Mobil Oil Corporation

William C Hunt, Iii

Craig H Phelps

David S Koons

A method for minimizing damage to downhole equipment utilized in controlled pulse fracturing (CPF) where a drag reducing fluid tamp is used. Said tamp has a viscosity sufficient to reduce the flowing pressure drop thereby diminishing frictional forces along fluid/solid interfaces. The CPF device is submersed in said tamp. Upon ignition of a CPF device, the upwardly traveling pressure forces the tamp of drag-reducing characteristics to pass the downhole equipment thereby minimizing tool and equipment damage. Afterwards, the pressure is allowed to leak off slowly into the formation.

Method to reduce movement of a CPF device via a drag-reducing fluid tamp

A method for minimizing damage to downhole equipment utilized during controlled pulse fracturing ('CPF') where an oil based thickened fluid is used as a tamp. A gelled oil based fluid overlies a CPF propellant device thereby creating a tamp. When the propellant contained in the device is ignited, this high viscosity gelled fluid prevents the remnant of said device and wireline from moving upwardly which minimizes damage thereto.

Method to reduce movement of a CPF device via a gelled petroleum based

A method for minimizing damage to downhole equipment utilized during controlled pulse fracturing ('CPF') where a shear thickening fluid is used as a tamp. A shear thickening aqueous fluid having particles therein overlies a CPF device thereby creating a tamp. Movement of the fluid by pressure forces resultant from the ignited propellant causes the fluid to thicken. This thickened fluid prevents and device and wireline from moving upwardly which minimizes damage thereto.

Method to reduce movement of a CPF device via a shear-thickening fluid

In a cyclic method of solvent stimulation of a single oil well penetrating a viscous crude oil-containing formation, the well is first produced and a portion of the produced crude oil is subjected to a visbreaking operation to produce a hot visbroken crude oil having reduced viscosity. Production is terminated and a predetermined amount of the hot visbroken produced crude oil is injected into the formation via the well as a solvent, the formation is allowed to undergo a soak period, and the well is returned to production. Thereafter, production may be continued until the percentage of visbroken crude oil in the produced fluids is less than 12 percent and the above cycle may be repeated.

Cyclic thermal solvent recovery method utilizing visbroken produced

A method for the recovery of viscous crude oil from a subterranean, viscous crude oil-containing formation penetrated by an injection well and a spaced-apart production well wherein produced crude oil recovered from the production well is subjected to a visbreaking operation to produce a hot visbroken crude oil solvent reduced in viscosity and injecting the hot visbroken crude oil solvent into the formation via the injection well to reduce the viscosity of oil remaining in the oil formation and thereby enhance recovery of oil from the formation. A predetermined amount or slug of the hot visbroken crude oil solvent may be injected into the formation followed by injection of another fluid such as a gas or an aqueous fluid to drive the hot solvent and the oil through the formation toward the production well for recovery of fluids including oil.

Thermal solvent recovery method utilizing visbroken produced crude oil

The method combines the driving of oil by steam from an injection well to a production well with the overriding tendencies of the steam to give both good temperature conformance and good vertical sweep by completing the injection and production wells in limited intervals in the oil-containing formation. The injection well is completed in the bottom 20-30 percent of the vertical thickness of the oil-containing formation and the production well is completed in the bottom 40 percent of the vertical thickness of the oil-containing formation. Once the wells are completed over the limited intervals, steam is injected into the oil-containing formation at a rapid rate and fluids including oil are recovered from the formation via the production well. Injection of steam is continued until the fluid being recovered contains an unfavorable amount of steam or water. If the oil-containing formation overlies a water-saturated formation, optimum vertical conformance is obtained with the completion interval of the injection well in the bottom 20-30 percent of the vertical thickness of the oil-containing formation and the production well completed over 30-40 percent of the vertical thickness of the oil-containing formation beginning at a point above the water-saturated formation a distance of about 10 percent of the vertical thickness of the oil-containing formation.

Selected well completion for improving vertical conformance of steam

Disclosed is a method for recovering oil from a dipping subterranean, viscous oil-containing reservoir having an underlying body of water. An in situ combustion operation is initiated using an oxidizing gas injected through an injection well in fluid communication with the lower portion of the reservoir near the oil/water interface. Fluids including oil and effluent gas are recovered from the reservoir through a production well in fluid communication with a shallower portion of the reservoir. After a predetermined amount of time, injection of the oxidizing gas is terminated and the reservoir is allowed to undergo a soaking period for a predetermined amount of time. Thereafter, a water drive is initiated by injecting water into the injection well and fluids including oil are recovered from the reservoir through the production well.

Thermal recovery of viscous oil from a dipping reservoir

A method for recovering viscous oil from a subterranean, viscous oil-containing formation by initiating an in-situ combustion operation in the formation using a mixture of oxygen and an inert gas having a low oxygen concentration, preferably about 21 vol. %. After a predetermined period of time, the oxygen concentration is increased to a predetermined higher level, preferably within the range of 95 to 99.5 vol. %. Once the oxygen concentration has reached the desired value, water may be simultaneously injected continuously or intermittently. After a predetermined period of time, produced combustion gas enriched in carbon dioxide separated from the produced oil is compressed and recycled as a diluent for the injected oxygen in place of the inert gas. Thereafter, wet in-situ combustion operation is continued and the oxygen concentration of the injected mixture of oxygen and combustion gas diluent is maintained at a predetermined value so that the concentration of oxygen in the produced combustion gas is maintained at a predetermined value low enough to avoid the danger of an explosion or burning of the production well. After a predetermined period of time, injection of oxygen is terminated and injection of produced combustion gas and water is continued until the combustion front in the formation is discontinued. Finally, water is injected to scavenge heat in the formation. In-situ combustion may be initiated using air followed by injection of a mixture of oxygen and an inert gas having a predetermined oxygen concentration greater than air, preferably 95 to 99.5 vol. %.

Use of recycled combustion gas during termination of an in-situ

The vertical conformance of a steam drive process is improved and steam override reduced by utilizing a solvent push-pull process in the lower portion of the formation adjacent the production well. Steam is injected into the injection well with production of fluids from the production well. The production well contains two flow paths from the surface, the first being in fluid communication with the upper portion of the formation. Production is continued until there is a water breakthrough from the formation via the first flow path in the production well. After production via the production well is terminated, a predetermined amount of solvent is injected into the lower portion of the formation via the second flow path in the production well while continuing to inject steam into the injection well. After the slug of solvent has been injected, production is immediately resumed by recovering fluids including solvent and oil from the formation via the second flow path in the production well until the amount of solvent in the produced fluid has decreased to a value less than 12 percent by volume. The sequence of solvent injection followed by fluid production is continued for a plurality of cycles until there is water breakthrough at the production well.

Solvent push-pull process for improving vertical conformance of steam

Oil may be recovered from viscous oil-containing formations including tar sand deposits by first establishing a fluid communication path in the lower portion of the formation intermediate at least one injection well and a production well. At least one additional interior production well in fluid communication with the upper portion of the formation is drilled within the formation defined by the injection well and production well. A hydrocarbon solvent having a density less than oil contained in the formation under formation conditions is injected into the fluid communication path via an injection well and fluids including oil are recovered from the production well until solvent is detected in the fluid recovered. Thereafter, the production well is shut-in and the interior production well is opened to production for recovering fluid including oil while solvent is continued to be injected into the fluid communication path via the injection well until the fluid recovered from the interior production well contains a predetermined amount of solvent. The injection well, production well, and interior production well are shut-in to permit the formation to undergo a soak period for a variable time, preferably from 1 to 10 days per vertical thickness in feet of the viscous oil-containing formation. Thereafter, a driving fluid such as water is injected into the formation and oil is produced via the production well until there is an unfavorable ratio of oil to driving fluid.

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Farmers Branch, TX, United States of America

William C Hunt, Iii