- Development of a mathematical model that simulates polymer crosslinking processes.
- Kinetic study of the reaction between chromium acetate and polyacrylamide.
- Development of a mathematical model that simulates the transport of chromium acetate through carbonate rocks.
- Experimental study of the effect of gelant composition and oil/water pressure gradients on disproportionate permeability reduction (DPR).
The application of gels to improve volumetric sweep efficiency is limited by the lack of gel systems that can be used for in-depth treatment, i.e., by an inability to have the gels penetrate large distances into the reservoir away from the treated well. Researchers have demonstrated that the formation and growth of pre-gel aggregates is a major factor that inhibits deep penetration of gels into reservoir rock. One task of this project was to develop a mathematical model of the aggregate growth. A second problem during the placement of gelants occurs in carbonate reservoirs where fluid-rock interactions interfere with the gelation chemistry. Researchers studied the role of carbonate dissolution on the in-depth propagation of gelants. Water production in production wells can be reduced by using gel systems that exhibit DPR. The mechanism producing this beneficial phenomenon has been elusive for several investigators. The project performer has developed a conceptual model of DPR. Development of this model allows the opportunity to develop systems that can be used to control water flow without significantly affecting oil flow into a production well
A mathematical model was developed that simulates the chemical reactions where polymer molecules are crosslinked to form a three-dimensional network or gel. The model was based on statistical probabilities of reactions and yields information on various molecular-weight quantities as functions of conversion of reactive sites and time. Incorporated in this model are results of a kinetic study of the reaction of chromium acetate and polyacrylamide, currently the most commonly used gel system. A second mathematical model was developed that describes the fluid-rock interactions that occur during flow of gelant components through carbonate rocks.
Ganguly, S., Willhite, G.P., Green, D.W., and McCool, C.S., Effect of Flow Rate on Disproportionate Permeability Reduction, SPE 80205, SPE International Symposium on Oilfield Chemistry, Houston, TX (February 5-7, 2003). Jin, H., McCool, C.S., Willhite, G.P., Green, D.W., and Michnick, M.J., Propagaton of Chromium(III) Acetate Solutions Through Dolomite Rock, SPE Journal, 8, June 2003, pp. 107-113. Jain, R., McCool, C.S., Green, D.W., Willhite, G.P., and Michnick, M.J., Reaction Kinetics of the Uptake of Chromium(III) Acetate by Polyacrylamide, scheduled for publication in SPE Journal, December 2005. Nguyen, T., Green, D.W., Willhite, G.P., and McCool, C.S., Effect of Composition of a Polyacrylamide-Chromium Acetate Gel on the Magnitude of Gel Dehydration and Disproportionate Permeability Reduction, SPE 89404, SPE/DOE Fourteenth Symposium on Improved Recovery, Tulsa, OK, April 17-21, 2004. Cheng, M., Wang, C., McCool, C.S., Green, D.W., and Willhite, G.P., Modeling of Pre-Aggregate Growth During the Gelation of a Polyacrylamide-Chromium(III) Acetate Gel System Using the Theory of Branching Processes, SPE 93354, SPE International Symposium on Oilfield Chemistry, Houston, TX (February 2-4, 2005). |