METHOD FOR CONDUCTING MULTI-STAGE HYDRAULIC FRACTURING IN CONDITIONS OF THIN BRIDGES Russian patent published in 2021 - IPC E21B43/26 

FIELD: petroleum industry.

SUBSTANCE: invention relates to the field of the petroleum and gas industry and can be applied for stimulation of boreholes by hydraulic fracturing. Proposed is a method for hydraulic fracturing, including the following stages: a liner with external packers and equal-pass hydraulic fracturing sleeves is lowered, then a wrench is lowered on the tubing/coiled tubing string used to open the sleeves, wherein the tubing/coiled tubing string is placed above the lower sleeve, the external interval is washed with the fitting open on the surface and without back pressure in the annular space. The pumps are stopped simultaneously and the pressure drop curve is recorded. At the second stage of processing, cleaning is performed, wherein the hydraulic fracturing fluid is pumped in order to remove the residual drilling fluid and mud cake, wherein the stage of maintaining the material balance is executed, and the output of the fluid on the surface is monitored by evaluating the content of solid substancing therein, while the fitting is not applied, the pumps are stopped, and the pressure drop curve is recorded. At the third stage, the hydraulic fracturing pressure gradient is estimated by performing a mini hydraulic fracturing with a step test at different flow rates, wherein the fitting is closed to determine the hydraulic fracturing gradient, the pumps are stopped, and the pressure drop curve is recorded. At the fourth stage, the formation is subjected to acidising by placing a volume of acid, equal to the volume of the open wellbore annulus, along the annulus, with the fitting closed on the surface, wherein the entire volume of acid is pumped into the formation at a pressure below the hydraulic fracturing pressure. At the fifth stage, hydraulic fracturing is performed, the interval of the borehole is washed from the acidising reaction products by circulation of 2 to 3 volumes of the treated interval until the reaction products are output, the fitting is closed on the surface, and a cushion is pumped, developing a fracture along the wellbore, the fitting is closed on the surface, and pumping of the hydraulic fracturing fluid is started, developing a fracture along the wellbore. In case of low leakage of the working fluid into the reservoir, with low permeability of the reservoir and an increase in the bottomhole pressure creating a risk of developing the fracture in height, part of the pressure is drained through the fitting on the surface. When the proppant is supplied to the flow, the fitting is closed completely until the end of the work, the pumps are stopped, and the pressure drop curve is recorded, the isolation packer is lifted and the transition to the next processing interval in the borehole is executed, then the operations are repeated in the same sequence until complete coverage of the entire length of the borehole.

EFFECT: limited vertical growth of the hydraulic fracture for the purpose of ensuring uniform development of productive formations and, accordingly, increased petroleum recovery of the reservoir with simultaneously minimised risk of breaching into the over- and underlying formations.

1 cl, 8 dwg