Abstract: Noise in drilling operation measurements can be eliminated or reduced using machine learning. For example, a system described herein can receive one or more measured signals in a logging-while-drilling process for drilling a wellbore. The system can determine a coupling factor for noise in the one or more measured signals. The system can generate a corrected signal by removing the noise multiplied by the coupling factor from the one or more measured signals. The system can output the corrected signal for use in drilling operations in the wellbore.

Abstract: A method including, without removing a BHA from a wellbore of a well extending into a formation, extending, into an interior flow bore of the BHA, a first component of a wet latch assembly to provide an extended first component of the wet latch assembly, conveying downhole via a wireline cable, from a surface through an interior flow bore provided by a drill string, a second component of the wet latch assembly, and coupling the second component of the wet latch assembly with the extended first component of the wet latch assembly such that an electrical connection is established between the first component and the second component and between the BHA and the surface via the wireline cable, and testing the formation with a formation tester of the BHA, while providing power and/or data telemetry for the formation tester via the wet latch assembly and the wireline cable.

Abstract: A downhole communication system for communication between a first and second location in a subsea oil and/or gas well installation. The oil and/or gas well installation comprises out of hole metallic structure comprising a riser 3 running upwards away from the mudline ML, and downhole metallic structure 2 running down into the well. The communication system is arranged so that at least part of a signal path for communications between the first and second locations is provided by the downhole metallic structure 2 such that, in use, data to be communicated between the first and second locations is carried by electrical signals in the downhole metallic structure 2.

Abstract: A velocity of a flow of drilling fluid is adjusted to a magnitude that is within the operating range of a mud pulser disposed in the flow of the drilling fluid. A stator in the mud pulser directs the flow of drilling fluid along one or more separate paths. The paths are defined by channels that extend axially along an outer surface of the stator and that are spaced angularly apart from one another. Also in the mud pulser is a rotor that alternatingly blocks the paths. The velocity is adjusted with a plug assembly that blocks flow through a designated channel. One type of plug assembly is a disk with passages that register with less than all of the channels, and that mounts on a downstream end of the stator. Other types of plug assemblies mount in the designated channel to block the flow path.

Abstract: A combinatorial frequency system and method for transmitting data from LWD downhole operations to a surface location is provided. The system and method include obtaining data from at least one downhole sensor, encoding data by combinations of different harmonics, and (optionally) modulating the data using various frequency modulation techniques to produce a series of 3-40 bit rates. The system and method include transmitting the series as pressure wave signals through drilling fluid or through earth media by electromagnetic waves, detecting the signals, identifying at a surface location each frequency, modulating characteristics of each frequency, decoding each signal and forming output signals.

Abstract: A downhole measurement tool assembly is for measuring at least one quantity in a well-bore, and has: i) a pressure housing; ii) a sensor for measuring the quantity in the wellbore; iii) a memory for storing values of the quantity to obtain stored measurement data for later read-out; iv) an antenna for allowing wireless communication of the stored measurement data between the downhole measurement tool assembly and an external read-out system while the downhole measurement tool assembly resides at the surface out of the wellbore, wherein the antenna is mounted at an external side of the pressure housing such that it is exposed to pressure in the wellbore when residing in the wellbore; v) a transceiver for controlling the communication via the antenna, and vi) a pressure connector in an external sidewall of the pressure housing, wherein the antenna is coupled to the internal transceiver via the pressure connector.

Abstract: Systems and methods for communicating between surface equipment and a downhole tool installed in a well. First and second toroidal transformers are positioned around an inner one of a pair of coaxial structural members of a well completion (e.g., a pump rod and tubular, or a tubular and a well casing) which are electrically coupled to form an electrical circuit. A transmitter generates a data signal which is applied to the first toroidal transformer, causing a corresponding electrical current to be induced in the circuit, which then induces the data signal on the second toroidal transformer. A receiver coupled to the second toroidal transformer receives the data signal induced on the second toroidal transformer. The transmitter and receiver may be components of transceivers that may communicate bidirectionally. Additional toroidal coils and transceiver may be provided to communicate with equipment at additional locations in the well.

Abstract: Hydrocarbon wells and associated methods that utilize radio frequency identification (RFID) tags and flowable interrogators to interrogate the hydrocarbon wells are provided. The hydrocarbon wells include a wellbore, a downhole tubular that defines a tubular conduit and extends within the wellbore, and a plurality of RFID tags. The hydrocarbon wells also include a downhole interrogator storage structure that includes a plurality of flowable interrogators and a well-side communication device. Methods of operating the hydrocarbon wells are also provided.

Abstract: Systems and methods for wireless power transmission in a well, wherein first and second structural members of a well completion are electrically connected to form an electrical circuit, with first and second toroidal transformers positioned around the second structural member at different axial locations. A power source coupled to the first toroidal transformer is configured to generate an output voltage which is applied to the first toroidal transformer, inducing a corresponding electrical current in the electrical circuit. This in turn induces a second voltage on the second toroidal transformer, which is provided to a downhole tool. The tool may include conditioning circuitry, which rectifies the received power and charges a battery. The downhole electric tool is then operated using the received power.

Abstract: An apparatus (100) for operation in a tubular channel (199), the apparatus comprising a first part and a second part connected to the first part, wherein the second part comprises a first electronic device adapted to generate a data signal and a first communications device for wirelessly transmitting the generated data signal via a wireless communications channel, wherein the first part comprises a second communications device for wirelessly receiving the transmitted data signal via said radio-frequency communications channel.

Abstract: A wellbore assembly for use downhole in a wellbore may include a casing string comprising a mandrel. The mandrel may include a side pocket in an inner region of the mandrel. A downhole device may be positioned within the side pocket of the mandrel. The downhole device may include an electronics package, a power source, and a transmitter for transmitting data from the downhole device via a wireless communications link to a downhole tool for transmitting the data to a surface of the wellbore for monitoring a downhole environment of the wellbore.

Abstract: The present invention discloses a testing device and method for simulating longitudinal-transverse-torsional coupled nonlinear vibration of a drill string in deep-water riser-free drilling. The testing device comprises a pool (1), a motor (2) and a hook load adjustment device (3), wherein a guide wheel (4) is provided on the top of the pool (1); a support seat A (5) and a support seat B (6) are fixed on the bottom surface of the pool (1); an organic glass tube (8) is fixed between the support seat A (5) and the support seat B (6); a casing (9) is respectively provided on the top surface of the support seat B (6) and the top surface of the trailer (7); the left end of the plastic tube (10) extends into the organic glass tube (8) along the axis of the organic glass tube (8). The present invention further discloses a simulation method.

Abstract: Systems and methods are described to create radio daisy chains for convenient and aesthetically pleasing high-density radio deployments.

Abstract: A downhole power delivery system for use in a well comprising downhole metallic pipe (2) running in a borehole of the well with a downhole sealing plug (31) provided in a bore or annulus at least partly defined by the downhole metallic pipe. The power delivery system comprising below plug apparatus (5) located in the borehole below the plug (31) including a downhole device (53) requiring electrical power and downhole power supply apparatus (6) located in the borehole above the plug (31). The power supply apparatus (6) comprises at least one battery (64) for powering the downhole device and the downhole power supply apparatus (6) and below plug apparatus (5) being arranged for delivering electrical power from the downhole power supply apparatus (6) to the downhole device (53) across the downhole sealing plug (31).

Abstract: A well installation comprising downhole power delivery apparatus for delivering electrical power from a surface power source S to a downhole tool T. The well installation comprises downhole metallic structure (2) running down into a borehole. The apparatus comprises an electrical cable (3) for carrying electrical power from the surface power source S, a power transfer arrangement (4) and a power pick up arrangement (5). The cable 3 runs down into the borehole together with the metallic structure (2) to the power transfer arrangement (4) which is provided at a first downhole location for transferring electrical power carried by the electrical cable (3) onto the downhole metallic structure (2) for onward conduction. The power pick up arrangement (5) is provided at a second downhole location, spaced from the first, for picking up electrical power from the downhole metallic structure (2) for supply to the downhole tool T.

Abstract: A method of operating a wellbore using a plurality of acoustic emission transducers. The method comprises deploying acoustic emission transducers in association with at least one of a member of a drill string, a bottomhole assembly, and a drill bit coupled to the drill string in a wellbore. The acoustic emission transducers are coupled to a controller comprising a processor and memory. The processor is programmed to determine one or more of a frequency of the acoustic emissions, an amplitude of the acoustic emissions, an energy of the acoustic emissions, a duration of the acoustic emissions, a rise time of the acoustic emissions, and a frequency centroid of the acoustic emissions. The method includes measuring acoustic emissions generated by acoustic events originating within the wellbore with the acoustic emission transducers. Downhole acoustic systems for monitoring drilling operations of a wellbore are also disclosed.

Abstract: A method for processing sonic data acquired with a downhole sonic tool is provided. The method comprises detecting coherent noise based on a plurality of waveforms obtained from one or more receivers issued by one or more transmitters. The plurality of waveforms correspond to propagating acoustic waves in a formation. In addition, the method comprises building a slowness filter for removing the coherent noise, and applying the slowness filter to the plurality of waveforms.

Abstract: Embodiments described herein comprise a wellbore system having a controller, one or more downhole tools, and a conveyance configured to lower the one or more downhole tools into the wellbore. The one or more control nodes are located in at least one of the downhole tools and wherein the control nodes activate a portion of the downhole tool and data is exchanged between the control node and the controller using a direct sequence spread spectrum signal.

Abstract: A detection system to detect an object in a blowout prevention system of a production system includes a sensor coupled to the blowout prevention system and configured to send an ultrasonic pulse toward the object. The sensor is further configured to receive a signal including the ultrasonic pulse and noise after the ultrasonic pulse interacts with the object. The detection system also includes a controller coupled to the sensor and configured to identify the ultrasonic pulse in the signal using a first cancellation signal at a first time and a second cancellation signal at a second time. The controller is further configured to determine that the first cancellation signal corresponds to the noise in the signal at the first time, and determine that the second cancellation signal corresponds to the noise in the signal at the second time. The controller is configured to determine a characteristic of the object based on the ultrasonic pulse.

Abstract: A telemetry and communication system and method for communication between a well production system and a well assist system. The system may comprise a well production system, which may comprise a telemetry sensor disposed in a production well below a highly conductive layer and a transmitter. The system may further comprise a well assist system comprising a sensor which is operable to receive information from the transmitter. A method for providing telemetry and communication may comprise determining a location of a well assist system for a well production system, deploying the well assist system to the location, disposing a sensor from the well assist system below a highly conductive layer, and receiving information with the sensor, the information being transmitted from a transmitter of the well production system disposed below the highly conductive layer.

Abstract: A vehicle for detecting fields relevant to the suitability of a location for EM telemetry reception. The vehicle may include a magnetometer, a voltage monitoring system and position sensors. A wireless transmitter may transmit readings from the meters, monitoring systems and/or sensors to a receiver. The vehicle may include equipment for inserting or removing ground conductors for use in receiving electromagnetic telemetry signals. The vehicle may be driven or may drive itself autonomously. The vehicle may obtain measurements of magnetic field and/or potential differences at spaced apart locations along a path. Data obtained by the vehicle may be analyzed to identify hot spots. After selecting hot spots, the vehicle may be configured to insert ground conductors at selected locations within the hot spots. After installing ground rods, the vehicle may be configured to continuously monitor the area to maintain an optimum configuration of ground conductors.

Abstract: A monitoring well installation comprising metallic casing (2) and a sealing material plug (6) provided downhole in the borehole for sealing the borehole against the egress of fluid from a zone below the plug. There is an uncased length of borehole at least 10 m in length in which the plug seals against the formation. There is provided a downhole sensing tool (3) located below the plug (6) and a communication arrangement (31, 5, 4) for use in transmitting data from the sensing tool towards the surface, which comprises an across plug communication apparatus (5) comprising a pair of spaced contacts (51) contacting the casing and/or the formation and a transmitter located below the plug (6) for transmitting signals carrying data across the plug towards the surface.

Abstract: In described examples, there are systems and methods for deployment in proximity to an abandoned well. The systems and methods may help monitor conditions at an abandoned well and/or help communication with downhole communicate devices. In some examples, there is described a communication system that is configured to be deployed in proximity to an abandoned well having a metallic well structure severed below a ground region. The system may include a plurality of receivers configured to be deployed at the ground region in proximity to the abandoned well, and configured to receive data signals from the metallic well structure of the abandoned well via the ground region. The system may comprise a processing unit, in communication with the receivers, and configured to receive and process data signals from the receivers.

Abstract: A system for removing wellbore liquids from a wellbore, the wellbore traversing a subterranean formation and having a tubular that extends within at least a portion of the wellbore. The system includes a positive-displacement solid state pump comprising a fluid chamber, an inlet and an outlet port, each in fluid communication with the fluid chamber, at least one solid state actuator, a first one-way check valve positioned between the inlet port and the fluid chamber, and/or a second one-way check valve positioned between the outlet port and the fluid chamber, the at least one solid state actuator configured to operate at or near its resonance frequency, the solid state pump positioned within the wellbore; and means for powering the solid state pump. A method for removing fluids from a subterranean well is also provided.

Abstract: A dynamic monitoring system for dynamically monitoring injection operations on wells by determining the extent of fracturing using downhole pressure measurements. The system comprises a downhole pressure gauge, means to transmit data from the downhole pressure gauge to the surface and a surface data acquisition unit wherein, on inducing a pressure change in a wellbore by an injection operation, the downhole pressure gauge records a pressure trace as data, the data is transmitted to the surface at a first sampling frequency, the data is stored in the surface data acquisition unit and fracture length is calculated from the stored data to indicate extent of fracturing. Sampling frequencies are outside the known operating ranges.

Abstract: A method and system for an electromagnetic sensor. A method may comprise introducing an electromagnetic induction tool into a wellbore. The electromagnetic induction tool may comprise an insulated section and an electromagnetic device. The method may further comprise performing a first measurement with the electromagnetic induction tool; adjusting an impedance parameter of the insulated section; performing a second measurement with the electromagnetic induction tool; including the first measurement and the second measurement in an inversion process, wherein the inversion process calculates the downhole electromagnetic parameters; and adjusting at least one operational parameter of a well operation based at least in part on the downhole electromagnetic parameters. An electromagnetic sensor system may comprise a conductive body, an electromagnetic device, and a microcontroller configured to adjust an impedance parameter of the insulated section.

Abstract: A downhole electromagnetic modular system has two or more antenna modules incorporated into a drill string, each antenna module comprising an antenna sub and an antenna. The antenna modules may be spaced apart by one or more spacer modules, battery modules, spacer-battery modules, and/or downhole tools. The connected modules (and/or downhole tools) provide an electrical pathway throughout the modular system. An antenna module may have an inner connector formed on its antenna sub between the antenna of that antenna module and a retainer of that antenna sub. An antenna module may have two antenna groups located towards opposite ends of the antenna module and spaced apart by more than half the length of the antenna module. If an antenna group has more than one antenna, those antennas may be co-located or in proximity to one another. A probe may be held fixed by the retainer of the inner pin connector.

Abstract: A comprehensive tire pressure maintenance system for use with motor vehicles that includes a TPMS with an externally mounted battery, tubular battery configured for deployment on a valve stem configured to accommodate deployment of the tubular battery, a self-inflating pressure-optimizing tire arrangement, and a self-inflating run-flat tire arrangement and a wireless tire pressure gauge.

Abstract: A system of near-bit measurement while drilling system includes motor system, measurement transmission system, wireless receiving system and non-magnetic short sub. The measurement transmission system is set inside the motor system, and the transmitting device from the measurement transmission system and the receiving device from the wireless receiving system are set inside the non-magnetic cavity. In the process of drilling via drill bit, the azimuth gamma and the well deviation parameters on the formation where the drill bit is located is able to be measured in real time more accurately and then will make real-time wireless transmission toward the wireless receiving system. Compared with conventional measurement while drilling work, the measurement location of the near-bit measurement while drilling system is nearer to the drill bit with non-hysteretic description of well trajectory and formation gamma measurement so as to enhance the drilling-encounter ratio significantly.

Abstract: Aspects of the disclosure can relate to a method for transmitting a pump-off pressure profile within a limited bandwidth. For example, a method may include selecting a compression protocol based upon at least one of a time length associated with the pump-off pressure data, a relative mean-squared error associated with the pump-off pressure data, or a maximum error associated with the pump-off pressure data. The method also includes compressing pump-off pressure data with the compression protocol to produce compression bits. The compression bits represent the pump-off pressure profile. The method also includes transmitting, via a communication module, the compression bits to a computing device.

Abstract: Methods and apparatus are provided for the measurement of the compressibility of reservoir fluid. A piezoelectric material is coupled to a wall of a fluid chamber. Compressibility is derived from measured pressure changes to the fluid resulting from volumetric changes to the fluid chamber imposed by the mechanical strain of the piezoelectric material resulting from an applied electric field.

Abstract: An example telemetry system for downhole operations in a subterranean formation comprises an electromagnetic (EM) radiation source and an EM radiation detector. A waveguide may be coupled to the EM radiation source and the EM radiation detector. A frequency multiplier may be coupled to the waveguide and positioned within a borehole in the subterranean formation.

Abstract: A method of interpreting a signal transmitted through a drilling fluid disposed within a telemetry channel of a wellbore that includes defining a finite number of distinct message signals for representing conditions within the wellbore. The method also includes transmitting one of the message signals through the telemetry channel, and receiving a distorted signal that includes the message signal as distorted by transmission through the telemetry channel. A channel impulse response is estimated and applied to at least one of the message signals to generate at least one predicted signal. A comparison is made between the predicted signal and the distorted signal, and an estimation is made as to which of the finite number of message signals is included in the distorted signal based on the comparison.

Abstract: A calibration method under a near-bit wireless short-transmission ground environment includes the following steps: placing an emitter and a receiver, which are connected across a screw, in a container containing a solution, connecting the emitter with the receiver through a copper wire to form a loop of an electric field signal, connecting the emitter with a transmitting circuit to achieve signal transmission, connecting the receiver with a receiving circuit to achieve signal reception, and calibrating an optimal transmitting power and a receiving gain by measuring an amplitude relationship between a transmitted signal and a received signal in a case where resistivity values of solutions are different.

Abstract: A system and method for an enhanced interconnect for downhole tools along a drill string used in subterranean operations is described herein. The system (300) may include a first drill string segment (302) comprising a first conductive element (306) and a second drill string segment (304) coupled to the first drill string segment. The system may also include a tool connect assembly (310) disposed within an internal bore of the second drill string segment. The tool connect assembly may comprise a second conductive element (312) electrically connected to the downhole tool, and the second conductive element may be electrically coupled to the first conductive element through at most two electrical interfaces.

Abstract: A system for drilling a subterranean wellbore includes a bottom hole assembly (BHA) coupled to a downhole end of a drill string. The BHA includes an electronic controller having a processor. The drill string includes downhole and uphole portions with the downhole portion made up of wired drill pipe and the uphole portion made up of non-wired drill pipe. The downhole portion further includes at least one downhole tool or sensor sub in communication with the BHA via the wired drill pipe communication link. Methods for making sensor measurements, downlinking data and/or commands to the BHA, and actuating a downhole tool make use of the system.

Abstract: Method and apparatus for generating fluid pulses in a fluid column, such as within a downhole well, are disclosed. A described example fluid pulse generator utilizes a moveable flow conduit through which at least a portion of a downwardly flowing fluid column will pass. The moveable flow conduit can be moved, such as by pivoting, in and out of registry with other components defining the fluid flow path to provide resistance to flow of a selected duration and pattern, and thereby to generate pressure pulses within the fluid column detectable at the surface. In some examples, magnetic actuators will be used to perform the described pivoting of the moveable flow conduit.

Abstract: A wellbore E-field wireless communication system, the communication system comprising a first E-field antenna, and a second E-field antenna, wherein the first antenna, and the second antenna are both arranged in a common compartment, such as an annulus of a wellbore and further arranged for transferring a signal between a first connector of the first E-field antenna and a second connector of the second E-field antenna by radio waves.

Abstract: An electro-acoustic system for downhole telemetry employs a series of communications nodes spaced along a string of casing within a wellbore. The nodes allow wireless communication between transceivers residing within the communications nodes and a receiver at the surface. The transceivers provide node-to-node communication of data indicating elastic waves generated as a result of the formation of subsurface fractures. The data is processed which generates a map of fracture geometry. A method of evaluating fracture geometry in a subsurface formation uses a plurality of data transmission nodes situated along the casing string which send signals to a receiver at the surface. The signals are analyzed which generates a subsurface map.

Abstract: Transmitting acoustic signals from a wellbore. At least some of the illustrative embodiments are methods including transmitting an acoustic signal comprising downhole data, receiving the acoustic signal (the receiving by a receiver disposed within the internal diameter of a casing in the wellbore) converting the acoustic signal to a corresponding first electromagnetic signal, and inducing a second electromagnetic signal in a tubing responsive to the first electromagnetic signal.

Abstract: A system or method includes providing coupler portions along a structure. The coupler portions are communicatively engageable with equipment in the structure.

Abstract: A system for monitoring equipment and transmitting data and/or signals from one or more satellite nodes to a base node for transmission to a monitor or controller for the equipment. The system may transmit high frequency acoustic signals from one or more satellite nodes embedded in the equipment through a structural component of the equipment to the base node, eliminating the need to hardwire the satellite nodes in harsh environments.

Abstract: A hybrid telemetry system for passing signals between a surface control unit and a downhole tool is provided. The downhole tool is deployed via a drill string into a wellbore penetrating a subterranean formation. The hybrid telemetry system includes an uphole connector, a downhole connector, and a cable operatively connecting the uphole and downhole connectors. The uphole connector is operatively connectable to a drill string telemetry system for communication therewith. The downhole connector is operatively connectable to the downhole tool for communication therewith.

Abstract: In accordance with aspects of the present disclosure, techniques for predicting, classifying, preventing, and remedying drilling fluid circulation loss events are disclosed. Tools for gathering relevant data are disclosed, and techniques for interpreting the resultant data as giving rise to an actual or potential drilling fluid lost circulation event are also disclosed.

Abstract: A technique facilitates an improved operation of a tool, such as a downhole tool. The tool is operated in a manner which provides a dynamic or cyclical loading. The dynamic or cyclical loading of the tool is sampled by a suitable sensing system at a frequency greater than the frequency of the dynamic or cyclical loading to collect detailed data on the dynamic or cyclical loading. The data is used to adjust the tool in a manner which improves operation of the tool. One technique for adjusting the tool is changing the dynamic or cyclical loading of the tool by adjusting the frequency of the dynamic or cyclical loading.

Abstract: An apparatus and method for well control and monitoring including an independent web server computer integrated with a pump controller located at each well in an oil field. The well controller locally controls the well pump, processes well and pump data, generates surface and downhole cards, and communicates production reports, recommendations for production improvements, and production statistics to remote sites via the internet. The controller can be queried remotely to provide production reports, etc. Furthermore, the controller can initiate alerts via email, text messaging, or internet messaging, for example, during fault conditions.

Abstract: The method of maintaining drill bit advancement in an underground formation that contains shale, including providing an electrical signal from an insulated gap location in a drill string substantially directly behind the bit in the formation, detecting substantial change in a signal as the bit advances, and changing the direction of drilling of the bit as a function of a signal change, to thereby maintain the direction of bit advancement in the formation. A method is disclosed for detecting the existence and direction of adjacent bed boundaries. A short hop transmitter assembly generates a signal that is detected by an associated receiver assembly. The received signal(s) are tied to the azimuthal orientation of the transmitter or receiver and processed to yield the direction and/or the distance of the bed boundary. This information is transmitted to the surface via surface telemetry for real-time control of the drilling assembly to stay within, or to enter, a pay zone.

Abstract: A system and method to synchronize distributed measurements in a borehole are described. The system includes a plurality of wired segments coupled together by couplers and a plurality of nodes configured to measure, process, or relay information obtained in the borehole to a surface processing system, each of the plurality of nodes comprising a local clock and being disposed at one of the couplers or between couplers. The system also includes a surface processing system coupled to a master clock and configured to determine a time offset between the master clock and the local clock of an nth node among the plurality of nodes based on a downhole generated synchronization signal.

Abstract: A drill pipe made according to one embodiment includes a number of serially connected tubulars with a communication device placed between the connecting ends of the tubulars, wherein the communication device provides a direct data communication link between the adjoining tubulars.

Abstract: A mud pulse telemetry tool is used in a drill string that has a drilling fluid flowing inside. The mud pulse telemetry tool may include a pulser disposed in the drill string and a drive system for driving the pulser. The pulser may include a non-rotating mud pulse stator and a mud pulse rotor disposed proximate to the stator. The drive system may include a turbine stator, a turbine rotor, and a rotatable inertial member magnetically coupled to the turbine rotor. The inertial member may be operatively connected at a first end to the mud pulse rotor. In the mud pulse telemetry tool, rotational energy may be transmitted from the turbine rotor to the rotatable inertial member by a magnetic coupling. The rotatable inertial member may be operatively connected to a supplemental motor that is adapted to supplement rotational energy imparted to the rotatable inertial member by the drive system.