热流固耦合作用下页岩渗透特性实验

Effects of heat flow fluid-solid coupling on the characteristics of shale permeability

为探讨地温对页岩渗流特性的影响规律,按照温度对页岩作用部位的不同,从流体动能、骨架应变、吸附解吸三个方面,分析甲烷内摩擦力对动能的影响、页岩热应力及热膨胀导致应变、甲烷解吸引起基质收缩随温度变化的规律,得出热流固耦合作用下页岩渗流特性。以渝东南酉阳龙马溪组页岩样品为分析对象,进行页岩型岩的温度渗流实验,提出三方面五因素的分析方法:温度增加,流体内摩擦力增大减小了流动速度;粘土矿物与有机质的差异性膨胀产生热应力,压缩了页岩骨架,加之基质热膨胀减小了基质间隙,双重作用使渗流通道减小;基质收缩效应对孔隙裂隙双重结构介质渗透量影响很小。温度升高对页岩渗流特性的主要影响体现为,内摩擦力的减速作用及热应力和热膨胀对渗流通道的压缩作用。

To study the influences of geo-temperature on the seepage properties of a shale,we analyzed the temperature-dependent patterns of viscous force change of methane,the formations of a shale by heat stress and expansion,and the matrix shrinkage caused by methane desorption.By using shale samples of Longmaxi Formation in Youyang of Southeast Chongqing,we conducted an experiment on the temperature dependence of the seepage of shale rock.The experiment shows that an increase in temperature leads to an increased viscous force of methane and reduced flow speed.The differences in expansion of clay minerals and organic matters produce thermal stress and compress the shale skeleton,and matrix thermal expansion reduces the substrate gaps,both leading to a decrease in the seepage channels.The matrix shrinkage has very little influence on the infiltration capacity of pores and cracks.The major effects of temperature on theseepage characteristics of shale are the decrease of flow speed of methane due to increased viscous force and compressed seepage channels due to thermal stress and thermal expansion.