Solids-free viscous fluids

摘要

The invention provides solids-free, viscous fluids (pills) for use in various well workover and completion operations including as displacement spacer pills, standard fluid loss control pills, post gravel pack in-screen pills, perforation sealing, and the like. The pills comprise a viscous solution of a polyethylene glycol having a molecular weight of 1,000 to 8,000,000 in an aqueous liquid comprising a solution of one or more soluble bromide salts having a density sufficient to provide the desired hydrostatic pressure at the location of use of the fluid in a well. The minimum concentration of the polyethylene glycol in the pill varies with the average molecular weight as follows: MW = 1,000 to 10,000 = 100 ppb; MW = 10,001 to 100,000 = 75 ppb; MW = 100,001 to 250,000 = 50 ppb; MW = 250,001 to 500,000 = 10 ppb; MW = 500,001 to 8,000,000 = 5 ppb.