Abstract: Oil degradable encapsulated breaker particles are used in fracturing operations to break hydro-carbon liquid gelled with salts of alkyl phosphate esters. The preferred breaker chemical is particulate urea coated with sulfonated EPDM.

Abstract: The present invention is based on the discovery that viscosification agents selected from sulfonated and neutralized sulfonated ionomers can be readily incorporated into oil-based drilling muds in the form of an oil soluble concentrate containing the polymer. Thus, one embodiment of the present invention provides an additive concentrate for oil-based drilling muds comprising a drilling oil, especially a low toxicity oil, and from about 5 gm to about 20 gm of sulfonated or neutralized sulfonated polymer per 100 gm of oil. Indeed, oil solutions obtained from the sulfonated and neutralized sulfonated polymers used as viscosification agents are readily incorporated into drilling mud formulations.

Abstract: An encapsulated breaker chemical composition used in a fracturing process in an oil or gas stimulation operation which comprises: (a) a breaker chemical; (b) a water soluble sealing layer, such as urea, having a thickness within the range of about 1 to about 30 microns deposited on the surface of said breaker chemical and encapsulating said breaker chemical; and (c) a pinhole free coating of a neutralized sulfonated elastomeric polymer of about 2 to about 80 microns thick deposited onto the surface of the coated breaker chemical, wherein said neutralized sulfonated polymer encapsulates the breaker chemical and is permeable to the breaker chemical.

Abstract: An encapsulated breaker chemical composition used in a fracturing process in the protection of an oil or gas stimulation operation which comprises: a breaker chemical; and a pinhole free coating of a neutralized sulfonated elastomeric polymer of about 2 to about 80 microns thick deposited onto the surface of the breaker chemical, wherein said neutralized sulfonated polymer encapsulates the breaker chemical, wherein the neutralized sulfonated polymer is permeable to the breaker chemical and the neutralized sulfonated polymer is non-reactive to the breaker chemical.

Abstract: An encapsulated breaker chemical composition used in an oil or gas stimulation operation which comprises: a breaker chemical; and a pinhole free coating of an ionically and covalently crosslinked neutralized sulfonated elastomeric polymer of about 2 to about 80 microns thick deposited onto the surface of the breaker chemical, wherein said polymer encapsulates the breaker chemical, wherein the polymer is permeable to the breaker chemical and the polymer is non-reactive to the breaker chemical.

Abstract: An encapsulated breaker chemical composition used in an oil or gas stimulation operation which comprises: a breaker chemical; and a pinhole free coating of an ionically and covalently crosslinked neutralized sulfonated elastomeric polyer of about 2 to about 80 microns thick deposited onto the surface of the breaker chemical, wherein said polymer encapsulates the breaker chemical, wherein the polymer is permeable to the breaker chemical and the polymer is non-reactive to the breaker chemical.

Abstract: An encapsulated breaker chemical composition used in a fracturing process in the protection of an oil or gas stimulation operation which comprises: a breaker chemical; and a pinhole free coating of a neutralized sulfonated elastomeric polymer of about 2 to about 80 microns thick deposited onto the surface of the breaker chemical, wherein said neutralized sulfonated polymer encapsulates the breaker chemical, wherein the neutralized sulfonated polymer is permeable to the breaker chemical and the neutralized sulfonated polymer is non-reactive to the breaker chemical.

Abstract: An encapsulated breaker chemical composition used in a fracturing process in an oil or gas stimulation operation which comprises: (a) a breaker chemical; (b) a water soluble sealing layer, such as urea, having a thickness within the range of about 1 to about 30 microns deposited on the surface of said breaker chemical and encapsulating said breaker chemical; and (c) a pinhole free coating of a neutralized sulfonated elastomeric polymer of about 2 to about 80 microns thick deposited onto the surface of the coated breaker chemical, wherein said neutralized sulfonated polymer encapsulates the breaker chemical and is permeable to the breaker chemical.

Abstract: A solid polymeric body comprising a polymer matrix containing a substantially water-insoluble reagent leachable into a substantially hydrocarbon liquid environment, the matrix being reagent permeative and the body preferably having a softening point substantially above that of the temperature of the liquid fluid environment in which it is to be employed. The body is useful for the introduction of an additive reagent into a substantially liquid hydrocarbon such as crude and refined oils.

Abstract: Subterranean formations are fractured by use of an aqueous fracturing fluid containing an effective amount of a copolymer of acrylamide and potassium acrylate crosslinked with a titanium or zirconium compounds. The fracturing fluid also contains an oxidative gel breaker. The method is particularly suited for treatment of deep, high temperature formations.

Abstract: The present invention relates to sulfonated thermoplastic terpolymers which are terpolymers of p-methyl styrene, styrene and sodium styrene sulfonate wherein these sulfonated terpolymers function as viscosification agents when added to oil-based drilling muds which are the fluids used to maintain pressure, cool drill fits and lift cuttings from the holes in the drilling operation for oil an gas wells. The sulfonated thermoplastic terpolymer of the latex have about 5 to about 100 meq. of sulfonate groups per 100 grams of the sulfonated thermoplastic terpolymer, wherein the sulfonated groups are neutralized with a metallic cation or an amine or ammonium counterion. A polar cosolvent can optionally be added to the mixture of oil drilling mud and sulfonated thermoplastic polymer, wherein the polar cosolvent increases the solubility of the sulfonated thermoplastic terpolymer in the oil drilling and by decreasing the strong ionic interactions between the sulfonate groups of the sulfonated polymer.

Abstract: A method of fracturing a subterranean formation involving the use of crosslinked gels to form a fracture and deposit particulate proppant therein followed by the introduction of dilute aqueous solutions of chlorine dioxide in the propped fracture to degrade the gel.

Abstract: A process for fracturing a subterranean formation surrounding a gas or oil well which comprises:(a) injecting into said subterranean formation under hydraulic pressure a fluid comprising a solution of terpolymer dissolved in a solvent system, said solvent system comprising an organic liquid and a polar cosolvent, said polar cosolvent being less than about 15 weight percent of said solvent system, said terpolymer comprising a water-insoluble, oil-soluble terpolymer dissolved in said solvent system, the concentration of said terpolymer in said solution being about 0.2 to about 10 weight percent and the viscosity of said solution being less than about 2,000 cps, said terpolymer having the formula: ##STR1## wherein R.sub.1 =C.sub.6 H.sub.5, C.sub.6 H.sub.4 --CH.sub.3, C.sub.6 H.sub.4 --(CH.sub.3).sub.3, Cn H.sub.

Abstract: A solid polymeric body comprising a polymer matrix containing a water-soluble reagent leachable into a fluid containing condensed water, said matrix being reagent permeative and insoluble in said fluid containing condensed water and the said body preferably having a softening point substantially above that of the temperature of the fluid environment in which it is to be employed is useful for the introduction of an additive reagent into said fluid particularly when said fluid is located in a subterranean formation.

Abstract: A cement fluid-loss composition and its use in a well cementing process are disclosed. The cement fluid loss composition comprises an aqueous slurry of about 35 to about 90 weight percent of water based on weight percent of dry cement; and about 0.1 to about 2 weight percent of a terpolymer based on weight percent of dry cement, said terpolymer having the formula: ##STR1## wherein x is about 40 to about 98 mole %, more preferably about 50 to about 95 mole %, and most preferably about 80 to about 90, y is about 1 to about 50 mole %, more preferably about 2 to about 20 mole %, and most preferably about 5 to about 10 mole %, and z is about 1 to about 50 mole %, more preferably about 2 to about 20, and most preferably about 5 to about 10, y is equal to z, B is about 1 to about 50 mole %, more preferably about 2 to about 20 mole %, and most preferably about 5 to about 10 mole %, wherein B, y and z are less than 60 mole %.

Abstract: A solid polymeric body comprising a polymer matrix containing a water-soluble reagent leachable into a fluid containing condensed water, said matrix being reagent permeative and insoluble in said fluid containing condensed water and the said body preferably having a softening point substantially above that of the temperature of the fluid environment in which it is to be employed is useful for the introduction of an additive reagent into said fluid particularly when said fluid is located in a subterranean formation.

Abstract: A method is provided for the controlled introduction of a reagent into a liquid, preferably a reagent peremeable substantially hydrocarbon liquid, which method comprises the steps of:(a) placing as in a geological crude oil reservoir solid polymeric bodies, each body comprising a reagent permeable polymeric matrix containing a substantially water insoluble reagent such as at least one of a wax crystal modifier, demulsifier, scale inhibitor, corrosion inhibitor, biocide, ashless dispersant, antioxidant and mixtures thereof in said liquid (includes both crude and refined hydrocarbon liquids); and,(b) leaching out said reagent from said bodies at a controlled and predetermined rate into said liquid.

Abstract: An aqueous slurry which comprises (a) a cement; (b) about 0.05 to 5.0 wt. % of a copolymer of N-vinylpyrrolidone and a salt of styrenesulfonic acid based on the dry weight of said cement; (c) about 0.05 to 5.0 wt. % of a formaldehyde condensed naphthalene-sulfonic acid salt based on the dry weight of said cement; and (d) water, said cement, said copolymer and said dispersant being dispersed in said water to form said aqueous slurry.

Abstract: An oil-based drilling mud which comprises:(a) a hydrocarbon liquid substantially immiscible in water;(b) about 1 to about 100 parts by weight of water per 100 parts of the hydrocarbon liquid;(c) about 2 to about 50 lb/bbl. of at least one emulsifier;(d) about 0.5 to about 5 lb/bbl. of a wetting agent;(e) about 50 to about 750 lb/bbl. of a weighting agent;(f) about 0.1 to about 25 lb/bbl. of a water insoluble, oil soluble terpolymer, said terpolymer having the formula: ##STR1## wherein R.sub.1 and R.sub.3 are selected from the group consisting of hydrogen and a methyl group, wherein R.sub.2 is selected from the group consisting of C.sub.3 H.sub.5, C.sub.6 H.sub.4 --CH.sub.3, C.sub.6 H.sub.4 (CH.sub.3).sub.2 and CnH.sub.2n+1, wherein n=1 to 30 and R.sub.4 is selected from the group consisting of C.sub.5 H.sub.4 N, CnH.sub.2n NH.sub.3 and CnH.sub.2n N(CH.sub.3).sub.

Abstract: An oil-based drilling mud which comprises an organic liquid substantially immiscible in water; about 1 to about 10 parts by weight of water per 100 parts by weight of the organic liquid; about 20 to about 50 lb./bbl. of at least one emulsifier; weighting material necessary to achieve the desired density; and about 0.25 to about 4.0 lb/bbl. of a hydrocarbon soluble polymeric complex formed from a water insoluble anionic polymer and a cationic polymer.