摘要
滨岸砂坝是南亚地区S区块主要的油气储层类型和勘探目标,一般认为滨岸砂坝储层具有“连通性好、高孔高渗”的特点,然而随着油气田评价开发的深入,发现该类型砂岩内部储层物性变化快、非均质性强,油气分布复杂。利用岩心、测井、地震和生产测试资料,开展滨岸砂坝储层精细描述,阐明砂坝储层内部差异性。结果表明:1)滨岸砂坝体处于相对高能的海岸沉积环境,长期受到波浪的淘洗改造作用,构成有利的岩性储层发育区带。2)滨岸砂坝细分为坝中、坝缘、坝间及泥岩隔层四种微相类型,沉积微相控制储集性能变化。坝中微相为纯砂岩,厚度大、地震相表现为低频强振幅反射,岩性以中—细砂岩为主,原生孔隙和次生孔隙均发育,储集性能最佳。坝缘微相处于砂坝侧翼,岩性变细,部分孔隙被充填,储层物性中等。坝间微相处于不同叠置砂坝之间,以微孔隙为主,储集性能较差。浅海或者局限海湾相泥岩隔层穿插于砂坝内部,加剧了储层的非均质性。3)砂坝储集性能的变化导致油气分布复杂。滨岸砂坝内部因不同微相类型岩性相互叠置,表现为砂坝内井间砂体厚度变化块、横向不连通且物性变化快,砂坝油藏被切割成若干相对独立的油藏。
Shoreland sandbars are the main hydrocarbon reservoir type and exploration target in S Block,South Asia area. Sandbar reservoirs usually feature high porosity and high permeability. However,further evaluation of the oil and gas field has found that the internal physical properties of sandbar reservoirs change rapidly. They are strongly heterogeneous with complex distribution of oil and gas. Core logging,seismic and production test data,detailed reservoir description and microfacies prediction of a sandbar were carried out in this study of sandbar,and internal differences in the reservoir were analyzed,with the following results:(1)The shoreland sandbar is located in a relatively high-energy coastal sedimentary environment and has experienced long-term wave washing,forming a favorable reservoir zone.(2)The sandbar complex is subdivided into four microfacies types:center bar,bar edge,interbar and mudstone interbeds. The sedimentary microfacies influence the reservoir properties. The center bar comprises a thick,pure,mainly medium-fine sandstone in which the facies seismicity is seen as low-frequency,high-amplitude reflections. Both primary and secondary pores are relatively well developed,giving the best reservoir performance.The bar edge microfacies are located on the flank of the sandbar. The lithology is fine-grained with some filled pores,giving a medium reservoir performance. Interbar facies,located between sandbars,contain mainly micropores with poor storage performance. The mudstone facies are shallow sea or confined bay deposits,and are interspersed throughout the sandbar,intensifying the reservoir heterogeneity.(3)The changes in the physical properties of sandbar reservoirs directly increases the complexity of the reservoir characteristics. Because the lithologies of the different microfacies overlap and intersect within the sandbar,it is not connected horizontally and the physical properties change rapidly. To summarize,the sandbar reservoir is cut into several relatively independent oil reservoirs.
作者
董玉文
桂志先
欧荣生
陈旭
宋昊
柯钦
董孟玲
DONG YuWen;GUI ZhiXian;OU RongSheng;CHEN Xu;SONG Hao;KE Qin;DONG MengLing(Hubei Key Laboratory of Petroleum Geochemisty and Environment(Yangtze University),Wuhan 430100,China;Exploration Department of Qinghai Oilfield,CNPC,Dunhuang,Gansu 736202,China;Institute of Mud Logging Technology and Engineering,Yangtze University,Jingzhou,Hubei 434023,China;Research Institute of Geophysics,Bureau of Geophysical Prospecting,CNPC,Zhuozhou,Hebei 072750,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2022年第3期838-848,共11页
Acta Sedimentologica Sinica
基金
湖北省青年自然科学基金(2020CFB372)
湖北省教育厅项目(B2021047)。
关键词
滨岸砂坝
沉积微相
内幕差异性
岩性油气藏
shoreland sandbar
sedimentary microfacies
internal difference
lithological reservoir
