METHOD FOR ISOLATING LOSS ZONES WHEN DRILLING WELLS Russian patent published in 2022 - IPC E21B33/138 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry and is intended for repair and insulation work in absorption zones during well drilling. The method for isolating loss zones during well drilling includes stopping drilling after opening a loss zone that does not allow further deepening of the well, flushing the well with a fluid flow rate sufficient to flush rock out of the loss zone, introducing a bridging compound into the loss zone in the form of a plugging solution with a bridging filler, taking into account injection pressure. After the absorption zone is opened, the absorption intensity of the flushing fluid and the static level in the well are determined, the working assembly is raised above the roof of the absorbing formation to a distance of the static level, a suspension of a viscous bridging composition with a finely dispersed filler with a particle size of up to 10 mm is prepared, injection is carried out through the space between the drilling the tool and the well wall without removing the drilling tool from the well, without exceeding the hydraulic fracturing pressure of the rocks under the previous casing string. The initial volume of the bridging composition is crushed with a buffer liquid into the absorption zone with a pressure not exceeding the allowable one. After a technological exposure sufficient to set the bridging composition and/or settling the bridging filler, the injectivity of the disturbance zone is determined, from which the required volume of the bridging composition and its composition are determined for pushing the buffer liquid into the absorption zone. Subsequent portions are pumped in a similar way until loss is obtained, allowing further drilling work, after which the deepening of the well with a drilling tool is continued.

EFFECT: invention provides the possibility of clogging highly injective absorption zones by pumping a portion of a drilling or cement slurry with a fine-grained filler in the space between the drilling tool and the well wall without removing the drilling tool from the well.

1 cl, 1 ex