Abstract: Communication from a well surface location at a well site to a downhole tool positioned within a wellbore may be performed such that fluid flow is not restricted through the downhole tool. For example, a method may include: sending a signal from an uphole location to a downhole tool located in a wellbore, wherein the signal comprises at least one event selected from the group consisting of a magnetic wellbore projectile, an acoustic pulse, and a pressure change; taking measurements with a sensor coupled to the downhole tool, wherein the sensor is at least one selected from the group consisting of a magnetic sensor, an acoustic sensor, and a pressure sensor; identifying the signal based on at least one of the measurements greater than an adaptive threshold value; and actuating the downhole tool from a first configuration to a second configuration upon identification of the signal.

Abstract: Material on a remote side of a partition separating first and second domains is evaluated by disposing at least one ultrasonic transmitter and a plurality of spaced ultrasonic receivers along a first side of the partition in the first domain. The transmitter is activated to form ultrasonic waveforms that comprise propagated quasi leaky-Lamb waves constituting extensional waves having symmetrical zero-order modes within the partition. The received ultrasonic waveforms are processed to determine the envelope of the waves propagating through the partition from a first receiver to a second receiver that is located more remote from the transmitter than the first receiver and whose separation from the first receiver is known. The integral envelope attenuation per distance of the wave propagating through the second domain over a predefined interval establishes that the second domain contains a solid when higher than a predetermined threshold.

Abstract: Apparatus and methods for identifying drilling cuttings downhole by extracting an echo from a pulse-echo waveform acquired utilizing a downhole ultrasonic tool having an acoustic device. An energy before echo profile preceding the extracted echo is determined, and then the energy before echo profile is processed to remove effects associated with the acoustic device. A cutting is then identified from the processed energy before echo profile.

Abstract: Methods and devices for imaging wells using phased array ultrasound imaging devices is described. The devices enable high resolution real-time imaging of a well during various operations in the well, including during completions, fracturing, milling, fishing and drilling operations. The phased array ultrasound imaging devices may be integrated with other well tools, such as a bottom hole assembly (BHA), fishing tools, milling tools, fracturing tools, and drilling tools, in order to integrate imaging capabilities into such tools.

Abstract: An apparatus, system, and method for mapping a conduit wall, of which the apparatus includes a shaft defining a central longitudinal axis, and a sensor module coupled to the shaft and including an emitter configured to emit a light beam directed at least partially radially with respect to the central longitudinal axis, and a sensor configured to detect a reflected portion of the light beam, such that the sensor module is configured to measure a distance between the conduit wall and sensor module. The apparatus also includes a centralizer coupled to the shaft and configured to position the sensor module at a center of the conduit.

Abstract: A measurement system and a method for determining steam quality (i.e. vapor mass fraction) measurements of multiphase fluid flowing through pipes are described. An acoustic sensor device consists of an acoustic transmitter and an acoustic receiver that are designed to be attached to a pipe. The acoustic transmitter and the acoustic receiver are exposed to an interior space of the pipe through openings in a wall of the pipe. Acoustic waves generated by the transmitter and captured by the receiver traverse the multiphase fluid flowing into the pipe. Swept-frequency acoustic interferometry (SFAI) technique is used to measure ultrasonic acoustic properties of a fluid. Machine-learning techniques based on principal component analysis, support vector machine regression and support vector machine classification are used for determining steam quality.

Abstract: A method for torsional wave logging in a borehole of a subterranean formation. The method includes obtaining a torsional wave measurement of the borehole, wherein the torsional wave measurement represents characteristics of a torsional wave propagating within a cylindrical layered structure associated with the borehole, wherein the cylindrical layered structure comprises the subterranean formation and a completion of the borehole, analyzing, by a computer processor, the torsional wave measurement to generate a quality measure of the completion, and displaying the quality measure of the completion.

Abstract: Downhole positioning systems and associated methods are disclosed. In some embodiments, the system comprises a downhole source, an array of receivers, and a data hub. The downhole source transmits an electromagnetic positioning signal that is received by the array of receivers. The data hub collects amplitude and/or phase measurements of the electromagnetic positioning signal from receivers in the array and combines these measurements to determine the position of the downhole source. The position may be tracked over time to determine the source's path. The position calculation may take various forms, including determination of a source-to-receiver distance for multiple receivers in the array, coupled with geometric analysis of the distances to determine source position. The electromagnetic positioning signal may be in the sub-hertz frequency range.

Abstract: An acoustic logging tool is provided with a first acoustic source that generates an acoustic signal primarily directed into the formation, the acoustic signal including a noise signal carried axially along the tool, a second acoustic source adapted to generate a noise canceling signal along the tool that actively and significantly cancels the noise signal, and a plurality of acoustic sensors axially spaced from each other along the tool and spaced from the first acoustic source and the second acoustic source. The acoustic sensors receive and record indications of pressure signals resulting from the acoustic signal and the noise canceling signal. The pressure signal indications may be processed in order to generate information regarding the formation.

Abstract: A method for making acoustic logging measurements includes grouping received acoustic waveforms into one of a plurality of groups, each group being representative of a measured borehole condition (e.g., a range of measured standoff values and/or a range of measured azimuth angles). The waveforms stored in at least one of the groups are stacked so as to obtain an averaged waveform. The averaged waveform may be further processed, for example, via a semblance algorithm to obtain at least one acoustic wave slowness.

Abstract: A tool is described for seismic data collection which may have sensors mounted along its entire length to sample both geophysical signal and noise including at least one of acoustic noise, system noise, and noise resulting from the interaction between the two. Systems and methods for acquiring borehole seismic data are also described. In contrast to conventional systems which attempt to avoid introducing noise into the collected data stream, the present systems include a sufficient type, number, and spacing of sensors to intentionally sample at least one source of noise. The methods include operating a borehole seismic acquisition system to sample both a target signal and at least one source of noise and using a processor with machine-readable instructions for separating the noise from the signal.

Abstract: A method for determining on a real time logging while drilling (LWD) basis gas within earth formations traversed by a borehole. Continuous LWD acoustic measurements are recorded and processed including coherent energy and attenuation attributes to detect downhole gas zones and kick during drilling operations.

Abstract: A downhole acoustic measurement tool includes at least one transmitter longitudinally spaced apart from a non-uniformly spaced longitudinal array of acoustic receivers. The array has a non-uniform spacing such that a first spacing between a first pair of consecutive acoustic receivers in the array is not equal to a second spacing between a second pair of consecutive acoustic receivers in the array. Non-uniform spacing of the receivers in the array reduces aliasing when the received waveforms are processed, for example, to obtain semblance data.

Abstract: A method for initializing the input of each of m receiver channels of a receiving transducer in a well logging tool comprising the steps of selecting a logging tool having a multi-element receiving transducer wherein each element of the multi-element receiving transducer operates in an anti-resonant mode below its resonant frequency, and executing a routine in an initialization mode wherein a predetermined number of run cycles are operated and receiver input responses are measured and averaged for each of the m channels while transmitter firing signals are disabled.

Abstract: A method of interrogating a formation includes generating a conical acoustic signal, at a first frequency—a second conical acoustic signal at a second frequency each in the between approximately 500 Hz and 500 kHz such that the signals intersect in a desired intersection volume outside the borehole. The method further includes receiving, a difference signal returning to the borehole resulting from a non-linear mixing of the signals in a mixing zone within the intersection volume.

Abstract: A downhole acoustic measurement tool includes at least one transmitter longitudinally spaced apart from a non-uniformly spaced longitudinal array of acoustic receivers. The array has a non-uniform spacing such that a first spacing between a first pair of consecutive acoustic receivers in the array is not equal to a second spacing between a second pair of consecutive acoustic receivers in the array. Non-uniform spacing of the receivers in the array reduces aliasing when the received waveforms are processed, for example, to obtain semblance data.

Abstract: A method for initializing the input of each of m receiver channels of a receiving transducer in a well logging tool comprising the steps of selecting a logging tool having a multi-element receiving transducer wherein each element of the multi-element receiving transducer operates in an anti-resonant mode below its resonant frequency, and executing a routine in an initialization mode wherein a predetermined number of run cycles are operated and receiver input responses are measured and averaged for each of the m channels while transmitter firing signals are disabled.

Abstract: In an acoustic logging system utilizing one or more acoustic sources, each with a specified radiation pattern around a source orientation, an acoustic signal is transmitted into a formation with a source oriented in a first source orientation. An acoustic waveform is received in response with a receiver oriented in a first direction. The slowness of the formation in the first direction is calculated using the received acoustic waveform.

Abstract: An apparatus for imaging an earth formation, the apparatus including: a logging instrument configured to be conveyed through a borehole penetrating the earth formation; a source of acoustic waves disposed at the logging instrument, wherein the source is configured to emit first acoustic waves having at least a first frequency and to enable intermodulation of the first acoustic waves in a medium having a nonlinear acoustic property resulting in generating new acoustic waves that are transmitted to the earth formation, the new acoustic waves having a new frequency different from the at least first frequency; and a receiver of acoustic waves configured to receive the new acoustic waves reflected from the earth formation, wherein the received new acoustic waves provide an image of the earth formation.

Abstract: Methods and systems for taking measurements related to subterranean formations. The methods and systems provide robust, reliable first arrival data for component signals of interest, which may be used to estimate formation slowness, characterize formation slowness zones, or act as an input to other processes. The methods and systems are capable of automatically providing good first arrival data based on signals received without any human interaction, and without setting or changing any parameters.

Abstract: Methods and systems for taking measurements related to subterranean formations. The methods and systems provide robust, reliable first arrival data for component signals of interest, which may be used to estimate formation slowness, characterize formation slowness zones, or act as an input to other processes. The methods and systems are capable of automatically providing good first arrival data based on signals received without any human interaction, and without setting or changing any parameters.

Abstract: Methods and systems for taking measurements related to subterranean formations. The methods and systems provide robust, reliable first arrival data for component signals of interest, which may be used to estimate formation slowness, characterize formation slowness zones, or act as an input to other processes. The methods and systems are capable of automatically providing good first arrival data based on signals received without any human interaction, and without setting or changing any parameters.

Abstract: A method for automatic classification, according to various selection criteria, of seismic or microseismic events picked up by seismic receivers coupled with an underground formation under development, according to whether the events are purely of microseismic nature or depend, on any account, on artifacts related to the outer environment or to formation development or monitoring activities, and for selection of the significant parts of traces for the purpose of analysis. The method has an application for monitoring of production or storage reservoirs under development.

Abstract: An apparatus (10) and method are disclosed for eliminating a noise signal from at least one source during an acoustic measurement of a subsurface geological formation or borehole. The apparatus (10) includes a longitudinal body for positioning in the borehole and a transmitter (22) supported by the body for transmitting acoustic signals into the formation and borehole. A sensor (23), substantially isolated within the body, is used to detect one or more noise signals and a receiver (24) is carried by the body for receiving acoustic signals traversing the formation and borehole, and for receiving one or more noise signals.

Abstract: Apparatus and methods are disclosed for enabling vapor handling in printing. In certain implementations, for example, one or more volatiles emitted during an ink-based printing process may be condensed into one or more liquids. The one or more liquids may be directed into absorbent materials such that the combined liquids and absorbent materials form a substance that qualifies as a solid, as determined by a given solid definition or regulatory standard. In certain (alternative but non-exhaustive) implementations, the volatiles emitted during printing may include water and oil, with the oil vapor being condensed into a liquid and added to the absorbent materials while the water vapor is being forwarded under the force of, e.g., negative air pressure.

Abstract: A borehole logging tool system includes a surface system, a logging array, and a logging cable providing power supply and data paths connecting the logging array to the surface system, wherein the logging array includes a series of discrete sondes connected together. The sondes in the logging array, for example a borehole seismic logging array, are connected to their neighbours by means of lengths of logging cable. Such cable can be the same as that connecting the logging array to the surface system. The logging array can also include a master controller module which communicates with the surface system and which includes a first controller module which connects to the surface system and a second controller which controls operation of the sondes in the logging array independently of any other borehole logging tools connected to the surface system.

Abstract: A method and apparatus for determining acoustic mud velocity and bore hole caliper in a downhole environment. A highly accurate acoustic signal is adjusted for mud velocity as continuously measured. The borehole standoff is utilized to compensated data collected downhole in determining a parameter of interest in the wellbore or an adjacent formation.

Abstract: A system for eliminating the tool mode signal from a received combined signal comprising both tool mode and formation mode components, comprising: a formation receiver for receiving said combined signal, a reference receiver for receiving a tool mode reference signal, a filter for processing said tool mode reference signal and generating a predicted tool mode component of the combined signal, and a summation element for subtracting said predicted tool mode component from said combined signal and generating a predicted formation mode component. The filter preferably incorporates a portion of the output of the summation element as an error signal, enabling the filter to adapt to changing conditions and update the algorithm on which it makes its predictions. According to an alternative system, an average value for the tool mode signal is updated according to a moving average to which new data points are added as they become available.

Abstract: A downhole acoustic logging tool having a random access memory for storing acoustic waveforms in digital format. The waveforms being transmitted from a surface logging system to the random access memory in the downhole logging tool. The logging tool playing back the stored waveforms by converting the stored digital format into an analog signal that is amplified sufficiently for driving an acoustic transmitter. A received pilot signal is used to determine the signal attenuation of the logging cable and a correction is made therefrom to the actual received acoustic signal. Complex waveform types may be programmed into the random access memory for specific formation characteristics. Tapered turn-on and turn-off of the signal waveform amplitudes reduce higher frequency spectral noise that may interfere when correlating the received acoustic signal with the transmitted acoustic signal.

Abstract: A method for detecting alteration of earth formations penetrated by a wellbore. The method includes determining a first arrival velocity of dipole acoustic energy propagated through the earth formations. A first frequency dependent velocity of the dipole acoustic energy is then determined. A first dispersion characteristic is determined from the difference between the first arrival and frequency dependent velocities. The method includes determining a frequency dependent velocity and a first arrival velocity for synthesized waveforms for an unaltered formation. The synthesis uses the first arrival velocity of the dipole acoustic energy as a shear velocity. A second dispersion characteristic, related to a difference between the frequency dependent velocity and the first arrival velocity of the synthesized waveforms is determined. The alteration is detected by finding a difference between the first dispersion characteristic and the second dispersion characteristic.

Abstract: A method of determining the acoustic propagation velocity of an earth formation penetrated by a wellbore by processing signals from an array acoustic wellbore logging tool. The tool includes a transmitter and a plurality of receivers axially spaced apart from the transmitter. The method includes the steps of combining signals generated by ones of the receivers in response to acoustic energy propagated through the wellbore from the transmitter, to generate a synthesized signal corresponding to another one of the receivers. The step of combining includes time shifting signals from the ones of the receivers by an amount corresponding to a predetermined velocity for each propagation mode and the axial distance between the ones of receivers and the other receiver. The synthesized signal is compared to the signal generated at the other receiver in response to the acoustic energy to determine a degree of correspondence between the synthesized signal and the received signal.

Abstract: A method for concurrently gathering acoustic and resistivity data for mapping the texture of the sidewall of a borehole using a single imaging tool. The data are sampled, formatted and merged to provide a single composite image of the borehole sidewall.

Abstract: A multi-mode receiver sonde having individual receiver stations. The receiver stations have transducers which have a flat frequency response over a selected bandwidth so that there is an approximately constant ratio in amplitude and substantially little phase difference between the response signal and an input acoustic signal from a liquid containing borehole.The wide-band output response signals are combined to form composite signals which represent selected borehole propagation modes. Accurate comparisons can then be made between the composite signals obtained by separate receiver stations so that changes in phase and amplitude over distance and time can be determined.In one highly preferred embodiment, the receiver sonde has a semi-rigid receiver array. The semi-rigid receiver array is adapted to decouple noise (tool-mode noise and/or road-noise) in one location within the array from other locations within the array by using compliant spacers between the receiver stations to absorb and scatter the noise.

Abstract: Methods and related apparatus for conducting shear slowness logging are set forth. The methods broadly comprise: detecting dispersive waves such as flexural or Stoneley waves; Fourier transforming the received signals; backpropagating the Fourier transformed signals according to equations using different dispersion curves; stacking the backpropagated signals; and finding semblances in order to choose the dispersion curve of maximum semblance and thereby identifying the shear slowness of the formation. Formation shear slowness may be plotted over borehole depth. Different embodiments are set forth. In one preferred embodiment (QDSTC), prior to Fourier transforming, the signals are stacked according to a previous estimation of slowness (S.sub.0), and are windowed for maximum energy. The reduced set of data in the window are then extracted for Fourier transformation, and prior to backpropagation, multiplied by S.sub.0 to reset them for backpropagation and stacking.

Abstract: The invention relates to a method and apparatus for acquiring borehole seismic data in two opposite directions in a borehole. Acquisition consists in emitting a pressure wave (R, R') at a point (E) in the borehole (PU), and, at a point (R) in the borehole (PU) that is offset relative to the pressure wave emission point (E), in detecting the echoes reflected and refracted by the adjacent geological formations (Ci) in such a manner as to discriminate between pressure waves reflected and refracted by the above-mentioned geological formations in a longitudinal plane of symmetry (P) of the borehole (PU). The discrimination is performed on the basis of detecting the sum and the difference of echo signals coming from opposite directions. The invention is applicable to determining horizons above and below an inclined borehole.

Abstract: A borehole logging tool having a dipole acoustic energy source and at least one spaced-apart dipole acoustic energy receiver is lowered into a deviated borehole. A motor rotates the source and receiver about the axis of the borehole tool. A first signal is produced representing source and receiver rotational position relative to a vertical direction. A second signal is produced representing a fixed reference level. A comparator produces a third signal of the difference between the first and second signals. The motor rotates so as to minimize such third signal, thereby maintaining the focus of the source and receiver in a horizontal direction that is perpendicular to the direction of eccentricity of the borehole tool with respect to the borehole axis.

Abstract: Improved techniques are provided for correcting signals from a downhole sensor on a drill collar eccentrically rotating within a borehole. The corrected sensor signal may be used to generate a well log which more accurately represents the conditions which the sensor would have generated had the tool been rotating such that the spacing between the sensor and the borehole well remained constant. The sensor signals are generated at time intervals of less than half the period of rotation of the drill collar. The frequency components of the time-varying sensor signals are plotted, and the frequency component attributable to the eccentric rotation between the drill collar and the borehole may be determined. The magnitude of this frequency component may be used to generate a correcting sensor signal, which then modifies the average sensor signal so that a more accurate well log may be obtained.

Abstract: Pulse echo apparatus and methods are disclosed for measuring characteristics of a borehole while it is being drilled. A component of a bottomhole assembly, preferably a drilling collar, is provided with one or more ultra-sonic transceivers. A pulse echo sensor of the transceiver is preferably placed in a stabilizer fin of the collar, but may also be placed in the wall of the collar, preferably close to a stabilizing fin. Electronic processing and control circuitry for the pulse-echo sensor is provided in an electronic module placed within such collar. Such pulse echo apparatus, which preferably includes two diametrically opposed transceivers, generates signals from which standoff from a borehole wall may be determined. A method and apparatus are provided for measuring standoff and borehole diameter in the presence of drilling cuttings entrained in the drilling fluid. In a preferred embodiment, such signals are assessed by the electronic processing and control circuity to determine if gas has entered borehole.

Abstract: A method for enhancing a plurality of recorded waveforms from sonic logging is disclosed. As a function of depth along a well borehole, a plurality of sonic waveforms is obtained. Adjacent waveforms are registered by time shifting so that common event coincides between adjacent waveforms. Typically this is the arrival of the P, S or S.sub.t wave component. Then, adjacent waveforms are subtracted from one another to provide a difference waveform, and the difference waveforms are then presented. This enhances oblique occurring events. Further, instantaneous waveform characteristics for each of the recorded waveforms are presented to further assist in data interpretation to locate and identify oblique occurring events.

Abstract: The technique according to the present invention is useful for generating a corrected well log which otherwise would include erroneous signals from downhole sensor. Such signal error may be caused, for example, by periodic movement of the drill collar axis with respect to the borehole axis, eccentric rotation of the drill collar with respect to the borehole, or a whirling or precessing of the drill collar in the borehole. According to the technique of the present invention, these sensor signals are generated at time intervals of less than one-half the period of the highest frequency of the periodic movement. Discrete sensor signals are averaged to generate an average sensor signal as a function of borehole depth. Discrete sensor signals are also recorded to generate a time-varying sensor signal profile, the magnitude of frequency components of the time-varying sensor signal profile is determined, and the average sensor signal is corrected as a function of the determined magnitude of the frequency components.

Abstract: The depth of a hydraulic fracture zone is determined by sensing and recording seismic wave motion at a series of spaced depths in a portion of a bore hole subjected to fracturing pressure during a shut-in period after the application of pressure while the fracture zone is unstable, and analyzing such motion recordings by eliminating components not attributable to the fracturing and discrete components from seismic sources attributable to the fracturing to determine an average background level of vertical and horizontal components, and comparing the average background level of the horizontal components of motion to the vertical component of motion to provide an indication of the presence or absence of fracturing at each depth.

Abstract: A well logging system includes a digital threshold crossing data generation system (TCDG System) disposed in a well tool, adapted to be disposed in a borehole, and a digital first motion detection (DFMD) software disposed in a memory of a well truck computer. The TCDG system generates a series of threshold crossings for each analog signal received from a receiver of the well tool, the threshold crossings including a plurality of threshold crossing events for each analog signal and representing compressed versions of digitized analog waveforms. The well logging truck computer receives the threshold crossing data from the TCDG system and executes the DFMD software. When the software is executed, a first set of compressional wave first arrival times are determined from a startup routine in the software using the threshold crossing data.

Abstract: The present invention is directed to filtering out unwanted components contained in acquired sonic well logging data, e.g., reflected wave components, converted wave components, casing arrivals, tool arrivals and/or noise. In the filtering method, the waveform components of each waveform are treated as vectors, each vector having n samples. The vectors, described in n-dimensional space, are rotated to a new coordinate system whose directions, characterized as eigenvectors, are aligned with the primary directions of the wave component vectors. The eigenvectors are ordered such that the first eigenvector represents the wave components' main direction, the second eigenvector represents the wave components' next main direction, et cetera. By projecting the waveform components onto the principal eigenvectors, the reflected wave components, converted wave components and/or noise component of each waveform is substantially eliminated. Methods are also disclosed for approximating the eigenvectors.

Abstract: A system is provided for acquiring and recording signals delivered by a set of sensors disposed in one or more probes lowered into a well at the end of a multi-function cable.The different signals to be transmitted are multiplexed before being applied to an acquisition chain adapted for amplifying them, digitizing them and coding them before applying them to a transmission channel in the form of blocks of digitized words. The multiplexing means may comprise several multiplexing units. The sampling frequency of each signal and the formation of the blocks of words are adapted to the number of units effectively used. In the surface installation, the blocks of words are dissociated and stored in a memory in a single mode suitable for all the blocks whatever their formation.

Abstract: A method of measuring the propagation velocity of one or more of a plurality of different types of elastic waves in a borehole. It employs a source of elastic waves at a given location in a borehole. The elastic waves generated have a given known frequency. There are a plurality of receivers spaced at different distances from the source. The signals developed by the receivers are digitally multiplexed at a high scan rate relative to the generated frequency. Then the multiplexed signals are analyzed to determine the wave lengths of the received signals. From the wave lengths the propagation velocities, v, may be computed by using the fundamental relationship v=f.lambda., in which f is the frequency and .lambda. is the wave length.

Abstract: Waveform data obtained in a borehole by a tool having a sonic source and an array of sonic detectors is analyzed to obtain an image of formation features within several tens of feet of the borehole, such as fractures, bed boundaries and other boreholes. A value of background sonic slowness is derived from the data and used to determine the sonic energy transit time from the source to each detector via each point in a grid of points extending into the formation and along the borehole. The time for a particular detector/point pair is used to extract the amplitude of the waveform from that detector at that time relative to operation of the source. Such amplitudes for the same point and for different detectors and tool positions are cumulated. The final values for all points are plotted as a variable density display which provides the desired image.

Abstract: A non-pyrotechnic lighting device is disclosed whereby intrusion into a restricted area can be monitored and detected by the use thereof. Triggering of the device is effected remotely by the unsuspecting subject.

Abstract: A method for evaluating the quality of the cement surrounding a borehole casing is provided. The method generally comprises obtaining signals which were recorded by a CET tool known in the art, and processing the signals by: dividing each signal into particularly defined time windows; determining absolute magnitudes for each signal which are functions of the energy of the signal in the respective windows; determining normalized magnitudes for each signal from the absolute magnitudes and normalization parameters; and evaluating the quality of cementation as a function of the fact that the normalized magnitudes for each signal obey a predetermined law, and as a function of the relationship between each normalized magnitude and a pair of threshold values respectively associated therewith.According to another aspect of the invention, information obtained from a CBL tool known in the art is compared to the information gained from the CET tool.

Abstract: In a representative embodiment of the invention described herein, a well logging system for investigating subsurface formations is controlled by a general purpose computer programmed for real-time operation. The system is cooperatively arranged to provide for all aspects of a well logging operation, such as data acquisition and processing, tool control, information or data storage, and data presentation as a well logging tool is moved through a wellbore. The computer controlling the system is programmed to provide for data acquisition and tool control commands in direct response to asynchronous real-time external events. Such real-time external events may occur, for example, as a result of movement of the logging tool over a selected depth interval, or in response to requests or commands directed to the system by the well logging engineer by means of keyboard input.

Abstract: Pulse echo apparatus and methods are disclosed for measuring characteristics of a borehole while it is being drilled. A component of a bottomhole assembly, preferably a drilling collar, is provided with one or more ultra-sonic transceivers. A pulse echo sensor of the transceiver is preferably placed in a stabilizer fin of the collar, but may also be placed in the wall of the collar, preferably close to a stabilizing fin. Electronic processing and control circuitry for the pulse-echo sensor is provided in an electronic module placed within such collar. Such pulse echo apparatus, which preferably includes two diametrically opposed transceivers, generates signals from which standoff from a borehole wall may be determined. A method and apparatus are provided for measuring standoff and borehole diameter in the presence of drilling cuttings entrained in the drilling fluid. In a preferred embodiment, such signals are assessed by the electronic processing and control circuity to determine if gas has entered borehole.