HEC PRECIPITATION AT ELEVATED-TEMPERATURE - AN UNEXPECTED SOURCE OF FORMATION DAMAGE

High-molecular-weight polymers are routinely used to viscosify brines for drilling, workover, and completion operations. Of the commercially available polymers, hydroxyethyl cellulose (HEC) is among the most ve rsatile and widely used products. HEC has been used in NaCl, NaBr, KCl , NH4Cl;, CaCl2, and CaBr2 brines over a wide range of brine density, pH environment, and temperature. Typically, the performance issues add ressed in HEC studies focus on dispersibility, hydration rate and visc osity development, rheology at elevated temperature, and formation dam age. Under typical oilfield conditions, the published data indicate th at HEC produces minimum formation damage and provides predictable rheo logical behavior when properly prepared.