Research On Sp Combination Flooding In Enhanced Oil Recovery For Chengdao Offshore Oilfield

Altough there is a huge amount of offshore oil resource in Bohai Bay,China.Due to the low recovery rate,low recovery degree,short platform life and other factors,a huge part of it keeps left in the reservoir.At present,most of the offshore oil fields are in the stage of polymer flooding with low recovery percent.And it is needed to search a rapid way to develop these oil reservoirs.WD oilfield,part of Chengdao offer oilfield,was chosen as the research object to study SP flooding in the reservoir.Based on reservoir development status and reservoir properties,the optimization of surfactant and polymer,the performance evaluation of SP flooding system and the influencing factors of displacement effect were conducted.The SP combination system(SS-1+A#)was gained,which owns low chromatographic separation effect,high shear stability,good emulsification and good aging properties of those SP flooding systems.The affective factors of displacement experiment were researched though flooding experiments,which included polymer concentration,surfactant concentration,permeability ratio and slug combination modes.Finally,the best optimum SP flooding scheme is obtainedResearches have shown that the viscosity of the system is the dominant position to improve oil recovery of SP flooding in this paper.Meanwhile,the system is at a low interfacial tension(10^-2 m N/m)rather than an ultra-low interfacial tension(10^-3 m N/m).The best SP flooding scheme is as follow.The main slug is 0.3%SS-1+2000 mg/L A#with 0.5PV injection volume.The polymer concentration is 2000 mg/L and the injection volume is 0.1PV in both the pre-slug and the subsequent slug.The slug combination mode can improve oil recovery by 24%.This study could achieve the goal of"gaining more oil early"in the platform life of in WD heterogeneous reservoirs.It provides a theoretical basis for the optimum formulation of offshore oil field,and also contribute a significant example for SP combination flooding flooding in similar offshore oilfields.