低渗凝灰质砂岩储层孔隙结构特征及低渗成因——以珠江口盆地陆丰凹陷古近系文昌组为例  

Pore structure characterization and low-permeability genesis of low-permeability tuffaceous sandstone reservoirs:a case study of the Paleocene Wenchang Formation in the Lufeng Sag within the Pearl River Mouth Basin

作　　者：王菲 李晓艳 孙阳子 臧起彪 刘金良 田鑫 牛建成 杨志玲 王彦昭 孙梦迪 WANG Fei;LI Xiaoyan;SUN Yangzi;ZANG Qibiao;LIU Jinliang;TIAN Xin;NIU Jiancheng;YANG Zhiling;WANG Yanzhao;SUN Mengdi(Shenzhen Branch of CNOOC,Shenzhen,Guangdong 518067,China;National Key Laboratory of Continental Shale Oil,Northeast Petroleum University,Daqing,Heilongjiang 163318,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518067 [2]东北石油大学多资源协同陆相页岩油绿色开采全国重点实验室,黑龙江大庆163318

出　　处：《东北石油大学学报》2024年第4期54-68,I0004,I0005,共17页Journal of Northeast Petroleum University

基　　金：中海石油“十四五”重大科技项目(CCL2022SZPS0323)。

摘　　要：陆丰凹陷古近系文昌组为典型低渗凝灰质砂岩储层,复杂的孔隙结构和储层低渗特征制约研究区增储上产。利用铸体薄片观察、XRD全岩及黏土矿物分析、高压压汞、恒速压汞和CT扫描等实验,基于分形曲线特征和孔喉结构参数划分储层孔喉类型,分析储层物性及填隙物特征,精细表征砂岩储层的孔喉—孔隙结构,探讨不同类型储层的孔隙结构特征及其对物性的影响。结果表明:珠江口盆地陆丰凹陷古近系文昌组储层发育长石石英砂岩、岩屑石英砂岩和岩屑砂岩。储层孔喉结构划分3种类型,Ⅰ类储层为优质储层,储层物性最优,平均排驱压力约为0.1 MPa;Ⅱ类储层次之,排驱压力在0.5~1.0 MPa之间;Ⅲ类储层最差,排驱压力大于1.0 MPa。研究区储层低孔低渗特征是填隙物类型、溶蚀作用程度和蚀变产物性质等因素共同作用的结果,凝灰质填隙物大量充填原生孔隙空间,受溶蚀作用程度低是研究区储层低孔的主要原因,溶蚀作用产物易堵塞喉道是储层形成低渗特征的主控因素。该结果为研究区低渗储层划分及有效开发提供指导。The Wenchang Formation in the Lufeng Sag is a typical low-permeability sandstone reservoir.The complex pore structure and reservoir heterogeneity are the keys to restricting the increase in reserves and production in the study area.The pore throat structure of sandstone reservoirs in the study area was characterized by experimental methods such as casting thin section observation,high-pressure mercury intrusion and constant velocity mercury induction.The pore throat types of reservoirs are divided based on fractal curve characteristics and pore throat structure parameters,and the pore evolution patterns of different types of reservoirs and their impact on physical properties are discussed based on the physical properties of the reservoir and the properties of interstitial materials.The findings delineate the classification of reservoirs within the study area into three distinct categories:typeⅠreservoirs are identified as those of exceptional quality,possessing optimal physical attributes with an average discharge pressure of 0.1 MPa;typeⅡreservoirs are acclaimed as superior,exhibit discharge pressures predominantly within the range of 0.5 to 1.0 MPa;whereas typeⅢreservoirs are regarded as the least favorable,characteristically have discharge pressures exceeding 1.0 MPa.The observed low porosity and reduced permeability of the sandstone reservoirs in this area emerge from a synthesis of variables including the type of fill material,degree of solubility,and the properties of alteration by-products.Predominantly,the extensive infusion of tuffaceous material within the primary pore spaces,compounded by a modest extent of dissolution and erosion,is the principal contributor to the diminished porosity of these reservoirs.Concurrently,the by-products of these processes tend to obstruct the pore throats,thus playing a pivotal role in the genesis of the low-permeability attributes of the reservoirs under study.The results provide guidance for the division and effective development of low-permeability reservoirs.

关 键 词：凝灰质砂岩 砂岩储层 孔隙结构 低渗成因 文昌组 古近系 陆丰凹陷 珠江口盆地 

分 类 号：P624.7[天文地球—地质矿产勘探] TE122.23[天文地球—地质学]