Predicting the Optimum Concentration of Partially Hydrolyzed Polyacrylamide Polymer in Brine Solutions for Better Oil Recovery, Experimental Study

摘要

Polymer injection is one of the most applications used in enhanced oil recovery. In order to achieve better sweeping efficiency, polymer is added to the injected water to increase its viscosity and ultimately minimize the viscous fingering. Partially hydrolyzed polyacrylamide (HPAM) is one of the polyacrylamide groups. It is characterized by the shape of straight chain polymer of acrylamide monomers in which some of it has been hydrolyzed. The viscosity of the polymer solution should be maintained in order to keep better sweep efficiency. Salinity, polymer concentration and temperature are the most important factors that strongly affect the polymer viscosity and behavior. The aim objective of this study is to estimate the optimum polymer concentration based on the suitable polymer solution viscosity. This viscosity will be suitable for preferable mobility ratio. In this work, five groups of polymer solutions were prepared with different salinities. In each group, several polymer solutions were prepared at different polymer concentration. The viscosity of prepared solutions was measured at different temperatures. New models correlate the flow behavior index (n) and flow consistency index (k) with polymer salinity, polymer concentration and temperature were developed and validated using the experimental data. In order to estimate the required optimum polymer concentration, the developed models were combined with other developed models that describe the polymer shear rate in porous media. Results show that, the cross plots of the measured and corresponded calculated (n) and (k) values indicated better prediction compared with the latest published correlations with a squared correlation coefficient of 0.9912 and 0.9962 respectively. In addition, the calculated average relative error of the predicted (n) and (k) were 0.97 % and 6.07% correspondingly. Using these models, the power law viscosity equation and shear rate in porous media equation, the required polymer concentration can be estimated with high accuracy. Consequently the required optimum polymer concentration needed to achieve better sweeping efficiency can be determined and therefore enhance the oil recovery. This technique will save time and effort spent to find the optimum polymer concentration using the traditional methods.