基于CT扫描的三维数字岩心孔隙结构表征方法及应用——以莫北油田116井区三工河组为例

Characterization Technique of Pore Structure by 3D Digital Core Based on CT Scanning and Its Application: An Example from Sangonghe Formation of 116 Well Field in Mobei Oilfield

为真实、精确、直观地表征储集层岩石的孔隙结构特征,对不同岩性的岩心样品进行CT扫描成像并构建三维数字岩心,应用最大球算法提取数字岩心的孔隙网络模型,最终实现岩心孔隙结构特征的三维显示和定量表征。该方法在莫北油田116井区三工河组储层应用取得良好效果,研究表明:该区储层孔隙类型以粒间孔、溶蚀孔和少量晶间孔为主,平均孔隙半径33.11μm,平均喉道半径1.47μm,喉道细小是造成研究区储层渗透率低的主要原因;与核磁共振Coates模型渗透率计算结果相比,数字岩心技术对于渗透率的计算更加精确;数字岩心孔隙结构表征结果与常规压汞资料对比,一致性较好,该技术还可定量识别孔隙和喉道,并具有形象直观、样品无损等特点,对于岩石孔隙结构的表征具有更大的优势。

In order to characterize the pore structure of reservoir rock really,accurately and intuitively,differ-ent rock cores are scanned by CT imaging technology and the 3D digital cores are reconstructed.Then the model of pore network is extracted by maximal ball algorithm form the 3D digital core.And finally the reservoir proper-ties and pore structure parameters are characterized quantitatively.This method of pore structure characterization has a good result after it is applied in Sangonghe Formation of 1 1 6 well field in Mobei oilfield.Our research indicates that the pore type here is mainly intergranular pore,emposieu pore and a little intercrystal pore.The average pore radius is 33.1 1 μm and the throat radius is 1.47 μm.The small throat is the main reason of low permeability in this area.Compared with the result of NMR Coates model,digital core can give a more accurate permeability result.The pore structure of digital core has a good concordance with mercury penetration result. However,the digital core method can identify the pore and throat respectively and it is more vivid,more direct, more accurate with little sample broken.So it is more applicative for pore structure characterization.