Abstract: Acid based micro-emulsions are disclosed comprising water, an acid blend, an anionic surfactant, a nonionic surfactant, a co-solvent, a solvent and an oxidizer. The micro-emulsions have particular utility in cleaning oil sludges and drilling mud residues from well cuttings, well formations and down hole and surface oil well drilling and production equipment.

Abstract: A method is given for completing an interval of an open-hole injection well penetrating a subterranean formation when the interface between the wellbore and the formation includes a zone invaded by a filter cake that includes bridging materials and other embedded solid materials. The method includes the steps of injecting a clean-up fluid and contacting it with the filtercake for a period of time sufficient to loosen some of the other solids embedded in the filter cake; removing the loosened solids by a high-rate displacement fluid containing suspending additives; and then injecting a dissolving fluid containing a diverter and an effective amount of a salt or acid capable of dissolving the bridging material.

Abstract: A method is provided for reducing lost circulation when aqueous, oil, or synthetic based drilling fluid is used. The method includes injecting two fluids into the well bore and lost circulation zone. The first fluid is an aqueous liquid containing at least one polymer capable of absorbing water in an alkaline environment. The aqueous liquid has a pH that inhibits at least one polymer from absorbing water. The second fluid contains a hardening composition in a base fluid having a pH sufficient to increase the pH in situ to allow at least one polymer to absorb water and expand with the absorbed water and substantially increase in size to close off the lost circulation zone and allow the hardening composition to create a plug in the well bore and set up.

Abstract: The present invention relates to foamed cement slurries, additives and methods. A foamed cement slurry of the invention comprises a hydraulic cement, sufficient water to form a slurry, sufficient gas to form a foam and an environmentally benign foaming and stabilizing additive comprising a mixture of an ammonium salt of an alkyl ether sulfate surfactant, a cocoamidopropyl hydroxysultaine surfactant, a cocoamidopropyl dimethylamine oxide surfactant, sodium chloride and water.

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: Viscous well treating fluids and methods of treating subterranean zones penetrated by well bores are provided. The viscous fluids are basically comprised of water, a gelling agent and a delayed viscosity breaker comprising pentanedione peroxide.

Abstract: A rheology modified aqueous fluid composition comprising clay, water, magnesium oxide, aluminum oxide hydroxide, sodium carbonate or potassium carbonate, and calcium oxide or calcium hydroxide. The magnesium oxide and aluminum oxide hydroxide are prepared by a specific thermal treatment protocol involving heating of appropriate precursors within a specified temperature range. The pH of the composition is at least about 10. The composition is prepared by admixing the components and, optionally, sodium oxide or sodium hydroxide for pH adjustment as necessary. A substantially dry rheology modification agent comprising the enumerated components, not including the water, is also included. The resulting composition preferably exhibits shear-thinning capability including very rapid thinning upon application of shear forces and also rapid viscosification upon removal of such forces.

Abstract: It has been discovered that carbonate powders and bicarbonate powders are useful to increase the pH and corrosion resistance of high-density brines, such as zinc bromide brines, without significantly reducing their densities. The carbonates and/or bicarbonates should be water-soluble and may be sodium, potassium, magnesium and/or ammonium carbonates and/or bicarbonates and the like. The carbonates and/or bicarbonates are easily added in powder or other finely divided solid form.

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: There is described a fracturing fluid comprising a polar base, 0.1-5.0% of a mid-molecular weight polyacrylate, and an activator for ionizing the polyacrylate to a hydroscopic state.

Abstract: Coatings for well screens that protect the screens from damage as they are inserted into the wellbore and once in the well, release reactive materials to react with and degrade potentially plugging materials such as drill solids, fluid filtercakes, fluid loss additives, and drilling fluids. The coatings can be specifically designed for individual well conditions and are comprised of a binder that either melts or dissolves within the wellbore and one or more reactive materials such as acids, enzymes, surfactants, chelants, oxidizers or free radical generators and the like which are released into the screen and the near wellbore area and which are effective in degrading or dissolving materials which could potentially plug the screen.

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: The invention is an interactive computer system for help in selecting well-services treatment fluid comprising a set of fluid families, a set of relevant fluid characteristics and a set of digital ratings of each fluid family with regard to these characteristics. The system further includes a set of job parameters pertaining to the treatment and qualitative ratings of said parameters estimating their relevance in the effective success of a treatment. An interface allows the user to enter the job parameters values known to him. Built in rules, associated with calculating means including an integrated spreadsheet, match fluid characteristics and job parameters and trigger the elimination of fluids that are not compatible with some value of the job parameters and compute a confidence index for the non-eliminated fluid families, said confidence index based on the one the sum of the products of the fluid families digital ratings and on the rating of the known job parameter.

Abstract: A method for in situ forming of an unstable oil in water emulsion includes the steps of providing a mixture of an aqueous alkali salt solution and a surfactant, and pumping the mixture down a well containing a crude hydrocarbon having an API gravity of less than or equal to 26 so as to provide an unstable emulsion in the well, the unstable emulsion having the hydrocarbon as a dispersed phase and the solution as a continuous phase and having a ratio by weight of the hydrocarbon to the solution of at least about 50:50.

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 method to synthesize chlorine dioxide blocking remover in an oil well, including: chlorate aqueous solution and some acidic substances that can dissolve in water and produce hydrogen ion are quickly injected into oil wells or water wells by injection pump. So as to make them react each other and produce chlorine dioxide.

Abstract: A low residue well treatment fluid comprises: an aqueous solvent; a gelling agent comprising one or modified polysaccharides, the modified polysaccharides having hydrophilic groups; and a crosslinking composition. The fluid may optionally further comprise a gel breaker, a buffer and/or a proppant. The fluids generate no or minimal residue upon being broken, and are particularly useful in well fracturing operations.

Abstract: This invention provides methods of fracturing subterranean zones, fracturing fluids and breaker activators for use in the fracturing fluids. The fracturing fluids are basically comprised of water, a gelling agent, a particulate proppant material, a delayed viscosity breaker and a breaker activator.

Abstract: The present invention provides xanthan gels hydratable in brine, methods of making these xanthan gels, and methods of using these compositions in subterranean formation applications, such as gravel packing.

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: Zeolite compositions having enhanced compressive strength and methods therefor are provided. In particular, methods and compositions for wellbore treating fluids, especially settable spotting fluids having enhanced compressive strength are provided.

Abstract: Methods and compositions for wellbore treating fluids, especially settable spotting fluids, that include zeolite and at least one carrier fluid.

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: Present invention relates to high brine carrier fluid, said carrier fluid selected from the group consisting of organic acids, organic acid salts, inorganic salts and combination of one or more organic acids or organic acid salts, a co-surfactant and an amount of a zwitterionic surfactant. The invention also relates to methods of treating a subterranean wellbore, including drilling, hydraulic fracturing, gravel placement, scale removing, mud cake removing, using said high brine carrier fluid.

Abstract: The present invention provides improved reactive cement compositions for sealing hydrocarbon containing subterranean zones and methods of using the cement compositions. The sealing compositions are basically comprised of water, a hydraulic cement, an organophillic clay, a hydratable gelling agent and a water soluble alkaline source in effective amounts.

Abstract: A method is provided for reducing loss of drilling fluid and for stabilizing a wellbore during drilling through depleted sands in a subterranean formation comprising depleted sands. The method comprises introducing into said wellbore and into said depleted sands an aqueous fluid comprising silicate or siliconate and resilient graphitic carbon in an amount effective at substantially plugging pores in said depleted sands.

Abstract: The invention provides in a water injection system and in a water injection process for secondary oil and/or gas recovery, the presence and use of a biocidally-effective amount of a sulfamate-stabilized, bromine-based biocide with injection water that is to be used in the system or process such that bromine-based biocide is present in at least a portion of the system and/or in at least a portion of the water in the system. A composition especially adapted for use in secondary oil recovery operations, is comprised of seawater with which has been blended a biocidally-effective amount of a sulfamate-stabilized, bromine-based biocide.

Abstract: High density, thermally stable, brine-based well fluids and methods of using the same are disclosed. In one embodiment a well fluid including water and a salt, the salt including at least one formate salt, wherein the weight-to-volume ratio of the well fluid is within the range of at least 120% to about 400% is disclosed. In another embodiment, a well fluid including water, a viscosifying agent, and a salt, the salt including at least one formate salt, wherein the weight-to-volume ratio of the well fluid is within the range of at least 120% to about 400% is disclosed. A method of treating a well using a well fluid, wherein the well fluid includes water and a salt, the salt including at least one formate salt, wherein the weight-to-volume ratio of the well fluid is within the range of at least 120% to about 400% is also disclosed.

Abstract: A method for enhancing the stability of a solids-stabilized water-in-oil emulsion by pretreating the oil prior to emulsification. The pretreatment step can be accomplished by adding dilute acid to the oil, adding a lignosulfonate additive to the oil, sulfonating the oil, thermally oxidizing the oil, thermally treating the oil in an inert environment, and combinations thereof. The emulsion can be used in enhanced oil recovery methods, including using the emulsion as a drive fluid to displace hydrocarbons in a subterranean formation, and using the emulsion as a barrier fluid for diverting flow of fluids in the formation.

Abstract: A method is provided for blocking high permeability regions in subterranean geological formations, using a reinforced swelling clay gel. A reinforced clay slurry is prepared by mixing swelling clay, such as bentonite, an aqueous solution containing the salt of certain cations, which inhibit clay swelling, and a reinforcing agent. The cations K+, Ca2+, Mg2+, Cs2+, Fe2+, Al3+ and NR4+, where each R can independently be H, CH3, C6H5, or CH2CH3, and combinations thereof, among others, are clay swelling inhibitors. The reinforcing agent is non-swelling particles, including, without limitation, particles of produced sand, silica sand, sandy or silty soil, crushed rock, minerals, mine tailings, and combinations thereof. The reinforced clay slurry is introduced into a geological formation, where it preferentially enters high permeability regions.

Abstract: Improved mud additive compositions are provided which are especially formulated to control hole enlargement due to salt bed erosion during drilling, and to assist in solubilization of deposited salt during well operations. The compositions include a first ingredient such as sodium or potassium ferrocyanide and mixtures thereof, and a second ingredient such as the a phosphonic acid, alkali or alkaline earth metal phosphonic acid salts, or mixtures thereof. The first ingredient is generally present at a level of from about 50-95% by weight in the particulate, dilutable form of the invention, whereas the second ingredient is present at a level of from about 5-50% by weight. The compositions hereof may be added to drilling mud during drilling operations or to fresh water for removing salt depositions.

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: A method for removing filter cake from a subterranean borehole comprising drilling the borehole with a drilling fluid that includes additives to form a filter cake having an oxidation-degradable component, preferably a polysaccharide. The filter cake is contacted with a clear brine containing a mixture of a persulfate salt in a variable density brine to degrade the polymers within the filter cake. The persulfate mixture breaks down the filter cake in well bores having temperatures ranging from about 65° F. to 165° F. Concentration of the persulfate sets the pace of the reaction.

Abstract: A formation treating fluid comprises one or more borate esters, a liquid carrier and, one or more cross linkable polymer wherein the formation treating fluid has an alkaline pH when the formation treating fluid is positioned in a formation. The formation treating fluid is useful in high temperature operations such as hydraulic fracturing.

Abstract: It has been found that a large variety of solid chemicals available in a bulk powder form could be added to subterranean treatment fluids with delayed release when said chemicals are delivered as capsules consisting of encapsulated granulates obtained by aggregating the bulk powder under pressure to form a densified material and optionally, dry comminuting said densified material to produce granulates at the desired size. The invention is particularly useful for delivering new types of breaking agents for stimulation fluids or additives for wellbore cementing.

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: 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 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 vanadium 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.

Abstract: A method for monitoring hydrocarbon and water production from different production zones/sections in a hydrocarbon reservoir and/or injection wells and detection of different phenomena such as e.g. local variations in pH, salinity, hydrocarbon composition, temperature, pressure, microorganisms, and the difference between production of formation and/or injection water from various zones/sections. The method includes dividing regions around wells in the reservoir into a number of zones/sections, and injecting or placing specific tracers with unique characteristics for each zone/section into the formation in these regions such that tracers are placed as integrated parts of the well completion or placed and immobilized in these regions through injection, squeeze or by other techniques. The tracers can also be immobilized or placed on a filter, a casing or other constructions surrounding the well in each zone/section. The tracers are specific or introduced to give specific information from each zone/section.

Abstract: Anti-corrosion additives and processes useful for oil drilling and similar applications. Heteropoly complex anions of transitional metal elements can be added to an oil well drilling solution which includes a metallic salt, optionally in combination with transition metal compounds or compounds of the metallic elements of Groups IIIa to VIa of the Periodic Table of Elements, to minimize corrosion of systems within which the solution is used.

Abstract: Methods of drilling well bores using an invertible oil external-water internal emulsion drilling fluid and then inverting the drilling fluid to a water external-oil internal emulsion are provided. The methods basically comprise the steps of contacting the oil external-water internal emulsion with an aqueous acid solution containing an anionic sulfonate surfactant for preventing aqueous acid solution-crude oil emulsions and crude oil sludging and a chemical for preventing the anionic sulfonate surfactant from reacting with the emulsifier in the oil external-water internal emulsion.

Abstract: A one step squeeze treatment of a subterranean formation involves the treatment with a treating solution comprising an acid, a scale inhibitor, and a reducing agent. The presence of the reducing agent prevents the iron ions in the system from reacting with and forming a precipitate with the scale inhibitor and maintains the iron ions in the ferrous state.

Abstract: Disclosed is a method and gellable composition for decreasing the loss of fluid during well drilling or servicing operations. The gellable composition comprises a superabsorbent polymer in an acidic aqueous liquid in which the superabsorbent is not swellable. Preferably the gellable composition also contains a viscosifier, preferably chitosan. The method is practiced by forming the gellable composition, placing it at the location of fluid loss in a well, and mixing it with a basic aqueous liquid to raise the pH and thus allow the superabsorbent to expand in volume. Advantageously, the superabsorbent, chitosan, and an acid, preferably a solid acid, preferably sulfamic acid, are admixed to form an additive for preparing the gellable composition.

Abstract: Acid based micro-emulsions are disclosed comprising water, an acid blend, an anionic surfactant, a nonionic surfactant, a co-solvent, a solvent and an oxidizer. The micro-emulsions have particular utility in cleaning oil sludges and drilling mud residues from well cuttings, well formations and down hole and surface oil well drilling and production equipment.

Abstract: A method for separating oil from geological formations by application of an aqueous oxidant. The oxidant breaks the interfacial attraction between the oil phase and the geological formation and also produces ketone moieties which assist in separating the oil phase from the mineral phase and also dissolve into the oil phase, thereby decreasing the viscosity. The method is especially useful in recovering heavy oil from geological formations wherein oil has been previously extracted to exhaustion by prior art methods.

Abstract: It has been discovered that dicarboxylic acids are useful in acidizing subterranean formations to improve their permeability, particularly at elevated temperature, e.g. between about 200° F. (92° C.) and about 400° F.(204° C.) Particularly suitable dicarboxylic acids include, but are not necessarily limited to, succinic acid, glutaric acid, adipic acid, and mixtures thereof.

Abstract: Disclosed is a method of increasing the low shear rate viscosity and the shear thinning index of aqueous fluids containing a divalent cation salt, a crosslinked amylopectin starch which functions as both a viscosifier/suspending agent and as a fluid loss control additive, and a bridging agent, the fluids resulting from the method, and the use of the fluids in drilling a well, wherein the bridging agent is a sized particulate magnesium carbonate or a mixture of sized magnesium carbonate and sized calcium carbonate. The median (D50) particle size of the magnesium carbonate is from about 2 &mgr;m to about 10 &mgr;m. The weight ratio of calcium carbonate to magnesium carbonate is from about 70/30 to about 0/100.

Abstract: A drilling fluid comprising a pyruvate-free xanthan, which may be an acetate-free pyruvate-free xanthan, and a high density calcium-based brine. Preferably the pyruvate-free xanthan is a genetically prepared pyruvate-free xanthan. A process for recovering crude oil from an oil-bearing subterranean formation by drilling the formation and using a drilling fluid comprising a pyruvate-free gum and a high density calcium-based brine.

Abstract: A well service fluid and method using same for brine-sensitive formations is disclosed. The fluid is an invert oil emulsion comprising heavy, solids-free brine, an oil or synthetic, and sufficient emulsifier to create the emulsion. The fluid has particular applicability in gravel packing a horizontal well.

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 an aqueous mineral acid solution, an electron donor agent and an electron transfer agent, the electron transfer agent being a source of molybdenum ions. When the aqueous mineral acid solution includes hydrochloric acid in an amount greater than approximately 17% by weight, the acidizing composition further includes a supplemental electron transfer agent, the supplemental electron transfer agent being a source of iodide ion or iodine. The electron donor agent and electron transfer agent 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.