SAGD Cycle Preheating Liquid Separation And Wastewater Treatment Technology Research

SAGD has been widely used in the field of exploiting heavy oil because of its high recovery technology.The ultra-heavy oil rromXinjiang oilfield is being exploited by SAGD,a large amount of SAGD preheated liquid discharged from underground during the circulating preheated stage.Dehydration of SAGD preheated liquid isfairly difficult on account of its high content of ultra-heavy oil(which contains plenty of resin and asphaltene) and small particle size silt, result in serious emulsification and strong stability., and brings about a big problem for putting on production of new SAGD well. Existing treatment methodhas disadvantages such as producing plenty of aging oil,complex process,the COD value of wastewater is high in consequence the use of chemical demulsifier.In this thesis, dehydrating agent is added to SAGD preheated liquid that lead to significantly decrease on the viscosity of heavy oil and increase on the differenceof density between oil and water. The speed of oil-water separation increase according to Stokes formula.The best dehydrating agent and optimum dehydration separation conditions are selected,the bottom phase is centrifuged for recycling ultra-heavy oil. After these operations,the ultra-heavy oil and water separated thoroughly.Theexperiment results indicated that concentration of 80% of homemadedehydrating agent SW- I was the best dehydrating agent. Under the conditions of reaction temperature 90?, reaction time 24h, the moisture content of ultra-heavy oil can be reduced to 1.02%,and the oil content of water can be reduced to 0.63%.The separation effect between oil and water is good. Theexperiment results also indicated that under the conditions of reaction temperature 140??150?, reaction time 2h, the recycling of dehydrating agent was conducted by atmospheric distillation, and the recycling rate was 99.70%,and during the process of recycling, the moisture content of heavy oilcan be reduced from 1.02% to 0.40% which is available to pipeline. After centrifuging,theoil content of wastewater can be reduced from0.63% to 0.07%.Flocculation and filtration processes were employed to treat the wastewater after dehydration,theexperiment results indicated that concentration of 120 mg/L PATV is the best flocculant,Under the conditions of reaction time 20 min, the oil content of wastewater can be reduced from 742mg/L to 1.8mg/L,the suspended solids content can bereduced from 2581 mg/L to below 5mg/L, the COD value of wastewater can bereduced from 40465.3 to 34.Proposed a technology process on removal of water from SAGD preheated liquid.Proposeda pilotscaletest process based on that.The pilotscaletestresults indicated that this technologyon removal of water from SAGD preheated liquid is available for field application. Proposed a conceptual design of device for removing water from the 7000m3/d SAGD preheated liquid.After preliminary calculation, approximate dimensions of major devices used during the process was calculated.