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: 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: Methods of fracturing subterranean zones to produce maximum hydrocarbon productivity are provided. The methods are basically comprised of providing a fracturing fluid comprised of water, a gelling agent present in an amount in the range of from about 0.06% to about 0.3% by weight of the water and an inorganic salt for preventing clay swelling present in an amount in the range of from about 0.01% to about 1% by weight of the water. The fracturing fluid is introduced into the subterranean zone at a rate and pressure sufficient to form fractures and the fracturing fluid is recovered from the zone.

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: 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: 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: 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: 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: 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: 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: An encapsulated breaker is enclosed within a hydrolytically degradable polymer coating. Compositions containing this encapsulated breaker, methods of making and methods of use are also described.

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: An encapsulated breaker slurry composition for reducing the viscosity of a fracturing fluid. The slurry has a flashpoint above 93° C., and the liquid of the slurry does not facilitate release of the breaker from the coating. Methods of using the slurry composition are also described.

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: An encapsulated breaker is enclosed within a hydrolytically degradable polymer coating. Compositions containing this encapsulated breaker, methods of making and methods of use are also described.

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: The invention relates to an aqueous well servicing fluid comprising in solution a potassium formate characterized in that said solution contains in addition potassium citrate. The potassium citrate, which can be added as a solid to a potassium formate solution, enhances the density of said fluid and minimizes any risk of caking which may be experienced if solid potassium formate is used.

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 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: 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: An oil-based fluid system has been discovered using a distribution of salt particle sizes, an oil or water/oil emulsion, a suspending agent for suspending the salt particles in the oil and a filtration control agent. It is important that the salt particles be distributed across a wide size range to effectively prevent filtration or fluid loss into the formation. Since the filter cake particles do not invade the well bore, no high pressure spike occurs during the removal of the filter cake. This high pressure spike indicates damage to the formation and well bore surface, which damage typically reduces overall permeability of the formation. The rheological properties of the fluid allow it to be used in a number of applications where protection of the original permeable formation is desirable. The applications include, but are not limited to, drilling fracturing and controlling fluid losses during completion operations, such as gravel packing or well bore workovers.

Abstract: Oil or water based drilling muds, together with other wellbore contaminants such as pipe thread sealants and lubricants are displaced from the well and the wellbore surfaces are cleaned by a system of four serially pumped fluid pills. The first stage fluid pill is a weighted spacer having an alkyl polyglycoside surfactant, a dispersant, a weighting agent and a viscosifier. The second stage pill is a drive fluid formed by water and a viscous polymer gel such as clarified xanthan gum having a viscosity/shear rate characteristic which minimizes mixing of the drive fluid pill with the displacement fluid pill. A buffer fluid pill comprising completion brine is interposed between the drive fluid pill and a fourth stage comprising a wash fluid pill using an organic solvent or a caustic alkyl polyglycoside as a final cleaning stage. The densities of the pills are controlled to minimize mixing and fingering of one pill into the other.