solved.The mid-deep strata with a number of favorable traps in Kongdian Formation has greatexploration potential.

关 键 词：古近系 地层结构 油气资源规模 有利目标 孔店组 黄河口凹陷 

分 类 号：TE122[石油与天然气工程—油气勘探]