Effect of Inorganic Polymer Gel Systems on Residual Resistance Factor in Fractured Core Model

Document Type: Research Article

Authors

1 Department of Chemical Engineering, Isfahan University of Technology, Isfahan, Iran

2 Chemical Engneering Department, Isfahan University of Technology

3 Petroleum Engineering Department, Chemistry & Chemical Engineering Research Center of Iran, Tehran, Iran

4 Petroleum Engineering Department, Chemistry & Chemical Engineering Research Center of Iran, Tehran, Iran

5 Department of Chemical Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-4838 Tehran, I.R. IRAN

Abstract

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.‎

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