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.