Structural Optimization And Application Research Of Critical Steam Injection Nozzles For Heavy Oil Horizontal Wells

Currently,the production of heavy oil reservoirs mainly relies on thermal recovery techniques,such as cyclic steam stimulation(CSS),steam flooding and steam-assisted gravity drainage(SAGD).Among them,CSS is the most commonly used.As horizontal well technique is widely used in oilfield development,it is also widely used in CSS.Uneven steam injection occurs during the steam injection process of horizontal well-based CSS(HW-CSS)which leads to the problem of uneven reservoir production,which seriously affects the development effect.To improve the uniformity of steam injection and the degree of reservoir production,this paper proposes a technique to install critical steam injection nozzles on the steam injection string of horizontal well.In this paper,the geological factors that affect the effect of steam absorption and the main controlling factors of injection-production factors are firstly determined,and then the basic structure of the critical steam injection nozzle is determined.On this basis,the rationality of the critical steam injection nozzle structural dimensions is verified by finite element analysis and laboratory experiments.The results of the study show that Based on the throat diameter,three sequential nozzles with throat diameters of 3mm,5mm and 6.5mm are designed to adapt to different steam injection conditions.Numerical simulation is used to calculate the pressure drop loss in the process of HW-CSS,and the optimized nozzle structure is verified,which provides the basis for subsequent verification experiments.The physical simulation verification experiment of nozzle-controlled steam flow is independently designed and carried out,and the experimental results are consistent with the numerical calculation results;the accuracy of the nozzle distribution design model is verified by the calculation results of the FCD model in the CMG.Compare and analyze the steam injection effect of steam injection after installing critical steam injection nozzle and conventional single-string steam injection.The uniformity of steam injection in horizontal wells is significantly improved after the nozzle is installed.The critical steam injection nozzle is applied to Well Leng 41-Ping 13 in Liaohe Oilfield,the nozzle application scheme is designed,and the steam chamber heating range and crude oil production range before and after the nozzle installation are simulated by numerical simulation software to predict the steam injection effect.