Expansion Of Steamflooding Theory And Optimization Of Injection And Production Parameters

Based on the production practice of qi 40 steam flooding test zones in LiaoHe oil field,this paper conducts theoretical analysis,numerical simulation and field test research on the steam flooding process,and obtains the expected research results:The mathematical model for temperature distribution of overburden is established to quantitatively describe the temperature at any point z of the cap layer at any time t after continuous injection into the semi-infinite solid space(ie,in the reservoir).Based on this,the heat flux equation at the surface of semi-infinite solid space is obtained.It is found that the water saturation in the steam zone depends on the balance between the gravity discharge rate and the steam condensation rate at the overlying rock/oil layer contact surface.The prediction method of water saturation change is establishe;the temperature distribution in the lower reservoir of the steam zone is almost the top,mirror image of temperature distribution in overburden lithosphere,same thing with Fourier law.the only difference between the mirror images in the top and bottom overburden is the thermal conductivity parameters of the reservoir rock,;nothing else makes any difference;The volume flow rate of drainage per unit area in the reservoir under the steam/steam condensate interface minus the flow rate in the steam zone is equal to the volume flow of displacement water generated by the movement of the lower boundary of the steam zone.the enthalpy of oil drainage and water transport per unit area in the reservoir under the steam/steam condensate interface minus the enthalpy of water transport in the steam zone,is equal to the product of the moving rate of the lower boundary of the steam band and the enthalpy difference between the upper and lower enthalpy of the steam/steam condensed water interface Vertical movement of the steam/steam condensate interface in a reservoir does not require changes in the temperature gradient in the reservoir below the adjacent interface;there is a functional relationship between the interface movement rate and the vertical flow rate of condensed water.The mathematical analysis error of Neuman steam flooding theory was corrected,and the energy balance equation of steam flooding reservoir,steam belt coverage area,steam belt thickness and steam belt volume calculation theoretical model were re-established and solved.The influence and change rule of each parameter are revealed.When steam breakthrough in steam flooding is set to occur,the injection rate equation of surface heat decrease under the condition that the coverage area of steam zone remains unchanged.The application range of Neuman steam flooding theory is extended,which provides the calculation method of oil displacement before and after steam breakthrough for steam flooding and constructs formula for calculating the complete calculation system of oil displacement of steamflooding.By improving the deficiency of the Jones model,three conversion coefficients between oil displacement and production of steamflooding are proposed.On this basis,the calculation model of steam flooding crude oil production is established and a numerical analysis method is proposed.Based on the actual parameters of the reservoir,a set of methods for determining the optimal injection and production parameters of steam flooding and an estimation method for the economic development period of steam flooding projects are proposed.This method provides a theoretical basis for dynamic prediction of steam flooding production and optimization of on-site construction technical parameters.In this paper,the field pilot test task of Qi 40 steam flooding is completed well,and the results of the pilot test of Qi 40 steam flooding site are successful examples of medium and deep heavy oil steam flooding.The obtained test results not only have economic benefits,but also are in good agreement with the theoretical values of this paper.This comparison result fully proves the correctness and practical value of the theoretical model.The research work in this paper is closely combined with the production practice,and its theoretical and experimental results have guiding significance and practical value for improving the development effect of steam flooding and optimizing injection and production parameters.