Comparison of HEC and XC Polymer Gravel Pack Fluids

Abstract

ABSTRACT Several service companies are promoting the use of XC polymers to replace HEC polymers in gravel pack fluids. The XC polymer system 1s advertised as providing better gravel carrying capacity and less formation damage than HEC polymer systems. Results of laboratory and field tests with XC and HEC polymers show that the final properties of the fluid system are dependent upon mixing procedures. Hydration and shearing of the XC polymer system prior to the addition of the salt gives a gravel pack fluid with the most consistent fluid properties. High shear and filtration through too fine a filter causes severe loss of gravel carrying capacity and viscosity for both the HEC and XC systems. Filtration through a ten (10) micron absolute cartridge filter is the last step in the preparation. Formation damage studies show that initial exposure to a XC polymer system causes minimal damage. The formation damage is minimized by proper mixing, proper filtration of the system and the proper amount of breaker. However, testing has shown that repeated exposure of the formation to the XC or HEC polymer systems after breaking causes substantial formation damage even with the proper mixing, filtering and breaker systems.