METHOD FOR REMOVAL OF COMPACTED PLUG FROM WELL Russian patent published in 2020 - IPC E21B37/00 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, namely, to methods for removal of compacted plugs during well repair. Method involves lowering to emergency well up to head of pipe string plug, equipped from below with helical non-self-braking mechanism - screw pair, which includes hollow cylindrical shaft and hollow cylindrical housing, having the possibility of rotation around its axis, which lower end is rigidly connected to bit, unloading pipe string into plug, at which translational movement of pipe string is converted into rotary motion of bit. Under action of axial force created by the pipe string weight on the plug, the hollow shaft is stopped and its translational movement downwards, at that, the hollow body rotates, by bringing into the bit rotation, the pipe string is reached when the hollow shaft reaches the extreme lower position limited by the upper stroke limiter, repeated completion of the pipe string, to continue drilling cycles until the stop in the lower stroke limiter with continued rotation of the bit during lifting of the pipe string, drilling the plug to the moment when friction forces do not stop its rotation. After lowering the pipe string to the plug head, a pump unit, a liquid flow switch and a chute reservoir are installed on the wellhead and tied to each other. Each cycle of plug removal includes circulation of liquid by direct flushing, drilling of compacted plug and drilled cuttings removal from well. Drilling cycle is performed by drilling part of plug by unloading pipe string until it stops in upper limit stop at continuing direct flushing. Sand is removed when the pipe string is lifted to the lower stroke limiter with simultaneous back flushing. Switching between direct flushing to back flushing and vice versa is performed with the help of fluid flow switch. After removal of the plug and the pipe string stop, the set of own weight of the pipe string is set in the face and back flushing is performed in 1.5-fold volume of the well and back flushing is performed.

EFFECT: increased reliability of method implementation at drilling of plug and efficiency of drilled cuttings removal from well, reduced duration of repair works.

1 cl, 4 dwg