METHOD OF INCREASING THE RATE OF HYDRATION OF ACTIVATED HYDROETHYL CELLULOSE COMPOSITIONS

摘要

The invention relates to a method of increasing the rate of hydration of polymeric viscosifiers/fluid loss additives in heavy brine well servicing fluids containing zinc bromide. It is based on the discovery that the rate of hydration of activated hydroxyethyl cellulose (HEC) in aqueous brines is greatest in brines containing no zinc bromide or in brines containing the largest possible concentrations of zinc bromide. This is achieved by either admixing a hydroxyethyl cellulose composition with a first solution containing at least 30% by weight zinc bromide to produce a viscosified solution and thereafter mixing this viscosified solution with a second solution containing calcium chloride, calcium bromide or mixtures thereof, or, admixing a hydroxyethyl cellulose composition with a second solution containing calcium chloride, calcium bromide or mixtures thereof to produce a viscosified solution and thereafter mixing this viscosified solution with a first solution containing zinc bromide.