Patent Application
20080093070
A pressure transducer device which is battery powered is housed in a pressure tight container. Also within the housing are batteries, preferably of the long life high density lithium variety, a micro processor and associated P.C.B., a memory portion for storage of the operating programme, a second memory provision for storage of the pressure history from the previous day, a high accuracy quartz oscillator to provide reference for a real time clock and one or more output actuators.
The device will monitor well pressure at a particular time each day for a set period such as one hour. The device will store pressure measurements taken during the period for comparison with other measurements taken in the subsequent period. In the event that the subsequent measurements plus previous measurements conform to a pre programmed profile contained within the tool, an output action will be allowed. This may be operation of an actuator or similar.
The device may be packaged along with a valve type apparatus which may be used to close off the flow from a particular wellbore zone but may also be used for a variety of other purposes. A valve apparatus may be electrically actuated, may be electro-hydraulic or may be purely hydraulic. Simple operating types will generally be of the on/off variety requiring two outputs from the invention. Logic within the device will record the current status of the output actuator(s) and will provide the opposite in recognition of the next signal, ie, opening will follow closure and closure will follow opening. Signalling to the device from surface may entail the same process in both cases.
Operation of a hydraulic device may be accomplished by actuating open a pilot valve for a period of time which allows well pressure to act on a piston. The piston may be housed in a sealed chamber with atmospheric pressure acting on the opposing face. The piston may be linked to the valve sleeve and upon receiving actuating pressure from the well, the piston will stroke and in so doing will close the valve sleeve. Opening the valve device will comprise a similar but reverse acting mechanism. The atmospheric side of the piston will be switched to reference well pressure and the previously well pressure referenced side will be switched to atmospheric pressure. The atmospheric pressure chamber will be required to contain a decent volume as with multiple use, the pressure within the chamber will increase.
An option to control a multi position device exists whereby the listening hour may be subdivided into, say, three individual twenty minute periods. Recognition of a signal in the first period on both days may correspond to an output from the device which allows ⅓ opening of the downhole valve. Recognition of a signal in the second period within the hour on both days may correspond to ⅔ opening of the device and the third period on both days, full opening.
The scope for a number of increased output options exists where recognition in one of the three twenty minute first day periods coupled with recognition in one of the three twenty minute second day periods (but still within the listening hour) may be recognised. The nine permutations achieved by selecting one of the three available first and one of the three available second day periods within the listening hour may correspond to nine different pre-programmed outputs. Accordingly, a device with nine operational positions may then be signalled and controlled. As before, with a one hour listening period, a maximum number of twenty four of these devices may be positioned in a wellbore (one for each hour) and each function independently of each other. Advantageously, malfunction of one or more will not effect the operation of the remaining devices.
Many other types of well equipment may benefit from use of the signalling method. One example is for use as a safety valve. Normal operation of a well will comprise flowing the well at maximum output without any interruption in order to maximise ecenomic returns from the well. Upon receipt of a platform or facilities alarm, a safety system will be tripped shutting all wells both at surface and at a downhole valve called a safety valve. Should the safety valve be replaced by a device according to the invention, closure may be accomplished by recognition of only one signal. The signal required may be a number of pressure measurements above a pre set pressure threshold such as would be demonstrated when a well is shut in at surface. In this instance, the well would be shut in at surface by the normal facilities system. The well pressure would build up downhole and this feature would be recognised by the device minutes later. The device would then actuate a valve shut off device which would close off the lower portion of the well.
Upon conclusion of the emergency situation, there would be a need to produce the well again and accordingly to open the valve which is closing off the well. In addition to the programmed pressure threshold to close the device, it would additionally have an opening programme. This may compare pressure traces over two hours for example and identify a definite event which may only be a deliberate action from the part of the production operator. This might be pumping into the well and bleeding back at the same point of each hour twice. Recognition of this event will serve to trigger actuation open of the invention.
The preferred embodiments of the invention therefore provide a new and inventive method and apparatus for controlling the operation of a flowing or producing well, whereby a control or actuating signal is transmitted to a downhole tool without any physical link to that tool.
There are many known method of communicating to downhole tools by providing a signal from the surface. These may be electronic, acoustic, electromagnetic, use dedicated hydraulic control lines or dedicated electrical cables, or may be pressure pulses which are applied to the wellbore, the wellbore annulus (the annular area between the production tubing and the casing) or a mixture of both.
The invention allows a command to be detected, not by application of some external input using one of the above techniques, but by changing the existing dynamics of a flowing well synchonised with time.
In one aspect, the invention provides a method of signalling from surface to a remote device disposed in a producing oil or gas borehole comprising: surface means for restricting flow; surface time indication means synchronised with:
Downhole electronics module comprising; real time monitoring means; pressure sensing means for sensing pressure changes; temporary memory means to store recent pressure history; multi processor means to control and schedule operation of the device, to match separate profiles of present and recent pressure history, to execute activation programme upon detection of matching profiles and to store defined logic/profile parameters;
battery means to provide electrical power to the device;
actuatory means to execute the received command;
whereby the dynamic properties of a flowing well are altered in order to provide a recognisable signal, detectable by the downhole device.
In a further aspect, the invention provides a method for signalling from surface to a remote device disposed in a producing oil or gas borehole comprising:
In a third aspect, the invention provides a method and apparatus for controlling the operation of a flowing or producing well utilising:
a downhole located pressure monitoring device which is operative to monitor a characteristic pressure profile of the flowing well, and to respond when a significant deviation to the pressure profile is introduced into the well as a control signal to the monitoring device; and
an actuator which is initiated into operation to control any required operation of the well when the monitoring device responds to the control signal.
Therefore, in a method and apparatus according to the third aspect, a significant improvement is provided whereby two separate pressure profiles are compared.
Conveniently, in a method and apparatus according to the invention for controlling the operation of a flowing or producing well, there is provision of means for utilising a non-predetermined signature.
If desired, the actuator is arranged to operate a flow control valve, or may be arranged to initiate an explosive charge if required.
A clock (not real time) may be arranged to compare events at predetermined intervals e.g. every three, five or seven hours, to correct for any possibility of “drift” with a real time clock which otherwise would result in the control signal being sent when the clock was not “listening”.
In a particularly preferred arrangement according to the invention, a self-learning capability is provided, by storage of any pressure profile for comparison with a later pressure profile for a finite time period.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0411121.7 | May 2004 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB05/01793 | 5/11/2005 | WO | 00 | 11/17/2006 |
