CT扫描技术在低渗透砂岩岩心试验中的应用

Application of computed tomography scanning technology in low-permeability sandstone core test

梁亚宁 张士诚 叶银珠 韩秀玲 段鹏辉

LIANG Yaning ZHANG Shicheng YE Yinzhu HAN Xiuling DUAN Penghui

中国石油大学石油工程教育部重点试验室，北京　102249 中国石油勘探开发研究院，北京　100083 中国石油长庆油田分公司超低渗透油藏研究中心，陕西西安　710018

MOE Key Laboratory of Petroleum Engineering in China University of Petroleum, Beijing 102249, China Research Institute of Exploration and Development, PetroChina, Beijing 100083, China Research Center of Ultra-low Permeability Reservoir of Changqing Oil field, PetroChina, Xi’an 710018, China

CT扫描技术能够观测到岩心内部的结构变化情况，在碳酸盐岩岩心试验应用较多。以低渗透砂岩岩心为基础进行CT扫描分析，首先分析CT技术的基本原理，然后按照一定的方法和步骤对某区块气层岩心进行试验，最后按照CT扫描步骤进行扫描分析，并从3个方面对岩心进行分析：干岩心的CT数、岩心的孔隙度及分布特征、力学试验前后的CT扫描。由试验结果可以观察到，岩心越致密，其CT数值相对就越大；CT试验分析的岩心孔隙度值同测量值非常接近；岩心在受力条件下破裂，其裂纹呈现多样化特点。试验结果认为，CT扫描能够判断岩心的致密程度，并且能够确定岩心的孔隙度值，同时能够观察岩心破裂后的裂缝变化情况，便于低渗透岩心裂缝扩展的研究。

Computed Tomography (CT), by which the internal change of core scan can be observed, is used more often in carbonate core test. On the basis of low-permeability sandstone cores CT scanning analysis, this paper firstly demonstrates the basic principles of Computed Tomography, and then conducts gas core test based on given test method and steps, finally does core analysis in terms of CT scanning steps from three aspects: one is the CT number of dry core; second is core porosity and distribution; and the last is CT scanning of core before and after the mechanical test. Test results show that the tighter the core, the more the CT number; the core porosity from analysis of CT test is very close to the experiment measured value; the core gives birth to diversified fractures under a certain force. Conclusion has been drawn from the results, CT scanning can diagnose the coMPact degree of cores, determine core porosity and meanwhile observe core fracture change after the core fractured, which supplies references to the study of low-permeability core fracture extension.