Dresser Industries, Inc.

Cassella Aktiengesellschaft

Jeffery C Dawson

Friedrich Engelhardt

Ulrich Riegel

Klaus Kuhlein

Steffen Piesch

Sigmar Von Halasz

Anthony R Reed

Juliane Balzer

Juliane Balzar

New copolymers soluble in water and aqueous acids are disclosed comprising in a statistical distribution in the macromolecule at least 5% by weight of entities containing a formylamino functionality and at least 10% by weight of entities containing an amino carbonyl functionality, which are stable in high concentrations of Bronsted-Lowery acids and can be used as friction reducers in the stimulation of oil or gas wells.

Water soluble copolymers

The present invention relates to macromolecular compositions crosslinked by a novel bridge having the formula --NR.sup.x --CH.dbd.N--CO--. This novel bridge is obtained by reacting a macro-molecule, preferably a polymer, having at least two amidocarbonyl groups with a compound having at least two formylamido groups in an aqueous medium under highly acidic conditions. The crosslinking bridge formed by the reaction of this invention is produced in accord with the following formula: ##STR1## Compositions containing macromolecules having at least two amidocarbonyl groups and a compound having at least two formylamido groups can act as viscosifying or gelling agents for aqueous acids where when added to aqueous acids, crosslinking occurs. Acids gelled in this manner have important use in the recovery of oil and natural gas from subterranean formations.

Cross-linkable and cross linked macromolecular compositions wherein

Water soluble copolymers for use in fracture-acidizing of wells

Water soluble, crosslinkable polymer compositions, their preparation and

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Katy, TX, United States of America

Jeffery C Dawson