Fluid loss control additives for oil-based well-working fluids
AssigneeSandoz Ltd.
InventorsDavid L. Connell, Anthony J. Gradwell
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Abstract
Fluid loss control additives for oil-based well-working fluids comprise a solubilized lignite derivative and an oil-swellable or oil-soluble polymer. The solubilized lignite derivative may be oil-solubilized (e.g. a lignite/amine complex) or water-solubilized (e.g. causticized lignite) and may be incorporated in a polymer matrix or added to a dispersion of a polymer in an aqueous medium.
Claims29
A fluid loss control additive for an oil-based well-working fluid comprising an oil-solubilized amine/lignite complex dispersed in a solid matrix of an oil-soluble polymer, said amine/lignite complex being a derivative formed by reacting untreated lignite, causticized lignite, humic acid or a humic acid salt with an oleophilic compound containing at least one C.sub.12-22 alkyl or alkenyl group and selected from the group consisting of amines, amine salts, quaternary ammonium salts, amides, amide-amines and nitrogen-containing heterocyclic compounds.
A fluid loss control additive for an oil-based well-working fluid comprising an intimate mixture of dissolved or dispersed water-solubilized causticized lignite and a dispersed oil-soluble or oil-swellable polymer in an aqueous medium.
Dependencies are inferred from the claim text.