The Effect and Analysis on Cr3+ Gel Improving Profile Control in Alkalescent Alkaline/Surfactant/Polymer Flooding

The emulsification of produced fluid and the scaling along production system have always been one of the most difficult problems in NaOH/surfactant/polymer flooding. To decrease those influences on production, the pilot test of Na2CO3/surfactant/polymer flooding was developed in Daqing Oilfield. The results show fluid emulsification and scaling of production system were prevented effectively, but scaling along the injection system appeared and reservoir heterogeneity was aggravated. This is becoming a new technical problem. By analyzing scaling mechanism and the property of profile control agent, the author presents a technical solution that using Cr3+ polymer gel is improving fluid entry profile of injection well in Na2CO3/surfactant/polymer flooding. Optimization of formula and evaluation of its property and its compatibility with Na2CO3/surfactant/polymer flooding system were investigated and a pilot test was conducted in well B2-1-P56 of Daqing Oilfield. The results shows polymer gel has dual function, i.e., removing scale and plugging off high permeability zone. The scale in the instrument of injection, pipes and well-side of wellbore is thoroughly cleared up. The fluid entry into high permeability layer is decreased from 100 to 64.9%, and fluid entry in low and intermediate permeability layer is increased from 0 to 35.1%. The profile control of injection well is effectively improved. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 2773-2780, 2009