不同渗透率储层超临界CO_(2)改造模拟研究  

MODELING STUDY ON THE S-CO_(2) FRACTURING OF RESERVOIRS WITH DIFFERENT ROCK MATRIX PERMEABILITY

作　　者：孙景行 孙晓冬 郭东明[1] 李守定[2] 赫建明[2] SUN Jingxing;SUN Xiaodong;GUO Dongming;LI Shouding;HE Jianming(School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;Key Laboratory of Shale Gas and Geo-engineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;CCTEG Coal Mining Research Institute,Beijing 100013,China)

机构地区：[1]中国矿业大学(北京),力学与土木工程学院,北京100083 [2]中国科学院地质与地球物理研究所,中国科学院页岩气与地质工程重点实验室,北京100029 [3]中煤科工开采研究院有限公司,北京100013

出　　处：《工程地质学报》2024年第4期1334-1346,共13页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:41877270,42090023)。

摘　　要：水力压裂是非常规能源开发中的一种高效储层改造方法,近年来超临界二氧化碳(S-CO_(2))被认为是一种很有前景的压裂液,相比于水基压裂液由于其具有更高的压裂能力而备受关注。但在基质渗透率(RMP)相对较高的储层岩石中,将超临界二氧化碳用于压裂会出现较高的滤失。本文通过离散裂缝网络(DFN)方法对考虑天然裂缝系统的不同储层进行了模拟,对用水压裂(WF)和用S-CO_(2)压裂(SCF)在不同岩石基质渗透率储层中的适用性及压裂能力进行了模拟研究。与常用的水基压裂液相比,在等同条件下S-CO_(2)的黏度和密度较低,更容易使储层岩石破裂并生成更为复杂的裂缝网络。但是在岩石基质渗透率相对较高的储层中,裂缝不断扩展会导致S-CO_(2)滤失量的不断加剧,严重影响裂缝流体压力的提升,并进一步影响到裂缝的扩展。数值模拟结果也呈现了压裂期间裂缝长度增长趋势出现近水平发展拐点,而这一现象恰恰反映流体滤失对裂缝扩展的影响。在这种情况下继续提高压裂液注入速度可以缩短压裂时间,从而有效降低滤失对压裂的影响。计算结果清楚地表明了岩石基质渗透率的重要性,这一结果可以直接用于S-CO_(2)压裂适用性及生产能力的理论指导。In recent years,supercritical carbon dioxide(S-CO_(2))has been considered as a promising fracturing fluid,which shows higher fracturing capacity compared with water-based fracturing fluid.However,an obvious defect of intensifying leak off occurs when S-CO_(2) is used for HF in reservoir rocks with relatively high matrix permeability.In this paper,simulations of the applicability of water fracturing(WF)and S-CO_(2) fracturing(SCF)in reservoirs with different RMP were conducted.Compared with water-based fracturing fluid,S-CO_(2) has lower viscosity and density under the same conditions,which makes it easier to form more complex fracture networks.However,especially in reservoirs with relatively higher RMP,the intensifying leak off of S-CO_(2) from the fracture propagation can seriously affect the establishment of fracture fluid pressure and the propagating of fractures.In this case,increasing the injection rate of fracturing fluid can shorten the fracturing time,so as to effectively reduce the impact of leak off.Modeling results clearly demonstrate the importance of rock matrix permeability,which can be directly used for the theoretical guidance of S-CO_(2) fracturing applicability and production capacity.

关 键 词：超临界二氧化碳 储层压裂 岩石基质渗透率 压裂液滤失 位移间断边界元方法 

分 类 号：TE37[石油与天然气工程—油气田开发工程]