Carl A. Robbins - Tomball TX Bill Schaecher - Houston TX Patrick D. Chesnutt - Houston TX
Assignee:
Halliburton Energy Services, Inc. - Houston TX
International Classification:
E21B 4900
US Classification:
166 66, 166113, 702 6
Abstract:
A system based on a series of data accumulation hubs, connected together by high speed communication backbone for routing a limited number of data and power cables is suggested. Each hub is connected to arrays of sensor pods which contain the actual sensor elements and minimal, if any, interface electronics. Preferably, as many as 20 sensor pods can be connected to each single hub element wherein a system including five hub elements with 20 sensor pods each would comprise a 100 element array. The data from the individual sensors are accumulated in the hubs, buffered, and conditioned for transmission to the surface data acquisition system through the high speed metal backbone comprising multiple paths of transmission for redundancy in the event of failure. Provisions are made within each of the hubs so that if a hydrostatic leak were to occur, the fault can be isolated and the remainder of the system will function as designed. A power delivery network is also preferably encased within the backbone along with the high speed data link.
Vimal V. Shah - Houston TX John W. Minear - Houston TX Robert Malloy - Katy TX James R. Birchak - Spring TX Wallace R. Gardner - Houston TX Carl Robbins - Tomball TX
Assignee:
Halliburton Energy Services, Inc. - Houston TX
International Classification:
H04H 900
US Classification:
367 82, 367 83, 367 79, 368 46
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.
James R. Birchak - Spring TX Robert L. Malloy - Katy TX Carl A. Robbins - Tomball TX Eugene J. Linyaev - Houston TX David J. Young - Houston TX
Assignee:
Halliburton Energy Services, Inc. - Houston TX
International Classification:
G01V 102
US Classification:
181113, 181111, 181104, 181106, 181108, 181119
Abstract:
An axially extended downhole seismic source is disclosed. In one embodiment, the seismic source includes multiple pressure storage chambers, each having an inlet valve and an outlet valve. The inlet valve is coupled between the pressure storage chamber and the interior of the drill string, and the outlet valve is similarly coupled between the pressure storage chamber and the annular space around the drill string. A compressible fluid may be provided in the pressure storage chambers, and pistons may be positioned to contact the compressible fluid. For each pressure storage chamber, an inlet piston contacts the compressible fluid and fluid inside the drill string, while an outlet piston contacts the compressible fluid and fluid in the annular space around the drill string. When the outlet valve is closed, the inlet valve can be opened to allow pressure inside the drill string to compress the compressible fluid inside the pressure storage chamber. Subsequently closing the inlet valve and opening the outlet valve causes fluid to be ejected into the annular space, thereby generating seismic waves.
David J. Young - Houston TX, US Carl A. Robbins - Houston TX, US Eugene Linyaev - Houston TX, US
Assignee:
Halliburton Energy Services, Inc. - Houston TX
International Classification:
H03B 5/32
US Classification:
331176, 331 2, 331158
Abstract:
A downhole crystal-based clock that is substantially insensitive to the factors that may cause frequency deviation as a result of downhole temperature. The clock may include a plurality of crystals, where a first crystal may be more stable, with respect to temperature, than a second crystal. The crystals may be thermally coupled together so that they may have substantially the same temperature. An error detector may monitor the differences between the frequencies associated with each crystal and provide this information to a storage device. This information may be determined prior to deploying the clock downhole. When deployed downhole, the signal from the error detector may be interpreted in light of the information in the storage device to provide a temperature measurement of the two crystals. The downhole temperature measurement then may be used to reduce frequency deviations in the downhole clock that may result from downhole temperatures.
Sinan Sinanovic - Sarajavo, BA Donald H. Johnson - Houston TX, US Wallace R. Gardner - The Woodlands TX, US Li Gao - Missouri TX, US Carl A. Robbins - Houston TX, US
Assignee:
Halliburton Energy Services, Inc. - Houston TX
International Classification:
H04H 9/00
US Classification:
3408554, 367 82
Abstract:
Acoustic telemetry devices and methods that provide directional detection. In one embodiment, a disclosed acoustic telemetry device comprises at least two acoustic sensors and an electronics module. The electronics module combines the detection signals from the acoustic sensors to obtain a combined signal that substantially excludes signals propagating in a direction opposite to the communication signal. The disclosed systems and methods can be trained in the field and will readily accommodate an irregular and unknown signal transmission medium between the two acoustic sensors.
Acoustic Telemetry System Using Passband Equalization
Wallace R. Gardner - Houston TX, US Vimal V. Shah - Sugarland TX, US Carl A. Robbins - Tomball TX, US
Assignee:
Halliburton Energy Services, Inc. - Houston TX
International Classification:
E21B 47/16
US Classification:
367 82, 367 81
Abstract:
An embodiment includes a method comprising transmitting and receiving an acoustic signal that is modulated along a jointed tubing. The acoustic signal may be transmitted in multiple passbands of the jointed tubing and may be modulated differently in different passbands. A swept frequency signal may be used to determine transmission characteristics of the jointed tubing and to select the multiple passbands. Additional embodiments are disclosed.
Acoustic Telemetry System Using Passband Equalization
Wallace Gardner - Houston TX, US Vimal Shah - Sugarland TX, US Carl Robbins - Tomball TX, US
International Classification:
H04H 9/00
US Classification:
367082000
Abstract:
An embodiment includes a method comprising receiving an acoustic signal that is modulated along a jointed tubing. The method also includes performing equalization over a passband of the acoustic signal to generate an equalized signal.
Symbol Synchronization For Downhole Ofdm Telemetry
Enhanced symbol synchronization methods suitable for use in narrowband orthogonal frequency division multiplexed (OFDM) telemetry systems. In at least some embodiments, a logging while drilling (LWD) tool assembly communicates with the surface using low frequency electromagnetic (EM) signals. The telemetry transmitter employs OFDM modulation to fully exploit the narrow range of available bandwidth, resulting in signals that have relatively long frames. At the surface a receiver digitizes the receive signal and applies an enhanced symbol synchronization technique to identify frame boundaries before demodulation is attempted. The enhanced symbol synchronization technique employs a pulse train filter to clean up a cyclic prefix correlation signal that otherwise behaves badly in the narrowband regime. The improved timing information from the enhanced symbol synchronization significantly reduces the error rate in the demodulated signal.