METHOD FOR DEVELOPMENT OF MULTI-FORMATION OIL DEPOSIT WITH CIRCULAR PRODUCTION WELL IN MIDDLE OF ELEMENT Russian patent published in 2025 - IPC E21B43/20 E21B43/30 E21B43/14 E21B47/00 

FIELD: mining.

SUBSTANCE: invention relates to a method for development of multi-formation oil deposit with circular production in the middle. Method includes performance of geophysical researches in wells, and as per results there determined is section of multi-formation deposit with interlayers that coincide in structural plan. Formation pressure is determined for each of interlayers, hydrodynamic connection between them is excluded during communication. In central part of deposit section drilling of circular production well is performed with entry into formation at angle of 3.5-4.5°, by hydrodynamic simulation providing drilling inclined injection wells at element corners and circular production well in middle of element with access to radius of circumscribing circle of 250 m and with a branch from the injection wells of the element located at the corners of the element of not more than 130 m therefrom, with deep perforation. Each perforation hole is spaced from the previous one by not more than 10 m. Well bottom is maximally close to the circular borehole and not more than 30-50 m from it, having in this case at least 47 holes arranged evenly along the well bore along the spiral with depth of 2 m and each with varying direction of perforation as the production borehole deepens. After drilling, geophysical investigations of the production well shaft are carried out so that in the upper and/or upper interlayers the perforation and/or perforations are oriented downwards at an angle to the well shaft of not more than 60°. In the following interlayers the angle is changed till flattening to horizontal and further rise of perforation hole direction to above-lying and/or above-lying layers, thus maintaining radius of circular well from entry point to the working face of 250 m. Well bottom is as close as possible to the circular shaft and not more than 30-50 m from it, and the distance from the injection well to the shaft of the circular well is not less than 130 m. Inclined injection wells are drilled so that injectivity profile in all interlayers from injection well to nearby production wells is uniform. In case when upper interlayer has lower permeability, and lower layer has higher permeability, injection well is built with distance as it deepens from circular shaft of production well. In case when upper interlayer has high permeability, and lower interlayer has lower permeability, injection well is built so that it approaches circular borehole of production well as it is deepened. After that, displacement fluid is pumped into each interlayer through injection wells and the deposit product is extracted from each interlayer through circular production well.

EFFECT: raised efficiency of development of multilayer oil deposit and increased profile of low-permeability interlayers.

1 cl, 1 dwg