Abstract: Methods for enhancing the stability of ester based drilling fluids for drilling, running casing in, and/or cementing a borehole in a subterranean formation are disclosed, as well as improved ester based drilling fluids for use at high temperatures. The advantages of the invention are realized by inhibiting hydrolysis of the esters in the drilling fluid by adding a monomeric or polymeric carbodiimide hydrolysis inhibitor to the drilling fluid.

Abstract: A lost circulation material and method for well treatment employing the material that is effective at sealing or plugging small fissures and large fractures and has utility over a wide range of temperatures, including high temperatures. The material has an optimized bimodal particle distribution and optionally has a polymer flocculent or water swellable polymer.

Abstract: In one embodiment, the present invention provides a drilling fluid composition that comprises a surfactant-free emulsion comprising an oleaginous fluid, a fluid that is at least partially immiscible with the oleaginous fluid, and a non-surfactant polymeric emulsifier. In another embodiment, the present invention provides a method of treating a subterranean formation comprising providing a treatment fluid that comprises a surfactant-free emulsion, the surfactant-free emulsion comprising an oleaginous fluid, a fluid that is at least partially immiscible with the oleaginous fluid, and a non-surfactant polymeric emulsifier; and treating the subterranean formation.

Abstract: An invert emulsion drilling fluid, and a method for the use thereof in drilling wellbores, with good rheological properties at high temperatures and pressures. One embodiment of the drilling fluids are free of organophilic clays and lignites, free of calcium chloride, and comprise an alcohol in the internal phase, a quaternary ammonium emulsifier, and argillaceous solids. In one embodiment, the alcohol is a glycerol, a polyglycerol, or a mixture thereof. In one embodiment, the base oil for the emulsion is a paraffin and/or mineral oil. The drilling fluids provide good lubricity and high rates of penetration.

Abstract: A slurry composition comprising an alkaline metal oxide, a chloride or phosphate salt, water, glass beads and a foaming agent. A foamed slurry comprising magnesium oxide, water, a chloride or phosphate salt, and glass beads, wherein the slurry has a density of from about 4 to about 12 pounds per gallon. A foamed slurry comprising magnesium oxide, water, a chloride or phosphate salt, and beads, wherein the slurry has a density of from about 4 to about 12 pounds per gallon and the set slurry is acid soluble.

Abstract: An inhibitive water-based polymer mud system and method for using the system in drilling and in stabilizing wellbores is disclosed for use in water sensitive formations as an alternative to oil-based muds. The system comprises a substantially non-ionic low molecular weight polyacrylamide in combination with a substantially non-ionic high molecular weight polyacrylamide, preferably long chain alcohol or an amine or silicate shale inhibitor, and poly anionic cellulose.

Abstract: The invention provides aqueous based well drilling and servicing fluids containing a polymer viscosifier with enhanced thermal stability provided by a diacid or diacid salt preferably having about two to about eight carbon atoms, such as, for example, sodium oxalate. The invention also provides a method of enhancing the thermal stability of aqueous based well drilling and servicing fluids containing a polymer viscosifer by adding diacid or diacid salt to the fluids.

Abstract: Diesel oil-based invert emulsion drilling fluids having fragile gel properties and improved performance. Methods are also disclosed for drilling, running casing, cementing, and/or producing hydrocarbons in a subterranean formation.

Abstract: A method for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid is disclosed, as well as compositions for use in such method. The method employs a drilling fluid comprising a fragile gel or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluid is especially advantageous for use in deep water wells because the fluid exhibits minimal difference between downhole equivalent circulating density and surface density notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluid, the fluid makes an environmentally acceptable and regulatory compliant invert emulsion drilling fluid. The fluid preferably contains no organophilic clays.

Abstract: A method of reducing the viscosity of invert emulsions and oil-based drilling fluids and well service fluids comprising such emulsions over a broad temperature range is disclosed. The method comprises adding to said invert emulsions of the invention a non-ionic surfactant alone or in combination with a co-thinner having the formula: R??—(C2H4O)n(C3H6O)m(C4H8O)k—H where R?? is a saturated or unsaturated, linear or branched, alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging from about 0 to about 10, and k is a number ranging from about 0 to about 10. The non-ionic surfactant is a reaction product of ethylene oxide, propylene oxide and/or butylene oxide with C10-22 carboxylic acids or C10-22 carboxylic acid derivatives containing at least in position 9/10 and/or 13/14 structural units of general formula (I) where R1 is a hydrogen atom or an OH group or a group OR2.

Abstract: An efficient oil based drilling fluid is provided that includes a polymer additive effective at imparting suspension characteristics without the presence of organophilic clays, while also providing filtration control. The fluid is shear thinning and has good fluid rheology over a broad temperature range. A preferred polymer for the additive is substantially linear and comprises mostly hydrophobic monomers and some hydrophilic monomers such as, for example, an emulsion copolymer of 2-ethylhexyl acrylate and acrylic acid.

Abstract: A lost circulation material and method for treatment employing the material is provided that has particular utility in offshore applications because the material may be used with saltwater or brine, as well as with fresh water, and is biodegradable. The material comprises a biodegradable superabsorbent polysaccharide polymer that is preferably uncrosslinked and non-ionic and that is capable of absorbing multiple times its weight in sea water.

Abstract: Metal cross-linked phosphate ester compositions impart fragile progressive gel structure to a variety of oil and invert emulsion-based drilling fluids at neutral or acidic pH. The fluids are useful for drilling wellbores in subterranean formations without need for organophilic clays to suspend drill solids. At greater concentrations, metal cross-linked phosphate ester compositions enhance fluid viscosity for suspending weighting materials in drilling fluids during transport of the fluids, as from a manufacturing or mixing facility to a drilling site.

Abstract: Methods for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid are disclosed, as well as compositions for use in such methods. The methods employ drilling fluids comprising fragile gels or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluids are especially advantageous for use in offshore wells because the fluids exhibit minimal differences between downhole equivalent circulating densities and surface densities notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluids, the fluids make environmentally acceptable and regulatory compliant invert emulsion drilling fluids.

Abstract: Aqueous wellbore treatment fluids having improved thermal stability are provided. The wellbore treatment fluids comprise at least one polysaccharide and an effective amount of at least one polyacrylamide to maintain its stability at a temperature greater than about 250° F. A formate compound is not required to achieve high-temperature stability in the fluid. Thus, the fluid is less expensive than conventional polymer-containing aqueous wellbore treatment fluids. The aqueous fluid may serve as, for example, a drilling fluid in the wellbore and thus may be circulated through the wellbore without being concerned that it could become unstable due to exposure to relatively high downhole temperatures.

Abstract: An improved composition and method is provided for preventing or alleviating lost circulation during the drilling of wellbores in subterranean formations, and particularly during the drilling of oil and gas wells. The method is suited for horizontal and directional wells as well as more vertical wells. The composition of the invention comprises a synergistic blend of resilient, angular, carbon-based material and a water-swellable, crystalline synthetic polymer. The method employs the composition of the invention in preventing lost circulation.

Abstract: A method and product is disclosed which provides emulsion stability and filtration control to invert emulsion drilling fluids. The product comprises a blend of a carboxylic acid terminated polyamide with distilled and processed tall oil fatty acids and/or distilled and processed tall oil resin acids. The product is extremely effective, even at temperatures as high as 350° F., decreasing by about two-thirds the amount of emulsifier generally required to formulate an effective drilling fluid. The product also greatly reduces and in many cases eliminates the need for conventional fluid loss additives, and additionally provides electrical stability. Moreover, the product has a pour point as low as about 20 degrees Fahrenheit with minimal solvents, thereby eliminating the need to ship large amounts of inert material for use, and may be transported in a highly active state.

Abstract: Methods for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid are disclosed, as well as compositions for use in such methods. The methods employ drilling fluids comprising fragile gels or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluids are especially advantageous for use in offshore wells because the fluids exhibit minimal differences between downhole equivalent circulating densities and surface densities notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluids, the fluids make environmentally acceptable and regulatory compliant invert emulsion drilling fluids.

Abstract: Methods of improving the thermal stability of an aqueous wellbore treatment fluid are provided. The wellbore treatment fluid comprises at least one polysaccharide and an effective amount of at least one polyacrylamide to maintain its stability at a temperature greater than about 250° F. A formate compound is not required to achieve high-temperature stability in the fluid. Thus, the fluid is less expensive than conventional polymer-containing aqueous wellbore treatment fluids. The aqueous fluid may serve as, for example, a drilling fluid in the wellbore. It may be circulated through the wellbore without being concerned that it could become unstable due to exposure to relatively high downhole temperatures.

Abstract: Methods for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid are disclosed, as well as compositions for use in such methods. The methods employ drilling fluids comprising fragile gels or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluids are especially advantageous for use in offshore wells because the fluids exhibit minimal differences between downhole equivalent circulating densities and surface densities notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluids, the fluids make environmentally acceptable and regulatory compliant invert emulsion drilling fluids.