Research On The Mechanism Of High-temperature Displacement Of Shale Gas Reservoirs In Northern Guizhou

With the increasing demand for energy and the continuous consumption of conventional oil and gas resources,the contradiction between the supply and demand of oil and gas is increasingly prominent.Therefore,through the study of shale gas adsorption characteristics and adsorption mechanism,a reliable stimulation program is proposed,which is of great significance to the current shale gas production.In this paper,the shale of the lower silurian Longmaxi formation from Ban Zhu1#,Northern Guizhou province,was taken as the main research object,and the isothermal adsorption experiment of the main gas components in shale was carried out by means of physical experiment,including CH₄ isothermal adsorption experiment and CO₂ isothermal adsorption experiment,and the CO₂ displacement of CH₄was analyzed.Based on the experimental results,from the perspective of economic benefits,the“High Temperature CO₂ Enhanced shale gas recovery”process was analyzed.Thus,the following innovative research results and useful conclusions were mainly obtained:In the temperature range of 60?to 100?,the shale of the Longmaxi formation in Northern Guizhou province rapidly increases with the increase of adsorption pressure in the phase of relatively low adsorption pressure,and the rate of rise gradually decreases.In the phase of relatively high adsorption pressure,the gas adsorption volume remains stable with the increase of adsorption pressure,which has a slightly decreasing trend.Under the same adsorption equilibrium pressure,the adsorption amount of the two gases is negatively correlated with the temperature.The higher the adsorption temperature,the smaller the adsorption amount of the gas.In the temperature range from 60?to 100?,CO₂ has more obvious competitive adsorption advantages over CH₄ at any adsorption pressure point.The adsorption capacity of CO₂ is better than that of CH₄.In this paper,we analyzed the mechanism of CO₂ displacement of CH₄.In the numerical simulation experiment,after CO₂ gas injected into shale reservoir,it is found that the concentration of CO₂component increases continuously,while the concentration of CH₄ component decreases continuously,that is to say CO₂ can continuously adsorb in shale and displace CH₄.Numerical simulation results demonstrate the feasibility that CO₂displacement of CH₄.We put forward the process of"high temperature CO₂ injection to enhance shale gas recovery"and studied it from the perspective of economic benefits.The results show that both operating temperature and injection pressure have obvious effects on the adsorption amount of CO₂ and CH₄.From perspective of economic,it is feasible to increase the economic benefits of a single well by setting an appropriate operating temperature.By means of theoretical analysis,physical experiment and numerical simulation,this paper systematically studies the mechanism of high-temperature displacement of shale gas deposits in Northern Guizhou province.The results of this study have important theoretical and practical significance in exploring the mechanism of CO₂displacement of shale gas at high temperature and seeking new shale gas stimulation and efficiency enhancement processes.