WELL BOTTOMHOLE WASHING METHOD Russian patent published in 2020 - IPC E21B21/00 E21B37/00 

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: invention relates to oil industry and can be used in flushing and cleaning of boreholes. Method comprises lowering to the bottom of the well tubing string with a skew cut, equipped with a conical mounting seat for replaceable nozzles at 2–2.5 meters above the current working face, pumping flushing fluid and its extraction through annular space of the well with gradual descent of the tubing string until the end of the skew cut into the plug and change in weight of the suspension. Then pumping is stopped and nozzle is released into inner part of tubing string, flushing fluid is supplied until nozzle seat is fitted in conical seat for replaceable nozzles, which is accompanied with sudden step-by-step increase of pressure, Then, flushing liquid is pumped through tubing string through nozzle and flushing fluid is withdrawn with mechanical fractions via annular space to achieve design depth. After that, pumping is stopped and well is switched to back flushing. At that, nozzle is removed together with flushing liquid and mechanical impurities on day surface. Nozzle has a water jet or cavitation configuration with diameter of 8–16 mm. Filling of the nozzle into the inner part of the column can be carried out in double or triple repetition, wherein in each subsequent repetition there used is a nozzle with a smaller inner diameter than the previous nozzle.

EFFECT: increased degree of destruction of compacted sand-clay and proppant plugs and reduced time of their destruction.

3 cl, 2 dwg