Abstract: In stimulation treatments to increase the production of hydrocarbons from subterranean formations, especially in treatments including hydraulic fracturing followed by gravel packing, desirable short wide fractures are created and filled with proppant by deliberately including in the first fluid/proppant slurry pumped a sufficiently high concentration of a bridging-promoting material, such as fibers, that reduces the mobility of the slurry when it dewaters so that screenout at or near the tip occurs.

Abstract: Selectively cross-linked starches are disclosed that are useful as fluid loss control additives in subterranean treatment fluids comprising starches that cross-linked to a Brabender peak viscosity of about 800 to about 1250 Brabender units after about 40 to about 70 minutes at about 92° C. and provide good fluid loss control over a temperature range of from about 20° C. to about 160° C. (68° F. to 320° F.).

Abstract: The improved recovery of hydrocarbons from subterranean formations by hydraulically fracturing a subterranean formation is accomplished. Fracturing fluids using a viscosifying surfactant fluid containing viscosifying micelles, for example, wormlike micelles, are useful to improve recovery of hydrocarbons and limit the loss of fracturing fluid into the formation fracture face. The invention further relates to novel fracturing and acidizing methods useful for increasing hydrocarbon production, limiting water production, resisting fracturing fluid loss into the subterranean formation, and reducing the equipment requirements in mixing and pumping fracturing fluid. The action of viscosifying micelles of surfactant in aqueous zones of the subterranean formation diverts fracturing fluid or acid from the aqueous zones to the hydrocarbon-bearing zones and also facilitates the flowback of increased amounts of hydrocarbons once a fractured well is placed back on production.

Abstract: For controlling filtration loss during the installation of climber cement in a well, the procedure entails the addition of a specific quantity of at least one derivative of galactomannan, hydrophilically and hydrophobically modified, a hydrophobically modified hydroxy propyl guar (HMHPG).

Abstract: A method of formulating an organo-zirconium compound is accomplished by combining in solution a dialdehyde such as glyoxal with zirconium carbonate. The reacting solution forms an organo-zirconium compound and carbon dioxide which is evolved as a gas from the solution. This eliminates the need to filter or wash the organo-zirconium compound in order to remove undesirable by-products. The organo-zirconium compound can be used as a crosslinking agent for crosslinking aqueous polymer gels used in fracturing fluids for fracturing subterranean formations of oil and gas wells.

Abstract: The invention, in one embodiment, relates to a fluid loss control additive or composition comprising a granular starch composition and fine particulate mica, in specified proportions. The invention further comprises a fracturing fluid containing a starch composition and mica, in a specified ratio. In yet a third embodiment, the invention comprises a method of fracturing a subterranean formation penetrated by a borehole, comprising injecting into the borehole and into contact with the formation, at a rate and pressure sufficient to fracture the formation, a fracturing fluid containing starch and mica, in specified ratios, and in an amount sufficient to provide fluid loss control.

Abstract: Hydrocarbon fracturing fluids are made by combining organic phosphate esters with polyvalent metal salts in hydrocarbon carriers to form gels; breaking of the gel is retarded or otherwise controlled over a wide range of water concentrations, through the use of slowly soluble alkaline earth metal compounds, preferably hard burned magnesium oxide, which may be added along with the gel component. The slowly soluble alkaline earth metal compound is employed together with an oily acid breaker retarding agent such as tall oil.

Abstract: Clay stabilizing agents used in fracturing fluids produce noxious odours, raise environmental concerns or are less than effective in subterranean formations of low permeability. Disclosed herein is an alternate stabilizing agent comprising at least one organic amine selected from the group consisting of primary diamines with a chain length of 8 or less and primary alkyl amines with a chain length of 4 or less. The organic amine is admixed with the fracturing fluid in an amount not less than 0.03% by volume of the fluid and typically in the range of from about 0.06% to 0.3% by volume of the fluid.

Abstract: The present invention provides a method of controlling fluid loss to a permeable formation penetrated by a wellbore. A novel fluid loss agent is prepared by forming a crosslinked polymer gel which then is sheared to break the gel into discrete particles of a particular size range. A slurry then is formed of the particles by dispersing the particles in an aqueous fluid having a density similar to that of the gel particles. The slurry then is introduced into contact with the permeable formation and a filter cake of the particles is formed upon contact with the formation and loss of the slurrying fluid to the formation. The filter cake provides further fluid loss control to the permeable formation.

Abstract: The present invention relates to a method of terminating undesirable gas migration in a well through one or more passages such as channels and microannuli in the cement sheath holding the casing in the well bore. The methods basically comprise forming one or more lateral openings through the casing and the cement sheath into a substantially gas impermeable formation penetrated by the well bore. One or more horizontal fractures are created in the formation extending from the lateral openings, and a fluid which sets into a substantially gas impermeable solid is deposited in the openings and fractures. The fluid is permitted to set into a substantially gas impermeable solid in the openings and fractures whereby passages in the cement sheath are plugged and gas migration is terminated.

Abstract: The addition of fibrous materials in intimate mixture with particulates for fracturing and gravel packing decreases or eliminates the flowback of proppant and/or formation fines while stabilizing the sand pack and lowering the demand for high polymer loadings in the placement fluids. Preferred fibers include glass, aramide, nylon and other natural and synthetic organic and inorganic fibers and metal filaments.

Abstract: The present invention provides a method of controlling fluid loss to a permeable formation penetrated by a wellbore. A novel fluid loss agent is prepared by forming a crosslinked polymer gel which then is sheared to break the gel into discrete particles. A slurry then is formed of the particles by dispersing the particles in an aqueous fluid having a density similar to that of the gel particles. The slurry then is introduced into contact with the permeable formation and a filter cake of the particles is formed upon contact with the formation and loss of the slurrying fluid to the formation. The filter cake provides further fluid loss control to the permeable formation.

Abstract: Fracturing fluids for hydraulically fracturing oil and gas bearing subterranean formations to increase flow of formation fluids into wells using a periodate or a metaperiodate salt as the viscosity breaker. The fracturing fluids are particularly advantageous when used in conjunction with curable resin-coated proppants and for fracturing subterranean formations which are at temperatures between about 50.degree. F. and about 120.degree. F., in conjunction with both uncured resin-coated proppants and other types of proppants.

Abstract: A method is provided to produce a polymer-thickened solution for injection into a wellbore, the method comprising the steps of:a) providing an aqueous polymer solution or suspension;b) dispersing the aqueous polymer solution or suspension into an aqueous stream not containing any of the polymer through nozzles wherein the nozzles have an opening of no larger than a circle of about 1/8-inch diameter;c) passing the aqueous stream containing the polymer solution or suspension through a static mixer having a residence time of at least about 0.5 seconds; andd) injecting the polymer-thickened solution into a wellbore. The polymer-thickened solution prepared according to the present invention may be used as a fracturing fluid, combined with gravel pack sand and used for gravel packing a wellbore, used as an acid treatment composition or used as a fluid loss composition.

Abstract: Water-soluble polymers comprising an N-vinyl amide such as an N-vinyl lactam are found to be useful in processes wherein the polymer is introduced into a subterranean wellbore.Polymers useful in the recovery of natural resources are prepared by polymerizing an N-vinyl lactam by free radical initiation with polymerization conducted in an aqueous solution polymerization medium preferably containing a mixture of dissolved electrolytes, or in a polymerization medium consisting essentially of a tertiary alkanol. Copolymers of such N-vinyl lactams with unsaturated amides, and terpolymers prepared by polymerizing an N-vinyl lactam and an unsaturated amide with a selected termonomer compound are also useful when prepared by these methods. The invention also broadly encompasses utilizing a water-soluble polymer comprising at least one of a hydrophilic vinyl-containing sulfonate, phosphonate or ester and/or a hydrophilic N-vinyl lactam for applications under hostile conditions.

Abstract: A method of stimulating a subterranean formation using a foamed cement composition. When hardened, the cement composition has a permeability of at least about 0.3 darcies. The inventive formation stimulation method comprises the steps of: (a) injecting the foamed cement composition into the formation at a pressure sufficient to fracture the formation and (b) allowing the cement composition to harden in the formation.

Abstract: The addition of relatively small quantities of a bacterial cellulose to hydraulic fracturing fluids improves their rheological properties for hydraulic fracturing of geological formations. Proppant suspension is markedly improved and friction loss through well casings is significantly reduced, resulting in lower pumping energy requirements. Computer models also indicate that formation fractures will be propagated for greater distances as will the propped portion of the fracture. Normally only about 0.60-1.8 g of bacterial cellulose per liter of fracturing fluid is needed. A preferred bacterial cellulose is one made in agitated fermentors using mutation resistant strains of a bacterium from the genus Acetobacter.

Abstract: The addition of fibrous materials in intimate mixture with particulates for fracturing and gravel packing decreases or eliminates the flowback of proppant and/or formation fines while stabilizing the sand pack and lowering the demand for high polymer loadings in the placement fluids. Preferred fibers include glass, aramide, nylon and other natural and synthetic organic and inorganic fibers and metal filaments.

Abstract: A two-fluid method for fracturing a subterranean formation to increase the production of fluids from a well therein has been discovered. In a typical operation, a fluid pad is injected into the well which essentially simultaneously fractures the formation and forms a low permeability filter cake on at least part of the fracture. A proppant transport fluid containing proppant is then injected to prop open the fracture once the pressure is decreased. The filter cake is removed to permit production to begin. Although many conventional fluids may be used for the fluid pad, one preferred fluid pad uses graded calcium carbonate particle sizes and a modified lignosulfonate as a filter control agent. Optionally, a thixotropic polymer may be present as a viscosifier.

Abstract: The method of using soap as a fluid loss additive in the hydraulic fracturing treatment of oil and gas wells includes choosing a soap having a titre value which will insure that the soap will dissolve and liquify at the formation temperature in the area where fluid loss is to be reduced. The formation temperature in this area is reduced to an extent where the soap will not liquify, while the soap is introduced into the area under pressure, and this lower temperature is maintained while a fracturing or cementing process is carried out. Subsequently, the temperature in the area where fluid loss is to be reduced is permitted to rise and liquify the soap which is then removed from the well.

Abstract: A fluid loss additive for a fracture treatment fluid, a fracture treatment fluid, and a process for fracturing a subterranean formation, utilize finely ground peanut hulls, wherein 10% or more of the finely ground peanut hulls is in the particle size range of less than 20 standard sieve mesh and greater than 500 standard sieve mesh.

Abstract: This invention relates to the optimum formulation of workover and completion fluids used in oil, gas, water, or mineral recovery wells. Specifically, it discloses a method of processing peanut hulls and combining these with a suitable suspending agent in order to effect a seal against permeable formations during workover, completion, coring, drill-stem-testing, or drilling operations, without causing permanent permeability damage. Moreover, it discloses that when the procedures discovered are practiced as taught by this invention, the sealing action is reversible by simple fluid circulation and placing the well on production.

Abstract: A liquid aluminum phosphate salt gelling agent comprising the reaction product of: a dialkyl phosphate formed from the reaction product of (1) a polyphosphate intermediate produced by reacting triethyl phosphate and phosphorous pentoxide and (2) a mixture of aliphatic alcohols having 6 to 10 carbons in their alkyl groups; an aluminum sulfate; and a solvent.

Abstract: A liquid aluminum phosphate salt gelling agent comprising the reaction product of: a dialkyl phosphate formed from the reaction product of (1) a polyphosphate intermediate produced by reacting triethyl phosphate and phosphorous pentoxide and (2) a mixture of aliphatic alcohols having 6 to 10 carbons in their alkyl groups; an aluminum sulfate; and a solvent.

Abstract: An organometallic compound which is the reaction product of (a) a zirconium halide or oxyhalide, (b) a polyol and (c) an alpha-hydroxy acid is claimed. The preferred polyol is sorbitol and preferred alphahydroxy acids are citric, malic or lactic acid. The compounds find use as cross-linking agents in fracturing fluids employed in the hydraulic fracturing of oil or gas-containing subterranean strata. The claimed compounds can be used to produce a slow or delayed gel formation in such fluids.

Abstract: A by-product of peanut growing is utilized in the drilling fluid while drilling boreholes to reduce friction and to reduce the normal adverse effects inherent in such drilling fluid.

Abstract: The production of oil or gas from a subterranean formation is enhanced by injecting into the formation, such as in acidized fracturing, an aqueous fluid containing as a viscosifier a crosslinked vinylamine polymer. Acidizing fluids are provided containing HCl and a viscosifying amount of a gel of the crosslinked polymer, preferably poly(vinylamine) crosslinked with a diisocyanate, a polyepoxide or epichlorohydrin.

Abstract: A thixotropic preflush fluid is employed in a well drilling operation to prevent loss of cement slurry to an air zone penetrated during the drilling operation. The preflush fluid comprises water, a cement, calcium sulfate, and a quick-hardening accelerator. Optionally, the preflush fluid also comprises a thickening agent.

Abstract: An improved hydrocarbon gelling agent is disclosed comprising the reaction product of (1) a polyphosphate intermediate produced by reacting triethyl phosphate and phosphorous pentoxide and (2) a mixed alcohol having a substantial hexanol component, together with methods of making and using such gelling agent.

Abstract: A fluid loss control additive for aqueous fracturing media including a blend of two or more modified starches or a blend of one or more natural starches with one or more modified starches.

Abstract: A melted polymer of hydroxyacetic acid with itself or with other hydroxy-, carboxylic acid-, or hydroxycarboxylic acid-containing moieties is subjected to high shear and injected into an organic liquid which is inert to the polymer to form an organic liquid dispersion of very fine polymer particles. In one aspect the melted polymer is combined with the organic liquid and the combination is thereafter subjected to high shear to form the fine particle polymer dispersion. A dispersion agent may also be used to aid in dispersing the particles. The dispersion is used for fluid loss control and gel breaking in subterranean formations.

Abstract: A method and composition for stimulating high temperature subterranean formations. The composition comprises a novel crosslinkable polymer containing anionic and cationic functional groups (a polyampholyte). The polyampholyte comprises a mixture of at least one from each of the following groups:Group I acrylamide, partially hydrolyzed acrylamide, N,N-dimethylacrylamide, N-substituted-(N'-dialkylaminoalkyl) acrylamides, aminoalkylacrylates, dialkylaminoalkylacrylates or mixtures thereof;Group II 2-acrylamido-2-methylpropane sulfonic acid, sodium salt, vinylphosphonic acid, partially hydrolyzed acrylamide or mixtures thereof; andGroup III methacrylamidopropyldimethyl-2,3-dihydroxypropylammonium sulfate having the formula ##STR1## In the performance of the method, the polyampholyte is inverted into an aqueous liquid to form a viscous liquid which is buffered to about 4 to 6.5 and admixed with a crosslinking agent capable of crosslinking dihydroxypropyl functionalities.

Abstract: Geothermal wells with lost circulation problems are treated with a lightweight, high temperature (i.e. 350.degree. C.) cement slurry which incorporates pressure resistant hollow microspheres into the slurry wherein the spheres have been pretreated with an alkali compound such as Ca(OH).sub.2 for up to 20 hours and at 100.degree.-300.degree. C. Preferably, the alkali solution is a saturated aqueous solution and the treatment is for 10 hours.

Abstract: Hydroxyacetic acid condensation product is used as a fluid loss material in a formation fracturing process in which a fracturing fluid comprising a hydrolyzable aqueous gel is used. The hydroxyacetic acid condensation product degrades at formation conditions to provide hydroxyacetic acid which breaks the aqueous gel, which provides restored formation permeability without the need for separate addition of gel breaker.

Abstract: A water-soluble zirconium chelate formed from a tetraalkyl zirconate and hydroxyethyl-tris-(hydroxypropyl) ethylene diamine, and use of the chelate as cross-linking agents in hydraulic fracturing fluids and in gels that are used for selectively plugging permeable zones in subterranean formations or for plugging subterranean leaks.

Abstract: Oil recovery from a subterranean, oil-containing formation having relatively highly permeable and/or fractured zones and relatively low permeability zones is improved by first injecting a predetermined amount of a plugging agent into the formation, preferably inorganic, non-polymeric solids suspended in a fluid such as drilling muds or bentonite or clay suspensions, that plugs the face of the highly permeable and/or fractured zones of the formation. Thereafter, injection of the plugging agent is continued or in the alternative a displacing fluid at a flow rate and pressure sufficient to initiate and propagate new fractures and/or extensions of existing fractures in the formation. Thereafter, a displacing fluid is injected into the formation at a pressure sufficient to maintain the new fractures and/or extensions of existing fractures open and displace oil from zones communicating with the new fractures and/or extensions of existing fractures toward a production well where it is recovered.

Abstract: This invention relates to a composition and method of temporarily reducing the permeability of subterranean formations penetrated by a wellbore. In particular, it relates to an inexpensive, low molecular weight condensation product of hydroxy acetic acid with itself or compounds containing other hydroxy-, carboxylic-acid-, or hydroxycarboxylic-acid moieties and method for preventing fluid loss during well treatment.

Abstract: Novel aqueous crosslinked gels are described herein which are useful for fracturing subterranean formations. The novel gels are comprised of a solvatable polysaccharide and a soluble zirconium crosslinking agent. The zirconium crosslinking agents are novel and are prepared by reacting a zirconium alkoxide with certain alkanolamines under anhydrous conditions. The zirconium compounds are activated by contact with water. As an example, a zirconium crosslinker was prepared by reacting zirconium tetra(n-propoxide) with triethanolamine in an n-propanol solvent under anhydrous conditions. The zirconium compound thus prepared was activated with water and used to form a stable aqueous crosslinked gel by blending the aqueous crosslinker into an aqueous hydroxypropylguar solution.

Abstract: Liquid fluid loss control additives for oil field cements are provided which have long storage lives without excessive settling and which can be mixed with cement slurries without the formation of gel balls or fish eyes. The liquid additives consist essentially of a liquid hydrocarbon, a hydrophilic water soluble polymer, an organophilic clay suspending agent, an organic sulfonate dispersant, a polyamide amine surfactant for oil wetting the polymer and a surfactant for stripping liquid hydrocarbon from the polymer when contacted with water.

Abstract: Novel aqueous crosslinked gels are described herein which are useful for fracturing subterranean formations. The novel gels are comprised of a solvatable polysaccharide and a soluble zirconium crosslinking agent. The zirconium crosslinking agents are novel and are prepared by reacting a zirconium alkoxide with certain alkanolamines under anhydrous conditions. The zirconium compounds are activated by contact with water. As an example, a zirconium crosslinker was prepared by reacting zirconium tetra(n-propoxide) with triethanolamine in an n-propanol solvent under anhydrous conditions. The zirconium compound thus prepared was activated with water and used to form a stable aqueous crosslinked gel by blending the aqueous crosslinker into an aqueous hydroxypropylguar solution.

Abstract: Fluid loss control additives for oil-based well-working fluids comprise a solubilized lignite derivative and an oil-swellable or oil-soluble polymer. The solubilized lignite derivative may be oil-solubilized (e.g. a lignite/amine complex) or water-solubilized (e.g. causticized lignite) and may be incorporated in a polymer matrix or added to a dispersion of a polymer in an aqueous medium.

Abstract: A method for hydraulic fracturing a subterranean formation region to control the fracture extent in vertical and horizontal directions characterized by the injection of cold liquid into the formation region to precool the region and reduce the stresses in the formation region so that a hydraulic fracture may be propagated at a lower fluid injection pressure. The shape of the cooled region may be controlled by injection of various quantities of leakoff control agent during injection of the cold liquid and extension of the hydraulic fracture may be carried out simultaneously with the cold liquid flooding or by raising the pressure after the flood front has progressed a desired radial extent from the wellbore. The fracturing operation may be completed by injecting a pad of cold liquid with a high concentration of leakoff control agent to seal the fracture face followed by injection of liquid carrying a sufficient quantity of proppant material to maintain the fracture width and conductivity at the desired level.

Abstract: Oil based well treating fluids comprise liquid mixtures of aliphatic and aromatic hydrocarbons containing aromatic hydrocarbons, polymeric materials inclusive of at least one block copolymer and polymer crosslinking agents, with the kinds and amounts of those materials tailored to the properties of the wells and the well treatment designs.

Abstract: Set retarded cement compositions for cementing across a zone or zones in a well having enhanced compressive strength development after placement across the zone or zones are provided. The cement compositions are comprised of hydraulic cement, sufficient water to form a pumpable slurry, one or more set retarders and a delayed retarder neutralizer comprised of one or more titanium chelates. Methods of cementing utilizing the compositions are also provided.

Abstract: An aqueous composition has been developed to treat subterranean formations whereby the compositions can maintain for a period of time a sufficient viscosity to function as a hydraulic fluid and optionally to support particulate matter. Subsequently, the viscosity of the composition decreases to facilitate the removal of the composition.

Abstract: An aqueous composition has been developed to treat subterranean formations whereby the compositions can maintain for a period of time a sufficient viscosity to function as a hydraulic fluid and optionally to support particulate matter. Subsequently, the viscosity of the composition decreases to facilitate the removal of the composition.

Abstract: A transition metal complex useful as a crosslinking agent for high temperature, high pH, water-based fracturing fluids incorporating polysaccharide polymers is provided. The crosslinker comprises a zirconium/triethanolamine complex having a Zr/TEA molar ratio of between about 1/6.0 and 1/10.0, with 1/6.5 to 1/9.5 being preferred. Methods for preparing the zirconium/triethanolamine crosslinker are also provided. The methods comprise mixing effective amounts of either n-butyl zirconate or n-propyl zirconate with triethanolamine until a uniform blend is obtained. Further, an improved hydraulic fracturing fluid incorporating a polysaccharide polymer, buffer, crosslinker, pH adjusting agent and antioxidant is provided wherein the improvement is utilizing a zirconium/triethanolamine crosslinker. Improved methods for crosslinking fracturing fluids and for hydraulically fracturing well formations are also provided.

Abstract: A cross-linking system is shown for use in a water based well fracturing fluid which includes a mixture of a titanate constituent and a boron constituent. The mixture is effective to produce a cross-linked water based fracturing fluid which is shear stable at normal fracturing pump rates and which is temperature stable at elevated well temperatures.

Abstract: The growth of upward vertical fractures during a hydraulic fracturing process is inhibited or prevented by (1) initiating the fracture with a first fluid which is a pad fluid, and (2) extending the fracture with a second fluid comprising a carrier fluid and a bouyant inorganic diverting agent. The second fluid is preferably pumped at a minimum rate to extend the fracture and carry the diverting agent without screening out. After the diverting agent is implaced, a viscous pad fluid and fracture fluid are subsequently pumped at treatment rates and pressures to complete the fracturing process.

Abstract: The present invention relates to a diverting material or fluid-loss additive for use in subterranean formations penetrated by a well bore comprising graded phthalimide particles. The phthalimide particles are introduced into the formation in a carrier fluid. The carrier fluid can include gelling agents or any of the various salts known to be useful in fluids employed in subterranean formation treatment. The phthalimide particles can be used in elevated temperature oil and gas producing formations.