西南石油大学学报(自然科学版) ›› 2024, Vol. 46 ›› Issue (2): 65-76.DOI: 10.11885/j.issn.1674-5086.2023.09.02.01

• 石油与天然气工程 • 上一篇    下一篇

超临界CO2对致密碳酸盐岩力学特性影响

苟波1, 王琨1, 李骁1, 詹立2, 刘超3   

  1. 1. 油气藏地质及开发工程全国重点实验室·西南石油大学, 四川 成都 610500;
    2. 中国石油川庆钻探工程有限公司井下作业公司, 四川 成都 610052;
    3. 陕西延长石油(集团)有限责任公司研究院, 陕西 西安 710065
  • 收稿日期:2023-09-02 发布日期:2024-05-11
  • 通讯作者: 苟波,E-mail:swpugb@163.com
  • 作者简介:苟波,1984年生,男,汉族,四川阆中人,副研究员,博士,主要从事油气藏增产技术研究与教学。E-mail:swpugb@163.com;王琨,1974年生,女,汉族,四川资中人,高级实验师,主要从事实验室建设与管理、石油与天然气工程实验教学与科研工作。E-mail:569381620@qq.com;李骁,1994年生,男,汉族,四川南充人,博士,主要从事油气藏增产技术等方面的研究。E-mail:279834235@qq.com;詹立,1994年生,男,汉族,四川德阳人,工程师,博士,主要从事油气藏增产改造理论与技术研究。E-mail:zhanliswpu@163.com;刘超,1983年生,男,汉族,内蒙古磴口人,高级工程师,博士,主要从事油气藏增产与现场应用技术研究。E-mail:lcok101@qq.com
  • 基金资助:
    国家自然科学基金(52374047,U21A20105)

Effect of Supercritical CO$_2$ on Mechanical Properties of Tight Carbonate Rocks

GOU Bo1, WANG Kun1, LI Xiao1, ZHAN Li2, LIU Chao3   

  1. 1. National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. Downhole Service Company, CCDC, Chengdu, Sichuan 610052, China;
    3. Research Institute of Yanchang Petroleum(Group) Co. Ltd., Xi'an, Shaanxi 710065, China
  • Received:2023-09-02 Published:2024-05-11

摘要: 采用超临界CO$_2$破致密碳酸盐岩具有破裂压力低,易形成复杂缝特点,但其作用的力学机理尚未清晰。选用马家沟组致密白云岩样,采用高温高压超临界CO$_2$饱和流体法,研究了岩样在超临界CO$_2$+地层水的流体中浸泡不同时间后的物性、声波响应、岩石力学特性和破裂形态特征。结果表明,随着浸泡时间增加,化学溶蚀作用引起溶蚀孔径增大,岩样孔隙度、渗透率增加,而声波速度、动态和静态岩石力学参数均下降;当浸泡时间大于1.0 d后,岩样物性参数增大和力学强度降低明显;随着浸泡时间增加,岩样破裂形态由单一低角度剪切缝向高角度剪切缝、共轭缝和剪切、张型复合缝等复杂形态发展;压裂短时间内(小于1.0 d)超临界CO$_2$+地层水形成的弱酸对岩石力学强度劣化程度有mbox限。

关键词: 致密碳酸盐岩, 超临界CO$_2$, 前置酸压, 力学强度, 破裂形态

Abstract: The supercritical CO$_2$ fracturing has the characteristics of low fracture pressure and easy formation of complex fractures in tight carbonate rock, but the mechanical mechanism of the effect of supercritical CO$_2$ on tight carbonate rocks is not clear. The physical properties, acoustic response, rock mechanical properties and fracture morphology of the tight dolomite samples from Majiagou Formation were studied by using the high temperature and high pressure supercritical CO$_2$ saturated fluid method, namely the samples were immersed in supercritical CO$_2$ + formation water for different time. The results show that with the increase of soaking time, the dissolution pore size and the porosity and permeability of the rock sample increase due to chemical corrosion, and the corresponding acoustic velocity, dynamic and static rock mechanical parameters all decrease. When the soaking time is longer than 1.0 d, the physical property parameters of the rock sample increase and the mechanical strength decreases obviously. With the increase of soaking time, the fracture morphology of rock samples develops from single low angle shear joint to high angle shear joint, conjugate joint and shear and tension composite joint. In short fracturing time($\leqslant$1.0d), the weak acid formed by supercritical CO$_2$ + formation water has limited deterioration degree to rock mechanical strength.

Key words: tight carbonate rock, supercritical CO2, pre-acid fracturing, mechanical strength, fracture pattern

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