Abstract: A method for generating an unaliased 3-D DMO operator using two dimensional sampling theory to the spatial traverse of the operator as well as to the temporal axis. First a continuous DMO operator is generated along the line segment connecting a source and a receiver directed at an arbitrary azimuth relative to a biaxial output grid. The operator is discretized at spaced-apart sample points along the DMO aperture segment, the spacing being equal to or less than the output grid dimensions. A exponentially tapered sinc filter function is applied to the samples which are then interpolated onto the output grid.

Abstract: Long-term changes in the distribution of a mineral in a subsurface deposit, due to commercial production of the mineral, are monitored by suitable instrumentation. The monitoring instrumentation is installed in combination with commercial mineral production equipment but the monitoring instrumentation is transparent to production. The monitoring instrumentation measures long-term changes in selected petrophysical attributes that are due to re-distribution of the mineral within the deposit in response to production.

Abstract: The modulus of stretch af a fibrous rope is reduced by impregnating a pluity of spaced-apart segments of the rope with an epoxy plastic thereby to reduce the modulus of stretch of the segment equal to zero after curing the plastic. The overall modulus of stretch of a re-manufactured rope taken as a whole is proportional to the ratio of the length of an impregnated segment relative to a unit length of the rope.

Abstract: An unconstrained transformation filter operator that is efficient in terms of computer resources and that improves circularly symmetric migrated impulse response for steep dips. The filter operator combines selected desirable attributes of the more efficient McClellan transformation filter with selected desirable attributes of the more accurate Laplacian transformation filter. The novel filter operator is not constrained along the k.sub.x and k.sub.y spatial axes by the requirement that it equal cos (k). The transformation filter is averaged over all azimuths to improve its accuracy of response.

Abstract: The two-way water-layer travel time, .tau., is derived from duel-mode seismic sensor data by cross-correlating the Fourier transforms of the sum and difference of the velocity and pressure signatures. The Z-transform of .tau. evaluates one of the two Backus variables, Z.sub.w. The second variable is R.sub.b, the water bottom reflectivity coefficient. The frequency-domain transforms of the above summed and differenced signatures are each multiplied by the Backus operator (1+R.sub.b Z.sub.w).sup.2 after initializing R.sub.b and the products are iteratively cross-correlated until the correlation function converges to a minimum. R.sub.b is perturbed after each iteration. The value of R.sub.b upon convergence is the local water bottom reflectivity coefficient.

Abstract: Wide-angle reflections that have been overcorrected using a simple two-term hyperbolic moveout correction are adjusted by application of a bi-quadratic term. The biquadratic term is derived by scanning the overcorrected reflections for residual velocity. The residual velocity is used to calculate an adjustment as a linear function of the first power of the travel time to each receiver versus the fourth power of the corresponding receiver offset.

Abstract: A high-order, polynomial regression curve is fitted to a global set of first-arrival pick times as a function of the nominal ranges between a plurality of acoustic sources having known geodetic coordinates and a plurality of acoustic detectors whose coordinates are imperfectly known. The polynomial is applied to the pick times to provide pick time distances with the vertical velocity gradient removed. The known source coordinates, the nominal detector coordinates and the pick time distances are combined to provide a quadratic surface to provide a common data block containing the coefficients for modeling the lateral velocity gradient. Using the so-determined coefficients, the imperfectly-known detector positions are iteratively updated using the Helmert blocking technique.

Abstract: A computationally economical method for applying multi-dimensional multiple-reflection attenuation to a marine seismic-signal data set comprised of a plurality of common shot gathers that have surface-multiple wavefields embedded therein. The multi-dimensional data are assumed to have been gathered from a plurality of parallel 2-D lines of survey. From every nth reference line, where n is a small number greater than 2, a common shot gather is selected. For every so-selected common shot gather, a reference surface-multiple wavefield is predicted as a function of offset and travel time with the aid of any well-known multiple attenuation routine, using a wavelet having fixed attributes in terms of amplitude, phase and frequency. A common shot gather is chosen from among the plurality of common shot gathers.

Abstract: A distributed seismic data acquisition system includes a vast plurality of Autonomous Data Acquisition Modules (ADAM) to each of which are interconnected a subplurality of data-collection channels. Each data collection channel is comprised of an array of seismic sensors for continuously measuring seismic signals. The ADAMs include a GPS satellite receiver for providing geographic coordinates and system clock. Measured seismic signals are quantized and continuously downloaded to the respective interconnected ADAMs from the data-collection channels. The system includes both field testing capability as well means for transmitting the results of self tests. Provision is made for servicing the ADAMs at the end of a multi-day recording session and for harvesting and cataloging the recorded data. The seismic signals gathered by use of the distributed data-gathering system may be processed to provide a subsurface earth model.

Abstract: An array of output image points is distributed over a velocity model of a subsurface region of interest. A fan of rays is shot from each of a plurality of acoustic source points along the surface, the angular separation between the rays being equal to .pi./n, where n is the number of rays. A family of traveltime wavefronts is erected at selected time intervals, .DELTA.t, along the ray trajectories. The resulting wavefront map is superimposed over the array of output image points. Sub-arrays of output image points will lie within discrete traveltime cells, the widths of which are defined by the separation between adjacent rays paths and the heights are defined by the wavefront separation distance. Ray segments, wavefront segments and output image points are identified by a velocity layer index. A velocity interface that may cut across a traveltime cell, divides the cell into two parts, each having a different layer index.

Abstract: A receiver consistent deconvolution operator models the damped oscillatory wavetrain that is related to geophone coupling to the water bottom. The operator is a best-fitting function that endeavors to describe the difference in coupling response between a well-coupled in-line geophone relative to an imperfectly-coupled cross-line geophone. The operator is applied to the cross-line signals to compensate the signals for the distortion due to imperfect cross-line ground coupling.

Abstract: A method for minimizing non-uniform insonification of subsurface formations in the presence of steep dips when advancing a swath of elongated parallel seismic streamer cables along a line of survey. A first acoustic source is stationed at the leading end of the swath and a second source is stationed at the trailing end of the swath. The sources are activated in alternate cycles at preselected timed intervals to provide down-dip and up-dip seismic data sets. The data sets are processed and merged to eliminate objectionable shadow zones.

Abstract: A cluster of seismic streamer cable utility modules is provided with a set of hinged latching members. The hinged latching members are adapted secure the cluster to the steamer cable by closing the hinged latches around corresponding collars mounted on the streamer cable. The collars form an inner race while the closed hinged latches form an outer race to allow free relative rotation between the streamer cable and the cluster of modules.

Abstract: A high-order polynomial regression curve is fitted to a global set of first arrival times as a function of the nominal ranges between a plurality of acoustic sources having known geodetic coordinates and a plurality of acoustic detectors whose coordinates are imperfectly known. The order of the polynomial is chosen to be that order that minimizes the variance of the parameters about the regression curve. The polynomial is used as a quasi-velocity function for iteratively optimizing the best estimate of the ranges between each detector and every source station. The best estimate of the detector position is derived by multi-lateration using the computed ranges.

Abstract: A seismic cable connector adapter assembly for coupling sub-diameter seismic streamer-cables to standard-sized instrumented cable connector modules.

Abstract: The rotatable cylindrical sleeve that comprises the female cable connector termination of a seismic streamer cable section is made in two telescoping parts. The two telescoping parts are indexed together by a shear pin to form a weak link assembly. If a streamer cable is snagged, the shear pin fails, allowing the telescoping parts of the sleeve to part company, releasing the snagged cable portions but without structural damage to the cable section. A feature of the device is its ease of retrofit.

Abstract: A plurality of sensors, each of which is coupled to a data channel, are mounted on a downhole logging tool for periodically measuring and sampling, at preselected timed sample intervals, petrophysical characteristics of the borehole sidewall material. The sample values are arranged in a two-dimensional array of a plurality of time series in channel-sequential order, indexed by consecutive sample number. Means are provided for transforming the plurality of time series from the time domain to the wavelet domain. The wavelet coefficients for each transformed time series are compressed by thresholding. The compressed wavelet coefficients corresponding to each time series are transmitted to a receiver where the compressed wavelet coefficients are decompressed by formatting same into a broken sequence of wavelet coefficients. The original time series is reconstructed by inversely transforming the broken sequence of wavelet coefficients from the wavelet domain back to the time domain.

Abstract: A computer-aided method for providing a de-aliased output data set d.sub.L (t,x.sub.L,y.sub.L) from a spatially aliased, three-dimensional, input data set of known seismic signals, a(t,x,y), where L is an interpolator. The known data set is zero-padded by L. The zero-padded data set is zero-masked. The zero-padded data set is divided by a zero-padded, zero-masked data set to provide an interpolation operator H.sub.L. L-1 zero traces are interleaved between the known traces of data set a(t,x,y) to provide a zero-inserted data set c.sub.L ((t,x.sub.L,y.sub.L) whose transform is C.sub.L (m,k.sub.xL,k.sub.yL). The product of (H.sub.L) with (C.sub.L) is (D.sub.L) which is inverse-transformed to provide the desired de-aliased data set d.sub.L (t,x.sub.L,y.sub.L).

Abstract: This invention describes a methodology to image features using an array of multiple piezo-electric elements which employs the selective use of mechanical and electronic beam focusing, electronic beam steering and amplitude shading to increase resolution and overcome side lobe effects. This invention introduces a novel signal reconstruction technique utilizing independent array element transmission and reception, creating focusing and beam steering. Application of the methodology can be used in wireline, measurement while drilling, pipe and pipeline and medical applications. Applications include, but are not limited to Bore hole Caliper, Bore hole Geometry, Bore hole Imaging, Casing Inspection, Cement Evaluation and Volumetric Scanning Applications (e.g. Fluid, Behind Casing and Open Hole). The configuration of the transducer array is preferably cylindrical, but may be conical, biconical, convex, concave or may take the form of a number of suitable geometric configurations.