Abstract: A fracturing system for a well, in which a stream of LPG, a mixture of propane and butane, is injected into the well at frac pressure. Proppant is supplied into the LPG stream, and carried by the LPG mix into the formation. Inert gas such as nitrogen is used for purging system components of LPG, and to help protect against risk of explosion. Nitrogen may also be added to the LPG mix during a frac of shale gas or coal gas formations.

Abstract: A method of stimulating and stabilizing an area of a subterranean formation comprising placing an acid fluid into an area of a subterranean formation and allowing the acid to at least partially dissolve a portion of the area of the subterranean formation; placing a consolidation fluid into the area of the subterranean formation; and, placing an afterflush fluid into the area of the subterranean formation. A method of stimulating and stabilizing an area of a subterranean formation comprising placing an acid fluid into an area of a subterranean formation and allowing the acid to at least partially dissolve a portion of the area of the subterranean formation; placing a consolidation fluid into the area of the subterranean formation; and, placing a fracturing fluid into the area of the subterranean formation at a pressure sufficient to create or extend at least one fracture therein.

Abstract: Viscoelastic surfactant based aqueous fluid systems useful as thickening agents in various applications, e.g. to suspend particles produced during the excavation of geologic formations. The surfactants are zwitterionic/amphoteric surfactants such as dihydroxyl alkyl glycinate, alkyl ampho acetate or propionate, alkyl betaine, alkyl amidopropyl betaine and alkylimino mono- or di-propionates derived from certain waxes, fats and oils. The thickening agent is used in conjunction with an inorganic water-soluble salt or organic additive such as phthalic acid, salicylic acid or their salts.

Abstract: A method of treating a well consists of introducing into the wellbore a biodegradable fluid system containing a blend of lactic acid ester, such as ethyl lactate, and a fatty acid ester, such as methyl soyate. The fluid system may be further in the form of a microemulsion that is formed by combining a blend with one or more emulsifiers, an alcohol, and water. The fluid system may be used in displacement, well remediation and stimulation as well as additional, alternative applications such as the cleaning of surface and/or downhole equipment.

Abstract: The present invention is directed to a method of increasing hydrocarbon production in an existing well in a hydrocarbon reservoir. The method includes the steps of forming a substantially horizontal transverse fractured wellbore that intersects the existing well and injecting a fluid remote from the existing well so as to form a fluid front that sweeps the hydrocarbons into the horizontal transverse fractured wellbore. Successive fractures can be sealed to control propagation of the fluid front and delay infiltration of the fluid into the production.

Abstract: A method is given for treating a subterranean formation penetrated by a wellbore with a viscosified fluid. The fluid contains a solid hydrolysable polyacid that upon dissolution and hydrolysis releases an acid that is a breaker for the viscosifying system. Suitable solid hydrolysable polyacids include polylactic acid and polyglycolic acid. The fluid also contains a pH control agent, present in an amount sufficient to neutralize any acid present in the solid hydrolysable polyacid before the injection and to neutralize any acid generated by the solid hydrolysable polyacid during the injection, so that the acid breaker is not available to break the fluid during the injection. In one embodiment the viscosifier is a viscoelastic surfactant fluid system and the solid hydrolysable polyacid is of a size selected to be a fluid loss additive, for example in fracturing or gravel packing.

Abstract: The present invention generally relates to a method for treating a subterranean formation with an aqueous viscoelastic treating fluid that an aqueous base fluid and one or more non-ionic amido amine oxide surfactant gelling agents. The treatment method comprises injecting the aqueous viscoelastic surfactant treating fluid through a wellbore and into the subterranean formation under conditions effective to control fluid loss, and breaking the gel of the aqueous viscoelastic treating fluid subsequent to treating said formation.

Abstract: Methods for the treatment of subterranean wells involving injecting a first fracturing fluid into a formation, and then injecting at least a second fracturing fluid into the formation in order to create extended conductive channels through a formation are described. The fracturing fluids can be similar in density, viscosity, pH and the other related characteristics. Alternatively, the fracturing fluids can differ in their densities, viscosities, and pH, allowing for variations in the conductive channels formed. Propping agents can also be included in one or both of the injected fluids, further enhancing the conductive channels formed. The described methods aid in minimizing proppant flowback problems typically associated with hydraulic fracturing techniques.

Abstract: Water soluble nonionic friction reducers and added to coacervate gels having excellent shear viscosities and other properties. A preferred gel comprises poly diallyl dimethyl ammonium chloride, a lesser amount of sodium lauryl sulfonate, and lauryl alcohol. Excellent friction reducing properties are manifested; a particularly practical use for the compositions is in subterranean formation fracturing.

Abstract: Method of treating a portion of a subterranean formation comprising: placing a pre-pad fluid into a portion of a subterranean formation wherein the pre-pad fluid comprises a low-viscosity aqueous tackifying composition that comprises an aqueous tackifier compound and an aqueous fluid; placing a fracturing fluid into the portion of the subterranean formation at a pressure sufficient to create or extend at least one fracture therein; and, activating the aqueous tackifier compound with an activator so as to consolidate the unconsolidated particulates.

Abstract: Disclosed herein is a method of treating a subterranean formation utilizing a fluid having a splittable foamer, i.e., a fluid that creates a stable foam when it contacts the formation but that loses its ability to foam as it remains in contact with the formation for extended time. The present method has the advantage that the fluid can be recovered from the well unhindered by the difficulties involved with recovering a foamed fluid from a well. The present method does not require the use of breakers, though the splitting of the foam can be accelerated by introducing an organic or inorganic acid into the well, if so desired.

Abstract: A method is provided for in-situ production of oil shale and gas (methane) hydrates wherein a network of fractures is formed by injecting liquified gases into at least one substantially horizontally disposed fracturing borehole. Heat is thereafter applied to liquify the kerogen or to dissociate the gas (methane) hydrates so that oil shale oil and/or gases can be recovered from the fractured formations.

Abstract: Propped fractures in formations from which fluids are produced are described that have wormholes extending out into the formations from the faces of the fractures at locations distant from boreholes. Methods are given for creating such propped fractures having wormholes in which either a closed propped fracture is formed and then the wormholes are formed, or the entire fracture and channel system is formed before the closure occurs.

Abstract: A formulation containing a copolymer derived from a cationic monomer effectively inhibits and controls the formation of inorganic scales. The formulation has particular application in the removal of zinc sulfide and iron sulfide scales formed when zinc bromide brines are used as completion fluids. The copolymer exhibit high solubility in high-density brines, such as zinc bromide brines. The polymers may be introduced into an oil or gas well as a portion of a carrier fluid or with brine. The preferred copolymer for use in the invention contains an acrylamide unit and a diallyldimethylammonium salt and, optionally, an acrylic acid or a salt thereof. The weight average molecular weight of such inhibitor copolymers is generally between from about 500,000 to about 5,000,000.

Abstract: A process for enhancing the productivity of a formation consists of introducing into the formation a viscoelastic fluid which contains at least one surfactant, at least one quaternary amine polyelectrolyte, water, and a non-aqueous solvent. The surfactant forms aggregation structures or vesicles. The fluid, which significantly enhances fluid viscosity and thermal stability, is particularly effective as a diverting fluid to divert an acid treatment package from a high permeability or undamaged portion of a formation to a low permeability or damaged portion of a formation as well as a fracturing fluid. In addition, the fluid is useful for sand control completion.

Abstract: Viscoelastic surfactants are described for use in aqueous systems to generate thickened fluids. The surfactants are alkyl amidoamine salts of inorganic acids and/or organic acids. The fluids may also contain inorganic salts, organic salts or mixtures thereof. Additionally, the fluids may contain a co-surfactant. These fluids are particularly useful in oilfield applications such as hydraulic fracturing, gravel packing, drilling, completion, etc. Viscoelastic fluids of the invention are also useful in industrial and consumer product fluid applications as rheology control agents.

Abstract: Reduced friction fluids comprising an aqueous liquid, carbon dioxide, and a polymer comprising acrylamide and an acrylamide copolymer derivative. And methods of treating a subterranean formation comprising the steps of providing a reduced friction fluid comprising an aqueous liquid, carbon dioxide, and a polymer comprising acrylamide and an acrylamide copolymer derivative; and, introducing the reduced friction fluid to a subterranean formation.

Abstract: Propped fractures in formations from which fluids are produced are described that have wormholes extending out into the formations from the faces of the fractures at locations distant from boreholes. Methods are given for creating such propped fractures having wormholes in which either a closed propped fracture is formed and then the wormholes are formed, or the entire fracture and channel system is formed before the closure occurs.

Abstract: The present invention provides variable density fluid compositions and methods for using such compositions in a subterranean formation. One exemplary embodiment of the variable density fluid compositions of the present invention comprises a variable density fluid comprising: a base fluid, and a portion of variable pressure weighting material particles.

Abstract: The present invention relates to a method and system for hydrating a gel for treating a wellbore penetrating a subterranean formation. The method includes directing a base fluid through an inlet into a mixer having an inner chamber housing a plurality of impellors extending radially from and rotating about a hub, causing a centrifugal motion of the base fluid, feeding a quantity of gel into the mixer, mixing the gel with the base fluid and discharging the now-hydrated gel from the inner chamber through an outlet of the mixer. A prewetting device may also be used. Thereafter, a variety of additives may be added to the gel fluid mix to form a fluid treatment to be introduced into a subterranean formation.

Abstract: The present invention relates to subterranean fracturing operations, and more particularly to fracturing fluids that includes a fluid loss control additive, and methods of using such fracturing fluids in fracturing subterranean formations. In one embodiment, a fracturing fluid of the present invention includes a viscosifier; and a fluid loss control additive that includes a deformable, degradable material.

Abstract: A method for recovering hydrocarbon trapped in a hydrate formation, comprising the steps of (a) contacting the hydrate formation with an aqueous solution comprising from 10% to 75% by weight of a salt such as potassium formate or acetate salt to liberate hydrocarbon from the hydrate formation and producing a mixture of hydrocarbon and water vapour; (b) transporting the hydrocarbon/water vapour mixture and the aqueous solution to a separator, whereby the said aqueous solution absorbs water vapour from the mixture during the transportation step, to form a more dilute aqueous solution of the alkali metal salt, thereby inhibiting formation of hydrocarbon hydrates; (c) separating hydrocarbon from said dilute aqueous solution; (d) regenerating the aqueous solution of step (a) by heating said dilute aqueous solution to remove absorbed water vapour; and (f) recycling the regenerated aqueous solution to step (a).

Abstract: A method for removing or dissolving calcareous materials in a subterranean formation or in a wellbore consists of two basic steps. In the first step, an aqueous acid solution is injected into the formation or wellbore. The aqueous acid solution contains between from about 15 to about 99 weight percent of an organic acid selected from formic acid, acetic acid or a mixture of formic acid and acetic acid. Water or brine is then injected into the formation or wellbore. The amount of water or brine injected into the formation or wellbore is an amount sufficient to reduce the concentration of organic acid in the formation or wellbore to no greater than 10 weight percent.

Abstract: A system for fracturing wells uses a primary propellant charge to initially produce pressures within the well in excess of the maximum fracture extension pressure of the surrounding formation, but below that which would cause damage to the well. A supplemental propellant charge burns for a substantially longer period of time than the primary propellant charge, and thereby maintains pressures within the well in excess of the maximum fracture extension pressure for a significant period of time following completion of the primary propellant burn.

Abstract: A well service fluid composition comprises a fracturing fluid and a gas hydrate inhibitor. Preferably, the gas hydrate inhibitor does not affect the function of the fracturing fluid and is present in an amount sufficient to control and/or minimize the formation of gas hydrates. The well service fluid composition is useful in hydraulic fracturing in which the composition is injected into a subterranean formation under sufficient pressure to initiate and propagate a fracture in the formation. The fracturing fluid may be subsequently recovered when the fracturing operation is completed.

Abstract: The present invention generally relates to aqueous, acidic compositions thickened with an amidoamine oxide gelling agent and/or viscoelastic surfactant of the general formula I: wherein R1 is a saturated or unsaturated, straight or branched chain aliphatic group of from about 7 to about 30 carbon atoms, R2 is a divalent alkylene group of 2–6 carbon atoms which may be linear or branched, substituted or unsubstituted, and R3 and R4 are independently C1–C4 alkyl or hydroxyalkyl groups or together they form a heterocyclic ring of up to six members, and R5 is hydrogen or a C1–C4 alkyl or hydroxyalkyl group. The aforementioned gelling agents advantageously provide gels that do not undergo phase separation over extended periods of time and exhibit high heat stability. The thickened acid gels of the invention have applications in household and industrial cleaners and degreasers, oilfield stimulation applications and the like.

Abstract: The present invention relates to methods of stimulating a subterranean formation. More particularly, but not by way of limitation, the present invention relates to methods of fracturing subterranean formations utilizing a fracturing fluid comprising a permeable cement composition that may be used as a propping agent. One method of stimulating a subterranean formation of the present invention comprises the following steps: preparing a permeable cement composition comprising a hydraulic cement, water, and a degradable material capable of undergoing an irreversible degradation downhole; injecting the permeable cement composition into the subterranean formation at a pressure sufficient to create a fracture in the subterranean formation; and allowing the permeable cement composition to form a proppant matrix having voids in the fracture.

Abstract: The present invention relates to fluid systems comprising a first fluid comprising carbon dioxide and a second fluid comprising an alkaline crosslinked fluid. The fluid combinations of the present invention may be used, for example, in hydraulic fracturing, frac-packing, and gravel packing. Some embodiments of the present invention provide systems for treating a subterranean formation comprising a first fluid comprising a foamed carbon dioxide fluid, an emulsion of carbon dioxide, or a carbon dioxide gel; and, a second fluid comprising an alkaline crosslinked fluid.

Abstract: A method is provided for diverting the majority of the fluid injected into a stratified subterranean formation, that has at least one problematic zone and at least one hydrocarbon zone, into the hydrocarbon zone. In the method, a viscous diverting fluid made with a gelling amount of a surfactant and an acid is injected before the main treatment; after the treatment the acid decomposes the surfactant. The main treatment may be hydraulic fracturing, acid fracturing and matrix acidizing. The fluid used as the diverting fluid may also be used as the carrier fluid in hydraulic fracturing or gravel packing. Destruction of the surfactant alleviates the potential of diverters or carrier fluids to damage formations.

Abstract: The present invention provides fluid compositions comprising water and a formate ester, and methods of using these fluids in subterranean formations. Optionally, other additives may be added.

Abstract: Methods are provided for fracturing subterranean formations using fluids having substantially reduced polymer loadings that have performance equivalent to conventional fluids. Reduced polymer loadings provide significant advantages such as reduced treatment costs and less damage to the fracture sand pack and surrounding subterranean formations.

Abstract: Aqueous treatment fluids that comprise water, and a friction reducing copolymer that comprises acrylamide in an amount in the range of from about 60% to about 90% by weight and acrylic acid in an amount in the range of from about 10% to about 20% by weight. Methods of treating portions of subterranean formation using the aqueous treatment fluid that comprise providing an aqueous treatment fluid comprising water, and a friction reducing copolymer that comprises acrylamide in an amount in the range of from about 60% to about 90% by weight and acrylic acid in an amount in the range of from about 10% to about 20% by weight; and introducing the aqueous treatment fluid into the portion of the subterranean formation.

Abstract: Fracturing fluids and methods of fracturing a subterranean formation using such fluids are provided. A fracturing fluid having a first pH is foamed by introducing a gas to the fluid. The fracturing fluid comprises a surfactant that facilitates formation of the foam at the first pH. The foamed fracturing fluid is subsequently pumped to the subterranean formation to fracture it. The pH of the fracturing fluid is then changed to a second pH at which the surfactant facilitates reduction of the foam. The fracturing fluid releases proppant contained in the fluid to the subterranean formation. The fracturing fluid is then allowed to flow back to the surface. It can be recycled by changing the pH of the fracturing fluid back to the first pH and adding a gas to the fluid, causing it to foam again.

Abstract: The present invention relates to methods of designing a hydraulic fracturing treatment in a subterranean reservoir and methods of treatment. Methods of the invention include quantifying reservoir parameters such as bottomhole temperature and formation permeability, then assessing the temporary variation in temperature of the formation due to the injection of calibration and/or clean up fluids. Treatment fluids are then design based upon the temporary temperature. The fluids are then pumped to treat the reservoir.

Abstract: Embodiments provide systems and methods in which a non-viscous fluid, having a heavy concentration of an appropriate breaker, is pumped into a well in front of viscosified fluid, such as a cross-linked polymeric fracturing fluid, to saturate permeable media with a breaker agent. When a polymer filter cake is subsequently formed on the surfaces of the media the breaker is provided good communication with the polymer filter cake for its breakdown and removal. Communication between the breaker and the polymer filter cake is substantially controlled by an operator in that the breaker remains saturated in the permeable media until such time as the operator decreases hydraulic pressure within the well to a point at which the hydraulic pressure of the media forces the breaker back into the well.

Abstract: A method for diverting the majority of the fluid injected into a stratified subterranean formation, that has at least one problematic zone and at least one hydrocarbon zone, into the hydrocarbon zone includes injection of a viscous diverting fluid made with a gelling amount of a surfactant and an acid before the main treatment; after the treatment the acid decomposes the surfactant. The main treatment may be hydraulic fracturing, acid fracturing and matrix acidizing. The fluid used as the diverting fluid may also be used as the carrier fluid in hydraulic fracturing or gravel packing. Destruction of the surfactant alleviates the potential of diverters or carrier fluids to damage formations.

Abstract: A well treatment fluid composition that comprises a carrier fluid and an amphoteric surfactant, and optionally a viscosifying agent and proppant, is well suited for use in fracturing coal beds to stimulate methane production. The composition preferably is a foam that comprises a gas such as nitrogen or air. Preferably, the surfactant has the formula R—NH2—(CH2)n—C(O)OX wherein R is a saturated or unsaturated alkyl group having from 6-20 carbon atoms, n is from 2-6, and X is hydrogen or a salt forming cation.

Abstract: Improved methods and compositions for consolidating proppant in subterranean fractures are provided. In accordance with a method of the invention, proppant particles coated with a furfuryl alcohol resin composition are mixed with a gelled liquid fracturing fluid and the fracturing fluid is pumped into a subterranean zone. The fracturing fluid forms one or more fractures in the subterranean zone and deposits the proppant particles coated with the resin composition therein. Thereafter, the hardenable resin composition on the proppant particles is allowed to harden by heat and consolidate the proppant particles into chemical and thermal degradation resistant permeable packs.

Abstract: Methods and compositions are disclosed for controlled addition of components that decrease the viscosity of the viscoelastic surfactant fluids or for controlled changes in the electrolyte concentration or composition of the viscoelastic surfactant fluids. One aspect of the invention relates to the use of internal breakers with a delayed activation. Another aspect of the invention relates to the use of precursors that release a breaking system such as alcohol by a process such as melting, slow dissolution, reaction with a compound present in the fluid or added to the fluid during or after the step of injecting, rupture of an encapsulating coating and de-adsorption of a breaking agent absorbed into solid particles. In another aspect of the invention, alcohols are included in a pad to reduce the low-shear viscosity and reduce the resistance to flow of the treatment fluids during a desired phase of the treatment.

Abstract: A method of fracturing a formation with a fracturing fluid wherein the formation has particulate material that swells or migrates upon exposure to the fracturing fluid comprises preparing a fracturing fluid comprising (1) a thickening compound comprising a first surfactant selected from the group consisting of a cationic surfactant having only a single cationic group, an amphoteric surfactant and a mixture thereof; and, an anionic surfactant; and, (2) water, wherein no or essentially no inorganic salt is added to the fracturing fluid; and using the fracturing fluid to fracture the formation. A method for recycling a fracturing fluid is also provided.

Abstract: Disclosed is a copolymer useful for preparing acid gels comprising a copolymer having a copolymer backbone, the copolymer having a general formula: wherein: (a) A is an H or other terminating group; (b) R1 is an OH or NH2; (c) R2 is an O or NH; (d) Z is an integer having a value of from 1 to 4; (e) X and Y are present in a ratio (X:Y) of from 3:2 to 4:1; (f) structures I and II are present as blocks or randomly distributed along the copolymer backbone; and wherein the copolymer has a molecular weight of from about 1,000,000 to about 10,000,000.

Abstract: Stimulation, particularly fracturing or acidising, of hydrocarbon wells having bores leading to hydrocarbon bearing uses a fluid including a continuous phase of or including a compound of the formula (1): (R2)p—Ph—(CH2)m—COO—(AO)n—R1 where R1, AO, n, m, Ph, R2 and p having defined meanings and particularly where the esters are alkyl or alkenyl benzoate esters. These esters are beneficial by having a range of viscosities, especially extending to low viscosities, and attractive toxicological and environmental profiles for use in well stimulation.

Abstract: The present invention relates to a method and system for hydrating a gel for treating a wellbore penetrating a subterranean formation. The method includes directing a base fluid through an inlet into a mixer having an inner chamber housing a plurality of impellors extending radially from and rotating about a hub, causing a centrifugal motion of the base fluid, feeding a quantity of gel into the mixer, mixing the gel with the base fluid and discharging the now-hydrated gel from the inner chamber through an outlet of the mixer. A prewetting device may also be used. Thereafter, a variety of additives may be added to the gel fluid mix to form a fluid treatment to be introduced into a subterranean formation.

Abstract: Methods are provided for stimulation of hydrocarbon production from low permeability formations by hydraulic fracturing, acid fracturing, and hydraulic fracturing followed by gravel packing in a single operation. The methods use a first injected viscous pad made with low concentration uncrosslinked polymer to initiate and propagate the fracture and control fluid loss, followed by a second injected fluid gelled with a viscoelastic surfactant for carrying proppant or acid into the fracture.

Abstract: Disclosed are methods and related compositions for altering the physical and chemical properties of a substrate used in hydrocarbon exploitation, such as in downhole drilling operations. In a preferred embodiment a method involves formulating a fluid, tailored to the specific drilling conditions, that contains one or more inactivated enzymes. Preferably the enzyme is inactivated by encapsulation in a pH responsive material. After the fluid has been introduced into the well bore, one or more triggering signals, such as a change in pH, is applied to the fluid that will activate or reactivate the inactivated enzyme, preferably by causing it to be released by the encapsulation material. The reactivated enzyme is capable of selectively acting upon a substrate located downhole to bring about the desired change in the chemical or physical properties of the substrate.

Abstract: A method of reducing friction resulting from turbulent flow in an aqueous fracturing fluid in an oil field fracturing process comprising adding to the aqueous fracturing fluid an effective friction-reducing amount of one or more dispersion polymers, wherein the dispersion polymer is composed of from about 5 to about 95 mole percent of one or more nonionic monomers and from about 95 to about 5 mole percent of one or more cationic or anionic monomers and has a molecular weight of at least 100,000.

Abstract: The present invention relates to methods, aqueous treating fluids and friction pressure reducers for the treating fluids. A treating fluid of the invention comprises water and a non-toxic environmentally acceptable friction pressure reducer comprising a mixture of a copolymer of acrylamide and dimethylaminoethyl acrylate quaternized with benzyl chloride and a stabilizing and dispersing homopolymer of ethanaminium,N,N,N-trimethyl-2-[(1,oxo-2-prbpenyl)oxy]-chloride.

Abstract: A well treatment fluid composition that comprises a carrier fluid and an amphoteric surfactant, and optionally a viscosifying agent and proppant, is well suited for use in fracturing coal beds to stimulate methane production. The composition preferably is a foam that comprises a gas such as nitrogen or air.

Abstract: The present invention provides a method for encapsulating a liquid within a semi-permeable membrane. In particular, the present invention provides a method for encapsulating free flowing liquids. The current invention also provides a method for treating the downhole region of a well using encapsulated well treatment chemicals. The method of treating the downhole region of a well is particularly useful in acid etching a fracture face.

Abstract: The invention concerns an aqueous viscoelastic fluid for use in the recovery of hydrocarbons. According to the invention, the aqueous viscoelastic fluid comprises a monomer, a dimer or an oligomer of a viscoelastic surfactant able to form a viscoelastic gel under downhole conditions, said surfactant comprising a hydrophobic tail and a hydrophilic head, and being of the following formulae: R—X—Y—Z where R is the hydrophobic tail of the surfactant, Z is the hydrophilic head of the surfactant, said hydrophilic head being charged, X is a stabilising group and Y chain is a linear, saturated or unsaturated, hydrocarbon chain of 1, 2 or 3 carbon atoms or a branched, saturated or unsaturated hydrocarbon chain wherein the main chain is of 1, 2 or 3 carbon atoms, possibly incorporating an aromatic ring.