Study On Steam-assisted Gravity Drive Control Technology For Super Heavy Oil Reservoir

Super heavy oil in X oilfield has a high viscosity and shallow burial.Conventional stimulation development can only use oil reservoirs with a viscosity of less than 20,000 m Pa·s,and the reserves with a viscosity of more than 20,000 m Pa·s account for 64% of the total.Conventional development cannot be effectively used.Similar reservoirs in foreign countries are developed using SAGD technology,and the recovery rate can reach 50-70%.According to the development and screening criteria of SAGD,67% of the reserves with a viscosity of over20,000 m Pa·s are suitable for SAGD development.But a lack of the supporting technology,domestic research experiments is technical bottleneck faced many challenges and difficulties,such as steam chamber to quantitative description research trials,growth rule,understanding unclear part well group production effect is not ideal,understanding of circulation preheat phase control factors is not clear,lack of circulation preheat phase control technology,which ended after preheating symmetry commonly connected short;Point connection or small segment connection between injection and production Wells in some groups;After the production is transferred to SAGD,the production effect is poor and the regulation is difficult,which will affect the development effect of SAGD.With the purpose of improving the development effect of SAGD,this paper divided the configuration units based on the geological characteristics,described the development pattern of SAGD between interlayers in detail,and conducted the geological modeling of SAGD between interlayers.The simulation study was carried out in stages with the key points of SAGD development,such as the connecting length of horizontal sections and the development degree of steam cavity.With the help of observation Wells and other dynamic monitoring data,a numerical simulation technique suitable for SAGD development was developed.From SAGD cycle preheat phase and production phase two parts as the breakthrough point,through the analysis of main factors that influence the effect of preheating,preheat preheat cycle divided into wellbore,balanced pressure,voltage loop,micro differential pressure drain four stages,clear the differential control as the core,determine SAGD production indexes,technology of dual horizontal well SAGD hot connected judgment judgment method is put forward,development zone connected degree above 75%;In the production stage of SAGD,the subcool dynamic balance theory was further understood,and the gas-liquid interface and injectionproduction parameters were taken as the main technical line to formulate the dynamic regulation principles.