METHOD FOR PROPPANT MULTISTAGE HYDRAULIC FRACTURING OF OIL FORMATION Russian patent published in 2019 - IPC E21B43/267 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and can be used in proppant multistage hydraulic fracturing of oil formation (MHFF) with variable size of propellant granules. Method includes drilling or selection of already drilled horizontal well, shutdown of well, multistage hydraulic fracturing of the formation – MHFF, determination of propagation zone of MHFF cracks, fixation of MHFF cracks by proppant, successive reduction of size of fractions of injected proppant, well development, extraction of products from well. According to the invention, the formation is selected with an average absolute permeability of the collector of less than 5 mD, the number of stages of the MHFF and the distance between the stages is determined based on the compression strength of the rock along the horizontal borehole, stages are arranged in sections with minimum compression strength of rock, total volume of injected proppant in each separate stage of MHFF is determined from volume of actual cracks of each separate stage of MHFF, fixed during hydraulic fracturing, cracks of each separate stage of MHFF are fixed by pumping several different portions of proppant, at that, every next portion of proppant is pumped in every stage of MHFF as smaller size of fraction and smaller volume: first proppant is injected with particle diameter D and total volume of portion V, proppant is pumped with second portion, respectively, with particle diameter D/6 and volume (0.2...0.1)·V, then, optionally, third – D/12 and (0.03...0.05)·V, fourth – D/24 and (0.02...0.03)·V, fifth – D/48 and (0.01...0.02)·V, between each stage of proppant pumping, process exposure is not more than 2 hours, wherein pressure at wellhead during process holding is maintained at level of not less than 50 % from maximum, at which propane injection was performed.

EFFECT: improving efficiency of multistage hydraulic fracturing of oil formation and increasing accumulated oil recovery of horizontal well.

1 cl, 5 ex