Remote actuation of downhole tools using fluid pressure from surface

Abstract

An apparatus for and a method of transmitting signals from the surface of a well to a location downhole in the well utilize a downhole fluid pressure sensor, a signal processing means located downhole in electrical connection with the pressure sensor and a downhole programmable logic unit capable of counting at least two signals received by the downhole pressure sensor. Typically, signals transmitted from the surface comprise a peak in pressure of downhole fluid located in production tubing run into a well bore and these signals are sensed by the downhole fluid pressure sensor. The logic unit outputs a signal to a tool to be actuated if it receives a number of signals within a particular time period, wherein the logic unit actuates the tool by the frequency of signals received rather than the amplitude of the signals received.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an apparatus and method of remotely actuating downhole tools from the surface by using pulses or signals of pressure.BACKGROUND TO THE INVENTION[0002]Conventionally, it is known in the oil and gas production industry to use downhole tools such as choke valves and the like that can be remotely actuated from the surface by pressure. Typically, such tools are mechanically actuated in that the actuation mechanism comprises a ratchet mechanism which is attached to a piston wherein an operator at the surface can pressure up fluid in the production tubing and the pressure will force the piston to move one length up the ratchet. Such conventional pressure operated ratchet mechanisms require a certain amplitude of pressure to move the piston sufficiently to cycle it and can therefore be thought of as amplitude dependent. Such conventional systems are usually arranged such that the downhole tool will only operate after the pressure ...

AI Technical Summary

Benefits of technology

"The present invention provides a method and apparatus for transmitting signals from the surface of a well to a location downhole in the well. The method involves using a downhole fluid sensor to sense changes in downhole fluid, installing a signal processing means downhole in electrical connection with the sensor, and installing a programmable logic unit downhole in electrical connection with the signal processing means. The programmable logic unit is capable of counting at least two signals received by the sensor and instructing actuation or operation of a tool based upon previously programmed logic. The signals transmitted from the surface of the well include a peak in pressure of the downhole fluid located in the well bore. The apparatus includes a downhole fluid pressure sensor, a signal processing means, and a programmable logic unit. The programmable logic unit is adapted to observe a peak in pressure and further adapt to output a signal to a tool to be actuated if it receives a particular number or value of signals within a particular time period. The logic unit is reset to zero if the time since the last peak or the time between a pair of peaks is greater than a particular maximum time value. The logic unit is further adapted to hold a set actuation value and compare the counter value with the set actuation value before instructing actuation of the tool."

Problems solved by technology

As shown in FIG. 1, such conventional systems can suffer from the disadvantage that they become inoperative or their performance is impaired if debris forms on top of or above the mechanically arranged pressure operated system in that the debris can prevent the pressure signal, sent from the surface, registering the sufficient amplitude against the piston.

Accordingly, the debris prevents such a conventional mechanical pressure mechanism from indexing / cycling and causes the downhole tool to fail to open on command.

Accordingly, failure of the downhole tool to operate will clearly be a significant problem and will likely result in rig down time and various intervention operations which are very costly.

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