Study On Process And Technology Of Enhancing Oil For Produced Water Disposal From High-Temperature Reservoir

During oilfield development, the produced water must be separated from the well fluid in order to satisfy the crude oil sale requirement. The demulsifier should be considered to add into the sepatator to facilitate improving water separation efficiency. However, the wastewater can be discharged to the environment directly and suitable disposal method should be studied to protect the natural environment. The demulsifier and polymer are screened, and the the surface process and technology for produced water handling are studied; meanwhile, two cases are evaluated and one is recommended for further action. The study is to ensure to deal with the oily water from the target oilfied and protect environment. Meanwhile, it can increase recovery rate, improve crude oil production and enhace the economic of oilfield development. Results of the study are as follows:M block crude oil contains wax and has a high tendency to be emulsified; therefore, it can form stable emulsion with water ratio of 75 percent. When the water ratio is more than 75 percent, phase inversion happens, that is to say, phase inversion of water-oil is more than 75 percent of water.In the case of no emulsifier, the oil with low water ratio gets high thermal stability. When the watered oil with water ratio not more than 75 percent is deposited by 30 minutes, water does not come out. The stability of watered oil with water ratio more than 75 decreases and more water comes out from the oil emulsion as the temperature increases. After screening with 10 kinds of demulsifiers, POI-2420 demulsifier presnets good dehydration effect for M oil with low water content. The dehydration effect improves as the increase of demulsifier dosage and dehydration temperature. POI-2420 is recommended with the conditions of operation 80℃,30 minutes of settlement, the water cut of oil can satisfy less than 0.5% with three stages of separation.Preliminary aging experiment is performed with 21 kinds of polymer whichare used very common in main oilfield in China. Five kinds of polymer are screened for high temperature of reservoir (1#,6#,8#,20#,21#); meanwhile, the experiments of aging stability, soluability, viscous charater, and hydrolysis have been performed. The results present that the five kinds of polymers all can satisfy the related standard requirement.Surface process and technology of polymer flooding are studied and it is recommended the suitable surface process for M block including Polymer powder sealed feeding process, Feeding Process Of Primary Polymer Liquor, Dispersing And Dissolving Process Of Primary Polymer Liquor, Primary Polymer Liquor Maturing Process (DNA twin screw stirrer, horizontal vessel), Polymer Injection Process, Oxygen Exclusion Measures, Nitrogen gas generation process, Deironing process, Deoxidation process, and single pump is used to inject liquid for one independent well, etc.There are two cases designed for surface process of polymer flooding, including Deironing system, Deoxidation system, Dissolving Process Of Primary Polymer Liquor and Primary Polymer Liquor Maturing system, Polymer powder sealed feeding system, maturing tanks, Nitrogen gas generation system, polymer injection pump, and pipeline. After comprehensive comparison, case 1 is recommended for further action. The main contents of the mother polymer solution will be prepared in Central Processing Facilities, and the low-pressure fluid is transported to each pad (Pad 1, Pad 2, Pad 3) through 4 independent flow lines. On each pad, the fluid will be pumped up to 20MPa and then injected into reservoir with high pressure wastewater.