Circulating Sub with Activation Mechanism and a Method Thereof

Abstract

The present invention relates to an activation method, an activation mechanism and a downhole tool comprising the activation mechanism. The activation mechanism com-prises a pressure switch for turning power to the electrical components, a control unit connected to a pressure sensor for sensing the internal pressure of the drilling fluid located in a first fluid conduit. The control unit controls an actuator unit connected to a moveable valve element. The actuator unit moves the valve element from a closed position when activated. A seat for the valve element is arranged relative to a second fluid conduit so that the valve element closes the second conduit when it is placed in its seat. This provides a very fast and accurate activation method that involves the use of balls or RFID tags. Furthermore, the downhole tool can be activated even if no actual flow is passing through the tool.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an activation mechanism for activating a circulating sub in a drill string, comprising a sensor sensing at least a pressure of a drilling fluid located in a first fluid conduit in the downhole tool when installed, a valve element arranged relative to a second fluid conduit in the downhole tool when installed, and a control unit connected to the sensor and configured to monitor the sensed signal and to electronically control the movement of the valve element based on the sensed signal.[0002]The present invention also relates to a circulating sub for positioning in a borehole, comprising a housing having an outer side surface facing an inner wall of the borehole, a first fluid conduit connected to a first opening in one end and a second opening in the other end for leading a drilling fluid through the circulating sub, and at least a second fluid conduit in fluid communication with the first fluid conduit, wherein the circula...

AI Technical Summary

Benefits of technology

The invention is a mechanism that allows for quick and accurate activation of a downhole tool. It is powered by an external or internal power source, like a battery, and can be controlled by a pressure switch that activates power when the pressure of drilling fluid exceeds a certain level. The control unit monitors the pressure and activates or deactivates the tool based on a stable pressure level. The control unit enters sleep mode again and the power is turned off if the activation or deactivation process is completed or if the pressure drops below the activation level. This saves power and increases the operation time of the downhole tool.

Problems solved by technology

Furthermore, the ball may be stopped in the fluid passageway by accumulated solid particles, thereby blocking the circulation of drilling fluid and causing an increase in pressure above the blockage which could damage the downhole tool or even the operation equipment located at ground level.

Both types of activation systems provide a slow and time consuming process since each ball or RFID tag first has to be pumped via the drilling fluid from the ground level to the selected downhole tool before the downhole tool can be activated or deactivated.

The disadvantage of this solution is that the sequence of modes is determined by the indexing mechanism, thus the operator must follow the indexing sequence to select a desired mode.

Furthermore, it is well known that such indexing mechanisms have a complex configuration that is prone to mechanical failures.

This activation mechanism can only be accessed and reset by taking the sub apart which adds to the complexity and costs of the sub.

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