Study On Seepage Mechanism And Capacity Evaluation Of Multi-Layer Gas Reservoirs

The total natural gas reserves of tight gas reservoirs discovered have exceeded 7000×108 m3.At present,the target and research objects are focused on tight gas reservoir.The tight gas reservoirs of China has the characteristics of low porosity,low permeability,high water saturation,complex gas-water relationship and strong heterogeneity,these characteristics caused a considerable amount of reserves to fail to be developed in time.In recent years,in the development of tight gas reservoirs,many domestic units have carried out research on the seepage mechanism of tight gas reservoirs,mainly focusing on the experimental and theoretical analysis of non-Darcy flow in tight gas samples.Based on the previous studies,the following research was carried out on the seepage mechanism and capacity evaluation of multi-layer gas reservoirs:(1)Through the pressure gradient experiment of the tight sandstone in the Linxing block,the influence of the starting pressure gradient on the tight gas production capacity in the Linxing block is studied,and the core flooding starting pressure under different confining pressures and different temperatures of the target gas layer is completed.Determination of the gradient;(2)Through the stress sensitivity experiment of the tight sandstone in Linxing block,the influence of stress sensitivity on the tight gas production capacity in Linxing block is studied,and the core permeability under the two processes of rising and confining pressure of the target gas layer is completed;(3)Through the analysis and evaluation of the laboratory pressure gradient and stress sensitivity results,a mathematical model is established to describe the pressure gradient and stress sensitivity of different reservoirs in the Linxing block.Based on the experimental data,the sensitivity analysis of the influence of starting pressure gradient and stress sensitivity on the productivity of Linxing block(direct well and directional well productivity)was carried out,and a mathematical model of capacity prediction considering the starting pressure gradient and stress sensitivity was established.(4)By establishing a numerical simulation mechanism model,the key factors affecting multi-layer mining are determined,and a multi-layer mining scheme is preferred.