渤海海域辽中凹陷南部古近系东营组三段重力流砂岩优质储层特征及成因  

Characteristics and origin of high-quality gravity-flow sandstone reservoirs in the 3rd member of the Dongying Formation,southern Liaozhong Sag,Bohai Sea

作　　者：王冠民[1] 庞小军[1,2] 黄晓波 张雪芳 潘凯 WANG Guanmin;PANG Xiaojun;HUANG Xiaobo;ZHANG Xuefang;PAN Kai(School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Tianjin Branch of CNOOC(China)Limited,Tianjin 300459,China)

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [2]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《石油与天然气地质》2024年第1期81-95,共15页Oil & Gas Geology

基　　金：国家自然科学基金项目(41972131);“十三五”国家科技重大专项(2016ZX05024-003)。

摘　　要：为解决渤海海域中-深层重力流砂岩储层物性差异大、优质储层预测较难的勘探难题,基于常规物性、铸体薄片、黏土矿物和地球化学等分析测试手段,结合测井、录井、岩心和地震等资料,研究了渤海海域辽中凹陷古近系东营组三段(东三段)深水重力流砂岩储层的沉积特征及优质储层主控因素。结果表明:渤海海域辽中凹陷东三段重力流的沉积类型为砂质碎屑流,储层以中-低孔、中-低渗为主。储集空间中的粒间溶蚀孔最发育,原生孔次之。中砂岩和粗砂岩储层物性最好,细砂岩次之,粉砂岩较差。控制优质储层发育的关键因素是:(1)物质基础好,表现为分选好、泥质含量低、富含长石。(2)东营组早成岩期的快速沉降形成欠压实超压条件,使原生孔隙得以大量保存;超压延长了有机酸的生成时间,为砂岩中的钾长石和方解石等矿物溶解提供了充足的酸性流体。(3)断层沟通了储层和烃源岩,进一步促进了中-深层储层的溶解作用,有利于大量溶蚀孔的形成。(4)构造抬升和侧向挤压造成的储层破裂作用又形成了大量裂缝和溶缝带,改善了储层物性。Gravity-flow sandstone reservoirs in the medium to deep parts of the Bohai Sea exhibit significantly varying physical properties,making it difficult to predict high-quality reservoirs.This study aims to address this oil/gas exploration challenge.Based on the analyses and tests of conventional physical properties,casting thin sections,clay mineralogy,and geochemistry,as well as data from well logging,core observations,and seismic survey,we investigate the sedimentary characteristics of the deep-water gravity-flow sandstone reservoirs in the 3rd member of the Dongying Formation(also referred to as the Dong 3 Member)in the Liaozhong Sag,as well as primary factors influencing the development of high-quality reservoirs.The results show that the gravity-flow deposits in the Dong 3Member in the study area are of the sandy debris flow type,with reservoirs primarily characterized by medium-to-low porosity and permeability.The storage spaces in the reservoirs are dominated by intergranular dissolution pores,followed by primary pores.Among the reservoirs,medium-and coarse-grained sandstones exhibit the optimal physical properties,followed by fine-grained sandstones,while siltstones show poor physical properties.The key factors influencing the development of high-quality reservoirs include:(1)Good sorting,low clay content,and feldspar enrichment act as the material basis for the formation of high-quality reservoirs;(2)In the early diagenesis stage of the Dongying Formation,the rapid subsidence led to undercompaction-induced overpressure,preserving numerous primary pores.During the hydrocarbon generation in the late stage,overpressure prolonged the generation period of organic acids,producing sufficient acidic fluids for the dissolution of minerals like potassium feldspar and calcite in sandstones;(3)Faults connected the reservoirs and source rocks,leading to enhanced dissolution in medium-deep reservoirs,which facilitated the formation of dissolution pores in quantity;(4)Tectonic uplift and lateral compression caused reservo

关 键 词：砂质碎屑流 超压 裂缝 优质储层 东营组 辽中凹陷 渤海海域 

分 类 号：TE122.1[石油与天然气工程—油气勘探]