Document Type: Research Article
Department of Chemical Engineering, Isfahan University of Technology, Isfahan, Iran
Chemical Engneering Department, Isfahan University of Technology
Petroleum Engineering Department, Chemistry &amp; Chemical Engineering Research Center of Iran, Tehran, Iran
Petroleum Engineering Department, Chemistry & Chemical Engineering Research Center of Iran, Tehran, Iran
Department of Chemical Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-4838 Tehran, I.R. IRAN
Excessive water production through fractures become an important problem in oil exploration of fractured reservoirs. For this purpose, polymer gels were prepared by crosslinking of aqueous solutions of polymer and crosslinker for the purpose of water management in high water cut fractured reservoirs. A copolymer of sulfonated polyacrylamide was used as polymer and chromium triacetate (Cr(OAc)3) and aluminum nitrate nonahydrate (Al(NO3)3.9H2O) were used as inorganic crosslinkers at 90oC. Two quadratic models were presented for the two inorganic polymer gel systems to predict the gelation time by using central composite design which showed highly significant result. The results also showed that polymer concentration was the main effect on gelation time. Increasing of polymer concentration leads to accelerate the gelation process and then decrease of gelation time. Based on the gelation time and strength of three dimensional structure of polymer gel, the selected polymer gels of Cr(OAc)3 and Al(NO3)3.9H2O were applied to study the performance of polymer gel system in fractured core with the same polymer concentration of 37071 ppm and the crosslinker concentration of 13096 ppm and 2707 ppm, respectively. Also, gelation time of these polymer gels were determined 12 h and 34 h, respectively. For this purpose, coreflooding test was carried out to measure the output flow rate before and after polymer gel treatment in order to calculate residual resistance factor (RRF). As a result, after polymer gel treatment, output flow rate decreased intensively and by increasing of injection pressure, the RRF decreased gradually. The polymer gels of Cr(OAc)3 and Al(NO3)3.9H2O in the fracture were renitent up to 70 and 60 bar against the water pressure drop, while these polymer gels were renitent up to 60 and 40 bar against the oil pressure drop, respectively. The polymer gel of Cr(OAc)3 demonstrated higher residual resistance factor than polymer gel of Al(NO3)3.9H2O.