Abstract: Encapsulated water soluble chemicals for use in controlled time release applications, methods of encapsulating the chemicals and methods of using the encapsulated chemicals are provided. The methods of encapsulating the chemicals are basically comprised of forming a first coating of a dry hydrophobic film forming material or a sparingly soluble material which provides a dry shield on the chemical and then forming a second coating of a porous cross-linked hydrophilic polymer on the first coating which prevents the substantial dissolution of the resulting encapsulated chemical for a selected period of time.

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: This invention relates to a well treatment fluid and a method to treat an/or fracture a subterranean formation comprising: injecting a well treatment fluid into the formation at sufficient pressure to fracture the formation wherein the fluid comprises: (a) one or more amphoteric surfactants; (b) water; (c) one or more nonaqueous solvents; (d) optionally, an acid forming compound; and (e) provided that if the acid forming compound is present a hydrophilic alcohol may also be optionally present; wherein the all or part of the fluid forms vesicles.

Abstract: Methods and compositions for reducing the precipitation of fluoride compounds following the contact of an aluminum containing subterranean formation with an acid solution containing hydrofluoric acid are provided. In accordance with the methods, a hydroxy carboxylic acid is combined with the hydrofluoric acid solution and the subterranean formation is contacted with the resulting acid solution.

Abstract: Well drilling and servicing fluids for use in producing formations and methods of removing filter cake therefrom are provided. The methods basically comprise using a drilling or servicing fluid basically comprised of water, a water soluble salt and a particulate solid bridging agent selected from magnesium oxychloride cement, magnesium oxysulfate cement, magnesium potassium phosphate hexahydrate, magnesium hydrogen phosphate trihydrate and magnesium ammonium phosphate hexahydrate. Thereafter, the filter cake deposited by the drilling or servicing fluid is contacted with an aqueous clean-up solution for a period of time such that the bridging agent is dissolved thereby.

Abstract: A viscous fluid is shown which is useful in treating subterranean formations. The fluid is formulated from an aqueous base, an alkyl sarcosinate surfactant and a buffer suitable for adjusting the pH of the blended fluid to a range in which the fluid is suitably viscosified. The fluid can also include an additional source of anions, such as chloride or fluoride ions, in order to increase the temperature stability of the fluid. The fluids have application for conventional well fracturing, coiled tubing fracturing, gravel packing and frac packing, as well as for use as selective water control additives and other applications.

Abstract: Subterranean formation treating fluid concentrates, treating fluids and methods are provided by the present invention. The treating fluid concentrates are basically comprised of water and a substantially fully hydrated depolymerized polymer. The treating fluids which are formed by adding water to the treating fluid concentrates are basically comprised of water, a substantially fully hydrated depolymerized polymer and a crosslinking agent for crosslinking the hydrated depolymerized polymer.

Abstract: A method for increasing the permeability of a subterranean formation is disclosed in which an amount of an aqueous mixture, sufficient to increase the permeability of the formation, comprising specified aminopolycarboxylic anionic species, and specified cationic species, is injected into the formation matrix.

Abstract: Pumpable multiple phase compositions for carrying agents and components downhole and controllably releasing them by breaking the suspensions are described. The multiple phase composition may have an external or third phase, which in turn has a first pumpable emulsion internally. The first pumpable emulsion has a second phase containing a first phase which bears the agent to be controllably released. The entire pumpable multiple phase composition may thus be an oil phase-in-aqueous phase-in-oil phase emulsion, or an aqueous phase-in-oil phase-in-aqueous phase emulsion. The agent may be released by one or more of a variety of mechanisms. For example, a water-soluble shale stabilizer could be delivered downhole in an aqueous phase-in-oil phase-in-aqueous phase multiple phase emulsion by injecting the multiple phase composition into a water-based drilling fluid, and then the suspension broken by rotary bit nozzles under high shear stress to release the shale stabilizer at the drilling zone.

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: Well drilling and servicing fluids for use in producing formations and methods of removing filter cake therefrom are provided. The methods basically comprise using a drilling or servicing fluid comprised of water, a density increasing water soluble salt, a fluid loss control agent, a hydratable polymer solid suspending agent and a particulate solid bridging agent which is soluble in an aqueous ammonium salt solution. Thereafter, the filter cake deposited by the drilling or servicing fluid is contacted with a clean-up solution comprised of water and an ammonium salt for a period of time such that the bridging agent is dissolved thereby.

Abstract: An acidizing composition and a method of acidizing a hydrocarbon bearing subterranean formation in the presence of ferric ions are provided. The acidizing composition includes a strong mineral acid solution, an electron donor agent, a primary electron transfer agent and a secondary electron transfer agent. The primary electron transfer agent is a source of rhenium ions. The secondary electron transfer agent is a source of iodide ion or iodine. The electron donor agent and primary and secondary electron transfer agents function together to reduce ferric ion present in the mineral acid solution to ferrous ion which in turn prevents ferric hydroxide and/or free sulfur from precipitating out of the solution and reduces the formation of sludge in crude oil in the formation. The particular electron transfer agents used in connection with the invention function with virtually all known electron donor agents.

Abstract: The invention provides clay-free, preferably biopolymer free, well drilling and servicing fluids comprising an aqueous divalent cation-containig water soluble salt, a bridging agent, and a pre-gelatinized crosslinked amylopectin starch suspending agent and fluid loss control additive. The concentration of the starch derivative is sufficient to provide the fluid with the following charactristics: (a) a low shear rate viscosity less than about 10,000 centipoise; (b) a high shear rate viscosity at 511 sec−1 in the range from about 15 to about 70 centipoise measured at 120° F.; (c) a fluid loss less than about 10 milliliters as measured at 185° F. and 250 psi differential pressure across a 5 micron disk for 30 minutes; and (d) anti-settling characteristics as exhibited upon static aging the fluid for 16 hours at 185° F.

Abstract: Methods of treating wells for cementing operations and for improving placement of cement in wells containing water swelling clays include treatment of the well with a fluid containing clay precipitating agents capable of coagulating clays in the well. The coagulating fluid can contain quaternary ammonium salts, aqueous salts of potassium or cesium, or silicates as the clay coagulating agent. The coagulating fluids can be applied to convert soft mud cake into hard mud cake prior to placement of cement.

Abstract: Liquids comprised solely of anions and cations (“ionic liquids”) are disclosed as novel components of fluids (and techniques relying upon those fluids) for stimulation of hydrocarbon wells. In particular, the fluids disclosed are useful in matrix acidizing. Formation of the ionic liquids of the present Invention is highly exothermic, hence the heat generated can be used, for instance, to melt de-watered drilling fluid in the near-wellbore region of the formation. Further, reaction of the ionic liquids with water results in acid generation; this acid can be used to, for instance, to stimulate a formation, either by conventional matrix acidizing or fracture acidizing. In addition, certain preferred species of the ionic liquids of the present Invention are highly stable solvents, hence they can be used as carrier fluids for highly reactive super acids (e.g., SbF5+HF) in connection with matrix acidizing.

Abstract: The invention relates to compositions and methods for gelling liquid hydrocarbons by the introduction of certain phosphate esters, a crosslinking agent, and an enhancer. The enhancer of the present invention is preferably an oxyalkylated amine or a blend of an oxyalkylated amine with another amine or a non-nitrogen-containing component. Mixed phosphate esters containing an oxyalkylene group are useful in the practice of the invention. Gel-forming compositions for addition to liquid hydrocarbons, as well as methods for forming fracturing fluids, are encompassed. The present compositions and methods are an improvement in the field of hydrocarbon gelling, e.g., in fracturing formations, by providing more rapid gellation and greater viscosities.

Abstract: Methods and acidizing compositions for reducing the corrosion of the metal surfaces of tubular goods and the like and reducing the precipitation of metal sulfide from the acidizing compositions are provided. The methods basically comprise the steps of combining an aldol-amine adduct with an aqueous acid solution to preferentially react with sulfide ions subsequently dissolved by the aqueous acid solution and thereby prevent subsequently dissolved metal ions from reacting therewith and precipitating, and then introducing the aqueous acid solution containing the aldol-amine adduct into a well or other location to be acidized.

Abstract: The invention relates to iron control in an acid medium for forestalling the formation of precipitates known as “sludges” (asphaltic products) in contact with certain crude oils. Use is made of compounds comprising a mercaptan function, and, in combination, a selection of catalysts. Application to acid treatments for oil, gas, water, geothermal and analogous wells, as well as to industrial cleaning.

Abstract: The invention provides clay-free, preferably biopolymer free, well drilling and servicing fluids comprising an aqueous divalent cation-containing water soluble salt, a bridging agent, and a pre-gelatinized crosslinked amylopectin starch suspending agent and fluid loss control additive. The concentration of the starch derivative is sufficient to provide the fluid with the following charactersitics: (a) a low shear rate viscosity less than about 10,000 centipoise; (b) a high shear rate viscosity at 511 sec−1 in the range from about 15 to about 70 centipoise measured at 120° F.; (c) a fluid loss less than about 10 milliliters as measured at 185° F. and 250 psi differential pressure across a 5 micron disk for 30 minutes; and (d) anti-settling characteristics as exhibited upon static aging the fluid for 16 hours at 185° F.

Abstract: This invention relates to novel compositions and methods whereby a carboxylate based brine solution is used in drilling and/or well bore treating operations to inhibit corrosion of fluid handling equipment. In one embodiment of the invention the carboxylate based brine solution consists of a carboxylate salt dissolved in water. This brine solution is used to prepare halide-free drilling fluids. Use of halide-free drilling fluids inhibits corrosion stainless steel surfaces of fluid handling equipment. In an alternative embodiment of the present invention a mixed salt brine containing a carboxylate salt and a halide salt is provided for use in a drilling and/or well bore treating operations.

Abstract: According to the present invention, a composition and method for hydraulically fracturing a subterranean formation is provided. The composition comprises an aqueous mixture of a hydrated polysaccharide, preferably a galactomannan gum, the hydrated polysaccharide having a plurality of bonding sites; a crosslinking agent for crosslinking the hydrated polysaccharide at the bonding sites at the conditions of the subterranean formation with a polyvalent metal ion to form a polyvalent metal crosslink, thereby increasing the viscosity of the hydrated polysaccharide; and a controlled solubility compound for releasing a chelating agent for controllably breaking the polyvalent metal crosslink and bonding with the polyvalent metal ion released by breaking the crosslink, thereby decreasing the viscosity of the hydrated polysaccharide.

Abstract: A wellbore service fluid comprising viscoelastic surfactants in combination with means for controlling the concentration of at least partially charged sites within the fluid is described.

Abstract: A composition and method for acidizing a formation in the presence of ferric ion, free sulfur and/or sulfides is disclosed. The composition employs a ferric ion reducing agent and a sulfide reactant separately or in combination. The ferric ion reducing agent is a thioalkyl acid. The sulfide reactant compounds include &agr;-diketones and saturated and &agr;-unsaturated cyclic ketones. In another aspect, the reducing activity of the thioalkyl acid is accelerated by the presence of a catalytic quantity of a compound or mixture of compounds which yield in acid solution cuprous ion, cupric ion or combinations thereof with iodide ion.

Abstract: The present invention relates to methods of treating subterranean formations with viscosified aqueous well treating compositions which break into thin fluids at static temperatures in the range of from about 150° F. to about 200° F. A breaker system is included in the compositions comprised of an alkali metal or ammonium persulfate breaker and a breaker activity delaying agent comprised of an alkali metal chlorite or hypochlorite.

Abstract: A method of fracturing a subterranean formation, in which subterranean formation being in fluid communication with the surface includes creating a fracture in said subterranean formation, said fracture having more than one fracture faces; and injecting into said fracture an encapsulated formation etching agent, wherein said encapsulated formation etching agent includes a formation etching agent and an encapsulating agent and wherein said formation etching agent etches the fracture faces of the fracture so as to form a flow channel in said formation. The formation etching agent may be selected from mineral acids and mixtures thereof, organic acids and mixtures thereof, mineral acids and mixtures of mineral acids mixed with gelling agent, organic acids and mixtures of organic acids mixed with gelling agent, water soluble hydroxides and mixtures of water soluble hydroxides, and water soluble hydroxides and mixtures of water soluble hydroxides mixed with gelling agent.

Abstract: Methods and compositions for reducing the permeabilities of subterranean zones are provided. The methods of the invention are basically comprised of introducing an aqueous composition comprised of a chelated organic gelling agent and a copolymer of an ethylenically unsaturated polar monomer and an ethylenically unsaturated ester or a terpolymer or tetrapolymer of an ethylenically unsaturated polar monomer, an ethylenically unsaturated ester and a monomer selected from AMPS® and/or N-vinylpyrrolidone into the zone and then allowing the aqueous composition to form a cross-linked gel in the zone.

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 present invention provides improved methods of sealing a subterranean zone to remedy the uncontrolled flow of fluids into and out of the zone. The methods basically comprise preparing a sealing composition and placing the composition into the zone to be sealed. The placement of the composition is controlled in a manner whereby portions of the sealing composition are continuously converted to sealing masses which are successively diverted into permeable portions of the zone until all of the permeable portions are sealed.

Abstract: A method for removing filtercake from a subterranean borehole comprising drilling the borehole with a drilling fluid that includes additives to form a filtercake having an oxidation-degradable component, preferably a polysaccharide. The filtercake is contacted with a clear brine containing bromine or bromate generating agents to degrade the polymers within the filtercake. The brine contains bromide salts and an oxidant capable of delayed oxidation of the bromide to bromine at downhole conditions.

Abstract: A method is provided for blocking high permeability channels in subterranean geological formations, using swelling clay. A slurry is prepared by mixing swelling clay, such as bentonite, into an aqueous solution containing the salt of certain cations, which inhibit clay swelling. The cations K.sup.+, Ca.sup.2+ and Mg.sup.2+, among others, are inhibitive of clay swelling. The clay slurry is introduced into a geological formation, where it preferentially enters channels of high permeability. There the slurry is contacted by NaCl brine solution present in natural or injected drive fluids, and the inhibitive cations bound to the clay particles are replaced by Na.sup.+ ions, which attract water molecules and promote clay swelling. The Na.sup.+ -clay swells to up to 10 times its original volume, causing the slurry to acquire a gel-like consistency. The clay gel so formed is capable of blocking the flow of water, and can resist pressure of up to 500 kPa per meter.

Abstract: A method is disclosed for reducing the concentration of metal soaps of partially esterified phosphates from a hydrocarbon flowback fluid resulting from a hydraulic fracturing fluid operation using an alkaline aqueous-based additive solution.

Abstract: A composition is provided which comprises a polymer comprising repeat units derived from an unsaturated amide, an N-vinyl lactam, and optionally, a vinyl acid. Also provided is a water-based fluid composition which can be used as drilling fluid wherein the composition comprises calcium chloride and the polymer. Further providing is a process for using a water-based fluid wherein the process comprises contacting a subterranean formation with the water-based fluid composition disclosed above to effect the control of fluid loss of the water-based fluid composition.

Abstract: Improved high temperature epoxy resin compositions, additives and methods are provided. A hardenable epoxy resin composition of the present invention is comprised of an epoxy resin, an aromatic diluent, a hardening agent and a hardening retarder for delaying the hardening of the epoxy composition at high temperatures comprised of a liquid which is soluble in the epoxy resin composition having a halide salt dissolved therein.

Abstract: The present Invention relates to hydrocarbon well stimulation, and more particularly to methods and compositions to remove (or more generally to transfer) fluid introduced into a subsurface fracture, in which the methods involve creating then exploiting chemical potential gradients at the fracture face to induce fluid flow from the fracture into the formation; the methods and compositions involve creating, or relying upon an intrisic or previously created, a selectively permeable membrane that is permeable to water but that does not allow solutes to pass through.

Abstract: A solubilized iron reducing additive for acid solutions and method for preparing such a solubilized iron reducing additive. The additive includes an iron reducing agent reactable with ferric ions to produce therefrom ferrous ions and a spent iron reducing compound. The spent iron reducing compound is incapable of reacting with ferric ions to produce ferrous ions. So that the reducing process may continue, a regenerating agent is mixed with the iron reducing agent, the regenerating agent being reactable with the spent iron reducing compound for regenerating the spent iron reducing compound back to the iron reducing agent state. Because it has been found that the iron reducing agent and regenerating agent readily fall out of suspension as precipitates after short periods of time after mixing, a solubility facilitator is admixed thereto for facilitating establishment of the solubilized additive for acid solutions.

Abstract: A process for the thermo-hydraulic control of gas hydrates in subsea production and injection wells as well as pipelines which transport liquid or gaseous hydrocarbons is described, the process making use of a Nitrogen Generating System foamed or in solution. The control may signify the prevention of the formation of the gas hydrates or the dissolution of the gas hydrate plug already formed. Under conditions of use designed for the prevention of the formation of gas hydrates the SGN fluid prevents the thermal conditions leading to the gas hydrate plugs. Under conditions of use designed to dissolve the already formed gas hydrate plugs, the SGN fluid alters the thermo-hydraulic conditions which favor the gas hydrate plugs, so that they are dissolved and return to the water+gas phase.

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: A method and composition for removing deposits of heavy hydrocarbonaceous materials and finely divided drilling fluid solids from a wellbore using a composition containing an alkyl polyglycoside, an ethoxylated alcohol, a caustic and an alkyl alcohol by injecting the composition into the wellbore, maintaining the composition in the wellbore for a selected time and thereafter producing the composition from the wellbore.

Abstract: A process for the treatment of oil wells having a high content of "acid gases", comprises circulating through or pumping into the well a slurry comprising a water-soluble, solid salt and a saline solution, which slurry does not react with the "acid gases" and which has a density of more than 13 and preferably of at least 14 lb/gal.

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.

Abstract: A well drilling and servicing fluid comprising a brine having dissolved therein a formate salt selected from the group consisting of potassium formate, cesium formate, and mixtures thereof, a biopolymer viscosifier, and a pre-gelatinized amylopectin derivative, and optionally a bridging agent and magnesium oxide. The amylopectin starch derivative is a crosslinked amylopectin starch (waxy) which has been crosslinked to the extent that the viscosity of an aqueous amylopectin starch suspension undergoing crosslinking is within about 25% to about 60%, preferably from about 25% to less than about 50%, of the maximum viscosity which can be obtained, and gelatinized.A process of increasing the low shear rate viscosity at ambient temperatures of the aqueous formate brine which comprises adding to the brine a biopolymer and the pre-gelatinized crosslinked amylopectin starch in amounts such that they interact to synergistically increase the low shear rate viscosity of the brine.

Abstract: Aqueous compositions for use as drilling fluids or as workover fluids/completion fluids comprise calcium chloride and calcium nitrate. The compositions have a density of at least 1.35 g cm.sup.-3 and the weight ratio of calcium chloride to calcium nitrate is 5:95 to 95:5. The compositions may be formulated so as to have low crystallisation temperatures. Additional densifying agents such as calcium bromide and/or zinc bromide may also be included.

Abstract: The invention provides methods for (1) reducing the fluid loss of and (2) reducing the concentration of polymer required to provide a desired degree of fluid loss control to, a well drilling and servicing fluid which contains at least one polymeric viscosifier, at least one polymeric fluid loss control additive, and a water soluble bridging agent suspended in an a liquid in which the bridging agent is not soluble, the methods comprising adding to the fluids a particulate, water soluble, ultra fine filtrate reducing agent having a particle size distribution such that at least 90% of the particles thereof are less than 10 micrometers and the average particle size is from about 3 to about 5 micrometers, the ultra fine filtrate reducing agent being insoluble in the liquid.

Abstract: A process which can be used to dissolve sulfur deposits or sulfur plugs in gas wells, oil wells, vessels, or conduits for transporting a fluid containing sulfur is provided. The process comprises contacting the sulfur deposits or sulfur plugs under conditions sufficient to dissolve sulfur wherein the composition comprises an organic sulfide, a base, a surfactant, and optionally, a mercaptan and is present in an amount effective to dissolve sulfur.

Abstract: A composition of matter for matrix conformance formed from an aqueous solution of an alginate polysaccharide and a method of forming an alginate polysaccharide gel. A Group IIA cation, Fe.sup.2+, Fe.sup.3+, Al.sup.3+, Mn.sup.2 +, Zn.sup.2+, a dialdehyde, or a diamine may be used to crosslink the resulting alginate gel. The gel may also comprise a modifier, such as a polyvinyl alcohol, a polycarboxylic acid, or a polyacrylamide. The rate and extent of crosslinking are controlled by varying the alginate molecular weight, the alginate concentration, or the type and concentration of crosslinker, or by adding a sequestering agent such as EDTA or citrate.

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

Abstract: A method and combination of materials for freeing stuck pipe involves first the spotting of a clear brine, preferably calcium chloride, calcium bromide or zinc bromide, or mixtures thereof, for a given period of time, preferably at least about 8 hours, in the stuck region of the pipe, followed by the spotting of a spotting agent selected from wetting agents, surfactants, lubricants, or mixtures thereof, in the region of the stuck pipe.

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: Elemental iodine is used to improve the performance of conventional corrosional inhibitors in oil field acidizing operations. The iodine, because of its solubility, may be used in a formulation which includes a corrosion inhibitor and surfactants dissolved in a suitable organic solvent.

Abstract: Improved fluid loss control in gravel pack placement fluids is achieved when a fluid loss control additive is provided comprising a selectively soluble particulate having a size of less than 1000 microns and having a linear size distribution when cumulative weight percent is plotted against the logarithm of the particle size. The preferred selectively soluble particulate comprises calcium carbonate.