This paper describes a study of water-soluble polymers used in workover and completion fluids, including xanthan gum and two new biopolymers. Comparisons were made of polymer solution rheology in brines, shear stability, viscosity at elevated temperatures, and formation-damaging characteristics. A mathematical model was used to show the role fluid rheology has in well-stimulation techniques. The paper includes the results of field treatments with xanthan gum fracturing systems.
Numerous studies have shown that proper attention to workover and completion fluid design is repaid many times over by the dividends of increased well productivity. The advent of "clean" low-solids fluids has been brought about by industry's usage of water-soluble polymers to provide viscosity and solids-suspending ability.
Today's oil prices are allowing the use of more expensive yet more effective workover and completion fluids. We have made a comparative study in the field of water-soluble polymers to determine if biopolymer systems could be considered as alternates to currently accepted designs and practices. This study presents an examination of polymer properties and attempts to relate polymer properties and attempts to relate polymer performance to workover and completion performance to workover and completion fluid design.
The following eight water-soluble polymers were chosen for the comparative polymers were chosen for the comparative study due to their common use in the field or possible application:
Guar Carboxymethylcellulose Xanthan gum PS-7 (Experimental) Hydroxypropylguar Hydroxyethylcellulose Polyacrylamide (partially hydrolyzed) ZANFLO (Kelco biopolymer)