Abstract: A method for the controlled de-functionalization of downhole polymers comprising contacting downhole, water-dispersible, polymeric material with a dehydrating agent until the water-dispersible polymeric material is sufficiently de-functionalized to be removed. The water-dispersible polymeric material can be found in the downhole formation of a filtercake on production walls, other downhole polysaccharide materials and in fluid loss pills. The contact between the dehydrating agent and the polymeric material is prolonged until the water-dispersible, polymeric material is sufficiently de-functionalized to allow the de-functionalized material to be removed by flushing the drilling fluid. The dehydrating agent is selected from concentrated inorganic salt solutions, concentrated organic salt solutions, acid anhydrides, esters, alcohols, ethers, ketones, aldehydes, amides, organic acids and mixtures thereof.