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: Disclosed is a concentrate composition for crosslinking polysaccharide polymers hydrated in an aqueous liquid, and well servicing fluids, preferably fracturing fluids, prepared therewith. Preferred polysaccharide polymers are galactomannan gums or derivatives thereof, preferably hydroxypropylguar. The concentrate comprises an alkali metal formate solution, preferably potassium formate, a crosslinking agent for the polysaccharide polymer, preferably a sparingly soluble alkali metal or alkali metal alkaline earth metal borate, and a suspension agent, preferably a clay mineral selected from the group consisting of smectite clays, palygorskite clays, and mixtures thereof Exemplary clays are hectorite, sepiolite, and attapulgite. The concentrate may, optionally, contain a deflocculant and/or an anti-syneresis additive.

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: 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: 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: The invention provides solids-free, viscous fluids (pills) for use in various well workover and completion operations including as displacement spacer pills, standard fluid loss control pills, post gravel pack in-screen pills, perforation sealing, and the like. The pills comprise a viscous solution of a polyethylene glycol having a molecular weight of 1,000 to 8,000,000 in an aqueous liquid comprising a solution of one or more soluble bromide salts having a density sufficient to provide the desired hydrostatic pressure at the location of use of the fluid in a well. The minimum concentration of the polyethylene glycol in the pill varies with the average molecular weight as follows: MW=1,000 to 10,000=100 ppb; MW=10,001 to 100,000=75 ppb; MW=100,001 to 250,000=50 ppb; MW=250,001 to 500,000=10 ppb; MW=500,001 to 8,000,000=5 ppb.

Abstract: A method of forming a shallow-deep trench isolation (SDTI) is provided that includes the steps of forming a pair of deep trenches through a silicon on insulator (SOI) layer without substantially disturbing an underlying buried oxide (BOX) layer. Once the deep trenches are formed, the trenches are filed with suitable electrical isolating materials, such as undoped poly-silicon or dielectric material, and etched back to obtain a substantially planarized top surface. Subsequently, an active nitride layer is deposited on the planarized top surface, and then a pair of shallow trenches are formed. The shallow trenches are formed using a low selectivity etch to uniformly etch a deep trench liner oxide, the SOI layer and the electrical isolating material which have interfaces at non-perpendicular angles with respect to the direction of the etching. Once the shallow and deep trenches are formed, subsequent processing including filling the shallow trench, annealing and chemical-mechanical polishing can be performed.

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: The invention provides water base well drilling and servicing fluids containing a biopolymer viscosifier and a water soluble polyalkylene glycol shale stabilizing additive therein having enhanced thermal stability, as indicated by the low shear rate viscosity at 0.06 sec.sup.-1, the enhanced thermal stability being provided by an amorphous silica viscosifier therein.A method of enhancing the thermal stability of aqueous base well drilling and servicing fluids containing a biopolymer viscosifier and a water soluble polyalkylene glycol shale stabilizing additive therein is disclosed which comprises adding to the fluid an amorphous silica viscosifier.

Abstract: A method and apparatus of expanding tubulars is the disclosed. In the preferred embodiment, a rounded tubular is inserted through a larger tubular while suspended on a mandrel. A stop device, such as a liner hanger, is attached to the larger tubular after delivery downhole on the mandrel. Upon engagement of the liner hanger or other stop device to the larger tubular, the mandrel is freely movable with respect to the stop device. The mandrel contains a deforming device such as a conically shaped wedge located below the tubular to be expanded. A force is applied from the surface to the mandrel, pulling the wedge into the tubular to be expanded. When the wedge clears through the tubular to be expanded, it releases the stop device so that the stop device can be retrieved with the mandrel to the surface. Thus, the stop device is supported by the larger tubing while the smaller tubing is expanded when the wedge is pulled through it.

Abstract: Disclosed are invert oil emulsion drilling fluids in which the internal aqueous phase contains one or more water soluble polyethylene glycols dissolved therein. The fluids are characterized by an elevated low shear rate viscosity, hence excellent suspension properties, an elevated Shear Thinning Index, hence excellent drilling characteristics, and a high shale stability index, hence excellent cuttings stabilization and formation protection. Preferred polyethyleneglycols have a molecular weight from about 500 to about 10,000, preferably from about 1000 to about 10,000. Preferred fluids contain from about 5% to about 40% by weight of the polyethyleneglycol in the aqueous phase, most preferably from about 10% to about 30% by weight. Also disclosed is a method of enhancing the thermal stability of invert emulsion well drilling and servicing fluids which comprises dissolving in the aqueous phase thereof one or more polyethyleneglycols.

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: (1) a process to enhance the removal of solids such as clays, clay-like solids, and shale solids-drill solids-from the surface of a borehole, the solids being deposited from well drilling, completion, or workover fluids during well servicing operations; and (2) a process to enhance the removal of such solids from screens or other sand control devices present in a borehole. The process comprises contacting the solids with an acidic soak solution containing a polyglycol or mono ether derivative thereof and thereafter contacting the surface of the borehole with a wash solution to remove the solids from the borehole.

Abstract: The invention provides alkaline water base well drilling and servicing fluids which deposit an easily degradable and removable filter cake on the sides of a borehole during well drilling and servicing operations. The fluids contain one or more polysaccharide polymers, sized bridging particles, and a peroxide selected from the group consisting of alkaline earth metal peroxides, zinc peroxide, and mixtures thereof. The fluids deposit a filter cake containing the peroxide.

Abstract: The invention provides brine based well drilling and servicing fluids which exhibit relatively thermally stable rheological and filtration characteristics. The fluids comprise a brine, an amorphous silica viscosifier, a biopolymer viscosifier, a fluid loss control additive, and a bridging agent. By utilizing both a silica viscosifier and a biopolymer viscosifier to provide the desired rheological characteristics, the fluids have enhanced thermal stability thus maintaining their suspension and hole cleaning properties over an extended temperature range.

Abstract: Disclosed are low solids, high density fluids useful as drilling, workover, and completion fluids and the like in oil and gas well operations. The fluids comprise a brine having dissolved therein a zinc salt such as zinc bromide, and optionally one or more additional water soluble salts, a viscosifier which is a high surface area silica, a biopolymer viscosifier, a fluid loss control additive which is preferably a starch derivative, zinc carbonate, and, optionally, an alkaline buffer, a polar additive, and a bridging agent.It has been found that zinc carbonate will increase the low shear rate viscosity of fluids containing a zinc salt dissolved therein. Additionally, the combination of zinc carbonate and zinc oxide as the alkaline buffer provides fluids having increased thermal stability as indicated by the low shear rate viscosity of the fluids.

Abstract: The invention provides brine based well drilling and servicing fluids containing a fluid loss control additive selected from the group consisting of (1) a crosslinked ether derivative of a partially depolymerized starch, (2) a partially depolymerized crosslinked ether derivative of starch, or (3) mixtures thereof. The fluid loss control additive provides decreased fluid losses at much lower viscosities than the corresponding starch derivatives which have not been partially depolymerized. This enables their use in fluids at concentrations sufficient to provide excellent filtration control, the fluids having a viscosity sufficient for circulation of the fluids in the borehole. The invention also provides a method of reducing the fluid loss of well drilling and servicing fluids utilizing the fluid loss control additives (1) and/or (2).

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: Disclosed are low solids, high density fluids useful as drilling, workover, and completion fluids and the like in oil and gas well operations. The fluids comprise one or more brines having a density greater than about 1500 kg/m.sup.3, a viscosifier which is a high surface area silica, a fluid loss control additive which is preferably a starch derivative, one or more water soluble or acid soluble bridging agents, and, optionally, an alkaline buffer and a polar additive.Also disclosed is an additive for the preparation of low solids, high density fluids which comprises a fumed silica and a bridging agent in a weight ratio of bridging agent to fumed silica from about 2 to about 20, and optionally, an alkaline buffer in a weight ratio of alkaline buffer to fumed silica from about 0.03 to about 2.5.

Abstract: The invention provides alkaline water base well drilling and servicing fluids which deposit an easily degradable and removable filter cake on the sides of a borehole during well drilling and servicing operations. The fluids contain one or more polysaccharide polymers, sized bridging particles, and a peroxide selected from the group consisting of alkaline earth metal peroxides, zinc peroxide, and mixtures thereof. The fluids deposit a filter cake containing the peroxide. The invention also provides processes for enhancing the removal of the filter cake which comprises depositing a peroxide-containing filter cake on the sides of the borehole, or on the filter cake already present on the sides of the borehole, and thereafter contacting the peroxide-containing filter cake with an acidic solution to activate the peroxide which thereafter degrades the polysaccharide polymers in the filter cake.