Abstract: A well screen for gravel-packing a wellbore interval comprising at least two joints connected by a well tool. Each joint is comprised of a length of screen section which has at least one, axially-extending shunt conduit thereon for carrying gravel slurry to different levels within the interval. The well tool has at least one by-pass tube therein which is adapted to align with and fluidly-connect the shunt conduits on respective joints whereby gravel can flow from one of the shunt conduit, through the by-pass tube, and into and out of the other shunt conduit. A packing means is mounted on the tool for preventing any substantial annular, axial flow past the tool when the tool is an operable position within the wellbore.

Abstract: The invention is a foam method for improving conformance during a steam flood or carbon dioxide flood in a subterranean, oil-containing formation penetrated by at least one injection well and at least one production well. In a steam flood oil recovery process, sweep efficiency is improved by injecting steam until steam breakthrough occurs at the production well after which a mixture of steam, a noncondensible gas, and an aqueous surfactant-polypeptide solution is injected into the formation. The aqueous surfactant-polypeptide solution forms a stable foam with the formation oil at formation conditions that reduce the permeability of the highly permeable steam swept zones thereby diverting the steam to other portions of the formation containing unswept oil. The polypeptide is used as a partial substitute for the surfactant to improve the cost of the foam-forming mixture without reducing its effectiveness in increasing sweep efficiency.

Abstract: A well screen for use in gravel packing completions which produces a good distribution of gravel over the entire completion interval. The screen is comprised of a base pipe and an outer surface (e.g. wire wrap). A plurality of flow paths (e.g. shunt tubes) are positioned in the annulus which is formed between the base pipe and the outer surface of the screen, thereby providing the necessary alternate flowpaths for the slurry without substantially increasing the overall, effective outside diameter of the screen.

Abstract: The invention is a foam method for improving conformance during a steam flood or carbon dioxide flood in a subterranean, oil-containing formation penetrated by at least one injection well and at least one production well. In a steam flood oil recovery process, sweep efficiency is improved by injecting steam until steam breakthrough occurs at the production well after which a mixture of steam, a noncondensible gas, and an aqueous surfactant-polypeptide solution is injected into the formation. The aqueous surfactant-polypeptide solution forms a stable foam with the formation oil at formation conditions that reduce the permeability of the highly permeable steam swept zones thereby diverting the steam to other portions of the formation containing unswept oil. The polypeptide is used as a partial substitute for the surfactant to improve the cost of the foam-forming mixture without reducing its effectiveness in increasing sweep efficiency.

Abstract: Steam quality is measured by mixing the steam with a small amount of surfactant to convert the steam to a stable foam, passing the stable foam through a capillary tube to determine foam quality (volume of vapor per volume of vapor and liquid) by measuring the streaming potential coupling coefficient of the foam passing through the tube, and converting foam quality (volume per volume) to steam quality (mass of vapor per mass of vapor and liquid) based upon the fluid density of the liquid-water and water-vapor phase of the steam.

Abstract: The present invention relates to the use of low frequency sonic energy within the range of 1.25 to 6.5 KHz, preferably less than 2.0 KHz and most preferably 1.25 KHz, for enhancing the dissolution of alkaline earth metal scales from well bores using a scale-removing solvent comprising an aqueous alkaline solution having a pH of about 8 to about 14 and containing EDTA or DTPA and a catalyst or synergist, preferably an oxalate anion. When the scale deposit is contacted with the scale removing solvent while simultaneously transmitting low frequency sonic energy through the solvent, substantially more scale is dissolved at a faster rate than previously possible.

Abstract: A well tool for delivering fluid (e.g. sand or gravel slurry) to different levels within a wellbore which is comprised of a delivery conduit which, in turn, has a plurality of exit ports spaced along its length. Each exit port has an exit tube connected thereto. Each exit tube includes a portion whose length lies substantially parallel to the longitudinal axis of the delivery conduit which permits larger exit ports to be used which, in turn, substantially reduces the likelihood of an exit port becoming blocked prior to completion of a well operation. Also, where at least a portion of an exit tube is inside the delivery conduit, the concentration of the sand flowing through the exit tube will be substantially the same as the original concentration in the slurry since sand particles will not tend to by-pass an exit port and remain in the slurry. This prevents the premature dehydration of the slurry and the resulting buildup of sand within the delivery conduit which is normally associated therewith.

Abstract: The present invention relates to a method of removing alkaline earth sulfate scale from the interior surface of downhole production tubing comprising contacting the scale with a solvent having a specific gravity of at least 1.2 while simultaneously milling the scale with a rotating mill head connected to a downhole motor.

Abstract: A method and apparatus is provided to determine the amount of oil and water or brine in a representative core sample of reservoir rock at an overburden stress which approximates reservoir stress conditions. The core sample is initially saturated with reservoir hydrocarbon (crude oil) and aqueous fluids (water or brine). The core sample is surrounded with an elastic jacket, or sleeve, and placed in a confining pressure vessel that simulates reservoir overburden stress on the core sample. The hydrocarbon (oil) fluids and aqueous fluids (water or brine) are than extracted from the core sample with a solvent capable of dissolving both aqueous and hydrocarbon fluids. The solvent and aqueous fluids are separated from the hydrocarbon fluids by evaporation. Thereafter the aqueous fluids are separated from the solvent by extraction. The amounts of oil and aqueous fluids from the sample may be separately determined.

Abstract: The invention is a foam method for improving conformance during a steam flood or carbon dioxide flood in a subterranean, oil-containing formation penetrated by at least one injection well and at least one production well. In a steam flood oil recovery process, sweep efficiency is improved by injecting steam until steam breakthrough occurs at the production well after which a mixture of steam, a noncondensible gas, and an aqueous surfactant-starch solution is injected into the formation. The aqueous surfactant-starch solution forms a stable foam with the formation oil at formation conditions that reduce the permeability of the highly permeable steam swept zones thereby diverting the steam to other portions of the formation containing unswept oil. The starch is used as a partial substitute for the surfactant to improve the cost of the foam-forming mixture without reducing its effectiveness in increasing sweep efficiency.

Abstract: Barium sulfate scale is dissolved by contacting the scale with an aqueous solvent having a pH of about 10 to about 14, preferably about 12, and comprising a chelating agent comprising a polyaminopolycarboxylic acid or salt of such an acid, and a synergist anion. The solvent containing the dissolved scale is regenerated by acidifying the solvent in the presence of an anion which forms a precipitate of an insoluble salt of the alkaline earth metal of the dissolved scale. The precipitate is then removed from the solvent. Thereafter, the pH of the solvent is increased to a pH of about 10 to about 14, preferably about 12, to recover a regenerated solvent for reuse, in dissolving scale.

Abstract: Alkaline earth metal scales, especially barium sulfate scale is removed from a well (the wellbore and the adjacent formation) by contacting the scale with a scale-removing solvent and thereafter sparging the solvent with air or insert gas to dissolve the scale. The sparging aids in achieving a flushing action by the solvent relative to the scale thereby enabling the solvent to more effectively dissolve the scale in the well. Temperature and caustic compatible surfactuants (anionic and non-ionic) may be used in the solvent to generate a column of foam which increases the extent of cleaning oil from the scale surfaces, enabling the solvent to more effectively remove the scale.

Abstract: Barium sulfate scale is dissolved by contacting the scale with an aqueous solvent having a pH of about 10 to about 14, preferably about 12, and comprising a chelating agent comprising a polyaminopolycarboxylic acid or salt of such an acid, and a synergist anion. The solvent containing the dissolved scale is regenerated by acidifying the spent solvent with an acidic chelating agent such as EDTA or DTPA, preferably DTPA, that release alkaline earth cations which react with sulfate ions present in the solvent to form a precipitate of an insoluble salt of the alkaline earth metal. The precipitate is then removed from the solvent by settling/decanting, filtering, or centrifuging. Thereafter, caustic is added to increase the pH of the solvent to a pH of about 10 to about 14, preferably about 12, to recover a regenerated solvent for reuse, in dissolving scale.

Abstract: A method for removing calcium sulfate scale from a well comprising mixing carbon dioxide and water at a downhole location within the well to form an acidic solution containing an equilibrium mixture of carbonic acid, bicarbonate and carbonate ions that will convert the calcium sulfate scale to calcium carbonate scale and subsequent in situ dissolution of the calcium carbonate scale into the acidic solution that flows into the formation about the well.

Abstract: Barium sulfate scale is dissolved by contacting the scale with an aqueous solvent having a pH of about 8 to about 14, containing a chelating agent comprising a polyaminopolycarboxylic acid or salt of such an acid, and a synergist anion. The aqueous solvent containing the dissolved scale is regenerated by first acidifying the aqueous solvent sufficiently to generate free alkaline earth metal ions. The aqueous solvent is then mixed with a liquid membrane emulsion enveloped around droplets of an internal aqueous phase containing an anion that forms an insoluble precipitate with the free alkaline earth metal ions. The scale-free aqueous solvent is separated from the emulsion by gravity and recovered for reuse.In another embodiment, the internal aqueous phase may contain a chelating agent to remove the free alkaline earth metal ions by forming a stable complex with the ions.

Abstract: A method for recovery of oil from a subterranean, viscous oil-containing formation penetrated by one or more wells each of which is provided with at least one separate flow paths, the first flow path in fluid communication with the bottom of the formation from adjacent or below the formation and the second flow path in fluid communication with substantially the full vertical thickness of the formation. Steam is injected into the formation via the second flow path and fluids including oils are recovered from adjacent or below the bottom of the formation via the first flow path at a predetermined rate which is substantially less than the injection rate of steam so as to increase the formation pressure to a desired level. Formation pressure is maintained at the desired level while continuing injection of steam and production of fluids including oil until the fluids recovered contain an unfavorable amount of water.

Abstract: An alkaline flooding oil recovery process is enhanced by injection of aqueous solutions of foam-forming surfactant and gases, or pre-formed foams, either ahead of or behind conventional alkaline slugs. In a preferred embodiment, a slug of an aqueous solution containing an alkaline agent followed by a driving fluid is injected into the formation that displaces oil through the relative high permeability zones of the formation and oil is recovered via the production well. Thereafter, a slug of an aqueous solution of a foam-forming surfactant is coinjected into the formation with a gas creating a foam when the gas mixes with the foam-forming surfactant in the aqueous solution. The foam created from the aqueous surfactant and gas will go preferentially into the formation zones of relatively high permeability and low oil saturation substantially plugging these zones.

Abstract: A method for recovering viscous oil from a subterranean, viscous oil-containing formation underlain by a water zone. Steam is injected into the formation via the injection well at the oil/water contact and oil is recovered from the formation until steam breakthrough occurs at the production well thereby forming a hot plate at the oil/water contact. Thereafter, the production well is shut-in and a combustion-supporting gas, preferably pure oxygen, is injected into the formation at the oil/water contact causing an in-situ combustion reaction to occur at the oil/water contact and pressurization of the formation. Injection of the combustion-supporting gas is continued until the formation is pressurized to a specific pressure not to exceed the pressure at which fracture of the overburden above the formation would occur. Thereafter, the injection well is shut-in and oil is recovered from the formation via the production well.

Abstract: A method for inhibiting the formation of scale in a well penetrating a subterranean formation for the production of fluids from the formation comprising injecting into the formation an acidic aqueous solution having a pH effective to form a water-soluble complex of the inhibitor and the polyvalent cation, preferably in the range of 2 to 3, containing a mixture of a polyacrylate scale inhibitor having a molecular weight range from 500 to 10,000 and a polyvalent cation wherein the equivalent ratio of polyvalent cation to polyacrylate scale inhibitor is less than or equal to 0.5 in the acidic aqueous solution and allowing natural conditions in the formation to raise the pH of the solution an amount sufficient to cause controlled precipitation and increased deposition of the scale inhibitor in situ in the form of the polyvalent cation-polyacrylate complex.

Abstract: Volumetric sweep efficiency and oil recovery by CO.sub.2 flooding processes may be increased by injecting a surfactant solution into the formation which will form a gel in-situ in the high permeability zones via interaction of the surfactant with formation brine, oil, and CO.sub.2 under formation conditions. Thereafter, improved oil recovery efficiency is realized in displacing oil from the lesser permeability zones. The surfactant solution is selected from phase behavior experiments which show gel precipitation at conditions of temperature, salinity, oil composition, and CO.sub.2 pressure which are expected to exist or may be practically established in the particular oil-containing formation. Preferably, the gel is precipitated at CO.sub.2 pressures above the minimum miscibility pressure for CO.sub.2 miscible flooding, and below the prevailing formation pressure during the CO.sub.2 flooding.