Application Research on Modification of Oilfield Purified Sewage to Solve the Balance of Reinjection Water
The daily production of purified sewage at Q Transfer Station in H Operation Area of S Oilfield is 1 600 m3,and it is planned to transfer the surplus purified sewage from Q Transfer Station(Area C)to Area D,but due to the incompatible water types between the two blocks,which are easy to produce large amount of scale when mixed with each other,it is necessary to evaluate and deploy the mixed reinjection of different water types of the two regions and the water injection capacity of Block D.In response to the above issues,ScaleChem software is used to compare the water types of calcium chloride and sodium bicarbonate in different blocks,and to evaluate the stability and compatibility of water quality.A treatment process method of replacing clean water with purified sewage modification and transportation is proposed.Based on the actual situation of calcium carbonate scaling in the H opera-tion area,organic phosphate and imidazoline agents are selected as modifiers and mixed.By controlling the chemical balance,the driving force of chemical reaction can be reduced,and two different water types can reach the condition of chemical balance,the scale can disappear,the water quality is stable,the compatibility can meet the requirement of reinjection standard,and can be mixed in any propor-tion.It meets the requirement of corrosive carbon dioxide>1 mg/L and corrosion rate<0.076 mm/a af-ter modification of purified sewage in Block D,which solves the water balance contradiction,and the demand for partial fracturing water.This study has high promotion and application value in the fields of oilfield purified sewage modification and reinjection,as well as optimization of thin oil gathering and transportation systems in other blocks.
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