Study On Disposal Of Recovered Oil In Produced Water Sedimentation Tank Of EOR Dehydration System

Recently，as the oilfields development entering the high water cut stage，the crude oil isbecoming heavier and the enhanced oil recovery (EOR) technologies are applied widely，which lead to the most produced crude oil existed as emulsion and the emulsification degreeis seriously．Under a certain condition，some of the emulsion would stabilize and then gathertogether around the oil water interface，called aging oil，which has brought a series ofproblems for the oilfield normal production．Especially，lots of black solid particles，produced form aging oil，gathered in produced water sedimentation tank and electricdehydrator are harmful to the oil water separation equipment．This paper takes the Nansi dehydration system as the actual background．The physicaland chemistry properties，formation mechanism and reason of the aging oil in the dehydrationsystem are analyzed and studied．Due to the aging oil contains many inorganic substances，high-molecular polymer and chemical agents，the surface active substances of the aging oil isincreased and the stability is strengthened，which make it difficult to dispose the agingoil．The demulsifier screening test is conducted on the base of the effects of the aging oilcomposition on the demulsification and dehydration，and a demulsifier used for aging oildemulsification and dehydration in Nansi station is developed and named SO1006．Theelectrolyte of the middle emulsion layer in produced water sedimentation tank and theelectrical conductivity of the aging oil are both tested，and the results indicate that the electricdehydrator is not suitable for aging oil dehydration．Thermo-chemistry sedimentation disposalmethod is used to conduct aging oil dehydration experiment， and the dehydration effectsunder different dehydration temperatures and amounts of demulsifier (SO1006) areevaluated．In order to improve the dehydration effect of the aging oil，the aging oil is separatedfrom the primary disposal system，and an aging oil disposal system is established．Accordingto the aging oil dehydration experiment result，the thermo-chemistry sedimentation disposalmethod is used for aging oil dehydration field test．The test result confirms that thethermo-chemistry sedimentation disposal method is suitable for the aging oil dehydration inthe Nansi station．...