The Study On Adsorption Characteristics Of Marine Shale Of Longmaxi Formation In Changning Area,Sicuan Basin

Changling area Silurian Department of Longtaxi group developed a set of rich organic sea shale,is China's shale gas exploration and development of key areas.Because of the current characteristics of shale adsorption in Longmaxi Formation in southerm Sichuan,most of them have only one kind of adsorbed gas of methane or nitrogen,and the adsorption result is more single than that of adsorption experiment.Therefore,we selected more than 60 pieces of marine shale samples from Longmaxi Formation in Changning area,and selected more than 120 data from the mineral composition,organic characterization and Porosity characteristics of the three aspects of the characteristics of the shale.A total of 27 samples were selected for nitrogen gas isothermal adsorption experiment.Six samples were subjected to methane gas isothermal adsorption experiment to carry out the study of shale adsorption in this area,and the influencing factors of adsorption characteristics were analyzed according to the characteristics of shale reservoir.The study shows that:(1)The shale of Longmahe Formation in the study area is divided into five categories:silty shale,calcareous shale,carbonaceous shale,clay shale and mixed shale.(2)According to the genesis of porosity,the pore types of the study area can be divided into organic porosity and microcracks,intergranular pores,intergranular(dissolved)pores and intergranular pores.The organic matter porosity is the shale reservoir of Longmaxi Formation in Changning area The main pore type of the layer.(3)The isothermal adsorption curves of shale in the study area are divided into two types,H2 total HI type,accounting for about 25.9%,H3 type total 20,accounting for about 17.1%.The results show that the adsorbed gas is controlled by the organic carbon content,organic matter maturity and quartz content.(4)Based on the experimental results of methane adsorption at high temperature and high pressure,the influence factors of adsorption capacity of methane in the study area show that the adsorption capacity of shale in the study area is mainly affected by temperature,quartz content,organic carbon content and pore volume.The above four factors increase and increase.The adsorption capacity of the shale in the study area is 1.460-4.656 m3/t,with an average of 2.73 m3/t,using the formula of the adsorption gas which is affected by the pressure.The research results provide an important basis for evaluating the potential evaluation and scientific development of shale gas resources.