REDUCING SWABBING AND PIGGING EFFECTS IN WELLS Russian patent published in 2017 - IPC E21B21/08 

FIELD: oil and gas industry.

SUBSTANCE: group of inventions relates to oil and gas industry, in particular, to reduction of piston effects in a well. Method of reducing undesirable changes of pressure in a well due to movement of a well tool string includes selective reduction and increase of fluid communication between sections of well on opposite sides of well tool in well tool string. Fluid communication increases in response to detection of exceeding threshold displacement of well tool string relative to well. Tool string includes well tool, connected in well tool string and having a larger outer size relative to adjacent sections of tool string, flow channel extending between opposite ends of well tool, sensor and at least one flow control device, which selectively allows and shuts off fluid communication between opposite ends through flow channel in response to sensor output signal indicating movement of tool string.

EFFECT: higher efficiency of process of reducing undesirable changes of pressure in well.

30 cl, 9 dwg