Patent Application
20090033176
In many well related applications, various components are utilized downhole that require electrical energy for some aspect of operation. These components are powered either by electrical cables routed down through the wellbore or by remote power sources, such as batteries positioned downhole proximate the component to be powered. The use of power cables often is not feasible or cost-effective in many types of well related applications. However, providing a continual source of electrical energy with a battery located downhole also has limitations. For example, the battery has a limited life, particularly when in continuous electrical connection with the downhole component.
In completions and testing operations, communication of commands from a surface location to a downhole system can be necessary to control the actuation or other function of the downhole system. To process the commands, the downhole system has a receiver that remains operating to accept the commands. Operating the receiver requires power which can be supplied by a battery. However, the time period over which commands can be sent is limited by the amount of energy contained in the battery and by the need to maintain the receiver in an operational state.
In general, the present invention provides a system and method by which energy is physically/mechanically transmitted down through a wellbore. The energy may be in the form of waves created by a wave generator that directs the waves downhole along a fluid channel until they impinge on an energy converter positioned at a subterranean location, e.g. in the wellbore. The energy converter converts the physical or mechanical energy into electrical energy that is supplied to a downhole device.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present invention generally relates to a system and methodology by which a physical or mechanical energy can be transferred downhole along a wellbore and converted into electrical energy for use at a downhole location. This approach enables a variety of wellbore applications that can prolong the life of batteries or other electrical energy storage units deployed downhole. In some applications the use of batteries or electric lines routed downhole can be avoided completely. By way of example, mechanical/physical energy is transferred downhole via waves directed from a remote location, e.g. a surface location, to a downhole location. The energy within the physical waves is converted to electrical energy that can be used by a downhole device. In some applications for example, the downhole device comprises an electrical energy storage unit that can be charged with the electrical energy that results from the conversion.
Referring generally to
Well system 20 also comprises an energy conversion system 36 by which energy is transmitted downhole in one form and converted to another form for use by one or more well devices 38. The well devices 38 may be mounted in well equipment string 22 or at other locations within wellbore 24. The energy conversion system 36 comprises a remote mechanism 40 that may be located at surface 32 or at other suitable locations to generate a mechanical or physical energy that can be transferred downhole as represented by arrows 42. The energy transferred downhole is received by a converter 44 which converts the physical/mechanical energy into electrical energy for use by a device or devices 38.
One embodiment of energy conversion system 36 is schematically illustrated in
As the waves move downhole along fluid channel 48, energy is carried to energy converter 44 which changes the form of the energy to electrical energy that can be provided to one or more devices 38. The specific form of the energy converter 44 depends on the type of mechanical/physical energy transferred downhole and the manner in which that energy is directed to converter 44. In the embodiment illustrated, however, energy converter 44 comprises a pressure balanced membrane 50 that is acted on by the waves. The pressure balanced membrane 50 is coupled to a Helmholtz cavity 52 that drives a coil 54 located within a permanent magnetic field. The magnetic field may be created by permanent magnets 56 placed around coil 54. By driving the coil 54 within the permanent magnetic field, electrical energy is created and an electrical current can be output to device 38. The electrical output can be maximized by operating wave generator 46 to produce waves at the resonant frequency of the Helmholtz cavity.
One method of creating waves at the resonant frequency of the Helmholtz cavity is through the use of an acoustic source or acoustic generator, as illustrated in
In the embodiment illustrated in
For example, in the embodiment illustrated in
The energy stored in energy supply 70 may be used in a variety of ways depending on the specific wellbore application. For example, the energy may be used to power an acoustic or pressure detector. This type of detector senses the static or dynamic pressure in fluid channel 48, thus allowing communication from the surface to electronic device/controller 72 through controlled variations in pressure exerted on fluid channel 48 at the surface. By encoding information into the pressure variations, the downhole electronic controller can be commanded to undertake specific actions, including opening or closing valves, actuating packers, actuating sliding sleeves, causing the ignition of perforating charges or other charges, and/or selectively releasing chemicals in the wellbore.
In other embodiments, the energy can be used to power measuring instruments located downhole or to power a communication system for transmitting measurement data to the surface. By way of example, the measurement data can be transmitted uphole by using electro-magnetic telemetry, acoustic telemetry, or by modulating the acoustic reflectivity at the base of fluid channel 48.
In other alternate embodiments, stored energy supply 70 can be omitted, and the energy contained in the rechargeable electrical energy storage unit 66 can be used directly to perform downhole operations, e.g. to actuate a downhole well device. In this latter embodiment, switch 68 can be set to prevent energy use until unit 66 is sufficiently charged to carry out the desired operation.
The conversion of mechanical/physical energy into electrical energy at a downhole location can be useful in a variety of well related applications. Furthermore, once converted to electrical energy, this energy can be used to provide power to a variety of devices. The electrical energy can be used to recharge batteries, to turn on switches or other devices, or to actuate devices that are powered by other downhole energy sources. For example, the electrical energy can be used to turn on a dormant receiver which is then able to receive communications signals from the surface location, thereby increasing the life of the battery or other energy source used to power the receiver. In other applications, the electrical energy supplied by the converter can be used alone, i.e. without the aid of a separate electrical energy storage unit, to accomplish a desire downhole function.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.
