Evaluation of pH-Sensitive Polymer for Gravel-Packing Operations

Rheological data is presented for a type of polyacrylic acid polymer as a function of polymer concentration, pH, shear rate, and temperature. It was found that the viscosity of the polymer is strongly dependent on the pH of the solution. Compatibility tests showed that the polymer was compatible with most brines (NaCl, NH4Cl, and KCl) used for field applications. Core-flow results indicated that the filtration rate was low compared to that of hydroxethylcellusose (HEC). Our evaluation study shows that this anionic polymer would be an excellent nondamaging carrier fluid for gravel packing. It has excellent rheological and suspension properties and is easily broken down with a mild acid wash before flowback.