页岩气等温解吸特性研究

摘要

Shale gas is an unconventional natural gas reservoir that exists as adsorption,free and dissolved states.Adsorption is the main occurrence state of shale gas.It is very important to study the properties of shale gas adsorption and desorption for exploiting shale gas reservoir.Shale samples were selected from marine shale region in Jingmen,Hubei Province and Sichuan Province.A series of analyses are conducted to obtain the basic properties of shale,and the results indicate that the high degree of organic carbon content and organic matter maturity of the shale samples.MSB magnetic suspension balance adsorption instrument is used to proceed isothermal desorption experiments.The results show that the volume of desorption is low and nearly keeps no change under pressure of 33 MPa to 10 MPa.It increases rapidly when the pressure falls to the range of 10 MPa.The pressure range of 10 MPa to 0.5 MPa is the main period for desorbing the adsorption methane.Adsorption potential theory can be used to estimate the desorption status and desorption strength of shale samples.The larger adsorption potential leads to the more difficult desorption.%页岩气以吸附态、游离态和溶解态存在于页岩储层中,其中吸附态为主要赋存状态,考察页岩气解吸特征对于我国页岩气勘探开发研究有着重要的理论指导意义.选取了位于南方海相页岩储区的四川和湖北荆门等地的页岩样品,对其常规地球化学性质进行了分析,结果表明页岩样品有机碳含量较高且发育较为成熟;采用MSB磁悬浮天平等温吸附仪进行等温解吸实验并对解吸速率和解吸效率进行计算,结果表明:30～ 10 MPa时页岩解吸量很低并且无明显变化;10 ～0.5 MPa时页岩解吸量迅速上升,该阶段为主要解吸段;吸附势理论可用于判断页岩气解吸情况和页岩样品解吸性能强弱,吸附势越大越不利于解吸.