METHOD FOR CLEANING THE BOTTOMHOLE FORMATION ZONE OF A WELL Russian patent published in 2022 - IPC E21B37/00 

FIELD: oil industry.

SUBSTANCE: The invention relates to the oil industry, and in particular to methods for cleaning the bottomhole zone of an oil reservoir when the near-wellbore zone is contaminated. The method includes flushing an injection well by running a string of tubing along a string of working tubing - tubing, with a packer, followed by pumping an acid mixture for treating the formation and leaving it to react, followed by swabbing a volume of liquid that exceeds the sum of the internal volume of the tubing and internal the volume of the production casing below the packer and the volume of injected fluids, with the expectation of settling of suspended solids in the well sump and flushing the conduit before the subsequent start of the well. Coiled tubing with a bypass line above the packer, which is additionally equipped with an anchor, is used as the tubing string. The bypass line is made with the possibility of covering the swab located in the lower position, and after the packer and anchor are installed, the tubing is pulled and fixed on the wellhead with a force sufficient to prevent deformation when the swab is lifted up. The acid mixture is injected along the bypass line with the swab in the lower position, which, after injection, is raised to block the bypass line for the response time, after which swabbing is immediately started.

EFFECT: time between the reaction of the solution in the reservoir and swabbing is reduced, while the outflow of liquid to the surface and emergency situations during swabbing due to the tension of the tubing string are eliminated.

1 cl