裂缝发育程度对低孔隙度岩石渗流特性的影响  

Influence of Fracture Development on Seepage Characteristics of Low-porosity Rocks

作　　者：尚锁贵 高科超 高强勇 马金鑫 王培春 迟蓬 邢会林 闫伟超 SHANG Suo-gui;GAO Ke-chao;GAO Qiang-yong;MA Jin-xin;WANG Pei-chun;CHI Peng;XING Hui-in;YAN Wei-chao(Tianjin Branch of CNOOC Ltd.,Tianjin 300459,China;Bohai Oilfield Research Institute,Tianjin Branch,CNOOC Ltd.,Tianjin 300459,China;School of Geosciences,China University of Petroleum(East China),Qingdao 266580,China;Frontiers Science Center for Deep Ocean Multispheres and Earth System,Key Lab of Submarine Geosciences and Prospecting Techniques,MOE and College of Marine Geosciences,Ocean University of China,Qingdao 266100,China)

机构地区：[1]中海石油(中国)有限公司天津分公司,天津300459 [2]中海石油天津分公司渤海石油研究院,天津300459 [3]中国石油大学(华东)地球科学与技术学院,青岛266580 [4]深海圈层与地球系统教育部前沿科学中心,海底科学与探测技术教育部重点实验室,中国海洋大学海洋地球科学学院,青岛266100

出　　处：《科学技术与工程》2023年第23期9809-9819,共11页Science Technology and Engineering

基　　金：国家自然科学基金(52074251,92058211);山东省自然科学基金(ZR2020QD054)。

摘　　要：低孔隙度岩石中的裂缝对储层渗透率具有重要影响,但裂缝的存在导致岩心代表性样品选取和高精度岩石物理参数测量困难。为研究裂缝对低孔隙度岩石渗透率的影响,通过高精度电子计算机断层扫描(computed tomography,CT)实验构建了低孔隙度岩石的三维数字岩心模型,采用添加平板裂缝的方法构建了不同裂缝参数的低孔隙度岩石数字岩心,并利用格子玻尔兹曼(lattice Boltzmann method,LBM)方法计算了不同裂缝参数数字岩心模型的渗流场分布和绝对渗透率。结果表明,尽管低孔隙度岩石的数字岩心模型基质渗透率低,但裂缝的存在对岩石渗透率有一定程度的提高。然而,裂缝发育程度对渗透率影响规律不同:当单条裂缝孔隙度在0~0.4%时,裂缝对模型渗透率影响不明显;当单条裂缝孔隙度大于0.4%时,裂缝对模型渗透率具有显著影响;模型渗透率随裂缝开度增大而增大,随裂缝倾角增大而减小,随裂缝数量增加而增大。另外,裂缝与基质存在耦合作用,与裂缝相连的孔隙中流体流速明显提高,显示裂缝对基质孔隙的强连通作用。本研究结果对含裂缝的低孔隙度储层渗透率精确计算及储层压裂后的油气产能评价有指导意义。Fractures in low-porosity rocks have an important influence on reservoir permeability,but it is difficult to select repre-sentative rock samples and measure petrophysical parameters with high accuracy due to the presence of fractures.To study the influence of fractures on the permeability of low-porosity rocks,3D low-porosity digital rocks were constructed by high-precision CT(computed tomography)scanning experiments.The method of adding flat fractures to construct low-porosity digital rocks with different fracture pa-rameters was used,and the distributions of seepage fields and absolute permeabilities of digital rocks with different fracture parameters using the lattice Boltzmann method(LBM)were calculated.The results show that although the matrix permeability of the low-porosity digital rock is low,the presence of fracture increases the permeability of the rocks to some extent.However,the degree of fracture de-velopment has different patterns of influence on permeability.When the porosity of a single fracture is in the range of 0~0.4%,the fracture has no significant influence on the rocks permeability.However,when the porosity of a single fracture is greater than 0.4%,the fracture has a significant influence on the rocks permeability.The rocks permeability increases with increasing fracture aperture,decreases with increasing fracture dip,and increases with increasing fracture number.In addition,there is a coupling effect between the fracture and the matrix,and the fluid flow rate in the matrix pores connected with the fracture is significantly increased,showing the strong connecting effect of the fracture on the matrix pores.The results are instructive for accurate calculation of permeability of low-po-rosity reservoirs and evaluating oil/gas production after fracturing.

关 键 词：低孔隙度岩石 裂缝 数字岩心 渗透率 

分 类 号：P618.13[天文地球—矿床学]