摘要：As a caprock for CO2 geological sequestration, the mechanical properties of shale may change significantly from the long-term CO2-fluid interaction. To study the long-term effects of supercritical CO2-brine interaction on the mechanical properties of shale, the marine LMX shale was treated with supercritical CO2-brine at temperature of 110 ℃ and pressure of 30 MPa for 15, 30, and 60 days, respectively. The Brazilian tests combined with Acoustic Emission (AE) monitoring were conducted on shale before and after the treatments. The results show that: (1) Compared with the dry shale, the tensile strength of shale saturated with supercritical CO2-brine for 15, 30, and 60 days decreases by 40%, 48.6%, and 68.8%, respectively. The fracture morphology changes from a straightly single fracture to a fracture band consisting of two to four curved fractures; (2) The effects of supercritical CO2-brine interaction on the initiation and damage stresses are quantitatively analyzed. Taking the initiation and damage stresses of dry shale as the reference, the initiation stresses of shale saturated with supercritical CO2-brine for 15, 30, and 60 days decrease by 17.7%, 37.8%, and 48.4%; the damage stresses decrease by 35.5%, 58.3%, and 75.8%; (3) The AE characteristics of shale are closely related to fracture modes. The tensile fracturing of shale is sudden, manifested as an obvious step in the cumulative AE energy, while the shear fracturing of shale is gradual. With the supercritical CO2-brine treatment time, the fracture mode gradually changes from tensile-dominated to tensile-shear mixed failure mode, which can be inferred from that the slight step increases significantly and the ratio of tensile to shear events decreases from 10.7:1 to 0.8:1. The mechanical properties of shale weaken with the increase of supercritical CO2-brine treatment time. ? 2023 57th US Rock Mechanics/Geomechanics Symposium. All Rights Reserved.

ISSN号：9780979497582

卷、期、页：57th US Rock Mechanics/Geomechanics Symposium, 2023

发表日期：2023-06-25

期刊分区（SCI为中科院分区）：无

收录情况：EI（工程索引）

发表期刊名称：57th US Rock Mechanics/Geomechanics Symposium

参与作者：钟安海,鲁明晶,杨峰

通讯作者：邱仁怡

第一作者：张广清,周大伟

论文类型：会议论文

论文概要：邱仁怡,张广清,钟安海,鲁明晶,杨峰,周大伟，Effects of supercritical CO2-brine/shale interaction on fracturing behavior，57th US Rock Mechanics/Geomechanics Symposium，2023，57th US Rock Mechanics/Geomechanics Symposium, 2023

论文题目：Effects of supercritical CO2-brine/shale interaction on fracturing behavior