Experimental Research On Supercritical Carbon Dioxide Displacement Of Methane Under The Condition Of Multi-field Coupling In The Continental Shale

The continental shale gas zone in the Ordos Basin is another national demonstration zone,after commercial exploitation of marine shale gas in the Sichuan Basin.China needs a lot of natural gas,the efficient development of continental shale gas in the Ordos Basin is of great strategic significance for meeting the national energy demand.In this paper,the continental shale gas in Ordos Basin is taken as the research object.It analyzes the characteristics of shale gas reservoir media of the Ordos Basin,designed an experimental method and device for the replacement of shale gas by supercritical carbon dioxide in the continental shale under the different temperatures,the different axial pressure and the different mining way.The acquired achievements are as follws:1.It was completed that the study of reservoir characteristics in the study area.The reservoirs are mainly include quartz rich siliceous reservoirs and clay rich clay mineral reservoirs.Shale gas content exists in the form of adsorbed gas and free gas,mainly adsorbed gas,which reaches 25-75%in general.The specific surface area of the rock sample is concentrated from 4 to 10 cm2/g.The larger specific surface area indicates that the continental shale has higher adsorptivity.When the confining pressure is 30MPa,the compressive strength of continental shale samples is 210.3MPa.2.According to the experimental requirements,the physical properties of carbon dioxide and methane under high temperature and high pressure were studied.The physical properties of methane with different contents of CO2 were analyzed by simulation.3.An experimental setup for multi field coupling simulation is developed.The device consists of five major systems.It can simulate the underground shale reservoir environment and ensure that the experiment can more truly reflect the adsorption and desorption properties of shale reservoirs.4.It was completed that the experiments of replacing methane with supercritical carbon dioxide under multi field coupling,with eight sets of data.And analysing of the law of change.With the increase of axial pressure,the development of microcracks and the certain dissolution reaction of supercritical carbon dioxide with rock samples,the final recovery of methane is improved by comparison with natural failure mining,which shows that carbon dioxide has a certain role in the displacement of shale gas.