Abstract: Downhole drilling characteristic measurement systems for measuring a characteristic of drilling through the earth's subsurface and methods of the same are described. The systems include a downhole tool having an active measurement system, comprising a receiver, a first transmitter, and a second transmitter and a controller in communication with the first transmitter and the second transmitter, the controller configured to control the first transmitter and the second transmitter to transmit a first transmitted signal from the first transmitter and a second transmitted signal from the second transmitter. The receiver is arranged to receive a first received signal from the first transmitted signal and a second received signal from the second transmitted signal. A processor is configured to determine a characteristic of drilling from the first received signal and the second received signal.

Abstract: Methods, apparatus, systems, and articles of manufacture are disclosed to measure a formation feature. An example apparatus includes a pre-processor to compare a first measurement obtained from a first sensor included in a logging tool at a first depth at a first time and a second measurement obtained from a second sensor included in the logging tool at the first depth at a second time. The example apparatus also include a semblance calculator to: calculate a correction factor based on a difference between the first measurement and the second measurement; and calculate a third measurement based on the correction factor and a fourth measurement obtained from the first sensor at a second depth at the second time. The example apparatus also includes a report generator to generate a report including the third measurement.

Abstract: A method for expediently processing and inverting elastic wave data to reduce the amount of data and to determine a physical properties model of the material medium and a source properties model. The data are processed to generate waveforms containing the phase difference between compressional- and shear-wave arrivals using auto-correlation, cross-correlation, or deconvolution of said data sensed at each of an arrangement of sensors, whereby said lengthy elastic wave data records are reduced substantially in time. Said waveform data are thereafter inverted using waveform inversion by modifying the source term in the equation of motion, wherein the source term is mathematically expressed as a product of time-independent source properties volume defined at every location in space within said material medium and a space-independent source-time function, whereby no prior knowledge of the number of sources, spatial distribution of source location, source amplitude, or source focal mechanism is needed.

Abstract: A technique facilitates operation of an actuator via an operating module. The actuator and the operating module are constructed to enable operation in a wide variety of environments and applications. The operating module is coupled to the actuator and is operable in a plurality of modes, such as an electro-hydraulic mode, a pure hydraulic mode, and a mechanical mode. A desired mode of operation is selected and the operating module enables shifting of the actuator via the selected mode.

Abstract: In one embodiment, a sensor assignment apparatus includes a measured value storage, a generator, a calculator, and a selector. The measured value storage stores measured values of a plurality of sensors. The generator generates combinations of sensors and arguments of a function to diagnose sensors by assigning sensors to its arguments. The calculator calculates evaluation values which are based on the function values. The function values are obtained by applying diagnostic functions to measured values for all combinations generated by the generator. The selector selects at least one combination from the resulting set of the generator by considering the evaluation values of combinations calculated by the calculator.

Abstract: Systems and methods using a time-seismic-depth interval velocity curve and the difference between a time-depth interval velocity curve and a time-seismic depth interval velocity curve for validating depth-depth curves which calibrate a synthetic generated from well logs to depth seismic data.

Abstract: One or more specific embodiments includes a method for providing an estimated formation pressure comprising modifying a first data set to derive a second data set that corresponds to estimated pressures wherein modifying the first data set comprises using a variable matrix factor and a compaction coefficient.

Abstract: A non-contact testing system and method using acoustic sensors and a mobile sensing system using this system and method is disclosed. The leaky surface wave is recorded with directional microphones. A fast inversion analysis algorithm is introduced to estimate the shear velocity profile and elastic modulus for the subsurface layers of pavement structures, using the dispersion curves obtained from the acoustic signals. An electrical hammer is used to produce impact impulses automatically. A mobile sensing system is integrated on a mobile cart to perform the mobile subsurface sensing for pavement structures.

Abstract: A system for building a geological model of oil or other mineral deposit. In particular, the system allows the coefficients of correlation to be determined for a set of well-logging curves and marker depth positions to be established for which the values of correlation coefficient are maximal. A technical result is the improvement of the accuracy of evaluating the parameters that are used to construct a geological model of location of oil or other deposits. The system makes it possible, given a marker, which already has its marks in a group of wells, which is referred to as reference group, to calculate such marks for wells from another group. For any well W where the marker depth is to be determined, wells from the reference group are chosen lying within the specified distance from the well W, and a well with the maximal coefficient of correlation is chosen among them.

Abstract: Various resistivity logging tools, systems, and methods are disclosed. At least some system embodiments include a logging tool and at least one processor. The logging tool provides transmitter-receiver coupling measurements that include at least direct coupling along the longitudinal tool axis (Czz), direct coupling along the perpendicular axis (Cxx or Cyy), and cross coupling along the longitudinal and perpendicular axes (Cxz, Cyz, Czx, or Czy). The processor performs a multi-step inversion of said transmitter-receiver coupling measurements to obtain values for model parameters. Based at least in part on the model parameters, the processor determines borehole corrections for the transmitter-receiver coupling measurements and may further provide one or more logs derived from the borehole corrected transmitter-receiver coupling measurements.

Abstract: Methods for fracture characterization of unconventional formations are provided. Synthetic seismic fracture responses can be generated based on the derived fracture parameters. The synthetic seismic fracture responses may then be used to derive optimum seismic data acquisition geometry for fracture characterization. These methods of determining the seismic data acquisition geometry are advantageous over conventional methods in that these methods are more reliable and cheaper than existing empirical methods, particularly as applied to fractured unconventional formations. Moreover, these methods allow fracture parameters to be derived from limited but common well log data. Certain embodiments additionally contemplate determining the presence of gas filled fractures. These characterizations and evaluations of unconventional formations are useful for, among other things, determining optimal producing intervals and optimal drilling locations. These methods can eliminate the use of costly image logs and core data.

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: A method of detecting seismic waves traveling through a subsurface formation includes lowering a cable into a borehole in the subsurface formation, the cable having at least one optical fiber associated therewith, and causing descent of a remote end of the cable to be arrested. The method further includes feeding a further length of the cable into the borehole such that the cable is slack and in contact with at least part of a wall of the borehole, and using an interrogator coupled to the at least one optical fiber to detect seismic waves traveling through the subsurface formation and into the cable.

Abstract: A technique facilitates detection of an event in a subterranean environment, e.g. in a wellbore. A tool may be deployed to a desired wellbore location or other subterranean location for actuation between operational positions. An acoustic system also is deployed to detect a unique acoustic signature associated with an event related to operation of the tool. Upon detection of the unique acoustic signature, the acoustic system transmits data to a surface location or other suitable location to indicate occurrence of the event. An example of such an event is transition of the tool between operational positions.

Abstract: A technique is designed to facilitate obtaining of acoustic data. The technique comprises traversing a tool through a subterranean formation from a first depth to subsequent depths. The tool receives a seismic signal during pre-determined time windows. The seismic signal is generated by a seismic source which is activated at varying times relative to the predetermined time windows based on the depth of the tool.

Abstract: A surface seismic survey is generated or obtained from Earth's surface and is based on time in which acoustic waves are reflected to Earth's surface. One or more tools measure density and sonic velocity of a subsurface formation. An estimate of acoustic impedance is obtained from the density and the sonic velocity to generate a synthetic seismic survey. The synthetic seismic survey and the surface seismic survey are compared and/or correlated. The acoustic impedance can be iteratively estimated until the synthetic seismic survey matches the surface seismic survey. Matching the surface seismic survey with the synthetic seismic survey may ensure that the surface seismic survey may be calibrated in actual depth.

Abstract: An apparatus for use in deployment of downhole tools is disclosed. Preferably, the apparatus includes at least an in-ground well casing, a housing providing a hermetically sealed electronics compartment, a tool attachment portion, and a first flow through core. The housing is preferably configured for sliding communication with the well casing. The hermetically sealed electronics compartment secures a processor and a location sensing system, which communicates with the processor while interacting exclusively with features of the well casing to determine the location of the housing within the well casing. A preferred embodiment further includes a well plug affixed to the tool attachment portion, the well plug includes a second flow through core capped with a core plug with a core plug release mechanism, which upon activation provides separation between the second flow through core and the core plug, allowing material to flow through said first and second flow through cores.

Abstract: Methods and apparatus to calculate a distance from a borehole to a boundary of an anisotropic subterranean rock layer are disclosed. A disclosed example method includes transmitting a first signal from a first transmitter at a first location in a borehole traversing a subterranean formation, receiving the first signal at a first receiver after a first time period at a second location in the borehole, receiving the first signal at a second receiver after a second time period at a third location in the borehole, and calculating a first distance from the first transmitter to a first portion of a boundary of a subterranean rock layer adjacent to the borehole by compensating for an anisotropy of the subterranean rock layer based on the first time period and the second time period.

Abstract: A downhole tool deployment apparatus is disclosed, which preferably includes at least an in-ground well casing, a depth determination device providing a hermetically sealed electronics compartment, tool attachment portions, and a first flow through core. The depth determination device is preferably configured for sliding communication with the well casing. The hermetically sealed electronics compartment secures a processor and a location sensing system, which communicates with the processor while interacting exclusively with features of the well casing to determine the location of the depth determination device within the well casing. A preferred embodiment further includes a well plug affixed to the tool attachment portion, the well plug includes a second flow through core capped with a core plug with a core plug release mechanism, which upon activation provides separation between the second flow through core and the core plug, allowing material to flow through said first and second flow through cores.

Abstract: A transmitter generates an acoustic ping in a fluid in a borehole, and a receiver monitors waves resulting from the acoustic ping. Responsive to the monitored waves, an attribute of the fluid is estimated, including a sonic velocity, a mixture of gas and oil, a mixture of water and oil, an amount of sand, an amount of gas, an amount of skin effect, or a depth of fluid. An operation of the artificial lift device is then controlled responsive to the estimated attribute. Alternately, a sonic velocity is estimated for the fluid through an analysis of a sample pumped to the surface or through an analysis of monitored waves. A depth of the fluid is calculated responsive to the estimated sonic velocity for the fluid in the borehole and the monitored T-waves. The operation of the artificial lift device is then controlled responsive to the calculated depth of fluid.

Abstract: A method for obtaining a seismic wavelet using seismic data in a deviated well includes the steps of: (a) extracting seismic data along the well path; (b) calculating the well path in the time domain; (c) extracting a window of seismic data in the time domain along the well path in the time domain; (d) combining the extracted window of seismic data to obtain a composite seismic trace; and (e) extracting a seismic wavelet using the composite seismic trace.

Abstract: There is provided a method of processing geological data during drilling of a borehole for improving accuracy of the geological data. The method includes a first step of determining from instrumentation (100) associated with a string (50) of drilling pipes a spatial trajectory of a borehole (20, 200) in a subterranean region. A second step of the method involves determining from the spatial trajectory one or more points (P1, P2, P3) with reference to the geological data whereat the trajectory changes direction in one or more layers of strata (F) of the subterranean region. A third step of the method involves subdividing an offset log generated by the instrumentation (100) in response to the one or more points (P1, P2, P3) to generate corresponding sections of offset log. A fourth step involves mutually comparing the subdivided sections of offset log to find a condition of best comparison therebetween and thereby generate one or more error terms (E).

Abstract: A method for determining on a real time logging while drilling (LWD) basis the top of cement location between casing transition zones in a borehole using at least one sonic attributes of coherent energy, attenuation and slowness as a function of at least one of depth and time.

Abstract: A method of estimating geological location depths by converting horizon data from the time domain to the depth domain is provided wherein the method includes at least a data accumulation step and a data evaluation step, and wherein the data evaluation step further includes assignment of greater statistical weight to data derived from closer data acquisition points than to data derived from further data acquisition points using a weighted regression analysis, with distance being one of several weighting criteria. Layer-by-layer computation of geological formation depths is achieved by extracting values from horizon time data set at exact geographic locations in the next deeper horizon, thereby allowing interval computations to be carried out without the need for gridding.

Abstract: A downhole receiver for gathering seismic and sonic data from inside a borehole includes a substantially tubular housing adapted for axial connection to a tool string, and one or more sensors. A damping element is provided to flexibly couple each sensor to the tubular housing. An actuator extends the one or more sensors substantially radially with respect to the tubular housing to clamp the sensors against the wall of the borehole. In selected embodiments, the sensors may be one or multiple component geophones, accelerometers, hydrophones, vibrometers, or the like.

Abstract: A longitudinally segmented acoustic transducer for a cement bond logging (CBL) tool having a plurality of adjoining PZT ring-like segments driven synchronously in parallel by one or more pulses and caused to vibrate in an anti-resonant mode, substantially below the resonant frequency of an individual segment when used in a transmitting application. When used in a receiving application, each of the plurality of transducer rings are caused to vibrate by acoustic signals detected by the transducer array, also in an anti-resonant mode. High speed digital signal processing enables on-depth, high quality data for all azimuths at each depth to be obtained, processed, normalized and either sent to the surface in real time for each 20 Hz firing cycle, as the CBL tool is pulled toward the surface, or stored in a memory module in digital form for later retrieval. Built-in calibration factors used for normalizing the output signals to the operating conditions of use may be accessed at any time.

Abstract: A method for depth matching borehole images and/or core section images is disclosed wherein signals from sensors at different levels on a logging tool are converted into an averaged signal representing the average bed signal at the center of the borehole at each of the different levels. A depth matching technique is applied to the averaged signals from the sensors at different levels on the logging tool to determine the optimum depth offset necessary for matching two sets of signals from sensors at the different levels of the logging tool. In an alternative embodiment of the invention a Hough transform is utilized to process the well log images and generate three-dimensional images in Hough space. The three dimensional images are converted into two-dimensional extremum curves. Depth matching is performed on the two dimensional extremum curves to calculate an offset to match the two dimensional extremum curves. The calculated offset is then applied to the well log images to depth match them.

Abstract: A method of predicting earthquakes includes the step of positioning a first transducer array adjacent to a seismically active region and below the water table, i.e., within the zone of saturation. The first transducer array includes a first plurality of seismometers, at least one first clock, and at least one first digitizer. The at least one first clock is in communication with at least one of the first plurality of seismometers, and the at least one first digitizer also is in communication with at least one of the first plurality of seismometers. The method also includes the steps of detecting a plurality of wave movements resulting from dilation of the crust of the Earth prior to an earthquake, and converting at least one of the wave movements into a first voltage. The method further includes the step of discriminating between wave movements resulting from dilation of the crust of the Earth and movements resulting from at least one other event.

Abstract: A modular system for packaging of sensors and related electronics for an MWD system. A drill collar housing is provided with one or more cavities for receiving sensor modules that are adapted to sense one or more wellbore conditions. The sensor modules are removable and replaceable so that a desired sensor package may be installed within the drill collar housing. The drill collar housing is installed within the drill string, and a desired sensor module or modules are secured within the cavity(ies) of the drill collar housing. Replacement or repair of the sensor portions requires only that the module or modules be removed from the cavity(ies). The drill collar housing need not be removed from the drill string. The replaceable sensor modules may be interchangeably used in drill collar housings of different sizes without resulting in a degradation of sensed information.

Abstract: A method of predicting earthquakes includes the step of positioning a first transducer array adjacent to a seismically active region and at least about 3 meters below the surface of the crust of the Earth. The first transducer array includes a first plurality of seismometers, at least one first clock, and at least one first digitizer. The at least one first clock is in communication with at least one of the first plurality of seismometers, and the at least one first digitizer also is in communication with at least one of the first plurality of seismometers. The method also includes the steps of detecting a plurality of wave movements resulting from dilation of the crust of the Earth prior to an earthquake, and converting at least one of the wave movements into a first voltage. The method further includes the step of discriminating between wave movements resulting from dilation of the crust of the Earth and movements resulting from at least one other event.

Abstract: A method for generating a depth-indexed data structure for a reaming operation includes receiving, by a software process, i) well logging data that includes time-indexed data and depth measurement data for an oil well drilling rig, ii) a selection identifying a depth range for a reaming operation by the drilling rig, and iii) values for a certain parameter indicating an operating mode for the drilling rig. Then the software process extracts, responsive to the selected depth range and one of the values of the parameter, a section from the well logging data within the selected depth range, and generates from the section the depth-indexed data structure for the reaming operation.

Abstract: The present invention provides an ink jet recording apparatus including a carriage to which a recording head for effecting recording on a recording material by discharging ink and an ink tank for containing ink to be supplied to the recording head are detachably mounted in a separate exchanging permitting manner and which shifts the recording head and the ink tank in a direction perpendicular to a conveying direction of the recording material, comprising an ink tank exchanging position which is a position of the carriage, where the ink tank is to be exchanged, and a recording head exchanging position which is different from the ink tank exchanging position and which is a position of the carriage where the recording head is to be exchanged.

Abstract: Acoustic logging data are obtained using a logging tool including at least on transmitter and a plurality of receivers. A waveform matching inversion is performed to obtain formation slowness profiles at various resolutions ranging from the total length of the receiver array to the inter-array receiver spacing. Using overlapping sub-arrays of reduced aperture provides for resolution enhancement. The enhancement is achieved by minimizing the noise contamination effects by maximizing the information redundancy in waveform data. The method achieves this by isolating the wave event of interest and matching the waveform of the event for all possible receiver pairs allowed by the sub-array. The high-resolution slowness curve successfully resolves the laminated features in a geological formation. This invention is a useful tool for evaluating thin beds in laminated formations using borehole acoustic logging.

Abstract: A sample catcher comprises an inclined sampling screw conveyor which intercepts a continuous stream of drill cuttings from a shaker. A vaned metering rotor accepts a plurality of discrete samples from adjacent the conveyor's discharge. The vaned rotor is rotated at a lag rate proportional to the rate of penetration at the time the stream of cuttings with drilled. The plurality of discrete samples are discharged as a substantially continuous sample stream which is directed through a second conveyor to one or more analytical instruments. Further, the sample stream can be directed to a sample bag carousel which is index advanced for associating the bag contents with the drilling. The apparatus enables a method of analyzing cutting samples which correlate to the cuttings when drilled and in a process which is continuous.

Abstract: The general object of the present invention is to provide a method for determining and displaying the relative changes of elastic moduli and that of density of geologic formations and for utilizing these relative changes and plottings for gas/oil exploration, especially for direct gas and light oil detection. The said relative changes of elastic moduli are the relative change of Lame constant .DELTA..lambda./(.lambda.+2.mu.), the relative change of shear modulus .DELTA..mu./(.lambda.+2.mu.) and/or .DELTA..mu./[.kappa.+(4/3).mu.], the relative change of bulk modulus .DELTA..kappa./[.kappa.+(4/3).mu.]; and the relative change of density is .DELTA..rho./.rho..

Abstract: The present invention is concerned with a system for the real time location of deep boreholes while drilling. The system includes a plurality of sensors sensitive to seismic vibrations disposed in an area where a borehole is to he drilled, the sensors being adapted to selectively pick up the vibrations emitted by the drilling bit as it progresses through the rock. The data picked up by the sensors is then processed and the results are displayed in real time, thus allowing the operator to know precisely the location of the drill bit as the hole is being drilled.

Abstract: The present invention is a system for determining the depth of a logging tool attached to a cable extended into a wellbore penetrating an earth formation. In a preferred embodiment, the system includes a circuit for generating a measurement of phase shift in a sinusoidal electrical signal traversing the cable, the phase shift corresponding to a length of the cable. The system also comprises an accelerometer disposed within the tool and electrically connected to a bandpass filter and thence to a double integrator connected to the bandpass filter. The integrator calculates displacement of the tool coaxial with the wellbore. The phase shift measurement is filtered in a low pass filter. The low pass filter and the bandpass filter comprise at least some amount of bandpass overlap. The integrator output is used to generate a scale factor, which is applied to the filtered phase shift signal. The scaled phase shift signal is combined in a computer with a signal generated by a depth encoder.

Abstract: The present invention relates to the transformation of measurement while drilling (MWD) data acquired during various time intervals into corresponding equal depth intervals. Once the data are transformed into the depth domain, depth based statistical, filtering sensor resolution matching and depth shifting techniques are utilized. The transformation process maximizes sensor vertical resolution while minimizing observed and statistical errors associated with sensor response.

Abstract: A method of dipmeter processing fits a thickness conserving mathematical model to a folded or faulted subsurface sedimentary geological structure, and may be used with vertical as well as nonvertical or deviated boreholes. An initial estimate of the geometry of the structure is made and then used to generate a theoretical dip profile for the model. The dip profile is compared to an actual dip profile recorded in a borehole drilled in the structure. The estimates are modified by an iterated process until satisfactory concordance is obtained between the theoretical dip profile and actual dip profile. The iterated result gives geometric parameters which accurately model the structure. The model is graphically displayed to represent the structure. The model allows the prediction of dip configurations along any other borehole to be drilled in the structure.

Abstract: The method comprises using a transmitting unit and at least two receiving units (8,10) arranged in two different places along well equipment (2). Each receiving unit forms an image or signature of wall portions which pass it. The signatures of wall portions formed by the lower receiving unit (8) when the well equipment is being lowered into the well are stored and the upper receiving unit (10) stores signatures coming from the wall portions which were previously stored by the lower receiving unit. A comparison (for example a correlation) of the signatures respectively coming from the two receiving units allows a common wall portion which has produced two substantially identical compared signatures to be identified. The time interval between the formation of the two substantially identical signatures is measured and the rate of penetration is calculated. As application of the invention is for the measurement of the true rate of penetration of a well tool or of a measuring sonde.

Abstract: An echo sounding system includes an acoustic gun which is mounted to the wellhead of a borehole. The acoustic gun produces an acoustic pulse which is transmitted down the borehole. A tubing string is installed in the borehole and has substantially evenly spaced collars. Fluid is pumped from the borehole, or well, by use of a reciprocating pump driven by a pump rod extending to the surface. Fluid is received from a surrounding formation and collects in the borehole. The acoustic pulse produces reflections when it strikes the tubing collars and the surface of the fluid. A microphone detects the reflections to produce a return signal. This signal is digitized and stored. The digitized signal is processed to detect the rate of the collar reflections and the stored signal is narrowband filtered with a passband filter centered at the rate of receipt of the collar reflections. The data signal is further processed to determine the time of occurrence of the acoustic pulse and the liquid surface reflection.

Abstract: Seismic data is combined with well log data to generate a two-dimensional geopressure prediction display; this permits deviated and horizontal well planning plus lithology detection. Shale fraction analysis, compaction trend, and seismic velocity may be automatically or interactively generated on a computer work station with graphics displays to avoid anomalous results. Corrections to velocity predictions by check shots or VSP, and translation of trend curves for laterally offset areas increases accuracy of the geopressure predictions. Multiple wells' logs in a basin permits analysis fluid migrations.

Abstract: An echo sounding system includes a acoustic gun which is mounted to the wellhead of a borehole. The acoustic gun produces a acoustic pulse which is transmitted down the borehole. A tubing string is installed in the borehole and it has substantially evenly spaced collars. Fluid is pumped from the borehole, or well, by use of a reciprocating pump driven by a pump rod extending to the surface. Fluid is received from a surrounding formation and collects in the borehole. The acoustic pulse produces reflections when it strikes the tubing collars and the surface of the fluid. A microphone detects the reflections to produce a return signal. This signal is digitized and stored. The digitized signal is processed to detect the rate of the collar reflections and the stored signal is narrowband filtered with a passband filter centered at the rate of receipt of the collars. The data signal is further processed to determine the time of occurrence of the acoustic pulse and the liquid surface reflection.

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: A method and apparatus are described for removing noise by smoothing fine resistivity measurements made with a tool from inside a borehole penetrating an earth formation. Pixel values representative of the resistivity measurements are examined to determine the directions of features in the measurements and a smoothing of the pixel values is then made along the measured directions. The orientations of the features are obtained with a similarlity investigation of pixels in sub-array windows along parallel lines whose slope is varied. Optimal slope lines along which the pixel values in a window best resemble each other are determined as the direction of the features. Smoothing is done along the optimal slope lines. Substantially noise free pixel measurements are obtained to enable subsequent automatic signal processing such as the detection of edges between layers of different resistivity. The edges are recorded with an emphasis on a visual display for enhanced visual analysis.

Abstract: A method of determining the continuity of a lithographic layer located between two vertical boreholes is disclosed. A seismic source is lowered in the first borehole while simultaneously a receiver pair, preferably a pair of "vertical" geophones spaced apart by about two feet, are lowered in the second borehole to develop a "differenced signal". The recording of high amplitude signals within a layer is an indication of a continuous, low velocity layer. The middle of a layer can also be discovered using a single vertical receiver and finding the place of phase reversal.

Abstract: A method and apparatus are described for generating a quick look display of an acoustic investigation of a borehole wherein a parameter of interest is derived from vertically spaced sonic receivers and displayed in a laterally continuous display log where the parameter values from respective receivers are recorded at preassigned positions. A fracture sensitive parameter is measured such as the energy in a low frequency Stoneley wave and when the parameter values are laterally recorded areas indicative of fractures become visually enhanced particularly with a laterally expanded display log. Techniques for the detection and evaluation of fractures are described.

Abstract: A device is provided for acquiring data coming from sensors distributed in several probes which may be anchored in a well or borehole and transmission thereof to a central control and recording system, including a remote control assembly for checking operating parameters. An acquisition apparatus includes a main multiplexer for seismic channels and an auxiliary multiplexer. The control assembly includes different modules delivering signals indicative of the position of the anchorage arms, of the operating temperature, of the power supply voltage, etc, means for testing the sensors and the seismic channels, and means for detecting any malfunction in the advance of the probes along the borehole. Different lines connected to the auxiliary multiplexer transmit the signals delivered by the control assembly.

Abstract: A method and means for determining the amount of stretch in a well logging cable is disclosed. An optical fiber is run into a well with a logging cable and looped back to the surface. A second optical fiber of nominal length is maintained on the surface. A source of monochromatic light is passed through both fibers and recombined. As the well logging tool is raised and lowered in the wellbore, the number of interference fringes passing a fixed point is determined. The change in length of the optical fiber and, therefore, the cable will be equal to 1/2 the number of interference fringes passing a fixed point times the wavelength of light used. A precise determination of vertical location can then be made when this information is combined with information from a surface mounted odometer or encoder. This information further allows a precise determination of interval bulk density or other formation parameters in which it is important to know the depth of a tool.

Abstract: A method and an apparatus for recording the depth of a well logging apparatus is provided. The method and apparatus include the direct acquisition of broad depth information from the logging system conversion of the broad depth information to an acceptable digital signal and recording that signal on the audio track of a video cassette recorder. A microcontroller is used to convert broad depth information from either the logging system or the video cassette recorder (in the playback mode) to actual depth and depth rate for use by other displays and plotters.