Method of preparing and using acidizing and fracturing compositions, and fluid loss additives for use therein
AssigneeHalliburton Company
InventorsWalter R. Dill, Eugene A. Elphingstone
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Abstract
A well acidizing or fracturing composition is prepared by adding to an aqueous acid solution or emulsion or fracturing composition, a cross-linked copolymer of a sulfonic acid-modified acrylamide and a polyvinyl cross-linking agent. The cross-linked copolymer functions as an effective fluid loss additive and/or diverting agent. From about 25 pounds to about 100 pounds of the additive is utilized per 1000 gallons of the aqueous acid solution or acid emulsion.
Claims17
An acidizing composition for use in acidizing a subterranean formation comprising
- an acidic base fluid;
- and
- from about 25 pounds to about 100 pounds per 1000 gallons of the base fluid of a crosslinked copolymer of a sulfonic acid-modified acrylamide monomer and a polyvinyl crosslinking agent;
- wherein said sulfonic acid-modified acrylamide monomer is characterized in having the structural formula:
- ##STR2## wherein R' and R" are selected from the group consisting of CH.sub.3 --, CH.sub.2 Cl--, CH.sub.3 --CH.sub.2 --, CH.sub.3 --CH.sub.2 --CH.sub.2 --, and H, and may be the same or different;
- and
- wherein said polyvinyl crosslinking agent is an alkylidene bisacrylamide in which the alkylidene group contains from one to three carbon atoms;
- and still further
- wherein said crosslinked copolymer contains from about 0.1 to about 20 weight percent of the polyvinyl crosslinking agent and the balance is the sulfonic acid-modified acrylamide monomer.
The method of preparing a treating composition for injection into a subterranean formation to increase hydrocarbon production therefrom comprising:
- the step of reacting with an alkylidene bisacrylamide crosslinking compound, in which the alkylidene group contains from one to three carbon atoms and in the presence of a suitable copolymerization catalyst and water, a sulfonic acid-modified acrylamide monomer having the formula ##STR3## wherein R' and R" are selected from the group consisting of CH.sub.3 --, CH.sub.2 Cl--, CH.sub.3 --CH.sub.2 --, CH.sub.3 --CH.sub.2 --CH.sub.2 --, and H, and may be the same or different, to form a crosslinked copolymer;
- and
- the step of adding an effective diverting agent amount of said copolymer to an aqueous solution to form small particles of an aqueous copolymer gel in the aqueous solution;
- wherein said reacting step is carried out by initially preparing a first substantially neutral aqueous solution containing
- (a) from about 0.5 to about 3.0 pounds of said monomer neutralized with base per gallon of aqueous solution,
- (b) from about 0.01 to about 0.70 pound of crosslinking compound per gallon of the aqueous solution, and
- (c) an effective amount of a tertiary amine copolymerization catalyst;
- then
- adding to said first solution, in a volumetric amount substantially equivalent to the volume of said first solution, a second aqueous solution containing from about 0.1 to about 0.5 pound of an oxidizing compound initiator per gallon of said second solution to form said copolymer.
A method of temporarily diverting an aqueous treating fluid from portions of a subterranean formation to improve the permeability of other portions of the formation comprising:
- combining with said treating fluid, a copolymer of from about 0.1 to about 20 weight percent N,N'-methylenebisacrylamide with the balance being a sulfonic acid-modified acrylamide monomer having the formula ##STR4## wherein R' and R" are selected from the group consisting of CH.sub.3 --, CH.sub.2 Cl--, CH.sub.3 --CH.sub.2 --, CH.sub.3 --CH.sub.2 --CH .sub.2 --, and H, and may be the same or different;
- introducing the aqueous treating fluid containing the copolymer into the formation to form a gelatinous film over portions of the formation from which the treating fluid is to be temporarily diverted;
- and
- subsequently removing the gelatinous film from the formation.
Dependencies are inferred from the claim text.