PROCEDURE FOR REMOVING PIPES FROM WELL AND FACILITY FOR IMPLEMENTATION OF THIS PROCEDURE Russian patent published in 2009 - IPC E21B31/00 

FIELD: oil and gas production.

SUBSTANCE: group of inventions refers to drilling oil and gas wells, notably to procedures of removing column of frozen pipes from well. The procedure consists in lowering a facility into a well to operational depth on the right working pipes; the facility consists of a mechanism of fixation and of a mechanism of reverse, to the output shaft of which by means of a sub and a connecting pipe there is connected a fishing tool with a left thread; the facility is lowered till the fishing tool contacts a head of the frozen column; further the procedure consists in fixation of the facility by means of supply of flushing fluid into the mechanism of fixation and moving out spring-loaded anchors; in screwing the fishing tool to the left onto the head of the frozen column under influence of flow string right rotation converted with the reverse mechanism into left rotation of the fishing tool; in unscrewing the thread in the connection of flow string; in unfixturing the facility; and in removing part of pipes unscrewed from the frozen column out of the borehole of the well to surface. Upon determining the upper boundary of freeze-in and place of location of the mechanism of fixation (facility for unfixturing pipes -FUP) in the borehole and calculation of length of a connecting pipe, there is calculated M1 - maximum allowed torque for the structure of the free part of the frozen column; also weight P of the structure of the complex flow string is calculated; and maximum allowed stretching force for the structure of the complex flow string is calculated. Upon installation and screwing on the fishing tool on the head of the string and unfixturing FUP to the head of the working pipes there is applied maximum allowed for the structure of the complex flow string stretching strength at the well head; upon fixation of FUP in the well there is applied torque M1 to the flow string and there is performed smooth decreasing of stretching force to value P. If unscrewing of the flow string in the thread connection at the top of the frozen pipe does not commence, then there is performed successive stage reductions of stretching force by value corresponding to weight of the pipe in the free part of the frozen string starting from weight of the pipe screwed on to the frozen pipe. Upon each reduction of stretching force value beginning of unscrewing is controlled by readings of a sensor on the rotation drive.

EFFECT: increased reliability and efficiency of removing frozen pipes.

3 cl, 7 dwg