Abstract: Compositions relating to fluid loss control operations are provided. In some embodiments, fluid loss treatment fluid compositions are provided that may comprise ceramic particulate bridging agents, wherein at least a portion of the ceramic particulate bridging agents comprise chemically bonded particulates, a partially depolymerized starch derivative, and a base fluid are provided. In other embodiments, fluid loss treatment fluid compositions are provided comprising ceramic particulate bridging agents, wherein at least a portion of the ceramic particulate bridging agents are substantially insoluble in water; a partially depolymerized starch derivative, and a base fluid.

Abstract: A method of servicing a wellbore comprising introducing to the wellbore a wellbore servicing fluid comprising an additive composition comprising a polysaccharide having carboxylate and sulfonate groups. A method of servicing a wellbore comprising preparing at the well site an additive composition comprising a polysaccharide having carboxylate and sulfonate groups,introducing the additive composition into a wellbore servicing fluid, and placing the wellbore servicing fluid into a subterranean formation. A method of preparing a wellbore servicing fluid comprising contacting a polysaccharide composition with an oxidizing agent to form an oxidized polysaccharide, and contacting the oxidized polysaccharide with a sulfonating agent to form a carboxylated sulfonated polysaccharide, and contacting the carboxylated sulfonated polysaccharide with a wellbore servicing fluid.

Abstract: An initial chemical composition comprising selected surfactants, dispersants, and degreasers that liquefy, disperse, demulsify, degrease, inhibit corrosion and scale formation, and lower the pour point of a petroleum, coal, Fischer-Tropsch synthesized, or naturally occurring paraffin-based wax and asphaltene. Such a product is capable of converting crystalline wax (paraffin) in, for example, slop oil into an amorphous form of wax at room temperature, allowing the wax to be dissolved in, for example, crude oil without the need for heating, and maintaining it in solution at room temperature, substantially reducing, indeed in some applications, preventing, for example, wax build-up in pipelines, processing and transportation equipment, etc., and the recovery of the hydrocarbons in the slop oil. In a second aspect of the invention, the pre-blend addition of a hydrotrope-demulsifier, a chelating agent and a wax plasticizer can result in a BS&W of zero for the recovered hydrocarbon blend.

Abstract: A wellbore fluid including a peroxide degradable polymer and an encapsulated peroxide source. The peroxide degradable polymer may be a polysaccharide. The peroxide source may include an inorganic peroxide, including zinc and alkaline earth metal peroxides, such as magnesium peroxide. The encapsulating material may be a polymer, including enteric polymers. The release of peroxide, from peroxide sources generally, can be controlled by means of pH such that peroxide source can be activated, and peroxide released, by a change in pH. In a wellbore, this pH change can be effected by using produced fluids to lower the pH of a more basic wellbore fluid.

Abstract: Methods are provided that include a method comprising providing a treatment fluid comprising a base fluid and a gelling agent that comprises a diutan composition; providing a breaker that comprises an acid composition; allowing the breaker to interact with the treatment fluid; and allowing the viscosity of the treatment fluid to decrease. In some embodiments, the treatment fluid may comprise a base fluid, a gelling agent that comprises a diutan composition, and a breaker that comprises an acid composition. In some embodiments, the treatment fluid may be introduced into a portion of the subterranean formation at or above a pressure sufficient to create or enhance one or more fractures in the portion of the subterranean formation. Additional methods are also provided.

Abstract: A drilling fluid for use in high oil viscosity formations containing tar, sand and oil entrained therein. The drilling fluid can be comprised of a polymer in an amount from between 0.05% and 5% by volume, a solvent in an amount from between 1% and 20% by volume and de-emulsifier in an amount from between 0.05% and 10% by volume.

Abstract: An electropositive and water-based production well treating fluid system exhibits electropositivity by using a cationic viscosifier meanwhile matched with a cationic fluid loss additive and, optionally, contains a mud-building agent, an electrical stabilizing agent, a colloid-stabilizing agent, lubricant, an oil layer protective agent and/or a weighting agent. The electropositive production well treating fluid can beffer solve the contradiction of technical requirements between “treating fluid stability” and “bore hole stability”, and features a strong ability to inhibit the dispersion of clay, a good effect of protecting oil-gas reservoirs, fast drilling speeds, regular shape of bore holes and good resistance to salt.

Abstract: Sulfonated graft copolymer obtained by radical graft copolymerization of one or more synthetic monomers in the presence of hydroxyl-containing naturally derived materials. The graft copolymer includes 0.1 to 100 wt %, based on weight of the total synthetic monomers, of at least one monoethylenically unsaturated monomer having a sulfonic acid group, monoethylenically unsaturated sulfuric acid ester or salt thereof, with the monomer and hydroxyl-containing naturally derived materials present in a weight ratio of 5:95 to 95:5.

Abstract: The drilling mud with a lowered coefficient of friction having a silicate-based mud and a lubricant selected from the group consisting of: glycosides, alkylpolyalkoxyalcohols, alcohol ester polymers, amine phosphates, starch and combinations thereof.

Abstract: Disclosed are drilling fluids suitable for use in connection with oil well drilling. The drilling fluids of the invention include in one embodiment a liquid base, an alkyl glucoside, such as methyl glucoside, and a borehole stability promoter that includes a maltodextrin, a carboxyalkyl starch, a hemicellulose-containing material, or a mixture of the foregoing. In another embodiment, the drilling fluid includes a liquid base and molasses solids, preferably in combination with an alkyl glucoside and more preferably in further combination with one of the aforementioned borehole stability promoters. The drilling fluids of the invention surprisingly have a reduced tendency to swell shale as compared with known drilling fluids. Also disclosed are a drilling apparatus and process. The drilling apparatus includes a drill string, which may be conventional, that is fluidically coupled to a source of drilling fluid, the source of drilling fluid including the drilling fluid of the invention.

Abstract: The invention provides well drilling and servicing fluids, and methods of drilling, completing, or working over a well therewith, preferred fluids comprise an aqueous liquid, a water soluble polymer viscosifier (preferably xanthan gum), a polymeric fluid loss control additive (preferably a partially depolymerized partially crosslinked hydroxyalkyl ether derivative of starch or a hydroxyalkyl ether derivative of a partially crosslinked and partially depolymerized starch), a bridging agent comprising a particulate calcined magnesia that has an Activity Index greater than about 800 seconds, and an additive selected from the group consisting of citric acid, alkali metal salts of citric acid, ammonium citrate, and mixtures thereof in an amount sufficient to increase the low shear rate viscosity of the fluids, preferably from about 0.05–5 ppb, most preferably from about 0.15–3 ppb.

Abstract: The invention provides well drilling and servicing fluids, and methods of drilling, completing, or working over a well therewith, preferred fluids comprise an aqueous liquid, a water soluble polymer viscosifier (preferably xanthan gum), a polymeric fluid loss control additive (preferably a partially depolymerized partially crosslinked hydroxyalkyl ether derivative of starch or a hydroxyalkyl ether derivative of a partially crosslinked and partially depolymerized starch), a bridging agent comprising a particulate calcined magnesia that has an Activity Index greater than about 800 seconds, and citric acid in an amount sufficient to increase the low shear rate viscosity of the fluids. The invention further provides a method of increasing the low shear rate viscosity of fluids which contain a water soluble polymer and a calcined magnesia bridging agent which has an Activity Index greater than about 800 seconds.

Abstract: Water based drilling, drill-in, and completion fluids comprising surfactant-polymer blends that are effective to generate effective rheology comprising low shear rate viscosity and effective fluid loss control properties. The water based fluids preferably are substantially solid free.

Abstract: This invention relates to divinyl sulfone crosslinking agents, viscosified treatment fluids, and methods of using these compositions in applications wherein viscosified treatment fluids may be used. In one embodiment, this invention provides a method of treating a portion of a subterranean formation comprising: providing a viscosified treatment fluid that comprises an aqueous base fluid and a crosslinked gelling agent, the crosslinked gelling agent comprising at least one alkyl sulfone bridge, and treating the portion of the subterranean formation.

Abstract: Methods and compositions relating to fluid loss control operations are provided. Examples of compositions may comprise ceramic particulate bridging agents and improved fluid loss control additives, and methods of using those compositions to provide fluid loss control. An embodiment of a method of providing fluid loss control from a first location to a second location may comprise the steps of: providing a treatment fluid comprising ceramic particulate bridging agents, a modified starch composition, and a base fluid; introducing the treatment fluid to the first location; and allowing the treatment fluid to form a filter cake to prevent fluid loss from the first location to the second location.

Abstract: The present invention generally relates to compositions of matter and methods of using those compositions. More particularly, and as part of one of the preferred embodiments, the present invention relates to compositions and methods of use of fluids useful for sealing formation fractures and/or inhibiting downhole fluid loss. The present invention is useful as a pill or series of pills that can be formulated and spotted to a particular formation zone.

Abstract: A new fluid system additive is provided that serves to disperse and maintain fluid system solids in a stabilized condition and also “toughen” the filter cake. Fluid systems containing this additive also tolerate calcium contamination better than existing additives, and in laboratory tests simulating well conditions, the treated fluid systems demonstrate good fluid properties at high temperatures (e.g. 250° F.) in contrast to similar fluid systems treated with conventional, more costly additives. In a preferred embodiment, a composition or additive for use in hydrocarbon exploitation includes a biopolymer derived from at least one species of the family Musaceae.

Abstract: A method for producing a precursor polymer dispersion for addition to a brine for use in drilling and completion operations comprising providing a precursor brine having a first salt content, and mixing a water-soluble polymer with the precursor brine at a sufficient concentration and under conditions sufficient to produce a precursor polymer dispersion effective at a sufficient concentration in a final brine having a second salt content to improve the rheology and/or fluid loss control properties of the final brine.

Abstract: An excavation fluid composition useful for enlarging a cavity in the earth includes a synthetic polymer and sodium silicate. The excavation fluid composition is formulated so as to enable the fluid in contact with unstable or sandy soils in the selected areas of the excavation to react and form silicate-based derivatives with lesser solubility, and movement and thus improve soil stability at the excavation wall.

Abstract: The invention relates to water based wellbore fluids used during a hydrocarbon recovery process, such as drilling, fracturing, gravel packing and wellbore workover. According to the present invention, said wellbore fluid comprises a fluid loss additive and a bridging material that are hydrophobic in nature, hydrophobically modified or oil wettable. The wellbore fluid generates an active filter cake that once formed, is impermeable to an aqueous phase, thus reducing fluid loss and ensuring reduced damage to the formation, yet simultaneously is permeable to the back flow of hydrocarbons during a hydrocarbon recovery process.

Abstract: A water-base fluid for use in drilling wells and other drilling operation includes a shale clay which swells in the presence of water. The fluid preferably includes: an aqueous based continuous phase, and a shale hydration inhibition agent having the formula: wherein R and R′ are independently selectable alkylene groups having 2 to 4 carbon atoms, and wherein x and y have independently selected values such that the sum of x and y is at least 1. The shale hydration inhibition agent should be present in sufficient concentration to reduce the swelling of the shale clay. The fluid may be used for formulating drilling fluids such as water-base drilling muds or clear brine drilling fluids. The fluid may also be used in the slurrification and disposal of drill cuttings that contain water swellable clays or shale clays.

Abstract: A dense drilling fluid additive used to control lost circulation, fluid loss and/or seepage loss of drilling fluid during drilling operations is disclosed. Such additive is formed from ground base materials, such as inorganic matter, and may be used to manage the rheological properties of drilling fluid.

Abstract: Liquid water soluble polymer suspensions in non-aqueous solvents are extremely stable over long periods of time with minimum separation of the solvent and no hard packing of the dispersed water soluble polymer. The suspensions enable a user to rapidly add the suspension to water, being mixed at low speeds, without the formation of lumps or fisheyes and without generating fugitive dust in the process. The suspensions are environmentally safe and biodegradable. Unlike many other liquid polymer suspensions, the suspensions exhibit minimal oil or grease upon dilution. They contain no surfactants that can add to the oil and grease determination. The suspensions and the fluids produced by diluting the fluids to a working concentration of the water soluble polymer exhibit low toxicity to marine organisms and to humans. The suspensions can be manufactured from ingredients suitable for use in personal care applications such as cosmetics, shampoos and the like.

Abstract: Well-working fluid compositions containing certain processed inorganic, oil and water wettable ground elastomeric crumb rubber materials to decrease the seepage loss of various fluids to subterranean formations in which these well working fluids are required and utilized are disclosed. Also disclosed is a method of reducing the seepage and whole mud loss of these well working fluids utilizing such ground elastomeric crumb rubber materials.

Abstract: Disclosed are drilling fluids suitable for use in connection with oil well drilling. The drilling fluids of the invention include in one embodiment a liquid base, an alkyl glucoside, such as methyl glucoside, and a borehole stability agent that includes a maltodextrin, a carboxyalkyl starch, a hemicellulose-containing material, or a mixture of the foregoing. In another embodiment, the drilling fluid includes a liquid base and desugared molasses solids, preferably in combination with an alkyl glucoside and more preferably in further combination with one of the aforementioned borehole stability agents. The drilling fluids of the invention surprisingly have a reduced tendency to swell shale as compared with known drilling fluids. Also disclosed are a drilling apparatus and process. The drilling apparatus includes a drill string, which may be conventional, that is fluidically coupled to a source of drilling fluid, the source of drilling fluid including the drilling fluid of the invention.

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: Methods of cementing in subterranean formations, cement compositions, and methods for making the compositions are provided. A cement slurry is passed into a subterranean formation, and a swelling agent is passed into the subterranean formation to reduce an amount of water flowing into the cement slurry. The swelling agent may be combined with a carrier fluid before being displaced into the subterranean formation. Alternatively, the swelling agent may be pre-mixed with the cement slurry to form a new cement composition, followed by displacing the cement composition into the subterranean formation. The swelling agent is present in an amount effective to, upon absorption of water and swelling to form a gel mass, substantially block the flow path of the water into the cement composition or reduce losses to low pore pressure intervals, thereby preventing the integrity of the cement composition from being compromised or lost to voidage, fractures, fissures, etc.

Abstract: A method of treating a well including injecting a thermally stable, substantially water-free well-treating fluid into the well, wherein the well-treating fluid comprises a polymer, a glycol compound, and a salt is disclosed. In another embodiment, a thermally stable, substantially water-free well fluid including a polymer, a diol compound, and a salt is disclosed.

Abstract: Methods of drilling and completing open hole well bores and methods of removing filter cake comprised of a gelling agent and calcium carbonate are provided. A method of the invention for removing filter cake comprised of a gelling agent and calcium carbonate from the walls of an open hole well bore is basically comprised of the steps of contacting the filter cake with a delayed clean-up solution comprised of water and a formate ester and removing the clean-up solution from the well bore.

Abstract: The present invention provides a well treatment fluid that contains water, an oxidized chitosan-based compound, and a water-soluble compound having carbonyl groups, wherein the oxidized chitosan-based compound has the property of being soluble in water up to about 2 wt % while maintaining a viscosity of less than about 1000 cp. The water used for the well treatment fluid is selected from the group consisting of fresh water, seawater, natural brine, formulated brine, 2% KCl solution, and any mixtures in any proportion thereof. The present invention also provides a method of treating a subterranean formation penetrated by a wellbore comprising the steps of: (a) forming the well treatment fluid, and (b) contacting the subterranean formation with the fluid.

Abstract: A drilling fluid includes a base fluid and a circulation loss reducing additive package having a polysaccharide, a cellulose derivative and a pH controlling component.

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: The present invention relates to biodegradable chemical compositions wherein core substrates, particularly oil well chemicals, are adsorbed onto particulate starch, particularly granular starch, providing a stable, controlled release formulation suitable for use in oil field applications. The invention further relates to the process of preparing obtaining these compositions.

Abstract: The present invention generally relates to compositions of matter and methods of using those compositions. More particularly, and as part of one of the preferred embodiments, the present invention relates to compositions and methods of use of fluids useful for sealing formation fractures and/or inhibiting downhole fluid loss. The present invention is useful as a pill or series of pills that can be formulated and spotted to a particular formation zone.

Abstract: This invention relates to aqueous-based oil well drilling fluids containing a starch polymer derived from a starch having an amylose content of at least 50% by weight. The starch polymers provide high temperature fluid loss performance while having a minimum impact on viscosity build when incorporated into well drilling fluids. They may also be used in other applications for which cellulosic polymers have heretofore been employed because of their high temperature tolerance and minimum impact on rheological properties compared to conventional starch polymers.

Abstract: This invention provides a water-free oil based fluid polymer suspension composition for use as a rheology modifier and fluid loss reducer in oil or gas well servicing fluids. It has been found that by using white medicinal oil as a carrier, high solids content and environmental friendly anhydrous fluidized polymer suspensions of xanthan gum, cellulose ethers, guar gum and derivatives thereof can be prepared. More specifically, in one aspect, an oil-based fluid polymer suspension (FPS) composition for use in oil or gas well servicing fluids is preferred containing: a) a hydrophilic polymer, b) an organophilic clay, c) a stabilizer, and d) a white medicinal oil having selected properties.

Abstract: A water-base fluid for use in drilling wells and other drilling operation includes a shale which swells in the presence of water. The fluid preferably includes: an aqueous based continuous phase, and a shale hydration inhibition agent having the formula: H2N—R—{OR′}x—Y in which R and R′ are alkylene groups having 1 to 6 carbon atoms and x is a value from about 1 to about 25. The Y group should be an amine or alkoxy group, preferably a primary amine or a methoxy group. The shale hydration inhibition agent should be present in sufficient concentration to reduce the swelling of the shale. The fluid may be used for formulating drilling fluids such as invert emulsion drilling muds or clear brine drilling fluids. The fluid may also be used in the slurrification and disposal of drill cuttings that contain water swellable clays or shales.

Abstract: The invention relates to a ligand-modified cellulose product comprising cellulose ether, calcium salt and at least one ligand as a chelating agent. The product can be used e.g. in drilling fluids.

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: Disclosed are drilling fluids suitable for use in connection with oil well drilling. The drilling fluids of the invention include in one embodiment a liquid base, an alkyl glucoside, such as methyl glucoside, and a borehole stability agent that includes a maltodextrin, a carboxyalkyl starch, a hemicellulose-containing material, or a mixture of the foregoing. In another embodiment, the drilling fluid includes a liquid base and desugared molasses solids, preferably in combination with an alkyl glucoside and more preferably in further combination with one of the aforementioned borehole stability agents. The drilling fluids of the invention surprisingly have a reduced tendency to swell shale as compared with known drilling fluids. Also disclosed are a drilling apparatus and process. The drilling apparatus includes a drill string, which may be conventional, that is fluidically coupled to a source of drilling fluid, the source of drilling fluid including the drilling fluid of the invention.

Abstract: Water-based drilling fluid comprising: (a) water, (b) at least one biopolymer of the polysaccharide type, (c) at least one filtrate reducer selected from starches with different cross-linking degrees in presence of cellulose microfibers, (d) optionally a hydrosoluble polymeric surface-active agent having an HLB from 10 to 16, preferably from 11 to 14.

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: Lubricating additives for drilling fluids are prepared from semi-solid highly viscous and/or high molecular weight lubricants, such as polyalkylenes (e.g., polybutene), by steam jet cooking a mixture of starch, water, and the lubricant in order to uniformly suspend micrometer-sized lubricant droplets in an aqueous starch matrix. These additives avoid the need for toxic emulsifiers, surfactants, or short-chain hydrocarbon solvents for dispersing the lubricants. They impart lubricity to drilling fluids (muds) and also inhibit fluid loss in geological formations by enhancing the filtration control properties of the fluid.

Abstract: A new stable liquid suspension containing non-soluble particles dispersed in a non-aqueous liquid medium having a concentration of a suspension aid and a method of making and use thereof.

Abstract: A process and composition are provided for permeability reduction in a hydrocarbon-bearing formation to improve hydrocarbon recovery therefrom. A moderately epichlorohydrin cross-linked, non-hydroxylpropylated starch is derived from high amylopectin waxy maize starch for use in drilling, workover and completion fluids. The starch is combined with xanthan gum and used in solutions of fresh water, non-saturated brine or saturated brine containing sized salt particles, typically sodium chloride, of various sizes, or sized calcium carbonate, or a combination of sized salt and sized calcium carbonate.

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: 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: Water based drilling fluid compositions which contain at least one viscosity builder and at least one rheological control agent wherein the rheological control agent is an amphoteric polymer, the cationic groups of the amphoteric polymer being quaternary ammonium groups.

Abstract: Selectively cross-linked starches are disclosed that are useful as fluid loss control additives in subterranean treatment fluids comprising starches that are 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: Compositions and methods useful in creating boreholes, tunnels and other excavations in unstable soils and earth formations, especially those composed partially or wholly of sand, gravel or other granular or permeable material are disclosed. The fluids include a polymer, and a soluble silicate ion source. The fluids of the invention, when used according to the methods of the invention, have unique dual functionality as excavating fluids and as earth-grouting or soil-hardening compositions.