RECOVERY METHOD OF SHALE CARBONATE OIL FIELD Russian patent published in 2017 - IPC E21B43/26 E21B43/27 

FIELD: petroleum industry.

SUBSTANCE: invention refers to the petroleum industry and may be used during the recovery of thick shale carbonate oil fields. The method includes drilling of horizontal wells, cementing of an annular space between a production casing and a reservoir in a horizontal shaft, the secondary penetration of the field with the orientation direction of perforations, conduction of multistage hydraulic fracturing, application of packers for separation of horizontal shaft to sites, and product extraction from the horizontal wells. According to the invention, the oil field with the average thickness of oil-saturated reservoir should be selected, H > 50 m and average absolute permeability of less than 2 mD, the oil field is drilled with the horizontal wells with parallel location of horizontal shafts, moreover, the horizontal shafts of injection wells are located over the horizontal shafts of production wells at the distance of h = (0.5-0.9)·H in the vertical direction and of s = (1.0-4.0)·H in the horizontal direction. The length of each horizontal shaft is performed equal to l ≥ 4·h. In the injection wells along a horizontal shaft, the bottom half of the circumference of the production casing and cement rock is perforated, and in the production wells, the top part of the circumference is perforated. All wells are subject to the acid multistage hydraulic fracturing with the distance between the stages of no more than 50 m. Moreover, the location of each corresponding stage of the fracturing in the injection and production wells does not match structurally. The rate and the volume of pumped acid are determined according to the conditions, firstly, of the formation of the structure of carbonate dissolving representing the branched hollows; secondly, of the half-length of fractures a = (0.8-2.0)·s and the height of fractures c = (0.5-1.0)·h. After the multistage hydraulic fracturing, the production wells is completed and commissioned into production. At each reducing of the oil production rate of the production wells to the values lower than economically reasonable, the large-scale acid processing is conducted in corresponding injection wells, moreover, before the acid feed, water with the total mineralization of more than 1 g/l and particles resistant to impacts of applied acids, is pumped into an injection well, with diameters; with diameters exceeding the average diameter of pore channels of the reservoir, water with particles is pumped until the pumping pressure rises at least five times. Therefore, the shale oil field is produced in the mode of acid and gravity drainage (AGD).

EFFECT: technical result lies in the increasing of oil production from the thick shale carbonate oil fields.

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