초록

A water-based drilling fluid composition is described which comprises an aqueous dispersion of a clay material containing, in the presence of a phosphate or a particular metal or both, an effective dispersing amount of a lignosulfonate modified by graft polymerization with acrylic acid.

대표청구항 ▼

A water-base salt or gypsum containing drilling fluid comprising a suspension of a clay material and an effective dispersing amount of a mixture of a graft copolymer which is the water-soluble reaction product of lignosulfonate and an acrylic compound selected from the group consisting of acrylic ac

A water-base salt or gypsum containing drilling fluid comprising a suspension of a clay material and an effective dispersing amount of a mixture of a graft copolymer which is the water-soluble reaction product of lignosulfonate and an acrylic compound selected from the group consisting of acrylic acid, acrylonitrile, acrylamide, and methyl and ethyl esters of acrylic acid and a water-soluble phosphate compound which is a phosphoric acid, condensed phosphoric acid or salt thereof, said reaction product being prepared by reacting lignosulfonate with from 5 to 30% of the acrylic compound using a free radical initiator, said reaction product having a weight average molecular weight not exceeding 80,000 and said phosphate compound being present in an amount, expressed as phosphorous, in the range of from 0.5 to 5 weight percent of the reaction product. A water-base drilling fluid comprising a suspension of a clay material and an effective dispersing amount of a graft copolymer which is the water-soluble reaction product of lignosulfonate and an acrylic compound selected from the group consisting of acrylic acid, acrylonitrile, acrylamide, and methyl and ethyl esters of acrylic acid, combined with a water-soluble compound of a metal selected from the group consisting of iron, titanium, manganese, zinc, copper, and chromium, said reaction product being prepared by reacting lignosulfonate with from 5 to 30% of the acrylic compound using a free radical initiator, said reaction product having a weight average molecular weight not exceeding 80,000, said metal compound being combined with the reaction product in an amount such that at least 0.6 weight percent of the metal, based upon the reaction product is present, said drilling fluid further being contaminated with non-swelling clays or shales.