Mobil Oil Corporation

Cities Service Company

Nizar F Djabbarah

Eve S Sprunt

Ralph V Garling

David T Hand

Jennifer Macfadyen

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. In another embodiment of the invention, the mixture of steam, surfactant-polypeptide solution and noncondensible gas may be injected into the formation surrounding a production well that has previously experienced severe steam breakthrough to significantly decrease the permeability of steam-swept zone surrounding the production well.

Foam mixture for carbon dioxide drive oil recovery method

Foam mixture for steam and carbon dioxide drive oil recovery method

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.

Method for determining steam quality using a foaming surfactant

A method for enhanced oil recovery in a reservoir having a substantial silicon content where an organosilicone surfactant is co-injected with steam to generate a foam. The organosilicone surfactant component of the foam prevents a dissolution of the silicon-containing formation since local equilibrium is assured. Prevention of formation dissolution reduces caving near the wellbore and minimizes permeability reduction away from the wellbore.

Enhanced oil recovery from low permeability reservoirs using

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. The volume of the hydrocarbon fluids and aqueous fluids is determined from their weight and density or from direct volume measurement. For a rock sample fully saturated with a combination of oil and aqueous fluids, the total pore volume is the sum of the volumes of the two fluids and the fluid saturation is then the ratio of the fluid volume to the pore volume.

Method for determining oil and water saturation of core samples at

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.

A method for time lapse electric logging in a cased hole in which electrodes are implanted in the casing or the hole is completed with a gravel packed non conductive, perforated liner that allows an open hole logging tool to be used for time-lapse logging. Thereafter, the implemented electrodes or a self-potential (SP) logging tool are used to monitor a steam-flooding EOR method by detecting two-phase flow with time lapse logging. A potential drop between the surface and zones of interest is measured with electrodes installed in a non-conductive casing or the SP logging tool.

Method including electrical self potential measurements for detecting

A process for modifying the minimum miscibility pressure (MMP) of a drive fluid and hydrocarbonaceous fluid mixture by addition of alcohol to the drive fluid. Alcohols which can be utilized include methanol through octanol. The preferred drive fluid comprises carbon dioxide. Selection of the alcohol will depend on the water saturation in the reservoir and gravity of the crude oil. MMP modification results in an increased and more efficient recovery of reservoir oil.

Miscible oil recovery process using carbon dioxide and alcohol

A gas-drive hydrocarbon oil recovery process comprises injecting into a subterranean, viscous oil-containing formation tall oil to reduce the minimum miscibility pressure (MMP) of the reservoir oil-displacing fluid system and increase the viscosity of the displacing fluid. The tall oil is injected as a separate slug either simultaneously with or before the injection of a slug of the displacing fluid. A drive fluid may also be injected into the formation after the injection of the displacing fluid and tall oil to aid in the recovery of the formation oil.

Tall oil as additive in gas drive hydrocarbon oil recovery

A method for sweep improvement during enhanced oil recovery in a subterranean oil-bearing formation concerns the generation of foam by the dispersion of the displacing fluid in an aqueous solution of a mixed surfactant system. The mixed surfactant system comprises a lignosulfonate foaming agent and a surfactant foaming agent.

Sweep improvement in enhanced oil recovery

Oil is recovered from oil-containing formations employing alternate injection of carbon dioxide and a mixture of carbon dioxide and an additive comprising an intermediate hydrocarbon or tall oil to improve sweep efficiency. First, carbon dioxide is injected and fluid including oil is recovered from the formation until CO.sub.2 breakthrough occurs at the production well. Next, a mixture of carbon dioxide and an intermediate hydrocarbon or carbon dioxide and tall oil is injected and fluids produced until the injection pressure increases to a value about 10% above the injection pressure when injection of the mixture is initiated. Thereafter, carbon dioxide is injected and fluids including oil are recovered until carbon dioxide breakthrough occurs at the production well. The sequence of injection of carbon dioxide followed by injection of a mixture of carbon dioxide and an intermediate hydrocarbon or carbon dioxide and tall oil is repeated for a plurality of cycles to more completely sweep the full volume of the formation defined by the injection and production well. The process should be applied to a formation in which adequate communication exists.

Oil recovery method employing carbon dioxide flooding with improved

The foaming characteristics of a foamant to be used in the recovery of oil from a subterranean oil-bearing formation by carbon dioxide foam flooding, are determined by passing carbon dioxide through a sample of the foamant in a test cell containing a porous medium under pressure conditions simulating reservoir conditions and measuring the quantity of foam formed. The pressure drop along the cell is also monitored in order to indicate the resistance to gas flow imposed by the foam.

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Richardson, TX, United States of America

Nizar F Djabbarah