Experimental Study On Filtering Material Selection Of Multi Tank Constant Flow Downhole Oil-Water Separator

In the late period of oil field development,the continuous increase of water content resulted in the increase of lifting costs.When the water content of the production well reached more than 98%,it was close to the limit of economic exploitation,which seriously affected the production of oil field.Therefore,how to reduce the moisture content of produced fluid and how to reduce the energy consumption of water injection and oil gathering and transportation system has become one of the key issues to maintain the effective and sustainable development of oil field.At the end of the 90 s of last century,the United States proposed the technology of oil and water separation in the downhole.The theory is that the oil and water mixture was separated directly in the underground,and the water was reinjected into the specified stratum,and the oil was lifted with the wellbore,this technology has been applied well in the field of oil control and oil stabilization abroad.In 2005,the multi tank constant flow downhole oil-water separation system was developed by the first oil production plant of Daqing oil field,and the related projects of multi tank constant flow downhole oil-water separator were carried out in cooperation with Northeast Petroleum University.In this paper,the structure,working principle and application range of two kinds of hydrocyclone type oil and water downhole separation system and gravity type oil and water downhole separation system are introduced.The development course of cup type structure of multi cup of multi tank constant flow downhole oil-water separator is introduced in detail,and its working process and theory principle are analyzed.The change of particle size and velocity of oil droplets before and after coalescence was deduced,and combined with the current three kinds of coalescence efficiency model,the coalescence efficiency and its influencing factors were analyzed.Finally,by discussing the coalescence of oil droplets on single fiber and the coalescence theory and coalescence model in the fiber bed,the wettability,bed thickness,and the thickness of the bed layer were separated.The influence of mixed liquid velocity and inlet oil concentration on oil-water separation efficiency was studied.Through the above theoretical analysis,it is found that the separation efficiency can be further improved by optimizing the filler in the multi tank constant flow downhole oil-water separator.The simulation experimental device for the oil-water separator was set up in the room.The change of water content before and after the separation was measured by spectrophotometer,and the influence of the kinds of packing,filling amount and diameter of filler in the cup on the separation efficiency was obtained.After comparing the separator with the separator,it is proved that the separator for filling 0.15 mm and 12 g nylon in the cup is better than the oil and water separation of the separator filled with coated quartz sand in the cup.