致密混积岩储层物性及孔径分布影响因素——以辽河西部凹陷雷家地区杜家台油层杜三段为例  

Reservoir property and pore-throat characteristics of mixed tight sedimentation： A case study of Dujiatai pay set in Leijia district, western Liaohe depression

作　　者：汪少勇[1] 王社教[1] 李登华[1] 郑民[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《地质科学》2016年第2期448-459,共12页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国石油天然气集团公司重大专项“油气资源评价--中国石油第四次油气资源评价”（编号：2013E-0502）和国家科技重大专项（编号：2011ZX05028-002）资助.

摘　　要：研究储层物性控制因素对储层评价至关重要。致密混积岩储层所含矿物成分多样，孔隙结构复杂，造成储层物性变化大。辽河坳陷西部凹陷雷家地区沙河街组四段位于浅湖一半深湖相带，其中的杜家台油层杜三段发育方沸石、白云石、长石、石英等多种组分混积储层，具有较大的致密油资源潜力。根据矿物成分可以将杜三段储层分为泥晶云岩、细粒混积岩和方沸石岩3大类。铸体薄片分析与扫描电镜分析结合，发现3大类储层均发育中微米孔（孔喉半径〉10μm）一微微米孔（孔喉半径为1～10μm）一纳米孔（孔喉半径〈1μm）多级孔喉系统。中微米孔主要为粒间溶孔及白云石、方沸石晶间和晶内溶孔。微微米孔主要为白云石晶间孔、碎屑矿物粒间孔及部分微溶孔。大部分白云石晶内溶孔、粘土矿物晶间孔属于纳米孔。高压压汞分析结果表明，3类致密储层的孔径均具双峰特征。泥晶云岩类储层微微米孔的孔径峰值约为4μm，纳米孔的孔径峰值约为10nm，二者所占比例分别为25。1％和63．1％。细粒混积岩主要发育中微米孔及纳米孔，所占比例分别为20．9％和79．1％。方沸石岩类储层的中微米孔和纳米孔所占比例分别为12．1％和85．9％。不同矿物成分发育的孔隙类型及大小控制了混积岩储层的整体孔喉结构，是造成混积岩储层孔径分布呈双峰特征的主要原因。由于白云石晶间孔连通性好，方沸石主要以充填物的形式出现，长石一石英碎屑易溶蚀，粘土矿物主要发育纳米级晶间孔等原因，致密混积岩储层孔隙度与方沸石含量负相关，与长石一石英碎屑含量正相关。在储层中裂缝广泛发育的背景下，致密混积岩矿物成分与渗透率相关性差。Due to the mineral composition complexity, mixed tight sedimentation develop complicated pore structures and varies reservoir properties. The mixed tight dolomite-analcite sedimentation has tight oil resource potential in Dujiatai pay set in the fourth Member of Shahejie Formation in Leijia district, western Liaohe depression. The mixed tight reservoir were divided as dolomicrite, fine grained diamictite and analcimolith based on X-ray powder diffraction （XRD） analysis. Casting thin sections and high resolution FIB/SEM image analysis are used to study the reservoir space types. It showed that these tight reservoirs have meso-micron, micro-micron and nano pore-throat system. Meso-micron pore throat （with pore throat radii above 10 Ixm） include intergranular dissolved pore, intergranular pore, and dolomite/analcime intracrystal dissolved pores. Micro-micron pore throat（with pore throat radii between 1 μm to 10 μm） include dolomite intercrystal pore, detrital minerals intergranular pore and some dissolved micro-pores. While most dolomite intracrystal solution pores and intergranular pores of clay minerals are nanopores, with radius below 1 μm. Mercury Injection Capillary Pressure was used to find pore size distribution of the three kinds of reservoirs. It showed the pore throat radius have duplex peak. The pore throat radius of dolomicrite is found to be around 10 nm within a nanopore range and around 4 μm within a micro-micron pore range. The proportion of the nanopore and micro-micron pore is 63.1% and 25.1% respectively. While the proportion of the nanopore and micro-micron pore is 79.1% and 20.9% in fine grained diamictite. The proportion of the nanopore and micro-micron pore is 79.1% and 20.9% respectively in analcimolith. The pore type and size of mixed tight reservoir are mainly controlled by mineral components. The pores complexities controlled by different mineral components are the main reason for duplex peak pore throat radius. The dolomite intergranular pores have good connectivity. Analc

关 键 词：储层物性 致密混积岩 孔径分布 雷家地区 

分 类 号：TE121.15[石油与天然气工程—油气勘探]