Study of the efficiency of fishing tool with the moving magnetic systems

Abstract

The variety of accidents that occur during the construction of oil and gas wells leads to the widespread use of magnetic fishing tools. A significant drawback of the known permanent magnet-based devices is the flat working surface of the magnetic system, which does not allow achieving sufficient attraction force with a trapped object of complex geometric shape. Therefore, the goal of this work is to increase the efficiency of removing objects of irregular geometric shape from wells. For this purpose, a new large-diameter fishing tool with movable magnetic systems capable of reproducing the shape of the captured objects has been developed. Each magnetic system, consisting of rare earth permanent magnets and concentrically placed magnetic cores, is held in place by the magnetic field of adjacent systems of opposite polarity. The increase in lifting force is due to the axial movement of the magnetic systems and the increase in the area of contact with the emergency objects. In order to confirm the performance of the developed tool, theoretical studies were carried out using the finite element method. As a result, models of magnetic induction distribution were obtained, illustrating the high strength characteristics of the magnetic systems. The calculated values of the lifting force during the interaction of the magnetic systems with a cutter and the whole drill bit confirm the ability to grip objects of irregular geometric shape. A slight decrease of the attraction force was also found when catching objects made of alloy steels. The application of the developed magnetic device will make it possible to remove ferromagnetic objects of any shape, mass and position on the bottom hole.