砂砾质辫状河储层构型解剖及层次建模——以新疆油田重32井区齐古组油藏为例

Architecture Anatomy and Hierarchical Modeling of Sand⁃Gravel Braided River Reservoirs:A Case study of Zhong32 wells area,Qigu Formation reservoir,Fengceng oilfield

针对准噶尔盆地风城油田上侏罗统齐古组砂砾质辫状河储层,利用岩芯、露头及密井网资料,结合砂砾质辫状河储层构型层次结构、模式拟合和嵌入式层次建模方法,确定了不同级次的构型界面,对砂砾质辫状河5~3级构型单元进行了识别,建立了不同级别构型分布样式、规模及三维构型模型。研究表明:1)研究区砂砾质辫状河4级构型单元主要包括心滩坝和辫状水道两类,辫状水道包括泥质半充填水道和泥质充填水道等构型单元,砂砾质辫状河3级构型单元包括心滩坝内部沟道及落淤层等;2)根据辫状河不同级次构型单元规模公式,对辫状河不同级次构型单元进行定量表征,结果表明,研究区单一砂砾质河道宽度50~180 m;单一充填河道宽度30~70 m,长度100~350 m;单一心滩坝宽度120~400 m,长度300~800 m;心滩坝内部落淤层长度和宽度分别为110~330 m、60~200 m,沟道长度和宽度分别为100~200 m、15~25 m;3)在精细构型解剖研究的基础上,提出利用层次建模与嵌入式建模结合的新方法建立构型三维模型。分层次建立了4级构型模型,而在心滩坝内部则采用规模约束建立落淤层、沟道以及填充河道3级构型单元模型,最终建立了与定性模式和定量规模相适应的多级次耦合三维构型模型。

The sand⁃gravel braided river reservoir of the Upper Jurassic Qigu Formation in the Fengcheng Oilfield,Junggar Basin,was studied using data for outcrops,cores and dense wells.Pattern⁃fitting and embedded hierarchical modeling of the reservoir architecture and hierarchy were used to locate the interfaces of different grades.The 5⁃3 ar⁃chitecture units were identified,and the distribution patterns and 3⁃D architecture of different levels were estab⁃lished.These indicated that:(1)The sand⁃gravel braided river 4⁃level architecture unit in the study area mainly in⁃cludes two types:braided bar and braided channel.The braided channel includes shale semi⁃filled channels and ar⁃gillaceous filling channels.The sand⁃gravel braided river 3⁃level architecture unit is composed of an inner channel of the shoal bar and a silt layer.(2)Quantitative analysis of the different hierarchies of the braided river units,includ⁃ing calculation of the size of different sediment grades,indicated that the width of a single sand⁃gravel channel in the study area is 50⁃180 m,and the width of a single filled channel is 30⁃70 m,and they are about 100 m to about 350 m long.The width of a single braided bar was about 120⁃400 m and about 300⁃800 m long.The length and width of the silt layer in the inner braided bar were 110⁃330 m and 60⁃200 m,respectively.The mini⁃channel length and width were 100⁃200 m and about 15⁃25 m,respectively.(3)A study of the fine architectural anatomy,combined with its distribution pattern,were the basis for constructing a 3⁃D quantitative embedded architecture model of the study area.