摘要:
The present disclosure is related to apparatuses and methods for estimating borehole parameters using a plurality of reflections caused by a plurality of acoustic pulses. The reflections may overlap each other and/or the acoustic pulses. The methods may include estimating an envelope of the received acoustic signal at the at least one element of the array of transducers; and estimating at least one arrival time of at least one of the plurality of overlapping events from the envelope of the received acoustic signals, the arrival times being characteristic of the geometry of the borehole. The method may also include imaging the borehole wall. The apparatus may include an array of transducers on a rotatable transducer assembly with at least one element on the array configured to generate a plurality of acoustic pulses and receive reflections and a processor configured to perform the method.
摘要:
The present disclosure is related to apparatuses and methods for estimating borehole parameters using a plurality of reflections caused by a plurality of acoustic pulses. The reflections may overlap each other and/or the acoustic pulses. The methods may include estimating an envelope of the received acoustic signal at the at least one element of the array of transducers; and estimating at least one arrival time of at least one of the plurality of overlapping events from the envelope of the received acoustic signals, the arrival times being characteristic of the geometry of the borehole. The method may also include imaging the borehole wall. The apparatus may include an array of transducers on a rotatable transducer assembly with at least one element on the array configured to generate a plurality of acoustic pulses and receive reflections and a processor configured to perform the method.
摘要:
A method of performing acoustic imaging includes: selecting a target location, and selecting a group of transducers from a plurality of transducers to transmit an acoustic beam to be electronically directed to the target location; selecting a transmitter having an orientation toward a location proximate to the target location, and transmitting an acoustic signal only by the transmitter; detecting an acoustic return signal by the transmitter and by a plurality of other transducers in the group; estimating a travel time for each of the group of transducers, the estimating including measuring a travel time for each of the other transducers, and estimating a travel time for the transmitter based on the travel time for each of the other transducers; and calculating beamforming delays based on the travel time, the beamforming delay configured to cause the group of transducers to direct an acoustic beam to the target location.
摘要:
The present invention provides a measurement-while-drilling (MWD) system having a downhole computer and multiple downhole sensors. Relatively large amounts of basic or “raw” data are measured by downhole sensors, and these data are processed within a downhole computer to be reduced to parameters of interest, which may be utilized to control the drilling operation by downhole devices, stored downhole, telemetered to the surface, or both. The measurements may be correlated downhole with stored reference data thereby providing additional information pertaining to the drilling operation. Downhole depth correlation between downhole measured parameters may be made by utilizing surface determined or downhole determined borehole depth.
摘要:
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. Subsequently, the downhole transceiver transmits encoded data from subsurface, borehole sensors to the surface transceiver. The preferred embodiment uses Minimum Shift Keying (MSK) modulation for both transmitting commands to the downhole unit and for transmitting data to the surface transceiver. To facilitate operation of a coherent communication system in the inhospitable environment of a borehole, the acoustic channel is characterized to enable the system to choose the best possible frequency and bandwidth for communication transmission. Additionally, the system achieves synchronous operation by transmitting synchronization signals between the downhole transceiver and the surface transceiver prior to the units exchanging commands and data.
摘要:
An acoustic transducer assembly includes: a carrier configured to be disposed in an earth formation, the carrier having a carrier axis; an array of transducer elements forming at least a semicircular shape, the array configured to emit acoustic signals in a radial direction relative to the carrier axis; and a circuit coupled to the array and configured to actuate a subset of the transducer elements and emit an acoustic beam therefrom, the circuit configured to actuate the subsets as a phased array to electronically rotate the acoustic beam about the carrier axis.
摘要:
The present invention provides a method and apparatus for using an acoustic logging tool conveyed in a borehole in an earth formation for determining a characteristic of the formation. The method comprises using a first acoustic source for generating an acoustic signal in the earth formation at a first frequency. A second acoustic source spaced apart from the first source is used for generating an acoustic signal in the earth formation at a second frequency different from the first frequency. An acoustic receiver is used for receiving a third acoustic signal indicative of said characteristic. The third acoustic signal has a frequency substantially equal to a difference between the first frequency and the second frequency. The third acoustic signal is produced by a nonlinear interaction between the first signal and the second signal in a portion of said earth formation.
摘要:
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 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.
摘要:
The present invention provides a system for drilling boreholes having a downhole subassembly which contains an acoustic measurement-while-drilling system. The acoustic system contains an acoustic transmitter and receiver for determining the acoustic velocity through the formations surrounding the borehole ad an acoustic transmitter and a set of receivers for determining the bed boundaries surrounding the borehole formation utilizing the acoustic velocities measured by the system. The downhole subassembly also contains a computing system which performs computations downhole and transmits certain answers uphole during the drilling operations. The bed boundary information is utilized to drill the wellbore along a desired wellbore path. The downhole computing system correlates the acoustic sensor measurements with other measurement-while-drilling measurements and transmits selected correlated information uphole. The downhole computing system contains predetermined well profile which is updated based on the bed boundary information. The system may be adapted to correct or update seismic data and offset well data based on acoustic sensor system measurements.
摘要:
The present invention provides a system for drilling boreholes having a downhole subassembly which contains an acoustic measurement-while-drilling system. It uses the acoustic velocity through the formations surrounding the borehole and an acoustic transmitter and a set of receivers for determining the bed boundaries surrounding the borehole formation. An acoustic isolator on the tool may be used to attenuate body waves traveling between the transmitter and the receivers. Additional attenuation of the body waves is provided by a threshold filter based upon the absolute maximum of the received signals. Semblance of the data is determined in a slowness/intercept-time domain. Coherence and semblance filtering methods are used to differentiate between reflection signals and noise. The position and orientation of the bed boundary relative to the tool are determined. A further processing step uses the relative position and orientation determined for a number of tool positions to further discriminate against noise and obtain an absolute position and depth of the bed boundaries.