不同升温速率下牛蹄塘组页岩力学性能及微观孔裂隙结构演化规律

Mechanical Properties and Micro-pore Fracture Structure Evolution Law of Niutitang Formation Shale under Different Heating Rates

开展高温下页岩的力学性能及微观孔裂隙结构演化研究,对实现页岩气高效开发具有重要意义。基于此,对中国米仓山地区下古生界牛蹄塘组页岩在不同升温速率下的力学性质和微观孔裂隙结构演化进行了研究。结果表明:低升温速率(2℃/min)下,页岩抗拉强度显著降低。随着升温速率的增大,抗拉强度先增大后减小;300℃是页岩热反应的阈值温度,在450℃附近孔隙度和渗透率达到最大值;低升温速率有利于微孔的发育,较高的升温速率有利于大尺度裂纹的发育。

Conducting research on the mechanical properties and microstructure evolution of shale under high temperature is of great significance for achieving efficient shale gas development.A study was conducted on the mechanical properties and Micro-pore fracture structure evolution of the Lower Paleozoic Niutitang Formation shale in the Micangshan area of China under different heating rates.The results show that at a low heating rate(2 degrees Celsius per minute),the tensile strength of shale significantly decreases.As the heating rate increases,the tensile strength first increases and then decreases;300 degrees Celsius is the threshold temperature for shale thermal reaction,and the porosity and permeability reach their maximum values near 450 degrees Celsius;A low heating rate is beneficial for the development of micropores,while a higher heating rate is beneficial for the development of large-scale cracks.