摘要:
Disclosed is an apparatus and method for accurately measuring torque in a rotating shaft. The apparatus comprises axially spaced magnet-detector pairs, mounted to rotate with the shaft and means for sensing relative rotation between the magnets.
摘要:
An acoustic attenuator includes a housing having an inner side surface which defines an interior chamber and at least one dampening member both physically and acoustically coupled to the housing and projecting into the interior chamber. Acoustic energy propagating within the housing is deflected into the dampening members for acoustically dispersal within the interior chamber. In various aspects thereof, the dampening members may include one or a group of two or more generally cylindrical sleeves having one end both physically and acoustically coupled to the housing and a second end projecting into the interior chamber. Preferably, when a group of two or more cylindrical sleeves are employed, the sleeves are nested within one another. The dampening members may further include a second, oppositely disposed, group of two or more acoustic attenuators nested within one another and interdigitated with the first group of cylindrical sleeves.
摘要:
Methods and systems for transmitting and receiving a discrete multi-tone (DMT) modulated signal in a fluid. Some illustrative embodiments may be a method comprising transforming an input data series into an information-carrying signal (the information-carrying signal carrying input data from the input data series as modulations of at least one of a plurality of evenly spaced frequency bins), and applying the information-carrying signal to a transducer that converts the information-carrying signal into pressure variations within a fluid.
摘要:
The present disclosure provides several methods for selecting and transmitting information from downhole using more than one channel of communication wherein data streams transmitted up each communications channel are each independently interpretable without reference to data provided up the other of the communications channels. Preferred embodiments incorporate the use of a combination of at least two of mud-based telemetry, tubular-based telemetry, and electromagnetic telemetry to achieve improved results and take advantage of opportunities presented by the differences between the different channels of communication.
摘要:
A reliable downhole acoustic telemetry system with increased data rate is disclosed. In one embodiment, the telemetry system includes a receiver having an envelope-detection demodulator and a multipulse-block distance detector that compares a baseband envelope signal to stored waveforms and indicates for each symbol interval the multipulse block having the waveform closest to the baseband envelope signal. The receiver may also include a timing recovery module that models the baseband envelope signal for the detected multipulse blocks and determines a distance for early-sampling and late-sampling of the baseband envelope signal. The timing recovery module then provides a sampling clock that minimizes the average difference between the early- and late-sampling distances. The telemetry system may further include a transmitter having an encoder and a modulator. The encoder converts a data signal into a sequence of multipulse blocks having a settling interval between the blocks. The modulator modulates the multipulse block sequence with a carrier frequency to produce an amplitude modulated signal. The telemetry system may have the transmitter and receiver coupled to a tubing string by an acoustic signal generator and an acoustic transducer, respectively. The acoustic signal generator converts the amplitude modulated signal into acoustic waves that propagate along the tubing string to the acoustic transducer, which then converts the acoustic waves into a receive signal. The system and method disclosed may advantageously provide a robust, low-power telemetry system that communicates telemetry along a tubing string at a rate that is at least an order of magnitude greater than existing acoustic telemetry methods.
摘要:
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.
摘要:
A communications system employing discrete multi-tone (“DMT”) modulated signals on a communications channel formed by inductively-coupled pipe. In one embodiment, the communications system includes a string of wired pipe joints that couple a transmitter to a receiver. Each pipe joint in the string possesses threaded ends configured for mechanically connecting with other pipe joints, a electrical or inductive coupler at each threaded end, and an insulated conductor that electrically connects the couplers. The transmitter and receiver communicate via DMT modulated signals transported by the wired pipe string. The system may further include multiple repeaters in the string. Each repeater may be configured to receive a DMT-modulated signal, to recover information from the DMT-modulated signal, and to retransmit the information in the form of a DMT-modulated signal.
摘要:
System, apparatus, and method of telemetering downhole sensor information to the surface while operations are performed in an oil or gas well using coiled tubing. Data are transmitted on coiled tubing as digital signals encoded in acoustic signals. In one implementation, a stripper packer through which coiled tubing is moved into a well is operated between at least a first state and a second state; and an acoustic communication device responds to operation of the stripper packer such that when the stripper packer is in the first state, the acoustic communication device is decoupled from acoustic communication with the coiled tubing, but when the stripper packer is in the second state, the acoustic communication device is coupled for acoustic communication with the coiled tubing.
摘要:
A process and apparatus for treating a wellbore, comprising subjecting a substantially same portion of the wellbore to vibratory waves produced by a plurality of vibratory wave generators. The vibratory waves may have about the same frequency or a plurality of frequencies, and the frequencies may partially overlap, not overlap, or be modulated across a range. Additionally, the frequencies may be modulated in an oval, hoop, and flexural modes. The vibratory waves may be produced by firing the vibratory wave generators simultaneously or in sequence. Combinations of a vibrating pipe, piston pulser, or valve may be used as vibratory wave generators. In a preferred embodiment, the thickness and change of thickness of a mudcake on the interior surface of a wellbore are measured to evaluate the effectiveness of the wellbore treatment.