Study On Numerical Simulation Method Of Tight Reservoir

Tight oil is known as "black gold" in oil industry.In recent years,our country has payed more attention to the tight oil,and it will become the hotspot and focus on unconventional oil and gas resources in China.The reservoir numerical simulation can provide the theory and method support for the reasonable and efficient development of tight reservoir,Thereby,enhancing the reservoir final recovery.Therefore,it is a great important significance to research tight reservoir numerical simulation owing the characteristics of the nonlinear seepage flow and imbibition.This paper has researched the characteristics of the reservoir? nonlinear seepage flow and the imbibition mechanism.Tight reservoir mathematical model of two-dimensional two-phase flow has been established under the condition of considering the imbibition effect between crack and matrix ? starting pressure gradient and stress sensitivity,and numerical model has been gained with the finite difference method.In the end,the effects of starting pressure gradient and stress sensitivity on oil well production dynamics are analyzed.The main research results are as follows.(1)The characteristics of tight reservoir are analyzed based on the CT scanning and casting lamella,and starting pressure gradient and deformation medium stress sensitivity are analyzed and the calculation method are gained.(2)The tight reservoir imbibition mechanism is studied.Through imbibition experiment of oil and water system using tight reservoir core,the effects of crude oil saturation? viscosity and wetting angle to imbibition are analyzed.(3)Tight reservoir mathematical model of two-dimensional two-phase flow has been established,based on considering the imbibition effect between crack and matrix? starting pressure gradient and stress sensitivity,and numerical model has been gained with the finite difference method.(4)Through VB6.0,combined with the tight reservoir mathematical model,the numerical simulator is written of considering imbibition? starting pressure gradient and stress sensitivity,and simulating the process of oil and water two-phase flow in tight fractured reservoir.The reliability of numerical simulator is proved by zero balancing and commercial software.(5)Combined with the actual oil field data,the effects of the imbibition on the yield are studied.The effects of starting pressure gradient and stress sensitivity on oil well production dynamics are analyzed from six aspects(production well pressure? daily oil production ? cumulative oil production ? average reservoir pressure ? average oil saturation and recovery percent).