高石梯-磨溪区块碳酸盐岩储层孔隙连通性综合评价

(1.中国石油大学(华东)地球科学与技术学院,山东 青岛 266580; 2.中国石油集团测井有限公司 西南分公司,重庆 400021)

地质资源与地质工程; 孔隙连通性; X射线CT扫描; 碳酸盐岩储层; 孔隙结构; 数字岩心

Comprehensive evaluation of pore connectivity in carbonate reservoirs of Gaoshiti-Moxi block
CUI Li-kai1,SUN Jian-meng1,HUANG Hong2,ZHANG Zhe-fu1,WANG Yong-jun2,CHI Peng1

(1.School of Geosciences,China University of Petroleum,Qingdao 266580,China; 2.South West Branch,China Petroleum Logging Co.,Ltd.,Chongqing 400021,China)

geological resources and geological engineering; pore connectivity; X-ray CT scanning; carbonate reservoir; pore structure; digital core

DOI: 10.13800/j.cnki.xakjdxxb.2019.0411

备注

碳酸盐岩储层发育有孔隙、洞穴和裂缝3种储集空间,孔隙空间组合关系复杂多样,储层物性差异大,均质性差,连通性评价难度大。为了综合评价碳酸盐岩储层孔隙连通性,以X射线CT扫描成像和数字岩心技术为基础,以四川盆地川中地区高石梯-磨溪区块龙王庙组和灯影组碳酸盐岩为例,将孔隙划分为主要孔隙、次要孔隙和死孔隙3种类型,从定性与定量2个方面开展碳酸盐岩孔隙连通性综合评价。结果 表明:研究区储层以溶蚀孔隙和溶蚀孔洞为主,同时裂缝较为发育,对储层渗流能力具有显著的改善作用。此外,连通性计算结果表明岩心主要孔隙连通率较高,平均占总孔隙体积的60%以上。主要孔隙占总孔隙的比值与储层渗流能力总体呈正相关关系。通过孔隙结构参数综合分析,对于高孔低渗的样品,孔隙为主要储集空间,但储层渗流能力受喉道半径和配位数影响较大; 对于低孔高渗的样品,喉道及配位数对流体渗流控制能力很小,但裂缝及溶洞显著提高了储层孔隙连通性,有效改善了储层的渗流能力。

There are three types of reservoir spaces in carbonate reservoirs,including pores,caves and fractures.The combination of pore space is diverse,and the reservoir has strong heterogeneity and differs greatly in physical properties,therefore it is difficult to conduct a connectivity evaluation.For comprehensive evaluation of carbonate reservoir pore connectivity,based on X-ray CT scanning and digital core physics,taking the carbonate rocks from Longwangmiao Formation and Dengying Formation of Gaoshiti-Moxi block in Sichuan basin as examples,the pore space was divided into three types,primary pores,secondary pores and dead pores.The comprehensive evaluation of pore connectivity was carried out from both qualitative and quantitative aspects.The results show that the reservoir in the study area is dominated by dissolution pores and dissolution caves.The fractures are also developed,which can significantly improve the permeability of the reservoir.In addition,the results of connectivity calculation show that the connectivity of primary pores is high,accounting for more than 60% of the total pore volume.The ratio of primary pores to total pores is positively correlated with reservoir permeability.Through the comprehensive analyzation of the pore structure parameters,for the samples with high porosity and low permeability,the pores are the main storage space,while the permeability of reservoir is obviously controlled by throat radius and coordination number.For the samples with low porosity and high permeability,the throat and coordination number have little control over permeability.The existence of fractures and caves,however,can improve the pore connectivity,thus promoting the permeability of reservoirs effectively.