| Water invasion is an important factor restricting the development benefit of natural gas reservoirs with edge and bottom water.Water trapping effect accompanied by water invasion will further reduce gas well productivity and gas reservoir recovery.The reservoir space type of carbonate gas reservoir with edge and bottom water is complex,the dissolution cavity and fracture are well developed,and the heterogeneity is strong,which results in the increase of water invasion risk and water trapping effect.At present,the effect of water trap has not been taken into account in numerical simulation of gas reservoirs,which leads to high prediction of recovery after water invasion and limited guidance for gas reservoir development.In view of this,understanding the micromechanism of water trapping effect,exploring the numerical simulation method of water trapping effect and analyzing its sensitivity to geological factors and development factors can provide theoretical basis and guidance for water control and water control of carbonate edge and bottom water gas reservoirs,and have important practical significance for the effective development of such gas reservoirs.In this paper,the water invasion,water blocking,phase trapping,phase permeability and capillary force lag in the process of gas reservoir development are fully investigated.On this basis,the micro-mechanism of water trapping effect is deeply understood,and the realization method of numerical simulation of water trapping effect is put forward.Then the sensitivity of water trapping effect to different influencing factors is analyzed by typical model.Finally,the development effect of a real gas reservoir considering water trapping effect is simulated and predicted.It is considered that the water trapping effect occurs in the displacement process of gas drive water after water invasion,and its micromechanism lies in reservoir wettability and Jiamin effect;the numerical simulation of water trapping effect can be realized by setting water phase retention,relative permeability lag of gas phase and water phase and capillary force lag;the heterogeneity of reservoir permeability and gas recovery rate will all influence water trapping effect.Water trapping effect will restrict the development effect of carbonate edge and bottom water gas reservoirs,so it is necessary to take measures in advance to delay or restrain water invasion and water trapping. |
