Abstract: A method and apparatus for fracturing a formation containing a wellbore comprising the steps of (a) injecting a gel into the wellbore; (b) permitting the gel to increase in viscosity and (c) fracturing the formation in the vicinity of the gel.

Abstract: An apparatus and method for selectively delivering a fluid to a targeted area through the use of vortices that are experiencing Taylor-Couette flow. Rotation of the outer surface of a body of the apparatus causes fluid within the annular area between a wellbore and the outer surface to form opposing vortices, which can then be used to selectively deliver the fluid to the targeted area, such as areas of low permeability of a reservoir, in order to improve flow characteristics of a producing area.

Abstract: Methods and compositions that include a method comprising: providing a treatment fluid comprising at least a plurality of degradable diverting agents that comprise at least one degradable material selected from the group consisting of a fatty alcohol, a fatty acid salt, a fatty ester, a proteinous material, and a combination thereof; and introducing the treatment fluid into a subterranean formation during a subterranean operation via a well bore.

Abstract: The present invention is directed to methods for extracting a kerogen-based product from subsurface (oil) shale formations, wherein such methods rely on fracturing and/or rubblizing portions of said formations so as to enhance their fluid permeability, and wherein such methods further rely on chemically modifying the shale-bound kerogen so as to render it mobile. The present invention is also directed at systems for implementing at least some of the foregoing methods. Additionally, the present invention is also directed to methods of fracturing and/or rubblizing subsurface shale formations and to methods of chemically modifying kerogen in situ so as to render it mobile.

Abstract: A method of selectively blocking fractures in a subterranean formation by injecting a diversion agent into the well is disclosed. According to one embodiment, the method comprises injecting a diversion agent into a subterranean formation to form an alkaline-earth carbonate precipitate from decomposition of a carbonyl compound, wherein the diversion agent includes the carbonyl compound and an alkaline-earth halide salt.

Abstract: An ionic liquid may be used to inhibit the swelling and/or disintegration of clay in a subterranean formation. A subterranean clay-containing formation may be treated with the ionic liquid by contacting the formation with a well treatment composition containing the ionic liquid dispersed or dissolved in a carrier fluid. Damage to the formation caused by contact with the well treating composition is reduced or substantially eliminated.

Abstract: An environment is moderated against microbial buildup, and especially bacterial buildup in an area where residual liquid wastes are collected or retained or added into natural ground formations. Water wastes are created, collected in storage areas or retained in natural land formations after the use of fluids to extract hydrocarbons contained in oil sand or oil shale or other hydrocarbon rich formations. The residual water wastes are of the type that generate or provide or promote in or above the fluid at least one waste selected from the group consisting of bacteria, carbon dioxide, hydrogen sulfide, ammonia, mercaptans and organic acids. A combination is provided of at least one of i) a friction reducing polymer for oil extraction and/or a polymer capable of absorbing at least ten times its weight in water (preferably a super-absorbing polymer) and ii) a combination of salts that react to liberate I2.

Abstract: Devices, systems, and methods relating to advanced, high pressure oxidation are described. The devices, systems, and methods can be used to decontaminate ground water in a well or opening in a ground water table, and to recover minerals and hydrocarbons from subterranean deposits.

Abstract: A plume of combined gases are infused into hydrocarbon-bearing formations, “inert” as the major gas and “reactive” as the minor gas, where the minor gas reacts with hydrocarbons to fully saturate hydrocarbons with supercritical fluid, which migrate hydrocarbons out of formations, even at great distances from the regulated fuel cell source. Coal, tar sands, petroleum-contaminated soil, and/or oil wells that have lost gas pressure can also be desorbed by this in-situ method.

Abstract: A tubular introduced into a wellbore is perforated at pre-selected locations after the tubular has been cemented into place. The locations of the perforations are determined by modeling inflow performance of a stimulation fluid within the formation. The inflow performance parameters include reservoir porosity, permeability, pressure, damage skin and intrusion depth, perforation diameter and penetration depth or perforation crushed zone damage and intrusion depth.

Abstract: Measuring a parameter characteristic of a formation in an oil well with a device configured to generate a sensing field within a volume of the formation and cause a flow through the volume in the presence of the sensing field. The device also comprises sensors responsive to changes in the volume, which indicate existent amounts of fluid, such as hydrocarbon and water saturations and irreducible hydrocarbon and water saturations. Measurements may be made before the flow affects the measuring volume and after onset of the flow through the measuring volume.

Abstract: A method is disclosed of drilling a wellbore, the method comprising arranging a drill string and an expandable tubular element in the wellbore whereby a lower end portion of the wall of the tubular element extends radially outward and in axially reverse direction so as to form an expanded tubular section extending around a remaining tubular section of the tubular element, wherein the drill string extends through the remaining tubular section, and axially extending the expanded tubular section by moving the remaining tubular section downward relative to the expanded tubular section so that said lower end portion of the wall bends radially outward and in axially reverse direction, wherein the expanded tubular section covers the wellbore wall in an upper portion of the wellbore. The drill string is operated so as to drill a lower portion of the wellbore, and a compound is transferred between the lower portion of the wellbore and a layer of the earth formation surrounding the lower portion of the wellbore.

Abstract: Viscoelastic surfactant (VES) based fluid systems are effective to pre-saturate high permeability subterranean formations prior to a treatment operation that would undesirably suffer from high fluid leakoff. The fluid systems may include brine, a viscosity enhancer, as well as the VES, and a high temperature stabilizer. The stabilizer may be an alkaline earth metal oxide, alkaline earth metal hydroxide, alkali metal oxide, alkali metal hydroxide, Al2O3, and mixtures thereof. The viscosity enhancer may include pyroelectric particles, piezoelectric particles, and mixtures thereof. The fluid system is easy to pump into the formation, and after initial pumping, the fluid system will soak into and occupy or “pre-saturate” the pores of the formation prior to pumping of a second treating fluid for fracturing, gravel packing, frac-packing, and the like. The methods are practiced in the absence of acids typically used in acidizing operations, such as hydrochloric acid and hydrofluoric acid.

Abstract: A process for controlling the production of loose sand particles within an underground formation through the use of magnetic forces is provided. The loose sand particles are magnetized and then subjected to a magnetic field of sufficient strength such that the operator can control the movement of the loose sand particles within the underground formation. In some instances, the present invention can provide an efficient process for keeping the loose sand particles within the formation, and thereby prolonging the useful life of the downhole equipment. In other instances, the present invention can provide an efficient process for sweeping the loose sand particles out of the underground formation in a controlled fashion. The present invention includes at least three embodiments for magnetizing the loose sand particles, including direct magnetization, contacting the sand particles with a magnetizing reagent, and contacting the sand particles with paramagnet nanoparticles.

Abstract: A process is disclosed for treating an underground formation, which process comprises: (a) introducing into the underground formation a micellar dispersion comprising water, one or more organic acid precursors, one or more surfactants and, optionally, one or more salts, co-surfactants and/or organic liquids that are not organic acid precursors; and (b) allowing (i) the micellar dispersion to solubilize hydrocarbons, emulsions or water blocks present in the underground formation, and (ii) at least a portion of the organic acid precursor to hydrolyze in-situ to produce sufficient organic acid to substantively dissolve acid soluble material present in or adjacent to filter cakes or other damage in the underground formation.

Abstract: An acid-in-oil emulsion having a corrosion inhibitor as the external phase has been found to prevent downhole corrosion when acidizing carbonate formations to enhance hydrocarbon recovery.

Abstract: A cross-linking system for hydratable polymers for using is formation fracturing applications is disclosed along with methods for using same, where the cross-linking system includes a reaction product of a transition metal alkoxide or alkanolate and a borate or borate generating reagent.

Abstract: Corrosion of metallic tubulars in an oil, gas or geothermal well may be inhibited by introducing into the well a dithiazine or dithiazine of the formula: wherein R is selected from the group consisting of a C1 to C12 saturated or unsaturated hydrocarbyl group or a C1 to C10 ?-hydroxy saturated or unsaturated hydrocarbyl group; R1 is selected from the group consisting of a C1-C24 straight chain or branched alkyl group or a C1-C24 arylalkyl; R2 is selected from the group consisting of X-R4-X, R4 being a C1-C6 alkyl group; and X is chlorine, bromine or iodine. The dithiazine may he isolated from a whole spent fluid formed by reaction of hydrogen sulfide and a triazine. Alternately, the whole spent fluid containing the dithiazine may be introduced into the well. The dithiazines of formulae (II) and (III) are quaternized derivatives of the dithiazine of formula (I).

Abstract: Corrosion of metallic tubulars in an oil, gas or geothermal well may be inhibited by introducing into the well a dithiazine of the formula: wherein R is selected from the group consisting of a C1 to C10 saturated or unsaturated hydrocarbyl group or a C1 to C10 ?-hydroxy saturated or unsaturated hydrocarbyl group. The dithiazine may be isolated from a whole spent fluid formed by reaction of hydrogen sulfide and a triazine. Alternately, the whole spent fluid containing the dithiazine may be introduced into the well. In addition, the dithiazine or whole spent fluid may be formulated with at least one component selected from alkyl, alkylaryl or arylamine quaternary salts; mono or polycyclic aromatic amine salts; imidazoline derivative or a quaternary salt thereof; a mono-, di- or trialkyl or alkylaryl phosphate ester; or a monomeric or oligomeric fatty acid.

Abstract: A method of treating a subterranean formation penetrated by a wellbore utilizes a treating fluid formed from an aqueous solution of a water-soluble polymer. The treating fluid further contains a crosslinking agent and an optional delayed release alkaline additive. The delayed release alkaline additive may be at least one of urea, a urea derivative, a solid alkaline earth metal carbonate, a solid alkaline earth metal oxide and combinations of these. The treating fluid further includes an acidic pH adjusting agent used in an amount to provide the treating fluid with a pH of less than about 5. The treating fluid is then introduced into the formation.

Abstract: An aqueous fluid system that contains an aqueous dicarboxylic acid solution, a viscoelastic surfactant as a gelling agent to increase the viscosity of the fluid, and an internal breaker such as mineral oil and/or fish oil to controllably break the viscosity of the fluid provides a self-diverting acid treatment of subterranean formations. The internal breaker may be at least one mineral oil, a polyalphaolefin oil, a saturated fatty acid, and/or is an unsaturated fatty acid. The VES gelling agent does not yield viscosity until the organic acid starts to spend. Full viscosity yield of the VES gelling agent typically occurs at about 6.0 pH. The internal breaker allows the VES gelling agent to fully viscosify the spent organic acid at 6.0 pH and higher, but as the spent-acid VES gelled fluid reaching reservoir temperature, controllable break of the VES fluid viscosity over time can be achieved.

Abstract: A method of treating a subterranean formation penetrated by a wellbore to mitigate the production of unwanted fluids from the wellbore is carried out by forming a treatment fluid containing at least one of an oil-wetting or water-repelling surfactant and a carrier fluid. The treatment fluid is then introduced into the wellbore. The treatment or treatments may be performed remedially or prophylacticaly. The treatment may include the completion and production of zones containing the undesirable fluid(s) and the deliberate formation of cones therein.

Abstract: Methods are given for making scale inhibitors, that were previously incompatible with fluids containing fluoride ion, compatible with fluids containing fluoride ion. Examples of such scale inhibitors include phosphonates and phosphino-polycarboxylates. The method is replacing alkali metal and alkaline earth metal cations, present in salts or bases, or as counter ions of the scale inhibitors, with hydrogen or ammonium ions. Methods of inhibiting scale formation and of dissolving scales are also given.

Abstract: An acidizing fluid for sandstone formations is provided, along with methods of acidizing a sandstone formation penetrated by a wellbore. The aqueous acid treatment is a mixture of an aqueous liquid, a fluoride source, and an effective amount of at least one homopolymer or copolymer of a polycarboxylic acid, salt thereof or derivative thereof, which is introduced into the wellbore, and allowed to acidize the formation and concurrently inhibit calcium fluoride formation and impart calcium tolerance to the fluid.

Abstract: This invention presents innovative and off the beaten path methods to mainly produce suitable saline streams for oil-fields water injection operations. The production of such suitable saline streams can: (1) be achieved economically; and (2) meet the actual stringent requirements for injection operations to steadily enhance oil production from depleted and plugged wells.

Abstract: Methods of acidizing subterranean formations or well bores, and more specifically, to acidizing systems involving acid-generating fluids that comprise acid-generating compounds and associated methods are provided. An example of a method of the present invention comprises: providing an acid-generating fluid that comprises an acid-generating compound; placing the acid-generating fluid into a well bore penetrating a subterranean formation; and allowing the acid-generating compound to produce an acid that then acidizes at least a portion of the subterranean formation or damage contained in the formation or well bore.

Abstract: A method and composition for treating a subterranean formation with a fluid, including forming a fluid including a particulate and an organosilane with the chemical formula RnSiX4-n, wherein n is equal to 1, 2, or 3, R is an organic functional group, and X is a halogen, alkoxy, or acetoxy group, introducing the fluid into a subterranean formation with exposed surfaces, and modifying the wettability of a surface of the particulate or subterranean formation or both. A method and composition for treating a subterranean formation with a fluid including forming a fluid comprising a particulate and an organosilane, introducing the fluid into a subterranean formation with exposed surfaces, and modifying the wettability of the proppant or surfaces or both, wherein the wettability modification degrades.

Abstract: A system and process for extracting hydrocarbons from a subterranean body of oil shale within an oil shale deposit located beneath an overburden. The system comprises an energy delivery subsystem to heat the body of oil shale and a hydrocarbon gathering subsystem for gathering hydrocarbons retorted from the body of oil shale. The energy delivery subsystem comprises at least one energy delivery well drilled from the surface of the earth through the overburden to a depth proximate a bottom of the body of oil shale, the energy delivery well extending generally downward from a surface location above a proximal end of the body of oil shale to be retorted and continuing proximate the bottom of the body of oil shale. The energy delivery well may extend into the body of oil shale at an angle.

Abstract: An acidizing formulation for use in the stimulation of hydrocarbon production is stable when packaged and stored as a single fluid for periods exceeding one year. The formulation contains a miscibility solvent which substantially prevents any phase separation between the constituents and lack of dispersion of the additives in the fluid.

Abstract: A method of acidizing and cleaning up a formation is disclosed, the formation being above 150 degrees C. The formation is treated with a mutual solvent system comprising a mutual solvent of oil and water, an aqueous acid, a corrosion inhibitor, and an iron control agent. In some embodiments, the iron control agent is present in an amount of less than 1% by weight of the mutual solvent system. In some embodiments, the corrosion inhibitor may be present in an amount of less than 10% by weight of the mutual solvent system. In some embodiments, the mutual solvent system further comprises an intensifier.

Abstract: A method of treating a subterranean formation penetrated by a wellbore of a well having iron-containing components is carried out by introducing a treatment fluid into the wellbore of the well. The treatment fluid is formed from an aqueous solution, a mineral acid, a viscoelastic surfactant gelling agent and corrosion inhibitor system containing at least one of an alkyl, alkenyl, alicyclic or aromatic substituted aliphatic ketone and aliphatic or aromatic aldehyde. The treatment fluid is substantially free of any formic acid or precursor formic acid. In certain embodiments, the corrosion inhibitor system comprises a mixture of at least one of an alkenyl phenone or ?,?-unsaturated aldehyde, an unsaturated ketone or unsaturated aldehyde other than the alkenyl phenone and ?,?-unsaturated aldehyde, a dispersing agent, an extender and an alcohol solvent. A corrosion inhibitor intensifier may also be used in certain embodiments, which may include a mixture of cuprous iodide and cuprous chloride.

Abstract: This invention relates to enhancing hydrocarbon production from a subterranean formation via a well completed with a gravel pack. Gravel packs suffer plugging and damage over time from produced particles and other plugging materials brought into the pack as production continues. This invention relates to a chemical treatment for the gravel pack designed to remove damaging particulate matter from the pack via dissolution or displacement. Damaging material is forced sufficiently far into the producing reservoir to prevent its remigration back into the pack.

Abstract: A method for treating a subterranean formation includes forming a treatment fluid including a carrier fluid, a solid acid-precursor, and a solid scale inhibitor. The solid acid-precursor includes a material that forms an acid at downhole conditions in the subterranean formation. The method further includes adding a solid acid-responsive material into the treatment fluid, where the solid acid-responsive material enhances formation of acid from the solid acid-precursor in acidic conditions. The method includes performing an acid fracture treatment and inhibiting scale formation within the subterranean formation. The solid scale inhibitor allows for long-term scale inhibition after the treatment.

Abstract: A method of conditioning well bores and reducing the deleterious effects of water production in a subterranean formation by placing an aqueous phase polymer and/or resin, which at a designated set up time, solidifies and blocks water conduits and establishes post treatment gas and oil permeability. Novel polymers and/or resins for use as a water barrier are typified by phenolformaldehyde containing 1-2 weight % of at least one of sodium bisulphite, sodium metabisulphite or mixtures thereof. The method includes selecting a well having sizable hydrocarbon reserves with a production history of decrease of oil or gas production with concurrent increase of water production.

Abstract: The present invention relates to a split stream oilfield pumping system which utilizes recycled high Reid vapor pressure production fluids. The oilfield system is made up of two separate fluid streams: a first recycled fluid stream and a second new fluid stream. The recycled fluid stream is enclosed to reduce or eliminate vaporization of the recycled fluid, which typically will have a Reid vapor pressure >14 kPa. Wellbore treatment additives are added to the new fluid stream, and the resultant treatment fluid is mixed with the recycled fluid in a common manifold to provide a final wellbore treatment fluid to be delivered to the wellhead.

Abstract: This invention relates to compositions and methods of removing an organic deposit including introducing a fluid, wherein the fluid comprises at least two non-polar organic solvents and at least two polar organic solvents; allowing the fluid to dissolve at least a portion of the organic deposit; and removing at least a portion of the fluid. This invention relates to compositions and methods of removing an organic deposit including introducing a fluid, wherein the fluid comprises at least two non-polar organic solvents and at least two polar organic solvents, wherein the non-polar organic solvents comprise aromatic naphtha, terpenes, kerosene, and combination thereof, and wherein the polar solvents comprise heavy aromatic naphtha, cyclohexanone, N-2-methyl pyrrolidone, N-ethyl-2-pyrrolidone, and combination thereof, allowing the fluid to dissolve at least a portion of the organic deposit, and removing at least a portion of the fluid.

Abstract: A method and a composition for stimulating oil production from wells which have ceased production by pumping in a mixture of gluconic, oxalic and citric acids, isopropanol, ethylene glycol and sodium citrate between pre-flush and over-flush intervals, which composition and method does not include the use of hydrochloric acid or hydrofluoric acid.

Abstract: A method of treating a subterranean formation penetrated by a wellbore to mitigate the production of unwanted air from the wellbore is carried out by forming a treatment fluid containing a water-wetting surfactant and a carrier fluid. The treatment fluid is then introduced into the wellbore. The treatment or treatments may be performed remedially or prophylacticaly. The treatment may include the completion and production of zones containing the undesirable air and the deliberate formation of cones therein.

Abstract: A subterranean formation stimulation system, comprising a gas generator, a high pressure seal, and a fluid injection system. The high pressure seal may be a packer and or plug having an outer sealing surface on its outer periphery. The outer sealing surface is configured for metal to metal contact with the inner circumference of wellbore casing. The gas generator can be compressed gas or a propellant. A shaped charge can be included to activate the generator. The system is disposable in a wellbore on wireline, slick line, or tubing.

Abstract: A process for treating an underground formation, which process comprises: (a) introducing into the underground formation a treatment fluid comprising an organic acid precursor; (b) heating a zone within the formation, which zone contains at least a portion of the organic acid precursor, to a temperature which is above the natural formation temperature and sufficient to increase the rate of hydrolysis of the organic acid precursor; and (c) allowing the organic acid precursor to hydrolyse to produce an organic acid in an amount effective to acidize the underground formation.

Abstract: A fluid comprising a viscous hyposaline aqueous solution of first and second cationic polymers comprising quaternized ammonium groups, wherein the first cationic polymer comprises a hydrophilic base polymer structure and the second cationic polymer comprises a lipophilic base polymer structure, and a method comprising introducing the viscous fluid into an initial first interval of a subterranean formation, and diverting with the viscous fluid a treating fluid from the initial first interval to an initial second interval. The fluid and method are useful to modify a hydrocarbon reservoir formation for improved relative permeability of oil with respect to water to enhance hydrocarbon production from the reservoir.

Abstract: A system includes a wellbore in fluid communication with a formation of interest and a fracturing slurry include a carrier fluid with a low amount of a viscosifier, an amount of proppant including a first average particle size between about 200 and 2000 ?m, an amount particulates including a second average particle size between about three and ten times smaller than the first average particle size, and a third amount of particulates having a third average particle size smaller than the second average particle size. A sum of all of the particulates in the fracturing slurry exceed about 16 pounds per gallon of the carrier fluid. They system further includes a pumping device that creates a propped fracture in the formation of interest with the fracturing slurry, and a removal agent that removes the second amount of particulates and/or the third amount of particulates from the propped fracture.

Abstract: The productivity of hydrocarbons from hydrocarbon-bearing calcareous or siliceous formations is enhanced by contacting the formation with a well treatment composition which contains a hydrofluoric acid source, a boron containing compound and a phosphonate acid, ester or salt thereof.

Abstract: A method for well treatment by forming a temporary plug in a fracture, a perforation, a wellbore, or more than one of these locations, in a well penetrating a subterranean formation is provided, in which the method of well treatment includes: injecting a slurry comprising a degradable material, allowing the degradable material to form a plug in a perforation, a fracture, or a wellbore in a well penetrating a formation; performing a downhole operation; and allowing the degradable material to degrade after a selected time such that the plug disappears.

Abstract: Methods are given for making scale inhibitors, that were previously incompatible with fluids containing fluoride ion, compatible with fluids containing fluoride ion. Examples of such scale inhibitors include phosphonates and phosphino-polycarboxylates. The method is replacing alkali metal and alkaline earth metal cations, present in salts or bases, or as counter ions of the scale inhibitors, with hydrogen or ammonium ions. Methods of inhibiting scale formation and of dissolving scales are also given.

Abstract: A method is described for treating a subterranean formation with a low viscosity fluid system that contains a viscoelastic surfactant at a concentration too low to viscosify the fluid, but that is concentrated in the formation so that the fluid system gels. The fluid optionally contains a formation-dissolving agent. The fluid is used in matrix acidizing, acid fracturing, and diversion.

Abstract: Methods of hydraulically fracturing subterranean coal seams and formations resulting in improved permeability to stimulate Coalbed Methane. In one method, the coal seam is fractured using a proppant-containing fracturing fluid in alternating stages with an aqueous base solution that etches the fracture faces of the coal thereby creating channels for fluid flow. In another method, the coal seam is fractured using a fracturing fluid without propping agents in alternating stages with an aqueous base solution that is pumped at a pressure sufficient to maintain the fractures in an open position thereby etching the fracture faces to create channels for fluid flow. In yet another embodiment, a base solution is injected into the formation at a pressure sufficient to create fractures therein and simultaneously etch the faces of the open fractures to thereby form channels in the faces for increased fluid flow.

Abstract: The present invention is directed to a method of isolating hydrajet stimulated zones from subsequent well operations. The method includes the step of drilling a wellbore into the subterranean formation of interest. Next, the wellbore may or may not be cased depending upon a number of factors including the nature and structure of the subterranean formation. Next, the casing, if one is installed, and wellbore are perforated using a high pressure fluid being ejected from a hydrajetting tool. A first zone of the subterranean formation is then fractured and stimulated. Next, the first zone is temporarily plugged or partially sealed by installing an isolation fluid into the wellbore adjacent to the one or more fractures and/or in the openings thereof, so that subsequent zones can be fractured and additional well operations can be performed.

Abstract: Many methods are provided herein including, in one embodiment, a method comprising: providing a fluid that comprises an acid, crosslinked oxidized xanthan, and optionally, a base fluid; placing the fluid in a well bore penetrating a subterranean formation; and allowing the fluid to acidize at least a portion of the formation or damage contained therein. In another embodiment, herein provided is a fluid for subterranean uses comprising an acid and crosslinked, oxidized xanthan.

Abstract: Acidizing methods for subterranean formations formed of predominantly siliceous material as well as acidizing compositions. Some methods include injecting into a predominantly siliceous subterranean formation, an aqueous acidic mixture formed by blending an aqueous liquid, a fluoride source, and an effective amount of an alkane sulfonic acid, preferably methane sulfonic acid, to adjust the pH of the fluid where the alkane sulfonic acid where the alkane group may be an unbranched, a branched or a cyclic alkyl residue. Hydrofluoric acid (HF) may not be added to the fluid in some embodiments as the fluoride source, such as the case for an HF free fluid, and, in some instances, hydrochloric acid is not added to the fluid to adjust pH. Also described are compositions containing an aqueous acidic mixture formed by blending an aqueous liquid, a fluoride source, and an effective amount of an alkane sulfonic acid to adjust pH.