基于CT扫描的碳酸盐岩储层微观孔隙结构分形表征——以延安气田马家沟组为例  

Fractal Characterization of Microscopic Pore Structure of Carbonate Reservoirs Based on CT Scanning——A Case Study of Majiagou Formation in Yan′an Gas Field

作　　者：杨澜 马瑶 王超 相金元 石堃 王妍[6] Yang Lan;Ma Yao;Wang Chao;Xiang Jinyuan;Shi Kun;Wang Yan(School of Earth Science and Engineering,Xi'an Shiyou University,Xi'an Shanxi 710065;Shaanxi Province Key Laboratory of Hydrocarbon Accumulation,Xi'an Shaanxi 710065;Shaanxi Coal Group Yulin Chemical Co.,Ltd.,Yulin Shaanxi 719000;Engineering Technology Department,CNPC Western Drilling Engineering Co.,Ltd.,Urumqi Xinjiang 83001l;Natural Gas Evaluation Project Department,Changqing Oilfield Company,Qingyang Gansu 745000;School of Petroleum Engineering,Xi'an Shiyou University,Xi'an Shaanxi 710065)

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065 [2]陕西省油气成藏重点实验室,陕西西安710065 [3]陕煤集团榆林化学有限责任公司,陕西榆林719000 [4]中国石油集团西部钻探工程有限公司工程技术处,新疆乌鲁木齐830011 [5]长庆油田分公司天然气评价项目部,甘肃庆阳745000 [6]西安石油大学石油工程学院,陕西西安710065

出　　处：《中外能源》2022年第12期50-55,共6页Sino-Global Energy

基　　金：西北大学大陆动力学国家重点实验室开放课题基金资助“基于机器学习的致密砂岩储层分类”(编号:21LCD01);西安石油大学研究生创新与实践能力计划资助项目“基于分形理论的致密砂岩储层微观结构研究”(编号:YCS21213182)。

摘　　要：碳酸盐岩是世界上重要的油气储层类型之一,在多种多样的成岩作用下,其微观孔隙结构较为复杂,研究碳酸盐岩储层微观孔隙结构有助于合理评价储层。现根据分形理论的自相似性,选取延安气田马五12溶洞、裂缝较为发育的碳酸盐岩样品,运用CT扫描获取原始灰度图像,结合图像处理软件对其进行图像预处理获得二值图像,并求取分形孔隙度与分形维数。从精细化、无损化、直观化角度表征碳酸盐岩样品微观孔隙结构的复杂性和非均质性。研究结果表明,分形维数可以表征微观孔隙结构的非均质性,该样品分形维数介于1~2之间,分形维数越接近2,孔隙结构越复杂,微观孔隙结构非均质性越强;分形孔隙度与分形维数呈负相关,且该样品孔隙结构的连通性一般。因此基于CT图像的分形表征不仅在碳酸盐岩储层微观孔隙结构的直观刻画与定量描述方面具有显著优势,而且为后续评价延安气田马家沟组碳酸盐岩储层提供理论依据。Carbonate rock is one of the important types of oil and gas reservoirs in the world,and its microscopic pore structure is relatively complex under various diagenesis.The study on the microscopic pore structure of carbonate reservoirs is helpful to evaluate the reservoirs reasonably.According to the self-similarity of the fractal theory,the samples of carbonate rocks with well-developed karst caves and fractures in Ma512of Yan′an Gas Field are selected to obtain original gray images by CT scanning,the binary image is preprocessed by image processing software,and the fractal porosity and fractal dimension are calculated.The complexity and heterogeneity of the microscopic pore structure of carbonate rock samples are characterized in a refinement,nondestructive and intuitive way.The study results show that the fractal dimension can be used to characterize the heterogeneity of the microscopic pore structure.The fractal dimension of the sample is between 1 and 2.The closer the fractal dimension is to 2,the more complex the pore structure is,the higher the heterogeneity of the microscopic pore structure.The fractal porosity is negatively correlated with the fractal dimension,and the connectivity of pore structure of the samples is general.Therefore,the fractal characterization based on CT images has obvious advantages in the intuitive characterization and quantitative description of the microscopic pore structure of carbonate reservoirs,which provides a theoretical basis for the subsequent evaluation of the carbonate reservoirs in the Majiagou Formation in Yan′an Gas Field.

关 键 词：延安气田 马家沟组 CT扫描 孔隙结构 分形维数 

分 类 号：P618.13[天文地球—矿床学]