DEVELOPMENT METHOD OF OIL DEPOSIT WITH POROUS-CAVERNOUS-FRACTURED MANIFOLD Russian patent published in 2013 - IPC E21B43/20 

FIELD: oil and gas industry.

SUBSTANCE: according to the proposed method, productive formation is developed by drilling a pilot borehole with a zenith angle at the interval of 80°-95°; cutting-out means are arranged in the pilot borehole with possibility of increasing the zenith angle in order to reach the horizontal section during the drilling process; production casing is lowered and geophysical surveys are performed; and horizontal boreholes are drilled out of the pilot borehole in productive formation. Prior to the drilling process, predominant direction of cracks of natural fracturing is determined in productive formation and width of increased fracturing zone is estimated as per the data of geophysical surveys. Horizontal boreholes are arranged mainly perpendicular to direction of fracturing zone with an offset of mine faces from each other through the distance of not less than 40 m. A drilling passage is individually determined for each horizontal borehole; drilling roof of the drilling passage is restricted with productive formation roof, and bottom of drilling passage is assigned at the distance from the roof of not more than 1/2 of productive formation thickness and not less than 2 m to oil-water contact. Productive formation inlet point is assigned by determining the technical capability of increasing the borehole curvature. Length of pilot borehole from inlet point to the supposed zone of increased fracturing is chosen so that provision is made for possible drilling of the second and the third boreholes with azimuth entry to increased fracturing zone with an angle at the interval of 80°-95° and with an offset from pilot borehole of not less than 40 m. As per results of pilot borehole drilling in zone of increased fracturing, width of that zone is determined. Length of pilot borehole is restricted by passage of increased fracturing zone. Based on geological connection to pilot borehole, drilling of the second borehole is performed at the distance providing the possibility of opening the increased fracturing zone in the roof part of drilling passage, with entry to increased fracturing zone with zenith angle of 80°-95°, with an offset from pilot borehole of not less than 40 m, with passage of increased fracturing zone in roof part of drilling passage and with an offset from pilot borehole of not less than 40 m. Drilling of the third borehole is performed on the opposite side of the pilot borehole relative to the second borehole at the distance providing the possibility of opening the increased fracturing zone in the bottom part of drilling passage, with entry to increased fracturing zone with zenith angle of 80°-95°, with an offset from pilot borehole of not less than 40 m, with passage of increased fracturing zone in bottom part of drilling passage and with an offset from pilot borehole of not less than 40 m. Formation product is extracted through the drilled well.

EFFECT: increasing oil recovery of deposit.

2 ex, 1 dwg