Cpc International, Inc.

American Maize-products Company

Vilas L Wermers

Edward D DeBoer

Clarence F Harjes

H Paul Francis

What is disclosed is a cross-linked starch which provides better fluid loss control in well drilling fluids than conventional starches at elevated temperatures. The starch may be derived from any source.

High temperature drilling fluid component

There is disclosed malto-dextrins having a D.E. not substantially above about 20, prepared by the enzymatic hydrolysis of oxidized starch. Syrups of the malto-dextrins are capable of remaining haze-free for long periods of time at high solids concentrations. The malto-dextrins are prepared by first liquefying a highly oxidized starch with an acid or an enzyme to a D.E. not substantially above about 7, and in a subsequent step, converting the oxidized and liquefied starch with a bacterial alpha-amylase enzyme preparation to achieve a malto-dextrin product having a D.E. not substantially above about 20.

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Lemont, IL, United States of America

Vilas L Wermers