Abstract: The specification discloses algorithms for error recovery in pulse position modulation-based mud pulse telemetry. More particularly, the specification discloses detection and attempted correction of at least five possible error mechanisms: the missed detection of a pulse that creates an interval greater than maximum; the missed detection of a pulse that results in an interval still within acceptable boundaries; detection of an extra pulse; a pulse shift that results in data in contiguous intervals being affected; and a pulse shift resulting in a single interval data corruption.

Abstract: A method is disclosed for reducing noise in a measured telemetry signal. The method includes tracking a characteristic of at least one harmonic of a noise component in the measured telemetry signal band. The at least one harmonic has a frequency outside a telemetry signal band. The characteristic of the noise component is determined for at least one other harmonic thereof. The at least one other harmonic has a frequency inside the telemetry signal band. A noise reference is generated from the characteristic of the in band harmonic, and the noise reference is combined with the measured telemetry signal to generate a noise-canceled telemetry signal.

Abstract: A pressure pulse generator to generate pressure signals in drilling fluid for transmission to surface comprising: an outer housing (100) having an inlet (9) and an outlet for supply to the drilling assembly (59); a control element (10) slidably mounted in the housing (100) for opening and closing said inlet (9), said element being operative to generate a pressure pulses when it closes; a control passage (26, 27, 28) extending through the element (10) and closable by a valve element (36) arranged to be exposed to the pressure in the passage; and an actuator assembly (13, 14, 15, 17, 19, 21, 35, 36, 37) connected to the control element (10). The control element moves upon activation (10) relative to the inlet to generate a pulse. When deactivated, it blocks the flow through the passage (26, 27, 28) so that all of the fluid bypasses via the inlet.

Abstract: The invention is directed to a borehole logging apparatus for deep well drilling, with a signal transmitter for transmitting measured data obtained while drilling from a borehole through the drilling fluid to the earth's surface, and with an elongated housing which is adapted for insertion in the drilling fluid conduit of a drill string. Accommodated in the housing is a flow regulator with a control piston, which controls the cross-section of opening of a bypass opening in response to the pressure differential generated at an entrance opening of the housing and the force of a spring, in such manner that the part of the drilling fluid current delivered to the housing conduit, which is fed to the signal transmitter, is maintained substantially constant, and the remaining excess drilling fluid current is routed to the drilling fluid conduit via the bypass opening.

Abstract: A mud pulse telemetry system comprises a surface located fluid supply line having a drilling fluid flowing therein. A non-venting pulser is disposed in the drilling fluid in the supply line, and the non-venting pulser is adapted to generate pressure fluctuations in the flowing drilling fluid. A downhole receiver in hydraulic communication with the non-venting pulser is adapted to detect the pressure fluctuations in the drilling fluid. A method for transmitting pressure signals from a surface location to a downhole location in a wellbore, comprises disposing a non-venting pulser in a surface located fluid supply line having a drilling fluid flowing therein. The non-venting pulser is actuated to generate pressure fluctuations in the flowing drilling fluid according to a predetermined encoding scheme. The pressure fluctuations are detected with a downhole receiver in hydraulic communication with the non-venting pulser.

Abstract: In a borehole logging apparatus (1) for deep well drillings having a device for transmitting measured data obtained while drilling from a borehole through the drilling fluid to the earth's surface, there is arranged in the upper end of a housing (2) a signal transmitter (13) comprising a beaker-shaped rotor (24) and a stator sleeve (25) surrounding said rotor. Fluid impinges on the signal transmitter (13) through a central feed pipe (15) surrounded by an exchangeable bypass ring (14) to which the complete current of drilling fluid is routed through a filter pipe (3) and through which part of the drilling fluid current is routed back into the drill string (6). From a set of bypass rings (14) of different bypass cross sections it is possible to select one suited for the particular on-site conditions and insert it into the logging apparatus (1) in order to obtain a significant signal through the signal transmitter (13).

Abstract: A method and system for telemetry through a drilling fluid during drilling is disclosed. A reflector (110) is positioned downstream from the drilling mud pumps (80) and causes reflected pressure waves having the same pressure polarity as incident pressure waves traveling upwards. At least one pressure sensor (92) is positioned below the reflector (110) to sense pressure in the drilling fluid. The reflector can be a fixed orifice plate or an adjustable aperture.

Abstract: A well control valve assembly having a downhole portion with a primary valve, and electromechanical actuator connected to the valve and a first wireless communicator connected to the actuator. The assembly further includes an uphole portion having a pump, a second wireless communicator complementary to the first wireless communicator and being supported in the uphole portion of the valve assembly. The downhole portion and uphole portion are physically non-connected and informationally connected.

Abstract: A pressure pulse sensor and associated methods provide enhanced functionality and convenience in detecting pressure pulses. In a described embodiment, a hydrophone includes a stack of disc-shaped lead titanate piezoelectric crystals enclosed within an epoxy membrane and a mounting portion which is aligned with a center of mass of the crystal stack.

Abstract: Data is transmitted along a borehole containing a drill stem (2) by means of a transmitter (6) which converts electric data signals to acoustic signals propagating along the drill stem (2). The acoustic signals are converted back to electric form by a receiver (12) which also processes the signals. In the preferred form the signals are stored in a receiver memory (15) for subsequent retrieval using a pick-up tool (5) lowered into the borehole. The system is particularly useful in moving data past an obstruction such as a shut-in valve (4).

Abstract: An oscillating shear valve system for generating pressure fluctuations in a flowing drilling fluid comprising a stationary stator and an oscillating rotor, both with axial flow passages. The rotor oscillates in close proximity to the stator, at least partially blocking the flow through the stator and generating oscillating pressure pulses. The rotor passes through two zero speed positions during each cycle, facilitating rapid changes in signal phase, frequency, and/or amplitude facilitating enhanced, multivalent data encoding. The rotor is driven by a motorized gear drive. In one embodiment, a torsional spring is attached to the motor and the resulting spring mass system is designed to be near resonance at the desired pulse frequency. The system enables the use of multivalent encoding schemes for increasing data rates.

Abstract: An oscillating valve driven by the pressure in a mud pulser develops a pressure variation in the mud pulse signal that is at a frequency that is different than the frequencies of the mud system. The oscillating valve is coupled to or integral with the pulse drive cylinder, whether the drive means for operation of the pulser is upstream or downstream from the orifice, or whether or not the drive means and the poppet are on the same side or opposite sides of the orifice. The oscillating valve is a bistable valve which preferably forms one wall of the drive piston of the pulser. Pressure from the drive cylinder behind the drive piston is directed in such a way as to unseat the bistable valve. When the bistable valve unseats, pressure is bled from within the drive cylinder, which also bleeds the pressure that unseated the bistable valve in the first place.

Abstract: The invention describes a method and apparatus for effectively communicating data along the acoustic channel of a subterranean well. The method comprises optimally driving an acoustic transmitter with an adaptive transmitter controller. A data signal is transmitted along the acoustic channel and detected as a distorted signal along the acoustic channel. The distorted signal is input to the adaptive transmitter controller which, based on the detected signal, modifies later transmissions to counteract the distorting effects of the transmitter and acoustic channel. The adaptive transmitter controller preferably comprises a neural network. Another receiver may be employed, at a point further from the transmitter, to receive the optimized signals.

Abstract: A downlink telemetry system providing improved apparatus and methods for communicating instructions via pressure pulses from surface equipment to a downhole assembly. The apparatus comprises a surface transmitter for generating pressure pulses, a control system, and a downhole receiver for receiving and decoding pulses.

Abstract: A reciprocating pulser system for generating pressure fluctuations in a flowing drilling fluid comprising a reciprocating poppet and a stationary valve assembly with axial flow passages. The poppet reciprocates in close proximity to the valve assembly, at least partially blocking the flow through the valve assembly and generating oscillating pressure pulses. The poppet passes through two zero speed positions during each cycle, enabling rapid changes in signal phase, frequency, and/or amplitude thereby facilitating enhanced data encoding. The poppet is driven by a linear electric motor disposed in a lubricant filled housing. In one embodiment, the housing to shaft seal is a flexible bellows. In one embodiment, a force balance spring is used to essentially offset the hydraulic flow forces on the poppet. In one embodiment, a bypass poppet is used to adjust the differential pressure across the valve assembly.

Abstract: A subsea communication system is used to communicate between a position that is proximal to a surface of the sea and an apparatus of the seabed. The subsea communication system includes an umbilicalless communication system.

Abstract: An apparatus and method of communicating in a tubular system (20) through a media (65) disposed therein and actuating a controllable device (58)are disclosed. The apparatus and method utilize a transmission apparatus (16) at a transmission node that is in communication with the media (65). The transmission apparatus (16) generates pressure impulses that are propagated through the media (65). The pressure impulses may be either positive or negative pressure impulses depending upon the selected transmission apparatus. The pressure impulses are detected by a reception apparatus (77) at a reception node. The detection apparatus may detect the pressure impulses as variation in the media (65) or as variation in the tubular system (20) caused by the pressure impulses. Once the detection apparatus (77) has detected the appropriate pressure impulse or pattern of pressure impulses, a signal may be generated to actuate the controllable device (58).

Abstract: An acoustic transmission system is presented, wherein acoustic communication is transmitted over an acoustic medium comprising production tubing, well casing or over continuous tubing in a well (e.g., coil tubing, chemical injection tubing or dewatering string). More specifically, the acoustic medium has an acoustic tool associated therewith, which is permanently located downhole with the sensors and electromechanical devices typically employed in a well, and an acoustic tool associated therewith uphole. The downhole sensors are connected to the downhole acoustic tool for acoustic communication. The acoustic tool includes a piezoelectric ceramic transducer (i.e., a stack of piezoelectric elements) or an accelerometer for transmitting or receiving acoustic signals transmitting through the medium.

Abstract: A downhole string includes a system having an actuator module that is responsive to electrical power and signals communicated down a cable, such as a permanent downhole cable (PDC). In addition, a backup mechanism, such as an inductive coupler mechanism or another type of wireless apparatus, can be used as a backup to restore power and communications with the downhole system. For example, if the cable fails for some reason, power and signals can still be communicated with the inductive coupler mechanism or other wireless mechanism to control operation of the system or to receive signals from the system.

Abstract: A pressure pulse sensor and associated methods provide enhanced functionality and convenience in detecting pressure pulses. In a described embodiment, a hydrophone includes a stack of disc-shaped lead titanate piezoelectric crystals enclosed within an epoxy membrane and a mounting portion which is aligned with a center of mass of the crystal stack.

Abstract: The invention is directed to a borehole logging apparatus for deep well drilling, with a signal transmitter for transmitting measured data obtained while drilling from a borehole through the drilling fluid to the earth's surface, and with an elongated housing which is adapted for insertion in the drilling fluid conduit of a drill string. Accommodated in the housing is a flow regulator with a control piston, which controls the cross-section of opening of a bypass opening in response to the pressure differential generated by a flow restrictor and in response to the force of a spring in such manner that the part of the drilling fluid current fed to the signal transmitter through the flow restrictor is maintained substantially constant, and the remaining excess drilling fluid current is routed to the drilling fluid conduit via the bypass opening.

Abstract: A method and related system for detecting mud pulse telemetry by measuring pressure fluctuations in drilling fluid by measuring mud pressure pulses at two locations. A first location is somewhat downstream of the mud pump and desurger and a second location is proximate to the mud pump and desurger. Given these two pressure signals they are subtracted to create a difference signal where the presence or absence of mud pressure pulses is determined by pressure spikes caused by the interaction of mud pressure pulses. A second method measures the mud pressure pulse at only one location.

Abstract: A method and apparatus for communicating coded messages in a wellbore between a transmission node and a reception node is provided. The coded messages are messages are impressed upon a fluid column which extends between the transmission node and the reception node. A transmission apparatus is provided at the transmission node which is in communication with the fluid column, for altering pressure of the fluid column to generate at least a portion of the coded message. A reception apparatus is provided at the reception node. The reception apparatus includes a rigid structural component with an exterior surface which is in direct contact with fluid column and an interior surface which is not in contact with the fluid column, and a sensor assembly which detects elastic deformation of the rigid structural component. The transmission apparatus is utilized to alter pressure of the fluid column in a predetermined pattern to generate at least one coded message.

Abstract: A system is disclosed for synchronizing a clock in a well containing a drill string with a clock located near the surface of the well. The system includes devices for transmitting and receiving a pair of acoustic signals between locations associated with each clock and processing those signals. The system determines the time of arrival of each acoustic signal by analyzing the shape of a function of the acoustic signal chosen from a group of functions suitable to determine a clock offset with millisecond accuracy.

Abstract: A system and method in accordance with the invention communicator remotely with remotely controllable down hole tools in a well bore at a drilling installation. At the surface, high energy pressure impulses directed into the tubing or the annulus, or both, being at a level to propagate through an interface between very different impedances zones, such as an upper level gas zone and a lower level of mobile fluid media extending down into the desired downhole location. The pressure impulses, provided by directionally gating along the longitudinal confining path a pressure impulse initially having sharp leading and trailing edges, reach the downhole location as physical perturbations forming a discernible pattern that can be detected by one or more energy responsive transducers. With combinations of these signals, one of a number of separate control devices can be remotely actuated.

Abstract: An apparatus and method of communicating in a tubular system (20) through a media (65) disposed therein and actuating a controllable device (58) are disclosed. The apparatus and method utilize a transmission apparatus (16) at a transmission node that is in communication with the media (65). The transmission apparatus (16) generates pressure impulses that are propagated through the media (65). The pressure impulses may be either positive or negative pressure impulses depending upon the selected transmission apparatus. The pressure impulses are detected by a reception apparatus (77) at a reception node. The detection apparatus may detect the pressure impulses as variation in the media (65) or as variation in the tubular system (20) caused by the pressure impulses. Once the detection apparatus (77) has detected the appropriate pressure impulse or pattern of pressure impulses, a signal may be generated to actuate the controllable device (58).

Abstract: An acoustic telemetry system is disclosed that reduces any through-drillstring drilling noise which contaminates a through-drillstring telemetry signal. Normal filtering operations are provided to remove noise outside the frequency band of interest, and reference signal filtering operations are provided to reduce the in-band noise, thereby enhancing the telemetry system's data rate and reliability. In one embodiment, the acoustic telemetry system includes a transmitter and a receiver. The transmitter induces an acoustic information signal that propagates along the tubing string. Existing noise in the tubing string contaminates the information signal. The receiver is provided with sensors for measuring the corrupted information signal and a reference signal that is indicative of the noise present in the measured information signal.

Abstract: A reliable, high data rate, downhole acoustic telemetry system is disclosed. In one embodiment, the acoustic telemetry system includes a tubing string with an acoustic transmitter and an acoustic receiver mounted on it. The acoustic transmitter transmits telemetry information by modulating an acoustic carrier frequency that propagates along the walls of the tubing string. The transmitter is preferably mounted at a selected position relative to the end of the tubing string. The selected position is preferably less than &lgr;/4 from the end or approximately n&lgr;/2 from the end, where &lgr; is the wavelength of the carrier frequency in the tubing string, and n is a positive integer. In a more preferred embodiment, n may be the lesser of 4 times the number of cycles in the modulating toneburst and 40. The receiver is preferably mounted at approximately (2n−1)&lgr;/4 relative to the end of the tubing string, where n is a positive integer.

Abstract: A method and apparatus for acoustically actuating wellbore tools using two-way acoustic communication is disclosed.

Abstract: This invention is a method of conducting seismic prospecting operations using a drilling tool (1) acting at the bottom of a well (2), which creates very powerful seismic vibrations, transmitting reference signals representing the vibrations of the tool in real time or later, and correlating the seismic signals picked up by a receiving assembly (12) with the reference signals. The reference signals are furnished by sensors (7) in contact with the drill string and at a distance from the down-hole assembly constituted by tool (1) and associated drill collars (4). In order for these reference signals to be truly representative, a damping means (8, 19) and at least one filtering element (20) designed to attenuate to a great degree the multiple reflections in a frequency range useful for seismic prospecting are interposed into the drill string. The invention has application to the making of seismic recordings.

Abstract: A system is disclosed for generating and transmitting data signals to the surface of the earth while drilling a borehole, the system operating by generating pressure pulses in the drilling fluid filling the drill string. The system is designed to maximize signal strength while minimizing the probability of jamming by drilling fluid particulates. The system uses a rotary valve modulator consisting of a stator with flow orifices through which drilling fluid flows, and a rotor which rotates with respect to the stator thereby opening and restricting flow through the orifices and thereby generating pressure pulses. The flow orifices with the stator in a “closed” position are configured to reduce jamming, and to simultaneously minimize flow area in order to maximize signal strength. This is accomplished by imparting a shear to the fluid flow through the modulator, and minimizing the aspect ratio and maximizing the minimum principal dimension of the closed flow area.

Abstract: A system is used with a well that has a downhole tool which is responsive to a stimulus. The system includes a fluid circulation path that is connected to circulate a fluid and a flow restrictor that is connected in the fluid circulation path and located at the surface of the well. A controller causes the flow restrictor to selectively alter flow of the fluid in the circulation path, and a link is coupled to the circulation path to furnish the stimulus to the downhole tool in response to the alteration of flow by the flow restrictor.

Abstract: The method of remotely actuating a downhole device provides the initiation of an acoustic signal. The acoustic signal is amplified within a resonance chamber and is transmitted down a fluid column in the tubing string or in the annulus around the tubing string. The signal can be coded to allow activation of multiple downhole devices. The use of a resonance chamber allows for the amplification of the actuation signal to ensure that a downhole receiver can detect it. The receiver can be either a transducer or a hydrophone. The apparatus and method allow for remote actuation without the need for intervention into the well.

Abstract: An electromagnetic and acoustic signal repeater (34) for communicating information between surface equipment and downhole equipment and a method for use of the repeater (34) is disclosed. The repeater (34) comprises an electromagnetic receiver (48) and an acoustic receiver (49) for respectively receiving and transforming electromagnetic input signals (46) and acoustic input signals into electrical signals that are processed and amplified by an electronics package (50) that generates an electrical output signal that is forwarded to an electromagnetic transmitter (52) and an acoustic transmitter (51) for respectively generating an electromagnetic output signal (53) that is radiated into the earth and an acoustic output signal that is acoustically transmitted.

Abstract: An impedance matched jointed drill pipe for improved acoustic transmission. A passive means and method that maximizes the amplitude and minimize the temporal dispersion of acoustic signals that are sent through a drill string, for use in a measurement while drilling telemetry system. The improvement in signal transmission is accomplished by replacing the standard joints in a drill string with joints constructed of a material that is impedance matched acoustically to the end of the drill pipe to which it is connected. Provides improvement in the measurement while drilling technique which can be utilized for well logging, directional drilling, and drilling dynamics, as well as gamma-ray spectroscopy while drilling post shot boreholes, such as utilized in drilling post shot boreholes.

Abstract: A reverse VSP system is provided and uses a frequency-controllable modulator of an MWD tool as a downhole seismic source. The modulator has a rotor and stator arranged to provide substantially sinusoidal outputs, and is controlled to provide a "Vibroseis"-type frequency sweep (preferably from 1 Hz to 50 Hz). With the bit of the MWD tool in contact with the bottom of the borehole, the force generated by the frequency-controllable modulator will generate measurable axial compressional (P-) waves. These waves which move through the formation are detected by an array of geophones on the formation surface, and a reference signal is obtained by a kelly-mounted accelerometer or strain gauge. The reference signal and signals obtained by the geophones are processed using known signal processing techniques.

Abstract: A hydraulic system for supplying hydraulic fluid for operating a mud pulse generator includes an accumulator that has a reservoir. The accumulator is arranged to maintain the fluid pressure in the reservoir. The system also has a pressure operated, one way inlet valve that is arranged to allow hydraulic fluid to be added, under pressure, to the reservoir. The one way inlet valve also includes a valve core.

Abstract: The present invention is a method for monitoring contact levels of fluids in a subterranean oil reservoir. A monitoring wellbore is provided from an earthen surface into the oil reservoir which includes an oil zone, a water zone, and a gas zone, each having a level in the reservoir. The monitoring wellbore contains a plurality of fluids including an oil phase, a water phase and a gas phase, each have a level in the monitoring wellbore which substantially corresponds to the level of the oil, water and gas zones, respectively, in the reservoir proximal to the monitoring wellbore. The method includes positioning a transducer pair having a first and a second transducer in the oil phase of the monitoring wellbore, transmitting a plurality of first acoustic output signals from the first transducer in a first direction and transmitting a plurality of second acoustic output signals from the second transducer in a second direction.

Abstract: An improved servo-driven pulser is disclosed, for use in measurement while drilling applications. In the pulser, a battery powered on-board DC electric motor is used to operate a servo-valve, which in turn adjusts internal tool fluid pressures to cause operation of a main valve to substantially reduce mud flow to a drill bit, thereby creating a positive pressure pulse detectable at the surface. De-energizing the motor driving the pilot valve results in re-adjustment of internal fluid pressures, causing the main valve to reopen, thereby terminating the pressure pulse.

Abstract: A downhole tool containing instruments and a pulser is landed within a string of drill pipe. The pulser has a pulser body and an orifice on a lower end. A piston slides within a bore in the body and has a signal poppet on a lower end. In an extended position, the signal poppet extends into and obstructs the orifice to reduce the flow of drilling fluid. In an open position, the signal poppet does not obstruct the orifice to increase the flow of drilling fluid. A bidirectional solenoid valve is located above the piston and has upper and lower electromagnetic coils and an axially moveable rod. The rod is movable between a closed position in an opening in the body and an open position away from the opening. The rod is moved to both positions in response to the instruments which sends signals to the coils. The mud pulser also has an on/off flow switch which is actuated by the commencement of mud circulation. Initially, the rod is in the closed position.

Abstract: A method and apparatus is provided for communicating a control signal in a wellbore between a transmission node and a reception node through an acoustic transmission pathway which extends between the transmission node and the reception node. A transmission apparatus is provided at the transmission node which is in communication with the acoustic transmission pathway. The transmission apparatus generates a serial acoustic transmission which includes a control signal. A reception apparatus is provided at the reception node. The reception apparatus includes a sensor assembly which detects the serial acoustic transmission. Furthermore, the reception apparatus includes a means for decoding the control signal from the series acoustic transmission.

Abstract: A system and method for signal processing are disclosed. One problem in measurement-while-drilling systems including a downhole acoustic transmitter is the presence of uphole generated noise and reflected signals. By proper spacing and timing of multiple transducers and measurements, the present invention filters from the received, corrupted signal the uphole noise and reflected signals. Thus, a more accurate depiction of the transmitted signal is generated uphole.

Abstract: An apparatus for sending signals downhole during drilling operations uses a main pump to pump mud from a mud pit at a substantially constant flow rate. The bulk of the pumped mud goes downhole to maintain adequate circulation for the drill bit. A bypass pipe is provided with a shut-off valve that is controlled by an electronic controller. By pulsing the opening and closing of the shut-off valve, the volumetric flow downhole is pulsed. The pulse amplitude and duration can be controlled. These pulses in the flow rate are detected by a suitable downhole device such as a flow rate measurement device, a pressure detector or a turbine. The initial "wake-up" pulse is made long enough so that the detection device downhole is always able to detect it. Subsequent to this wake-up pulse, adjustments are made to the pulse duration, in steps of about 2 seconds, for the smallest pulse period that is detectable downhole.

Abstract: A system is disclosed for transmitting and receiving acoustic data signals in a well containing a drill string. The system includes devices for transmitting acoustic signals through the drill string, drilling mud, and formation, and further includes methods for transmitting and interpreting the acoustic signal so as to maximize accuracy of the transmission. The methods of the present invention include correlating signals transmitted along different paths or paths of different lengths, using frequency shift keying transmission, using shear waves to transmit signals through downhole equipment and using compression waves to transmit signals through the mud. The signals further give information about the frequency dependence of formation speed of sound and formation acoustic attenuation. The method also give information for imaging the locations of reflective boundaries in the material surrounding the borehole.

Abstract: A transducer is described especially for use in providing acoustic transmission in a borehole. The transducer includes a multiple number of magnetic circuit gaps and electrical windings that have been found to provide the power necessary for acoustic operation in a borehole while still meeting the stringent dimensional criteria necessitated by boreholes. Various embodiments conforming to the design are described. Moreover, the invention includes transition and reflector sections, as well as a directional coupler and resonator arrangement particularly adapted for borehole acoustic communication.An acoustic communication system is described especially designed for use in providing acoustic transmission of information in a borehole. The communication system comprises a surface transceiver and at least one downhole transceiver. The surface transceiver operates in conjunction with a host computer that sends commands to the downhole transceiver.

Abstract: In a drill string pressure pulses are generated by expansion and constriction of an elastic body to transmit information along the drill string.

Abstract: A method and apparatus for remotely generating pressure signals in a fluid stream for telemetry purposes with minimal insertion loss and susceptibility to blocking flow of the fluid stream by providing a straight through acceleration path for the fluid stream followed by a straight through diffusion path, wherein pressure pulses representing data are generated by turbulence resulting from periodic disturbances made in the diffusion path.

Abstract: A method and apparatus for retrieving logging data from a downhole logging tool is presented. The tool includes a plurality of sensors which acquire data which is stored in memory. Upon receiving an appropriate signal from a surface control unit, the logging tool transmits the logging data from memory. This can be accomplished when drilling has paused; for example, while the well is being conditioned.

Abstract: A fluid-powered siren of the type used for communicating information between points of a wellbore. In one aspect, responsiveness of the siren's rotor to low flow rates is improved through application of greater torque to the siren rotor. Also, improved capturing and channeling action by the turbine rotor fins causes fluid flow to drive the turbine rotor and siren rotor combination more efficiently than it can drive a siren rotor directly as may be the case in other fluid-powered sirens. In another aspect, the system provides for control of the rotational speed of the siren rotor in instances wherein the fluid flow rate is too high. Control is affected by use of an epicyclical gear reducer which is positioned between the turbine rotor and the siren rotor to operably interconnect the two components.

Abstract: Improved techniques are provided for drilling a deviated borehole through earth formations utilizing a rotary bit powered by a drill motor, and for obtaining information regarding the borehole or earth formations while drilling. An inclinometer is positioned below the drill motor and within a sealed cavity of a housing fixed to a drill motor sub, and a transmitter within the sealed cavity forwards acoustic or radial wave signals to a receiver provided in a measurement-while-drilling tool. The MWD tool may be provided within a non-magnetic portion of the drill string, and further houses an accelerometer for sensing borehole direction. Both borehole inclination and directional signals are transmitted to the surface by the MWD tool, and the drilling trajectory is altered in response to the signals.