An Experimental Investigation of Polymer Gels Injection in Carbonate Reservoirs to Study Disproportionate Permeability Reduction (DPR)

Excess water production is a serious problem in oil industry. Chemical controlling methods such as injection of certain polymers are cheap and easy to handle. These polymers in the reservoir forms a gellant network which causes disproportionate permeability reduction (DPR). In fact, this method reduces both oil and water permeability; but reduction in water production would be much more than that for oil. Therefore, little water will be produced. Four experiments using core sample from a carbonate reservoir were carried out by employing distilled water as reference case and water with addition of different salts to represent formation water. The water permeability drastically reduced with addition of polymer in the reference case. However, addition of various ions to water especially ions with double positive charge decreased water and oil perm abilities in a rather similar way. Therefore, it is concluded that prior to applying polymer injection technologies into a reservoir, the formation water should be analyzed for double positive charges.