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AssigneeClariant GmbH
InventorsReinhard J. Oswald, Roman Morschhäuser, Karl Heinz Heier, Aranka Tardi, Juergen Tonhauser, Christoph Kayser, Dan Patterson
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The invention relates to copolymers comprising a) 5-95% by weight of structural units which are derived from compounds of the formula 1 b) from 1 to 95% by weight of structural units which are derived from compounds of the formula 2 and c1) from 1 to 95% by weight of structural units which are derived from compounds of the formula 3 or, alternatively, to c1), c2) from 1 to 95% by weight of structural units which are derived from compounds of the formula 4 n which X is a cation. The copolymers according to the invention are suitable as a fluid loss additive for water-based drilling muds and for cement slurries in deep wells, for completion and clearing-out liquids and for water shut-off in production probes.
A process for reducing water loss in a petroleum production slurry selected from the group consisting of borehole cement, drilling mud, and completion and clearing-out liquid, said process comprising adding to said slurry a copolymer comprising
Dependencies are inferred from the claim text.