METHOD OF DEVELOPMENT OF CARBONATE SHALY OIL DEPOSITS Russian patent published in 2017 - IPC E21B43/27 

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to oil industry. The method of development of carbonate shaly oil deposits comprises drilling of the wells with horizontal tailing-in, annulus cementing in the bore between casing string and reservoir, secondary opening of the reservoir with oriented direction of the perforated holes to single row, multistage hydraulic fracturing (MHF), packers use to separate horizontal bores to sections, product recovery from the horizontal wells. Wherein carbonate deposits with average thickness H > 50 m and average absolute permeability of the reservoir below 2 mD. Deposits are drilled by multi-hole horizontal wells (MHHW). Each MHHW comprises two horizontal bores parallel in vertical plane at distance h = (0.5-0.9)·H from each other, length of each horizontal bore is l ≥ 4·h, in top horizontal bore the perforating holes row is oriented downwards, and in bottom - upwards, in vertical bore section between top and bottom horizontal bores the perforating holes are oriented in two rows along direction of the horizontal bores and in diametrically opposite direction. In horizontal bores acid NHF is performed with distance between stages 50 m maximum, wherein position of each appropriate MHF stage in top and bottom borers does not coincide in the structural plan view. In vertical bores the acid hydraulic fracturing is performed, speed and volume of the injected acid is determined depending first of all on creation of the structure for carbonates dissolution in form of branched cavity, and secondly by cracks height a in horizontal bores, wherein a^p_n+aⁱⁿ_n = (1.0-1.1)·h, where index p refers to bottom production well, in refers to top injection bore, n is No. of MHF stage, and thirdly on cracks height a^v in vertical bores, wherein a^v = (0.5-1.0)·h. After hydraulic fracturing the vertical and horizontal bores are developed and put into production. Upon each oil yield decreasing of MHHW below the economically profitable value in top horizontal bore large-scope acid treatment is performed. Prior to acid injection water is injected in the injection well with total mineralization not exceeding 1 g/l and suspended particles stable to action of the applied acids, with diameters exceeding average diameter of porous channels in the rock. Water with particles is injected till the moment when injection pressure will rise by 5 times minimum. For acid injection to the top bore and product recovery from the vertical and bottom bores equipment for simultaneous-separate production and injection is used with packer installation below kickoff of the top horizontal bore, so the shaly pay is developed under mode of acid-gravity drainage (AGD).

EFFECT: method of development of carbonate shale deposits pays increasing the oil recovery.

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