METHOD FOR DEVELOPMENT OF DEPOSITS OF HIGH-VISCOSITY OIL AND NATURAL BITUMEN Russian patent published in 2023 - IPC E21B43/24 E21B7/04 E21B49/00 

FIELD: oil industry.

SUBSTANCE: in the method for developing deposits of high-viscosity oil and natural bitumen, first, vertical appraisal wells are built in the area of deposits to delineate the productive formation with core sampling and laboratory tests of the core to obtain data on oil saturation, porosity, and permeability of the productive formation. Next, the structural maps of oil-saturated thicknesses are developed, referring to the productive layer thickness with a minimum oil saturation of 4.7% by weight, and vertical appraisal wells are liquidated. Then a horizontal production well is drilled 1 m higher than the bottom of the productive formation – formation thickness with a minimum oil saturation of about 4.7% by weight. Geophysical surveys are carried out to determine the geological and physical parameters along the horizontal wellbore of the production well: weighted average values of porosity, permeability, oil saturation along the length of the wellbore; then the distance is chosen between the horizontal sections of the production and injection wells, which makes it possible to create a hydrodynamic connection between the wells: the distance of 5 m with a reservoir permeability up to 0.78 µm², a formation porosity up to 0.27 and oil viscosity under standard conditions more than 8500 MPa⋅s; the distance of 7.5 m with a formation permeability f 0.77-1.16 µm², a formation porosity of 0.28-0.31 units and oil viscosity under standard conditions 4501-8500 mPa⋅S; the distance of 10 m with a formation permeability more than 1.77 µm², formation porosity more than 0.32 units and oil viscosity under standard conditions less than 4500 MPa⋅s; if geological and physical parameters are varied, the minimum distance from the possible ones is chosen. A horizontal injection well is built at a selected distance from the horizontal production well above in the same vertical plane and parallel to the horizontal production well. Geophysical research are carried out to determine geological and physical parameters along the horizontal wellbore of the injection well: porosity, permeability, oil saturation. Two parallel pipes of larger and smaller diameters are run into horizontal injection and production wells. Pipe ends of smaller diameter are located at the beginning of horizontal filtration sections in the zones with the highest porosity and permeability, and pipe ends of larger diameter are located in the second half of horizontal filtration sections of wells in the zones with the highest porosity and permeability. Steam is injected into both wells to provide hydrodynamic connection between the wells. Next, the steam supply to the horizontal production well is stopped, pipes are lifted and the pump is run to the beginning of the horizontal section. Then steam is injected into the horizontal injection well and liquid is withdrawn from the horizontal production well.

EFFECT: increased technological efficiency of the development of deposits of heavy oil or natural bitumen.

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