Abstract: Disclosed is a concentrate composition for crosslinking polysaccharide polymers hydrated in an aqueous liquid, and well servicing fluids, preferably fracturing fluids, prepared therewith. Preferred polysaccharide polymers are galactomannan gums or derivatives thereof, preferably hydroxypropylguar. The concentrate comprises an alkali metal formate solution, preferably potassium formate, a crosslinking agent for the polysaccharide polymer, preferably a sparingly soluble alkali metal or alkali metal alkaline earth metal borate, and a suspension agent, preferably a clay mineral selected from the group consisting of smectite clays, palygorskite clays, and mixtures thereof Exemplary clays are hectorite, sepiolite, and attapulgite. The concentrate may, optionally, contain a deflocculant and/or an anti-syneresis additive.

Abstract: Environmentally safe viscous well treating fluids and methods are provided by the present invention. The treating fluids are basically comprised of water, a viscosity producing polymer, a boron cross-linking agent for cross-linking the polymer, and a delayed cross-link delinker that chelates the boron and breaks the treating fluid into a low viscosity fluid selected from polysuccinamide and polyaspartic acid.

Abstract: Methods of treating subterranean zones and high density viscous aqueous treating fluids are provided. A high density viscous aqueous treating fluid of the invention comprises salt water comprising water and one or more oxidation resistant salts; a gelling agent; and a delayed oxidizing gel breaker.

Abstract: The invention provides an aqueous suspension/concentrate of a sparingly soluble borate, preferably as disclosed in Mondshine U.S. Pat. No. 4,619,776, which is effective in crosslinking aqueous solutions of a water soluble, borate-crosslinkable polymer, preferably guar gum and derivatives thereof. The aqueous suspension/concentrate comprises a saturated aqueous solution of a sparingly soluble borate, a suspension agent, suspended particles of a sparingly soluble borate, and optionally a stabilizing agent, wherein the saturated solution of the sparingly soluble borate is prepared prior to the particles of the sparingly soluble borate being suspended therein. The preferred suspension agent is a palygorskite clay such as attapulgite and sepiolite. The invention further provides a method of hydraulically fracturing a formation with the aqueous borate suspension/concentrate.

Abstract: Aqueous liquid compositions for increasing the permeability of a subterranean formation are disclosed, the compositions being characterized by provision of fluoborate anion (fluoboric acid) and a specified compound or compounds, or mixture thereof, which chelate aluminum ions and aluminum fluoride species. Methods of treating a subterranean formation by injection of the composition(s) into the formation are also described.

Abstract: Methods and compositions for treating subterranean zones penetrated by well bores utilizing environmentally safe viscous fluids including a solubility increasing boron complex or ester forming compound. A method of the invention comprises the following steps. A viscous treating fluid composition is provided comprising water, a viscosity increasing polymer and a water soluble delayed polymer breaker that comprises a mixture of sodium perborate tetrahydrate and a solubility increasing boron complex or ester forming compound. The viscous treating fluid composition is introduced into the subterranean zone wherein the viscous treating fluid is allowed to break into a thin fluid of reduced viscosity.

Abstract: Fracturing fluid compositions and methods for their preparation and use are disclosed. The compositions are useful in the oil and gas drilling operations, as well as in gravel packing operations, water blocking, temporary plugging for purposes of wellbore isolation and/or fluid loss control, and other uses. The compositions comprise a liquid, a polymer soluble in the liquid, having a degree of substitution of ionic groups of about 0.01 to about 0.1; and a crosslinking agent capable of increasing the viscosity of the fracturing fluid by crosslinking the polymer in liquid.

Abstract: Methods of fracturing subterranean zones with less pumping are provided. The methods basically comprise the steps of providing an aqueous fracturing fluid comprised of a brine having a density in the range of from about 9 to about 19 pounds per gallon, pumping the aqueous fracturing fluid into the subterranean zone at a rate and pressure sufficient to fracture the subterranean zone and recovering the aqueous fracturing fluid from the subterranean zone.

Abstract: A plugging fluid for plugging a subterranean formation zone surrounding a drill hole comprises an emulsion comprising a dispersed aqueous phase containing an aqueous base and a continuous hydrophobic phase containing a polymer consisting of a grafted cellulose ether derivative, a surfactant and a crosslinking activator of the polymer. The polymer is preferably 2-hydroxyethyl cellulose grafted with vinyl phosphonic acid. Upon shearing, preferably through the drilling bit, the emulsion inverts so that the rupture of the emulsion droplets releases the crosslinking activator into the water phase thus forming a gel structure.

Abstract: The present invention provides methods and compositions for treating subterranean zones penetrated by well bores utilizing environmentally safe viscous fluids. A method of the invention comprises the following steps. A viscous treating fluid composition is provided comprised of water, a viscosity increasing polymer and a water soluble delayed polymer breaker that comprises a mixture of sodium perborate tetrahydrate and a solubility increasing boron complex or ester forming compound. The viscous treating fluid composition is introduced into the subterranean zone wherein the viscous treating fluid is allowed to break into a thin fluid of reduced viscosity.

Abstract: Aqueous liquid compositions for increasing the permeability of a subterranean formation are disclosed, the compositions being characterized by provision of fluoborate anion (fluoboric acid) and a specified compound or compounds, or mixture thereof, which chelate aluminum ions and aluminum fluoride species. Methods of treating a subterranean formation by injection of the composition(s) into the formation are also described.

Abstract: Disclosed is a hydrophilic, water soluble polymer concentrate for addition to aqueous liquids to enhance the properties thereof, particularly to increase the viscosity or decrease the fluid loss of well drilling and servicing fluids, the concentrate comprising a hydrophobic, water insoluble liquid, an organophilic clay suspension agent, the water soluble polymer, and a stabilizing agent comprising one or more acids in an amount from about 0.001% to about 1.5%, one or more anionic surfactants in an amount from about 0.001% to about 1.0%, one or more nonionic surfactants in an amount from 0.001% to about 0.625% and, from about 0% to about 0.75% of one or more water soluble organic liquids, wherein the total concentration of the stabilizing agent is from about 0.1% to about 2.5%, these percentages being based on the weight of the concentrate.

Abstract: Methods and compositions for sealing subterranean zones having temperatures in the range of from about 80° F. to about 300°F. are provided. A method of the invention is basically comprised of the steps of providing a subterranean zone sealing composition that becomes substantially rigid when exposed to subterranean zone temperatures above about 80° F. and has a pH above about 8.5 comprised of water, a substantially fully hydrated depolymerized polymer and a cross-linking agent. The sealing composition is introduced into the subterranean zone whereby it becomes rigid and seals the zone. The sealing composition can subsequently be removed by contact with a fluid having a pH below about 8 when a boron compound is utilized as the cross-linking agent.

Abstract: Liquid suspensions of particles in non-aqueous solvents are extremely stable over long periods of time with minimum separation of the solvent and no hard packing of the dispersed particles. The suspensions enable a user to rapidly add the suspension to water and to mix at low speeds without generating fugitive dust in the process. In addition, a liquid dispersion can provide an easy to use liquid containing higher concentrations of the active dispersed phase than can be accomplished by simply preparing an aqueous solution of the dispersed phase. Alternatively, highly water-soluble particles may also be suspended which have poor storage, freeze/thaw, or heat/cool stability. In some cases, liquid dispersions can yield controlled release of the dispersed phase because the dispersed phase is not in aqueous solution. The suspensions are environmentally safe and biodegradable and may be used in environmentally sensitive applications, such as for oil well treating fluids for offshore areas.

Abstract: Improved methods of generating gas in and foaming well treating fluids introduced into a subterranean zone are provided. A method of the invention includes the steps of combining one or more gas generating chemicals with the well treating fluid and combining one or more delayed encapsulated activators having selected release times with the well treating fluid containing the gas generating chemicals so that the gas generating chemicals react with the delayed encapsulated oxidizing agent activators and gas and foam are formed in the treating fluid while the treating fluid is being pumped and after being placed in the subterranean zone.

Abstract: Improved methods of generating gas in and foaming aqueous well fluids introduced into a subterranean zone are provided. A method of the invention includes the steps of combining with an alkaline aqueous well fluid one or more gas generating chemicals and a mixture of foaming and foaming stabilizing surfactants so that the gas generating chemical or chemicals react with the alkaline aqueous well fluid and gas and foam are formed in the well fluid while it is being pumped, and then pumping the well fluid into the subterranean zone.

Abstract: It has been discovered that borate crosslinked fracturing fluid breaker mechanisms are improved by the inclusion of a cation-releasing material. When cations are released or liberated within the fracturing fluid, they complex with the hydroxide or carbonate pH buffers used within the borate crosslinked fracturing fluid, which in turn reduces the pH of the fracturing fluid. Once the pH is lowered, viscosity reduction (breaking) occurs by uncrosslinking of the polymer within the fracturing fluid, and by initiating or increasing activity of an enzyme breaker, if present. In one embodiment, the cations are divalent cations. The divalent cations are preferably slowly released over a period of time. Two specific, preferred materials for releasing divalent cations are calcium lignosulfonate and calcium chloride, the latter preferably in encapsulated form.

Abstract: It has been discovered that borate crosslinked fracturing fluid breaker mechanisms are improved by the inclusion of a polyol together with an enzyme. In fact, synergistic results may be achieved when both are used together as contrasted to the cases where each are used separately. Removing the borate ion from the crosslinked polymer reduces the pH of the fluid and in turn increases the activity of the enzyme. That is, once the pH is lowered, viscosity reduction (breaking) occurs by uncrosslinking of the polymer within the fracturing fluid, and by initiating or increasing activity of an enzyme breaker, if present. In one embodiment, the polyol has at least two cis-hydroxyl groups. In another embodiment, the polyols are monosaccharides such as glycerols and sugar alcohols, and may include mannitol, sorbitol, glucose, fructose, galactose, mannose, allose, etc. and mixtures thereof. Oligosaccharides and derivatives of monosaccharides and oligosaccharides are also useful.

Abstract: Herein is disclosed a well completion or stimulation fluid, comprising (i) a carrier fluid; (ii) a viscoelastic surfactant; and (iii) a fluid loss control additive (FLA) comprising at least one polymer and at least one crosslinker. The fluid may further comprise proppant or gravel, if it is intended for use as a fracturing fluid or a gravel packing fluid, although such uses do not require that the fluid comprise proppant or gravel. Also disclosed herein are methods of fracturing a subterranean formation, comprising (i) providing a fracturing fluid discussed above and (ii) injecting the fracturing fluid into the formation at a pressure sufficiently high to fracture the formation. In addition, disclosed herein are methods of gravel packing a wellbore, comprising (i) providing a gravel packing fluid discussed above and (ii) injecting the gravel packing fluid into the wellbore.

Abstract: A plugging fluid for plugging a subterranean formation zone surrounding a drill hole comprises an emulsion comprising a dispersed aqueous phase containing an aqueous base and a continuous hydrophobic phase containing a polymer consisting of a grafted cellulose ether derivative, a surfactant and a crosslinking activator of the polymer. The polymer is preferably 2-hydroxyethyl cellulose grafted with vinyl phosphonic acid. Upon shearing, preferably through the drilling bit, the emulsion inverts so that the rupture of the emulsion droplets releases the crosslinking activator into the water phase thus forming a gel structure.

Abstract: A well treatment fluid composition comprises a solvent (such as water), a polymer soluble or hydratable in the solvent, a crosslinking agent, an inorganic breaking agent, and an ester compound. Preferably, the hydratable polymer is a polysaccharide, such as galactomannan, cellulose, or derivatives thereof. The crosslinking agent is preferably a borate, titanate, or zirconium-containing compound. The inorganic breaking agent is preferably a metal-based oxidizing agent, such as an alkaline earth metal or transition metal-based oxidizing agent. The ester compound is preferably an ester of polycarboxylic acid, such as an ester of oxalate, citrate, or ethylenediamine tetraacetate. One example of a suitable ester compound is acetyl triethyl citrate.

Abstract: Aqueous liquid compositions for increasing the permeability of a subterranean formation are disclosed, the compositions being characterized by provision of fluoborate anion (fluoboric acid) and a specified compound or compounds, or mixture thereof, which chelate aluminum ions and aluminum fluoride species. Methods of treating a subterranean formation by injection of the composition(s) into the formation are also described.

Abstract: The present invention provides improved cross-linked well treating fluids and methods for preparing and using the fluids in treating wells such as fracturing subterranean zones therein. The improved cross-linked treating fluids comprise water, a galactomannan gelling agent, a cross-linking agent for cross-linking the galactomannan gelling agent, and a viscosity stabilizing agent selected from the group consisting of formaldehyde, formic acid, or mixtures thereof. The viscosity stabilizing agent alters the properties of the well treating fluids and enables them to retain their viscosity over prolonged periods of time when compared to prior well treating fluids.

Abstract: A composition for delaying the cross-linking of water soluble polymer solutions includes a boron source suspended by an organophilic clay in a solution of a non-aqueous solvent. One process of manufacturing the composition includes the steps of first suspending the organophilic clay in the non-aqueous solvent and then suspending the boron source in the organophilic clay-non-aqueous solvent suspension. Another process of manufacturing composition includes the steps of first mixing the boron source and the organophilic clay to form a dry mixture and then suspending the dry mixture of the boron source and the organophilic clay in a non-aqueous solvent. In a method of hydraulically fracturing a formation, a water soluble polymer solution with a pH between about 8.5 and 12.5 and the boron source suspended by the organophilic clay in the solution of the non-aqueous solvent are pumped into the formation under sufficient pressure to cause a fracture in the formation rock.

Abstract: A composition for delaying the cross-linking of water soluble polymer solutions includes a boron source suspended by an organophilic clay in a solution of a non-aqueous solvent. One process of manufacturing the composition includes the steps of first suspending the organophilic clay in the non-aqueous solvent and then suspending the boron source in the organophilic clay- non-aqueous solvent suspension. Another process of manufacturing composition includes the steps of first mixing the boron source and the organophilic clay to form a dry mixture and then suspending the dry mixture of the boron source and the organophilic clay in a non-aqueous solvent. In a method of hydraulically fracturing a formation, a water soluble polymer solution with a pH between about 8.5 and 12.5 and the boron source suspended by the organophilic clay in the solution of the non-aqueous solvent are pumped into the formation under sufficient pressure to cause a fracture in the formation rock.

Abstract: Improved high temperature, low residue viscous well treating fluids and methods of using the fluids are provided by the present invention. The improved viscous well treating fluids are basically comprised of water; a hydrated galactomannan gelling agent; a retarded cross-linking composition for buffering the treating fluid and cross-linking the hydrated galactomannan gelling agent comprised of a liquid solvent, an organotitanate chelate and a borate ion producing compound; and a delayed gel breaker.

Abstract: A fracturing fluid and method is disclosed comprising an aqueous metal hydrated galactomannan gum, buffered to a pH of from about 9 to about 11, and using reduced amounts galactomannan gum. Further, the invention provides a metal ion source, such as borate, to crosslink the galactomannan gum polymer in subterranean fractures. In one embodiment a slowly dissolving slurried borate is used in pumping an alkaline fracturing fluid into a subterranean formation to increase production of hydrocarbons. In another embodiment, an encapsulated borate source is used. A chemical stabilizer optionally may be used.

Abstract: The addition of fibrous mixtures in intimate mixtures with particulates for fracturing and gravel packing decreases or eliminates the undesirable flowback of proppant or formation fines while stabilizing the sand pack and lowering the demand for high polymer loadings in the placement fluids. Fibers are useful for forming a porous pack in the subterranean formation. In some cases, channels or fingers of void spaces with reduced concentrations of proppant may be introduced into the proppant pack.

Abstract: The crosslinking of galactomannan gum fracturing fluids by borate ion is delayed for high temperature applications by completing boron in a basic solution with an organic polyol. Low pumping friction pressures are achieved by the delay in the crosslinking with the boron being available at high temperatures to add high temperature stability to the fracturing fluid at temperatures ranging upto about 300.degree. F.

Abstract: Methods and apparatus are disclosed for fracturing subterranean formations using fracturing fluids that are hydrated from dry mix blends. One aspect of the invention comprises a dry blended particulate composition for hydraulic fracturing comprising a particulate hydratable polysaccharide, a particulate crosslinking agent, and a slowly releasing particulate base. The compositions employ controlled release methods of particle dissolution. The invention reveals a dry blended particulate composition capable of significantly improved high temperature stability. Further, methods of fracturing and apparatus for rapidly hydrating and pumping the fracturing fluid into subterranean formations are disclosed.

Abstract: The invention, in one embodiment, is a novel fracturing fluid composition comprising an aqueous metal hydrated galactomannan gum, buffered to a pH of from about 9 to about 11. In another embodiment, a method of fracturing a formation is disclosed, the method being characterized by the use of the compositions mentioned.

Abstract: A method is provided for controlling the delay time of aqueous borate-crosslinked polysaccharide-based fluids for hydraulic fracturing and related applications which allows on-the-fly control of the delay time without comprising overall fluid integrity. Without having to modify the total boron content nor pH of the fracturing fluid, the delay time is controlled by adding a polyol to the fracturing fluid at a first rate, determining the resulting delay time and then adjusting the rate of the polyol addition to the fracturing fluid until the desired delay time is achieved.

Abstract: The present invention provides borate cross-linked well treating fluids and methods of preparing and using the fluids in treating wells such as fracturing subterranean zones therein. The improved cross-linked treating fluids are basically comprised of water, a hydrated galactomannan gelling agent and a borate composition for buffering the treating fluid and cross-linking the hydrated galactomannan gelling agent comprised of water, a soluble boron source and an alkanolamine or alkylamine.

Abstract: A novel fracturing fluid composition comprising:(1) a carboxyalkyl derivatized polygalactomannan having a degree of substitution of between about 0.01 and about 3.0;(2) a zirconium salt crosslinking agent;(3) one or more thermal stabilizing agents;(4) one or more pH buffers; and(5) water;wherein said fluid is capable of maintaining at least 10 percent of its original cross-linked viscosity after three hours at a temperature greater to or equal to 250.degree. F. is provided.

Abstract: A method is shown for fracturing a subterranean formation in which a hydratable polymer, crosslinking agent and breaker are combined in an aqueous carrier to form a gelled fracturing fluid. The breaker is comprised of a substantially insoluble oxidant which is granulated and formed into a pellet or prill with a suitable binder. The pellet so formed can also contain a chelating agent and an activator in order to enhance the rate of breaking. The substantially insoluble oxidant is selected from the group consisting of alkaline earth and zinc salts of peroxide, perphosphate, perborate, and percarbonate.

Abstract: A novel fracturing fluid composition comprising:(1) a carboxyalkyl derivatized polygalactomannan having a degree of substitution of between about 0.01 and about 3.0;(2) a zirconium salt crosslinking agent;(3) one or more thermal stabilizing agents;(4) one or more pH buffers; and(5) water;wherein said fluid is capable of maintaining at least 10 percent of its original cross-linked viscosity after three hours at a temperature greater to or equal to 250.degree. F. is provided.

Abstract: Borated starch compositions useful for controlling the rate of crosslinking of hydratable polymers in aqueous media for use in drilling fluids.

Abstract: A solids-free, essentially all-oil wellbore fluid comprises (a) an organic fluid having (i) a melting point less than about 20.degree. C. (about 68.degree. F.), (ii) a flash point greater than about 54.4.degree. C. (about 130.degree. F.), and (iii) a dipole moment greater than 0 debye (D), and (b) a salt dissolved in the organic fluid. The wellbore fluid is employed in well drilling, completion, and work-over operations.

Abstract: A method is provided to fracture a subterranean formation along with a fracturing fluid useful in this method, the method comprising the steps of: a) providing a fracturing fluid, the fracturing fluid is an aqueous solution having an initial pH greater than about 8 and comprising a polysaccharide, a source of borate in an amount that is effective to crosslink the polysaccharide at a pH greater than 8, an oxidative breaker, and a precursor that hydrolyzes in an amount that is effective to lower the pH of the fracturing fluid after a time period that is greater than about one half hour and less than about two days; b) injecting the fracturing fluid into the formation at a pressure the is effective to fracture the formation and force at least a portion of the fracturing fluid into the fracture; and c) permitting the precursor to hydrolyze and thereby lowering the pH of the fracturing fluid to a pH that is less than about 8.

Abstract: The crosslinking of galactomannan gum fracturing fluids by borate ion is delayed for high-temperature applications by encapsulating the boron with a polymer coating. The crosslink-delay time is further adjusted by varying the concentration of an organic polyol. The polyol also acts as a stabilizer for the crosslinked fluid at elevated temperatures. Low pumping friction pressures are achieved by the delay in the crosslinking with the boron available at high temperatures to add high temperature stability to the fracturing fluid at temperatures ranging up to about 350.degree. F.