摘要
河流相沉积中蕴藏了大量以决口扇为代表的潜在储层,但有关决口扇的单独论述较少。该文以渤海湾盆地秦皇岛32-X油田为例,结合岩心、测井、分析化验等资料,对决口扇的沉积特征与储层物性进行详细研究。结果表明:在定性识别方面,决口扇粒度以细砂、粉-细砂为主,悬移质含量多为20%~50%,分选较差,磨圆为棱角状—次棱角状,岩相类型以块状层理细砂岩、沙纹层理细砂岩/粉砂质细砂岩、水平层理粉砂岩为主,成因序列以反韵律为主,单砂体厚度为0.2~3.0 m,砂体展布呈平面朵叶状、剖面楔状的特点;研究区决口扇的深双侧向电阻率值为1.8~7.5Ω·m,自然伽马值为68~82 API,且饱含油或富含油的决口扇其深双侧向电阻率值多为4.0~7.5Ω·m,并可以此作为定量识别的初步标准;研究区决口扇孔隙度平均值为29.26%,渗透率平均值为207.72 mD,属于高孔、中渗储层,为有利储层,但决口扇储层渗透性要远差于点坝与废弃河道。对决口扇进行深入研究有利于老油田挖潜增储并延长衰竭性老井的开采寿命。
Fluvial deposits contain a large number of potential reservoirs represented by crevasse splay,but there are few separate discussions on crevasse splay.Taking QHD 32-X Oilfield in the Bohai Bay Basin as an example,the sedimentary characteristics and reservoir physical properties of crevasse splays were studied in detail in combination with core,well logging,and laboratory data.The results show that:in terms of qualitative identification,the grain size of crevasse splays is mainly fine sandstone,and silty-fine sandstone;the content of suspended loads is mostly 20%-50%;the gradation is worse;the roundness is angular to sub-angular;the lithofacies types are mainly massive bedding fine sandstone,sandy bedding fine sandstone/silty fine sandstone and horizontal bedding siltstone;the genetic sequence is mainly reverse rhythm;the thickness of single sand body is 0.2-3.0 m,and the distribution of sand bodies is lobe shaped on plane and wedge shaped on section;deep dual laterolog resistivity(Rd)values of the crevasse splays in the study area are between 1.8-7.5Ω·m,with GR of 68-82 API;a crevasse splay that is saturated with oil or rich in oil has Rd values between 4.0-7.5Ω·m,which can be used as a preliminary criterion for quantitative identification;the crevasse splays in the study area have average porosity of 29.26% and average permeability of 207.72 mD,belonging to high-porosity and medium-permeability reservoir,with excellent reservoir potential;however,the permeability of crevasse splay reservoirs is much lower than that of point bar and abandoned channel.In-depth study of crevasse splays is conducive to tapping potential and increasing reserves in old oil fields and prolonging the production life of depleted old wells.
作者
陈薪凯
陈程
汪虎
Chen Xinkai;Chen Cheng;Wang Hu(China University of Geosciences(Beijing),Beijing 100083,China;CNPC Dagang Oilfield Company,Tianjin 300280,China)
出处
《特种油气藏》
CAS
CSCD
北大核心
2020年第5期22-29,138,共9页
Special Oil & Gas Reservoirs
基金
国家科技重大专项“大型油气田及煤层气开发及勘探评价”(2016ZX05060-002)。
关键词
河流相
决口扇
沉积特征
岩相类型
成因序列
储层物性
渤海湾盆地
fluvial facies
crevasse splay
sedimentary characteristics
lithofacies type
genetic sequence
reservoir physical properties
Bohai Bay Basin
