Optimization And Prediction Of Injection And Production Profiles Of SAGD Horizontal Wells In Oil Sands

Oil sands is rich in the world,accounting for nearly 33% of the world’s total recoverable oil.As conventional reservoirs are depleted,the effective development of oil sands is important.The Steam-Assisted Gravity Drainage(SAGD)is regarded as one of the most effective methods to develop oil sands.Affected by reservoir heterogeneity and wellbore variable mass flow,the nonuniformity of injection and production profiles along the horizontal wells is common in SAGD process,which seriously restricts the development effect of oil sands.SAGD dual tubing string injection and production technique and multi-point injection and production technique can effectively improve the uniformity of injection and production profiles and enhance the development effect of oil sands.However,at present,the coupling model of reservoir model and wellbore model of SAGD dual tubing string injection and production and multi-point injection and production is not perfect,and how to use these models to optimize parameters to improve the uniformity of injection and production profiles along the wellbore is not fully understand.Therefore,it is of great significance to develop the coupling model of reservoir model and wellbore model of SAGD dual tubing string injection and production and multipoint injection and production for optimizing and predicting the injection and production profiles along the horizontal wells.First,a three-dimensional reservoir model for three-phase flow in oil sands is presented.Second,considering the fluid flow characteristics in the slotted liner and the relationship between steam temperature gradient and steam pressure gradient,the model of fluid flow in SAGD conventional injection and production horizontal wells is developed;Take into account the dual tubing string injection and production technique,the mathematical model of fluid flow in SAGD dual tubing string injection and production horizontal wells is proposed;The model of fluid flow in SAGD multi-point injection and production horizontal wells is presented by considering the multi-point injection and production technology.Then,the coupling model of reservoir model and wellbore model of SAGD conventional injection and production,dual tubing string injection and production and multi-point injection and production is proposed,Finally,after model verification,the variation of injection and production profiles in SAGD conventional injection and production,dual tubing string injection and production and multipoint injection and production process is analyzed.The influence of reservoir physical parameters,steam injection parameters,slotted liner parameters,flow control device(FCD)parameters and injector wellbore configuration on the uniformity of injection and production profiles in SAGD conventional injection and production,dual tubing string injection and production and multi-point injection and production process are investigated.The results show that compared with the field monitoring data,experimental data and the simulation results of CMG,the maximum average error is less than 5%,the proposed model is shown to be reliable.Under different steam injection ratio,the smaller the difference in the steam injection rate between the long and short injection tubing strings,the higher are the uniformity of injection and production profiles and the steam chamber.Under different injector wellbore configurations,the closer the differences between the pressure drop from the landing position of the short injetion tubing string to the heel of the wellbore and the pressure drop from the landing position of the short injection tubing string to the toe of the wellbore,the better is the uniformity of injection and production profiles and the steam chamber.The simulation results of typical oil sands M block indicate that SAGD multi-point injection and production technique is the best.Compared with SAGD dual tubing string injection and production technique,SAGD multi-point injection and production technique can increase the uniformity of steam injection profile,liquid production profile,steam chamber and cumulative oil production by 81.97%,76.47%,76.19% and 13.84%,respectively.This paper proposes the injection and production profiles optimization and prediction methods of SAGD conventional injection and production,dual tubing string injection and production and multi-point injection and production,which provides a theoretical basis for improving the uniformity of injection and production profiles.