Abstract: Acoustic communication apparatus for use with downhole tools are described. An example acoustic communication apparatus for use in a wellbore includes a first acoustic transducer to generate first acoustic signals. The first acoustic transducer is mounted in an interior of a first drill collar to transmit the first acoustic signals via at least a portion of a body of a drillstring or a mud channel within the drillstring to a second drill collar. Additionally, the example acoustic communication apparatus includes a first receiver mounted to the first drill collar to receive second acoustic signals transmitted from the second drill collar.

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.

Abstract: An apparatus, system and method provides electrical power in a subterranean well. A radioisotope thermoelectric generator may be positioned and installed in a downhole location in a wellbore. The location of the radioisotope thermoelectric generator may be within a completion string. A radioisotope thermoelectric generator comprises a core having a radioisotope for producing heat, and a thermocouple. The thermocouple comprises at least two different metals, and is positioned adjacent to the core. The radioisotope thermoelectric generator flows heat from the core to the thermocouple to produce electricity that may be stored in an energy storage device, or used to power a component. The produced electrical power may be employed to activate downhole sensors, valves, or wireless transmitters associated with the operation and production of an oil or gas well.

Abstract: A data logging sub is mounted at the downhole end of a drill string, and a receiver, or detector is mounted at the top of the drill string at the well-head. The downhole logging sub includes a digital signal transmitter that is operatively connected to the drill string, such that it can send a series of charge pulses along the drill string. The receiver is mounted to detect changes in electrical charge on the drill string. The drill string leaks charge to the surrounding geological formation, but the time constant of the leakage is large compared to the quantity of charge of the charge pulses, and the low resistance of the drill string as compared to the resistivity of the surrounding formation. The leakage is high enough that the charge leaks off the drill string fast enough to permit a useful baud rate.

Abstract: A method for a hydraulic model for subterranean drilling fluids includes acquiring first and second axially spaced temperature and pressure measurements in the wellbore. The pressure measurements may be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density(ies) may be processed in combination with the temperature and pressure measurements to compute one or more unknown coefficients of the hydraulic model.

Abstract: A system for transmitting data along a borehole, comprises a drill string; a bottom hole assembly connected to the drill string including a drilling motor powered by flow of fluid from the drill string, a drill bit connected below the drilling motor and arranged to be rotated by the motor, and at least one sensor being positioned between the drilling motor and the drill bit; a first telemetry system for transmitting data from a first location below the drilling motor to a second location above the drilling motor, the first telemetry system comprising a first transmitter at the first location configured to induce an acoustic signal for propagation along the BHA, and a first acoustic receiver at the second location arranged to receive the acoustic signal; and a second telemetry system comprising two or more transmission channels for transmitting data received by the first acoustic receiver from the second location back up the borehole.

Abstract: A communication system for transmitting information via drilling rod linkages includes a drill drive, drilling rod linkages comprising a first drilling rod linkage and at least one second drilling rod linkage. The first drilling rod linkage comprises an electrical line, an upper end and a lower end which comprises a receptacle for a drill head. The second drilling rod linkage comprises at least one electrical line, an upper end and a lower end. A sensor and/or actuator is arranged at the lower end of the first drilling rod linkage and at the drill head and transmits data. A first communication unit and an electronics unit are arranged at a drive end. A further communication unit is arranged at the upper end of the first drilling rod linkage and at the upper and lower ends of the second drilling rod linkage. The first communication unit and the further communication units are radio modules which transmit/receive data.

Abstract: An expandable tubular sleeve having utility for lining a downhole tubular member includes a tubular body having a portion that is predisposed to initiate expansion thereof under the application of internal fluid pressure. The predisposed portion of the body may be a plastically-deformed portion formed, e.g., by application of mechanical force to a wall of the body. The predisposed portion of the body may be defined by a portion of the body having reduced wall thickness. The reduced wall thickness may be achieved, e.g., by reinforcing the wall thickness everywhere except the predisposed portion. The predisposed portion of the body may be formed by modifying the material properties of the body, e.g., by localized heat treatment. The sleeve and related apparatuses and methods are useful for securing and protecting a cable having one or more insulated conductive wires for transmission of signals between locations downhole and at the surface.

Abstract: Apparatus and systems, as well as methods, operate to acquire downhole data associated with a borehole casing, process a portion of the downhole data at a downhole location to provide processed data, and regulate surface motor power received at a motor downhole. The surface motor power is filtered and the processed data is transmitted to a surface location on a monoconductor that also carries the surface motor power. Additional apparatus, systems, and methods are disclosed.

Abstract: An electric system for measurement and control in an oil/gas well using transmission of electric signals and supply of electric power. The system is provided with a current loop having an essentially constant current in a current loop and a number of downhole network nodes (1N) which are connected to the system.

Abstract: A wireless communication and drill string telemetry system. The communication system is used for communicating information along a drill string between a boring tool and a boring machine. An insulator assembly provides an electrically insulated gap between the drill string communication path and a soil engaging electrode for the electrical return path. A transmitter assembly includes a data transmitter for encoding and transmitting a data signal. A signal coupler couples the data signal to the drill string and provides a controlled electrical connection between the drill string communication path and the soil engaging electrode. The signal coupler comprises a transformer and a current regulating circuit to adjust a voltage across the transformer's primary winding. A receiver assembly is disposed proximate the drilling machine and includes a toroidal pickup coil and a signal processing assembly.

Abstract: A system and method are provided for providing electromagnetic (EM) measurement-while-drilling (MWD) telemetry capabilities using an existing mud-pulse MWD tool. An EM tool intercepts the output from the mud-pulse tool and generates an EM signal that mimics a mud-pulse pressure signal. The EM signal is intercepted at the surface by a receiver module that conditions the signal and inputs the signal into the existing pulse tool receiver. Since the EM signal mimics a mud-pulse signal, the pulse tool receiver does not require software or hardware modifications in order to process an EM telemetry mode. The EM tool can be adapted to also provide dual telemetry by incorporating a conventional pressure pulser that would normally be used with the pulse tool.

Abstract: A measurement and communication system for use with a tubular string, comprises a tubular string having a plurality of self-powered, autonomous telemetry stations disposed at predetermined locations along the tubular string. Each autonomous telemetry station is adapted to receive at least one first signal and transmit at least one second signal related to the at least one first signal. Power is extracted from potential energy sources proximate each autonomous telemetry station. A method of communicating information along a tubular string comprises, disposing an autonomous telemetry station at predetermined locations along the tubular string. A preferred transmission path is autonomously determined at each of the autonomous telemetry stations. Information is transmitted along the tubular string according to the autonomously determined preferred path.

Abstract: Structure for deep MWD resistivity measurements suitable for both geo-steering and measurements ahead of the drill bit is disclosed. Alternating current is transmitted through a loop and an induction signal is measured by a two-coil bucking receiving system placed at some distance from the transmitter. To further reduce a parasitic effect of the currents in the pipe, a conductive copper shield wrapping around the pipe is used. The length of the shield is about one and one-half to two times longer than the longest transmitter/receiver spacing of the structure. The transmitter/receiver system is located in the center of the described electromagnetic shield.

Abstract: An acoustic isolator for use with tubular assemblies such as drillpipe or production tubing comprising an acoustic wave transmitter, the acoustic isolator comprising, in series connection, an odd integer ?/4 multiple tuning bar of first acoustic impedance adjacent the acoustic wave transmitter, an odd integer ?/4 multiple reflector tube of second acoustic impedance, and a snubber of third acoustic impedance, wherein there is an acoustic impedance mismatch between the odd integer ?/4 multiple tuning bar and the odd integer ?/4 multiple reflector tube and an acoustic impedance mismatch between the odd integer ?/4 multiple reflector tube and snubber, such that a ‘down’ wave propagated toward the isolator is reflected back substantially in phase with an ‘up’ wave propagated from the acoustic wave source away from the isolator.

Abstract: The present invention concerns application of a unique conductive electrode geometry used to form an efficient wideband, one- or two-way wireless data link between autonomous systems separated by some distance along a bore hole drill string. One objective is the establishment of an efficient, high bandwidth communication link between such separated systems, using a unique electrode configuration that also aids in maintaining a physically robust drill string. Insulated or floating electrodes of various selected geometries provide a means for sustaining or maintaining a modulated electric potential adapted for injecting modulated electrical current into the surrounding sub-surface medium. Such modulated current conveys information to the systems located along the drill string by establishing a potential across a receiving insulated or floating electrode.

Abstract: A communication module for transfer of information along a drill string has at least one antenna coil, wherein the communication module is configured such that a central coil axis of the antenna coil is substantially perpendicular to a longitudinal axis of a drill pipe to which it is affixed. Signals are relayed magnetically from node to node to exchange data along any desired length of drill string. The drill string itself forms a portion of the magnetic flux path and the earth and/or surrounding media forms another substantial portion of the closed flux path. Magnetic induction is advantageous because the steel drill pipe is ferromagnetic and exhibits a magnetic permeability of a few hundred to a few thousand times that of air.

Abstract: A downhole signal transmission system provides electric radiofrequency signals that are coupled to electrically conductive or non-conductive fluids through electrical insulators. A plurality of signal repeaters are tuned to the frequencies of the radiofrequency signals, and a plurality of transmission lines terminated by resonance circuits are also provided such that the terminating resonance circuits resonate on the frequencies of the electric radiofrequency signals. The plurality of signal repeaters and plurality of transmission elements are arranged to be redundant such that a failure of one or more of the signal repeaters or a failure of one or more of the transmission elements does not substantially affect the operation of the data transmission system. The signal repeaters and transmission elements also are arranged such that a failure of any of the signal repeaters or a failure of any of the transmission elements is communicated to the surface.

Abstract: A downhole communication device comprises a first energy harvesting device; a downhole transceiver in communication with the first energy harvesting device; an accumulator in communication with the energy harvesting device; and a microcontroller. The microcontroller manages communication between the first energy harvesting device, transceiver, and accumulator.

Abstract: A drill string component includes a box-end and a pin-end. Each end includes a signal transceiver, which are operably coupled together. Each signal transceiver communicates with another signal transceiver in another component to form a communication network in the drillstring. An end-cap may be placed in the central bore of the pin-end of a component to form an annular chamber between a side of the end-cap and a wall of the central bore of the pin-end when the end-cap is disposed in the central bore. In some embodiments, an electronics module may be placed in the annular chamber and configured to communicate with one of the signal transceivers. Accelerometer data, as well as other sensor data, at various locations along the drillstring may be sampled by the electronics module and communicated to a remote computer. Drillstring motion dynamics, such as vibration, may be determined based on the accelerometer data.

Abstract: A downhole signal receiving system where a pair of setting devices (51) are used to electrically connect with downhole structure and are connected to one another by a bulk conductor (52). Signals are extracted by using a detecting means (53) that does not interrupt the conduction path. The tool provides a low impedance conduction path along which signals from the surrounding structure can flow to facilitate detection.

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: A system for communicating between a first location and a second location comprises a jointed tubular string having a first section and a second section connected at a connection joint, with the tubular string having a fluid in an internal passage thereof. A first acoustic transducer is mounted in the internal passage of the first section proximate the connection joint, and a second acoustic transducer is mounted in the internal passage of the second section proximate the connection joint. A signal transmitted from the first location to the second location is transmitted across the connection joint as an acoustic signal in the fluid from the first acoustic transducer to the second acoustic transducer.

Abstract: An MWD data transmission system and method for determining and transmitting the environmental properties of the downhole borehole assembly (BHA) to surface data receivers via mud pulse telemetry, EM telemetry, or both mud pulse telemetry and EM telemetry based on one or more determined properties of the downhole environment.

Abstract: A method of signal processing includes providing at least a first pressure sensor and a second pressure sensor spaced in a drilling system and using an algorithm to separate the downwardly propagating waves from the upwardly propagating waves. In one or more examples, an algorithm may include determining a velocity of pressure signals in a wellbore, time-shifting and stacking pressure signals from at least the first pressure sensor and the second pressure sensor to determine a downwardly propagating noise signal, and subtracting the downwardly propagating noise signal from at least the signal from the first pressure sensor.

Abstract: A method and apparatus for estimating a change in length of a wellbore conveyance device in a wellbore. A reference signal is sent along a first path and a wellbore signal having a phase relationship with the reference signal is sent along a wellbore path. A change in length of the wellbore conveyance device is estimated from a phase shift between the reference signal and the wellbore signal. The frequency of the wellbore signal may be changed downhole. The wellbore conveyance device may have at least one conductor under a maintained tension. A length of the wellbore conveyance device is estimated from the estimated change in the length. For a drill string composed of a plurality of wellbore tubulars, a phase shift of the drill sting is determined upon adding a wellbore tubular to the drill string.

Abstract: An embodiment of a wireless telemetry system for providing signal communication across a wired-communication gap in a bottom-hole assembly (“BHA”), the BHA having an upper portion and a lower portion separated by the wired-communication gap, includes an upper transceiver positioned in the upper portion and in signal communication with a surface telemetry system and a lower transceiver positioned in the lower portion and in signal communication with a drilling tool, the upper and the lower transceivers in signal communication with one another via wireless induction telemetry. Each transceiver may include an antenna that is positioned within the bore of a drill collar adjacent to a thinned wall section in the drill collar. The thinned wall section may include one or more of increasing an inside diameter relative to a base inside diameter of the bore and decreasing an outside diameter relative to a base outside diameter of the drill collar.

Abstract: A method for enhancing downhole telemetry performance comprising enhancing a signal in order to offset signal-to-noise ratio reduction with increasing measured depth, wherein the signal is modified at specified measured depths which are inferred from acoustic wave velocity determination.

Abstract: A telemetry system for communication in a borehole uses two spaced-apart transducers. The outputs from the two transducers are filtered to decoupled tool signals traveling in opposite directions. One of the two signals may be it telemetry signal while other signal may be pump noise.

Abstract: A method and system are presented for transmitting data along tubing in a borehole, comprising generating an acoustic signal using a transmitter at a first location on the tubing, and receiving the acoustic signal at a receiver at a second location on the tubing. The method and system further comprise: (i) generating the acoustic signal at the transmitter at a first frequency and bit rate; (ii) receiving the acoustic signal at the first frequency at the receiver and attempting to synchronise the receiver at the first frequency, and (iiia) if the synchronization is successful, continuing to transmit the acoustic signal so as to pass the data from the transmitter to the receiver; or (iiib) if the synchronization is unsuccessful, adjusting the frequency and/or bit rate of the signal and repeating steps (i)-(iii) on the basis of the adjusted signal.

Abstract: A method of signal processing includes providing at least a first pressure sensor and a second pressure sensor spaced in a drilling system and using an algorithm to separate the downwardly propagating waves from the upwardly propagating waves. In one or more examples, an algorithm may include determining a velocity of pressure signals in a wellbore, time-shifting and stacking pressure signals from at least the first pressure sensor and the second pressure sensor to determine a downwardly propagating noise signal, and subtracting the downwardly propagating noise signal from at least the signal from the first pressure sensor.

Abstract: An acoustic telemetry apparatus and methods for communicating digital data from a down-hole location through a borehole to the surface or between locations within the borehole are described including a receiver and a transmitter linked by an acoustic channel (210) wherein acoustic channel has a cross-sectional area of 58 cm2 or less and the transmitter comprises an electro-active transducer generating a modulated continuous waveform.

Abstract: Non-contacting means of measuring the material velocities of harmonic acoustic telemetry waves travelling along the wall of drillpipe, production tubing or coiled tubing are disclosed. Also disclosed are contacting means, enabling measurement of accelerations or material velocities associated with acoustic telemetry waves travelling along the wall of the tubing, utilizing as a detector either a wireless accelerometer system or an optical means, or both; these may also be applied to mud pulse telemetry, wherein the telemetry waves are carried via the drilling fluid, causing strain in the pipe wall that in turn causes wall deformation that can be directly or indirectly assessed by optical means. The present invention enables detection of telemetry wave detection in space-constrained situations. The invention also teaches a substantially contactless method of determining the time-based changes of the propagating telemetry waves.

Abstract: A casing sensor and methods for sensing using a casing sensor are disclosed. The casing sensor includes a casing shoe and a sensor coupled to the casing shoe. A casing data relay includes a downhole receiver coupled to a well casing and a transmitter coupled to the receiver. The casing sensor may be coupled to the transmitter. A drill string actuator may be controllable through the downhole receiver.

Abstract: Non-contacting means of measuring the material velocities of harmonic acoustic telemetry waves travelling along the wall of drillpipe, production tubing or coiled tubing are disclosed. Also disclosed are contacting means, enabling measurement of accelerations or material velocities associated with acoustic telemetry waves travelling along the wall of the tubing, utilizing as a detector either a wireless accelerometer system or an optical means, or both; these may also be applied to mud pulse telemetry, wherein the telemetry waves are carried via the drilling fluid, causing strain in the pipe wall that in turn causes wall deformation that can be directly or indirectly assessed by optical means. The present invention enables detection of telemetry wave detection in space-constrained situations. The invention also teaches a substantially contactless method of determining the time-based changes of the propagating telemetry waves.

Abstract: The disclosure has application for use in conjunction with an operation of drilling an earth borehole using: a drilling rig, a drill string having its generally upper end mechanically coupleable with and suspendable from the drilling rig, and a bottom hole assembly adjacent the lower end the drill string, the bottom hole assembly including a drill bit at its lower end.

Abstract: A method and apparatus for transmitting data across a tool joint connection. In one embodiment, the system includes a first data transmission element connected to a first downhole component, a second data transmission element connected to a second downhole component, and a biasing element biasing at least one of the first and second data transmission elements towards the other data transmission element such that the first and second data transmission elements are in data communication with each other.

Abstract: A drilling system utilizing a plurality of independent telemetry systems. The drilling system uses a drill collar as a pressure housing for downhole components of the system. One or more sensors are disposed within the pressure housing. These sensors can be MWD sensors, LWD sensors, or both MWD and LWD sensors. A plurality of independent borehole telemetry systems is used to telemeter sensor response data to the surface of the earth. Each sensor cooperates with a downhole component of at least one of the independent telemetry systems. The plurality of telemetry systems can be of the same type, such as a mud pulse systems. Alternately, the telemetry systems can be of different types including a mud pulse system and an electromagnetic system.

Abstract: A downhole electromagnetic telemetry unit for use with a tubing string (5) includes an insulated electrically conductive member (31) and a processing unit (15). The insulated electrically conductive member (31) is electrically coupled to the tubing string (5) at an upper measuring point (23) and a lower measuring point (25). The processing unit (15) is configured to process a voltage difference measured between the upper measuring point (23) and the lower measuring point (25) across the insulated electrically conductive member (31) and to derive therefrom a signal transmitted from a surface location (13).

Abstract: Acoustic communication apparatus for use with downhole tools are described. An example acoustic communication apparatus for use in a wellbore includes a first acoustic transducer to generate first acoustic signals. The first acoustic transducer is mounted in an interior of a first drill collar to transmit the first acoustic signals via at least a portion of a body of a drillstring or a mud channel within the drillstring to a second drill collar. Additionally, the example acoustic communication apparatus includes a first receiver mounted to the first drill collar to receive second acoustic signals transmitted from the second drill collar.

Abstract: A method for enhancing downhole telemetry performance comprising enhancing a signal in order to offset signal-to-noise ratio reduction with increasing measured depth, wherein the signal is modified at specified measured depths which are inferred from acoustic wave velocity determination.

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: A coaxial transmission line for an electromagnetic wellbore telemetry system is disclosed. An inner conductive pipe is disposed inside an axial bore of the outer conductive pipe. An insulator is positioned between the outer conductive pipe and the inner conductive pipe. In a specific embodiment, the inner conductive pipe is perforated or slotted.

Abstract: A cycleable downhole tool such as a Jar, a hydraulic hammer, and a shock absorber adapted for telemetry. This invention applies to other tools where the active components of the tool are displaced when the tool is rotationally or translationally cycled. The invention consists of inductive or contact transmission rings that are connected by an extensible conductor. The extensible conductor permits the transmission of the signal before, after, and during the cycling of the tool. The signal may be continuous or intermittent during cycling. The invention also applies to downhole tools that do not cycle, but in operation are under such stress that an extensible conductor is beneficial. The extensible conductor may also consist of an extensible portion and a fixed portion. The extensible conductor also features clamps that maintain the conductor under stresses greater than that seen by the tool, and seals that are capable of protecting against downhole pressure and contamination.

Abstract: A system or corresponding method provides for communicating data in confined waveguides containing a fluid. The system includes processing and transmitter/receiver operations at nodes in or alone the confined waveguides and transducers to produce a propagation signal that transmits modulated data via the fluid in the confined waveguide. Applications include sensing information about the fluid, such as the pressure, pH, or other parameter(s), and transmitting that data via the fluid in the confined waveguide. For example, the system may be distributed about an oil pipeline or network of oil pipelines. Nodes in the system may include turbines that generate power for use by the nodes at levels sufficient to support the node for its activities. Signal processing and multiple transducers at each node may be employed to extend distances up to kilometers between nodes for low-cost operation of the system.

Abstract: A power source for use in a downhole environment. The power source can include a microgenerator, where the microgenerator is comprised of a motive source, a rotor, a stator, and an electrical load. The motive source can be compressed gas, liquid, two-phase fluid, or combustion gases. The rotor may comprise a magnet and the stator may comprise a coil, such that rotating the rotor coaxially proximate to the stator produces electrical current. The electrical load includes any device used in downhole exploration and production that requires electrical energy.

Abstract: A method for enhancing downhole telemetry performance comprising enhancing a signal in order to offset signal-to-noise ratio reduction with increasing measured depth, wherein the signal is modified at specified measured depths which are inferred from acoustic wave velocity determination.

Abstract: Methods and systems are described for communicating with downhole locations and transmitting power to downhole locations. Use is made of a cable passing someway down into the well. This cable may be connected to a downhole sensor and may be used primarily for communicating with that sensor, but also used in the current techniques described herein. Electrical connection is achieved between the cable and the metallic structure of the well to allow signals to be transferred between the communications tool and the surface via the cable.

Abstract: A wired drill pipe for a drill string of a downhole tool positioned in a wellbore penetrating a subterranean formation is provided. The wired drill pipe includes a drill pipe, a cable and a wire retainer. The drill pipe has a slot at each end thereof. The slots are adapted to receive at least one transformer. The drill pipe has an inner surface defining a passage for the flow of mud therethrough. The cable extends from the transformer into the passage of the drill pipe. The wire retainer is positioned on the inner surface of the drill pipe. The wire retainer is adapted to secure the cable therein.

Abstract: A method whereby a downhole drilling transmission device that communicates to the surface automatically modifies its transmission parameters in order that it substantially improves its ability to adequately communicate with a surface receiver despite increasing signal attenuation between the two as the length of drillpipe increases. This utilizes a simple measure of localized downhole pressure that then relies upon a look-up table or similar that provides a correspondence between said pressure and measured depth. Such a look-up table or similar can be readily built by incorporating appropriate features of the planned well such as drilling fluid flow rate, drilling fluid density, drilling fluid viscosity, well profile, bottom hole assembly component geometry, drillpipe geometry, and indications as to whether the fluid is flowing or stationary.