METHOD OF CLEANING THE FILTRATION ZONE OF A HORIZONTAL WELL WITH ABNORMALLY LOW LAST PRESSURE Russian patent published in 2019 - IPC E21B37/00 E21B21/00 

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry and can be used when cleaning the filtration zone of a horizontal well with abnormally low formation pressure. Method comprises lowering a flexible pipe (FP) into a well at the level of a liquid, pumping an air-nitrogen mixture through it until the well fluid is completely replaced with gas, sequentially lowering the flexible pipe to the bottom, and simultaneously pumping a flushing fluid with an air-nitrogen mixture into the well. At the same time, after the FP is lowered at 20 m below the level of the fluid in the well, the flushing fluid is pumped through the flexible pipe simultaneously with the air-nitrogen mixture until it comes out and circulates from the well. Next, the FP is lowered to the beginning of the filter and, with a steady flow of fluid from the well, continue to descend to the bottom of the well at a constant speed of 0.015–0.5 m/s and maintaining a stable output of flushing fluid with an air-nitrogen mixture from the well. Then suspend the injection process and raise the FP to the initial depth of descent. Repeat the operation of washing the well and lifting the FP until the end of the removal of mechanical impurities to the surface.

EFFECT: technical result is an increase in the cleaning efficiency of the filtration zone of the well and the elimination of emergency situations due to the absence of fixed pipes in the well.

1 cl, 1 dwg