Abstract:
A device, system, and methods of power generation in situ in a hydrocarbon well are disclosed. A power generator for deployment in a hydrocarbon well tubular may comprise a housing adapted for deployment within a hydrocarbon well tubular; a mechanical to electrical power converter disposed at least partially within the housing, the mechanical to electrical power converter adapted to create an electric current when physically stressed; and a current converter operatively coupled to the mechanical to electrical power converter. Devices may be deployed downhole and operatively coupled to the power generator for their electrical power. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope of meaning of the claims.

Description:
FIELD OF THE INVENTION  
       [0001]     The inventions are related to generation of electrical power within a tubular. More specifically, the inventions are related to generation of electrical power within a hydrocarbon well tubular for use with electrically power devices also deployed in the hydrocarbon well.  
       BACKGROUND OF THE INVENTION  
       [0002]     For decades, operators have opened and closed valves across producing zones and used electrical cables for communications and power delivery for gauges deployed in the well. The idea was generally to allow a primary zone to produce to the end of its life and then to open a second zone for access to additional reserves. Traditionally, these valves were opened and closed mechanically through wireline. Such interventions, in shallow waters or onshore, are relatively inexpensive operations and usually involve only minimal loss of production time.  
         [0003]     As the industry moved farther offshore, the cost of support vessels for such operations and the complexity of re-entering subsea wells soon combined to make the cost of intervention sufficiently high as to scuttle the economics of any but the most significant secondary reserves.  
         [0004]     Over time, traditional mechanical actuation was replaced with remotely actuated hydraulics systems. The hydraulic systems deployment complexities have likely contributed to several failures offshore during the past few years, leading many service companies to the conclusion that, while hydraulics have their place, all-electric systems are the future of intelligent completions. Typically, electrical cables have been used to provide power and communications for gauges and flow control devices in the wellbore, raising the completions costs significantly. Cables are also one of the major sources of failures that impact the production of hydrocarbons. These failures created the risk of not being able to control the flow valve and to lose the ability to acquire data from downhole affecting the operator&#39;s ability to optimize production.  
         [0005]     In addition, the high costs and risks of wellhead design with cable entrance capability as well as downhole hardware deployment with cable feedthrough connectors make the deployment of intelligent completions and gauges uneconomical.  
         [0006]     It would therefore be desirable to eliminate surface system power generators and power cables running from the surface to allow smaller intelligent completions systems that can be deployed deeper in wellbores due to no losses through cables and elimination of flyback currents on cables. Such systems may further allow sensors to be deployed in well zones that may have not been accessible using electrical cables, e.g. using wireless communications modules powered by downhole power generators. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The features, aspects, and advantages of the present invention will become more fully apparent from the following description, appended claims, and accompanying drawings in which:  
         [0008]      FIG. 1  is a block diagram of an exemplary embodiment of a power generator;  
         [0009]      FIG. 2  is a block diagram of an exemplary embodiment of a power generator;  
         [0010]      FIG. 3  is a partial perspective of an exemplary doughnut shaped configuration;  
         [0011]      FIG. 4  is a partial perspective of a second exemplary configuration;  
         [0012]      FIG. 5  is a partial perspective of an exemplary system in partial cutaway illustrating use of the power generator in a system downhole; and  
         [0013]      FIG. 6  is a flowchart of an exemplary method.  
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0014]     Referring now to  FIG. 1 , downhole power generator  50  may be configured to be actuated downhole and used to generate electricity in well  10  ( FIG. 5 ), e.g. by using stressable material  52  such as piezoelectric or magneto-restrictive stressable material  52 . Downhole power generator  50  may provide for direct action between wellbore fluid flow and stressable material  52  to generate electrical energy and may be used to help eliminate inefficiencies related to picking up pressure fluctuations occurring inside the tubing walls.  
         [0015]     The main sources of energy in a wellbore include flow, vibration, pressure, and noise. Power generator  50  may be used to provide a non-movable or sealed hardware approach to harness or otherwise use the energy. In a preferred method, force generated by the flow is routed to power generator  50  which converts the mechanical motion of the force into electrical energy.  
         [0016]     Power generator  50  may comprise housing  74  which has been adapted for deployment within a hydrocarbon well tubular and in which a mechanical-to-electrical-power converter, e.g. power converter  51 , current converter  72 , and/or power storage medium  73 , are at least partially disposed.  
         [0017]     Mechanical to electrical power converter  51  will comprise stressable material  52  that, when stressed, creates an electrical current, e.g. by a stack of piezoelectric, magneto-restrictive material or any other material that would cause vibration near the power generator area. In currently preferred embodiments, stressable material  52  is either piezoelectric or magneto-restrictive material that will be stressed by the flow vibration created in the well. For example, stressable material  52  may be stressed by the vibration of the production tubing in the well, by the force exerted by the flow in the well, or by the generation of acoustic signals at downhole wireless gauges.  
         [0018]     Mechanical to electrical power converter  51  will typically convert vibrational stress to alternating current. In experimental environments involving piezoelectric material, the amplitude and frequency of the induced voltage was found to be directly proportional to the mechanical deformation of the piezoelectric material. The electrical charges developed by stressing the piezoelectric material decayed with time because of the internal resistance. Experiments performed in the past have indicated that at a one kilohertz frequency a power output of as much as one hundred watts per cubic centimeter and efficiency of as high as seventy percent has been obtained from piezoelectric material.  
         [0019]     Current converter  72  may be used to convert alternative current produced by stressable material  52  into direct current for storage in power storage medium  73 , e.g. a capacitor bank or a rechargeable battery pack.  
         [0020]     In some embodiments, power generator  50  will include mechanical vibration amplifier  70  that will interface with stressable material  52 . Mechanical vibration amplifier  70  may comprise a mechanical vibration amplifier to provide a higher level of vibration to increase the power generation capability of power generator  50 . For example, mechanical vibration amplifier  70  may be used to directly or augmentingly compress and release stressable material  52  to generate electricity.  
         [0021]     In a currently preferred embodiment, piezoelectric assemblies  52  are mounted on the inside of tubing  10  ( FIG. 5 ) and exposed to hydrostatic pressure in the well. A ceramic coating may be used to coat stressable material  52  to prevent or otherwise inhibit erosion as the hydrocarbons flow by stressable material  52 . The ceramic coating application to stressable material  52 , e.g. a piezoelectric assembly, may be performed at room temperature which helps eliminate concerns and problems related to applying coatings at extremely high temperatures that could damage stressable material  52 .  
         [0022]     Referring now to  FIG. 2 , downhole power generator  50  may be used to provide a direct interaction between the wellbore fluid flow and stressable material  52 , e.g. a piezoelectric stack, to generate energy. One or more electronics modules may be required to gather, rectify, and store the energy generated by stressable material  52 .  
         [0023]     In a preferred embodiment, power conditioner  53  comprises rectifier  53 , tank circuit  54 , harvester  55  and regulator  56 . An inductor may be operatively coupled to mechanical to electrical power converter  51 , the inductor adapted to cancel a capacitive part of impedance of the mechanical to electrical power converter  51 . This cancellation may minimize the impedance.  
         [0024]     Power conditioner  53  may comprise a rectifier or bridge.  
         [0025]     Tank circuit  54  may be present to accept the output of power conditioner  53  and act as a voltage regulator, e.g. a voltage doubler. The output of tank circuit  54  may be routed to one or more additional power conditioners. For example, the output of tank circuit  54  may be routed to power harvester  55 , which may include a harvesting monitor switch, and then on to voltage regulator  56 .  
         [0026]     Electrical energy may be stored in storage medium  73  which may include a capacitor bank, a rechargeable battery pack, or the like, or a combination thereof.  
         [0027]     Electrical energy, once generated and processed, e.g. by the circuitry illustrated in  FIG. 2 , may then be made available though numerous pathways, e.g. via wire or coaxial cable to one or more tools such as acoustic tool  60 .  
         [0028]     Referring now to  FIG. 3 , downhole power generator  10  may be configured in a doughnut or substantially toroid shape design, e.g. where stressable material  52  is located in pressure balanced apparatus  58  as part of a downhole tool. Hydrocarbon flow can impact pressure bellows  59  coupled to downhole power generator  10  ( FIG. 1 ) causing a force to be exerted onto stressable material  52  due to flow, causing electricity to be created. Note that only a few pressure bellows  59  and that only a few stressable materials  52  are marked in  FIG. 3 .  
         [0029]     Referring now to  FIG. 4 , downhole power generator  50  may be configured as a device, e.g. tool  58 , that can be interfaced to acoustic tool  60  such as an acoustic generator ( FIG. 6 ) that causes pipe  20  to vibrate inside wellbore  10 . In this exemplary embodiment, one or more housings  74  containing stressable material  52  may be arranged as part of a tool, e.g. tool  58 . The vibration causes stressable material  52  to generate energy which is routed at least partially to power storage medium  73  ( FIG. 1 ).  
         [0030]     Referring to  FIG. 5 , in an exemplary intelligent completion system well  10  with wireless communications module  60  and power generator  50 , use of a downhole power generation may eliminate use of an electrical cable and reduce the cost of the completions system. This may be especially true if power generator  50  is deployed downhole cooperatively with wireless communications system  60 . Accessibility to such power generation may allow deployment of intelligent completions in areas that were not accessible to cable based systems, e.g. by having in situ power generation and wireless communications.  
         [0031]     Casing  20 , autolock  21 , packer  22 , line handler  24 , packer  26 , and tie back seal stem  28  are all shown as illustrations of typical devices in downhole well  10  and are not meant to limit the present invention in any way. Other such typical devices may be sensors, control modules, or the like, as those terms are used herein, i.e. with respect to placement downhole.  
         [0032]     Traditionally, development of completion equipment has been based on the deployment of single devices that perform an individual function inside the wellbore and work independently of any other component of the completion. Consequently, the actuation of hydro-mechanical equipment and the acquisition of downhole parameters from electronics sensors have been difficult and costly. Further, measurement of downhole parameters during the production has typically been performed by tools that are lowered into, and retrieved from, the wellbore via wireline. Other methods of measuring downhole parameters may include installation of pressure and/or temperature tools and flow meters permanently in the production tubing string. These tools are typically placed on the outside of the production tubing and are connected to the surface data acquisition system through cables mounted along the outside of the tubing string. The actuation of downhole devices to control flow is normally performed manually, e.g. using a mechanical device attached to coil tubing or wireline, lowered into the wellbore and used to shift such devices as sliding sleeves or to set a packer.  
         [0033]     Further, wireless communications systems and the power generation system of the present inventions may also be used to create wireless-based sensor modules which may be located almost anywhere in wellbore  10 . The interface of these systems to intelligent completion systems may be used to allow for complete and independent hydrocarbon flow control and communications in and out of the wellbore in any section of well  10 .  
         [0034]     In an embodiment, downhole power generator  50  may be coupled with wireless communications system  60  and provide the capability to communicate through the production tubing, e.g.  20 , using stress waves to transmit and receive digital data and commands inside wellbore  10 . A system using wireless communications systems, e.g.  60 , and power generator  50  may be used in applications requiring information related to well status, geological formations, and production status. Wells where multiple zones are being produced, deep gas wells, and multilaterals may benefit from the development of such a system due to the ease of deployment and the elimination of cables that restrict the placement of gauges in the well. A system according to the present inventions may positively impact intelligent well applications, permit an increase in hydrocarbon production, and lead to a decrease in the operating costs by decreasing the number of interventions required in the well.  
         [0035]     System  100  may be adapted for downhole control and comprise a control module adapted (not shown in the figures) to be deployed downhole; wireless transceiver  60  operatively in communication with the control module, where wireless transceiver  60  is adapted to be deployed downhole; and power generator  50  operatively coupled to wireless transceiver  60 . In certain embodiments, system  100  may be further adapted for use with an intelligent completion system, as that term will be familiar to one of ordinary skill in these arts.  
         [0036]     The control module may further comprise a sensor, a gauge, a meter, a flow control device, or the like, or a combination thereof. For example, system  100  may be adapted for deployment at a subsea level at a hydrocarbon transmission pipeline to provide information related to the flow of hydrocarbon through the pipeline, the information comprising pressure, temperature, flow, or the like, or a combination.  
         [0037]     Transceiver  60  may comprise an active transceiver, a repeater, or the like, or a combination thereof.  
         [0038]     Power generator  50  comprises stressable material  52  adapted to create an electric current when physically stressed. Power generator  50  may be a separate power station deployed as part of the production tubing, e.g.  20 , and may be adapted to be used to generate and store power to be transferred to mobile system temporarily attached to power generator  50 . Power generator  50  may be deployed through tubing  20  for use with permanent or with systems that perform a temporary service in wellbore  10 .  
         [0039]     Fluid flowing in a downhole pipe may create vibrations, e.g. in pipe  20  used downhole, where the vibrations are usable by stressable material  52  to allow generation of electricity by stressable material  52 . The electricity generated may then be used to provide power for a sensor (not shown in the figures) operatively in communication with power generator  50 , e.g. disposed within or otherwise connected to power generator  50 .  
         [0040]     Systems  100  may be disposed proximate a subsea wellhead and control assembly may generate electricity as hydrocarbons flow from downhole to a surface location. Electrical power generated by power generator  50  may provide at least partial power for electronics and electro-mechanical devices located proximate the subsea wellhead.  
         [0041]     In the operation of exemplary embodiments, referring now to  FIG. 6 , in a preferred embodiment, power generation may be achieved by stressing stressable material  52  ( FIG. 1 ) such as piezoelectric or magneto-restrictive material, where the stress arises, at least on part, from production flow vibration induced in production tubing  20  ( FIG. 5 ). A mechanical vibration amplifier, e.g.  70  ( FIG. 1 ) may be used to increase the power generated by stressable material  52 . A battery pack and/or capacitor bank, e.g.  73  ( FIG. 1 ) may be used to store the energy generated by stressable material  52 . The amplitude and frequency of the induced voltage is typically directly proportional to the mechanical deformation of stressable material  52 . The electrical charges developed by stressing stressable material  52  will typically decay with time because of the internal resistance so that DC power cannot be generated. An AC to DC converter, e.g.  72  ( FIG. 1 ), may be included as part of the power circuit. The power output of stressable material  52  may be optimized by using an inductor to cancel the capacitive part of the impedance minimizing the source impedance. At resonance, the output power is typically limited by the resistive component of stressable material  52 .  
         [0042]     Electrical power may be generated from within tubular  20  ( FIG. 5 ) by deploying power generator  50  ( FIG. 1 ) within tubular  20  ( FIG. 5 ), where power generator  50  comprises mechanical vibration amplifier  70  ( FIG. 1 ), mechanical to electrical power converter  51  ( FIG. 1 ), power conditioner  72  ( FIG. 1 ), and power storage medium  73  ( FIG. 1 ) (e.g., steps  210 - 220 ). Power generator  50  is operatively coupled to a source of vibration, e.g. fluid flows or tubular  20  (e.g., step  230 ). Electrical current is generated using power generator  50  when exposed to the physical stress (e.g., step  240 ). An outlet for electricity generated by power generator  50  may be provided to allow access to the electricity generated by power generator  50 .  
         [0043]     For systems, e.g. the system illustrated in  FIG. 5 , a device that requires electric power such as acoustic module  60  may be operatively coupled within tubular  20  ( FIG. 5 ) to the outlet of power generator  50 . Acoustic generator  60  may itself be adapted to vibrate tubular  20 .  
         [0044]     A system comprising a downhole tool, e.g. as illustrated in  FIG. 5 , may be implemented by deploying a control module (not shown in the figures) downhole (step  200 ). In an embodiment, a device such as wireless transceiver  60  ( FIG. 5 ) may be deployed downhole, either before or after deployment of the control module where wireless transceiver  60  is operatively in communication with the control module (step  210 ). Power generator  50  ( FIG. 5 ) may be deployed downhole where power generator  50  is operatively coupled to wireless transceiver  60 , e.g. using wires or cables (step  220 ). As described above, power generator  50  comprises stressable material  52  ( FIG. 1 ) adapted to create an electric current when physically stressed. Power generator  50  is exposed to a source of physical stress downhole, e.g. production fluid flow or vibration (step  230 ). Power generator  50  generates electrical current when exposed to the physical stress and the power generated is used by the device, e.g. wireless transceiver  60 .  
         [0045]     A portion of the electricity generated by power system  50  may be stored in power storage system  73  deployed downhole, e.g. power generator  50  may comprise power storage system  73 .  
         [0046]     It will be understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated above in order to explain the nature of this invention may be made by those skilled in the art without departing from the principle and scope of the invention as recited in the following claims.