Development And Screening Of Low Permeability Dense Gas Reservoir Drying Agent

Tight sandstone natural gas has become an important area for exploration and development of unconvention natural gas resources around the world,and it has also led to the rapid development of global tight gas development.The efficient development of tight gas plays an important role in relieving the contradiction between natural gas supply and demand in China and reducing the dependence on external natural gas.Own to tight gas reservoirs often exhibit low porosity,low permeability,prominent capillary phenomena,high initial water saturation,poor gas flowability,and other features,it’s difficult to develop it.But if a corresponding method can be found to dry the reservoir,a large number of pore throats originally occupied by the water can be re-established as gas flow passages,so that the flow ability of the gas can be improved,and the recovery of the tight gas reservoir can be improved.In this paper,according to the characteristics of tight reservoirs,the selection principle and drying mechanism of drying agent are determined.Based on this,through a series of experimental tests and theoretical analysis,a suitable drying agent was selected.Then a large number of relevant drying experiments was established to analyze the drying effect of drying agents.Finally,The application effect of drying agent was further verified by example analysis.Based on the above research contents and analysis results,this article has obtained the following understanding.(1)The desiccation mechanism of the desiccant was determined,that is,the physical and chemical reaction between the desiccant and the formation water resulted in the generation of hydrocarbon gas,which achieved the purpose of increasing the permeability of the consumptive formation water.(2)Different kinds of drying agents were tested under different conditions.The optimal formulation of drying agent was ACHM which is a mixture of XC and ZC with a molar ratio of 0.25.(3)A series of drying experiments under high temperature and high pressure conditions have been established.Although the drying effect will decrease slightly with the increase of pressure,1 g of drying agent can still consume 10.6 ml of formation water and has good dryness.effect.(4)Drying experiments in porous media during high-temperature and high-pressure have been established.The experimental results show that after the drying,the permeability of the core increases.It shows that the drying agent has a good drying effect.(5)Analysis of gas well productivity before and after drying by example calculation shows that the production capacity of gas well increased significantly.