Chrome Micro-gel Profile Control Technology Research In Sub-saharan Oil Field Applications

Better production effect has been achieved since polymer flooding was developed in Daqing oilfield. The technology of polymer flooding has been important in production of oilfield. In order to further improve effect of polymer flooding, solve sewage discharge and reduce the cost of polymer flooding, it is necessary to study an new flooding system. In this paper, studies and applications of profile technology with chrome micro-gel have been developed in Sanan oilfield and studies in lab and application on site of chrome micro-gel system have also been carried out by using sewage in Sanan oilfield,confect water in polymer displacement and polymer with molecular weight 19000000 and chrome cross linking agent.Studies in lab show that gelling characteristic of chrome microgel system which are confected by clear water and diluted by sewage is better, which assure the gelling performance of chrome micro-gel system in stratum. The concentration of polymer is 400mg/L and cross linking agent is 500mg/L is recommended. Studies of influx characteristic,flow characteristic,seepage characteristic,flow gelling characteristic and displacement of oil characteristic and so on have been developed , which indicates chrome micro-gel system can be gelled under the condition of flow and gelled time may delay. No gelling near the injection well is in favor of injection of chrome micro-gel system and prevents chrome micro-gel system from jamming near the well. chrome micro-gel system is gelled during in the course of flowing in hole and gelled viscosity is higher than 30mPa·s, which has better gelled behavior and can flow after gelling. The system has better diffluent action and deep profile function, which can avoid highly permeable formation breaking early and channeling, better turning ability of liquid flow can make middle and low permeable formation that properties are worse be used effectively. The method that chrome micro-gel and polymer slug alternate displacement can not only make chrome micro-gel exert deeply profile adjustment and diffluent action, but enhance effect of displacement of oil distinctly by using fluidity control action of polymer. Recovery efficiency can be enhanced 24% in long parallel connection core model and enhanced 23% in non-homogeneous model among three formulations, which is greater 3～6% than polymer displacement.Experiments on site show primarily that chrome micro-gel system has profile performance, better contradiction between formations, enhance production effect and at present the extent of enhancing recovery efficiency is greater than polymer displacement.Flow law and displacement property of chrome micro-gel system during displacement have been studied roundly in lab and production law of displacement has also been understood elementarily though experiment on site, which make up for the disadvantage of polymer displacement and provide technical support for applying chrome micro-gel system in Sanan oilfield.