Western Atlas International, Inc.

Halliburton Geophysical Services, Inc.

Halliburton Company

Halliburton Logging Services, Inc.

Frederick J Barr

Josef Paffenholz

Joe I Sanders

Ronald E Chambers

Gary Arthur Sitton

Thomas R Beasley

James E Gaiser

Richard H Piggin

David L Nyland

The objective of this invention is to provide a method for estimating, in the frequency domain, deconvolution operators for removing spurious resonant coupling responses from the cross-line and the vertical seismic signal components in OBC surveys. The purpose is to balance the spectral response of the respective signal component in amplitude and phase in a manner consistent with the field geometry.

Horizontal and vertical receiver-consistent deconvolution for an ocean

A method for determining water bottom reflectivities whereby pressure signals and velocity signals are combined to generate combined signals having signal components representing downwardly-travelling energy substantially removed. The pressure and velocity signals correspond to seismic waves generated at source locations n in a water layer and detected by co-located pressure and velocity receivers at receiver locations m in the water layer. The combined signals correspond to each pairing of source location n and receiver location m. The combined signals are transformed from the time domain to the frequency domain, generating transformed signals. A source peg-leg term and a receiver peg-leg term is calculated for each transformed signal, generating filtered signals. An optimization algorithm is applied to the filtered signals, using the corresponding source and receiver peg-leg terms to determine the water bottom reflectivity values R.sub.n and R.sub.m at the source locations n and the receiver locations m, respectively.

Method for deriving surface consistent reflectivity map from dual sensor

A method for attenuating water column reverberations in a dual sensor seismic signal, whereby a pressure signal and a velocity signal are transformed from the time domain to the frequency domain, generating a transformed pressure signal and a transformed velocity signal, respectively. Values for weighting factors K.sub.p and K.sub.v are selected and multiplied times the transformed pressure signal and the transformed velocity signal, respectively, generating a weighted pressure signal and a weighted velocity signal, respectively. The weighted pressure signal and the weighted velocity signal are summed, generating a summed signal. Values for ocean bottom reflectivity R and Z, the frequency domain delay operator for two-way travel time in the water layer, are determined. A weighted inverse Backus filter is calculated and multiplied times the summed signal, generating a filtered signal. The filtered signal is transformed from the frequency domain to the time domain.

Weighted backus filter method of combining dual sensor traces

A method for determining ocean bottom reflectivities from dual sensor seismic data, whereby a first time windowed pressure signal and a first windowed velocity signal are summed to generate a first summed signal, and a second time windowed pressure signal and a second time windowed velocity signal are summed to generate a second summed signal. The first summed signal and the second summed signal are transformed from the time domain to the frequency domain to generate a first transformed sum and a second transformed sum, respectively. A value R for said ocean bottom reflectivity is selected and used to calculate an inverse Backus filter (1+Rz).sup.2, where Z is the Z-transform of the two-way travel time delay filter. The first transformed sum and the second transformed sum are multiplied by the inverse Backus filter to generate a first filtered sum and a second filtered sum, respectively. A cross spectrum is calculated from the first filtered sum and the second filtered sum to generate a trial cross spectrum. An optimization algorithm is applied to the trial cross spectrum to determine the ocean bottom reflectivity.

Method for improving the accuracy of ocean bottom reflectivity

A marine seismic surveying method recording with a first sensor a first signal indicative of pressure and with a second sensor a second signal indicative of motion, calculating a coupling mechanism filter for the second signal substantially correcting for the imperfect coupling of the second sensor, and applying a filter based on the coupling mechanism filter to at least one of the signals.

Method for correcting dual sensor data for imperfect geophone coupling

In the presence of an anisotropic near-surface earth layer, orthogonally oriented microspreads are provided from which shear-wave velocity vectors V.sub.si.theta. and V.sub.s.theta. may be determined. The respective velocities are calculated from measurements of the direct path first arrivals and of the velocity of the boundary waves propagating along the upper boundary of the near surface layer. The ratio of the near-surface shear-wave velocity vectors is used to scale the static time corrections attributable to seismic data received by shear wave sensors whose axes of responsivity coincide with the orientation of the microspreads.

Method for measuring the near-surface shear wave velocity for use in

A method for measuring the velocity of shear waves in a formation beneath a body of water. The shear wave velocity is derived from the parameters of water density, water-bottom reflection coefficient, formation compressional wave, velocity and the propagation velocity of a submarine ground-roll wave front.

Method for determining the shear-wave velocity beneath a body of water

A method for obtaining seismic data in frigid regions without interference from flexural ice waves. In an exemplary embodiment, seismic data is produced by using an energy source to generate a seismic wave in a floating ice sheet. Seismic disturbances caused by the energy source are detected by one or more hydrophones and geophones, which produce hydrophone and geophone response signals, respectively. In a first embodiment, the hydrophone response signal is integrated. The integrated signal and/or the geophone response signal are scaled, and the two signals are then added. Alternatively, instead of integrating the hydrophone response signal, the geophone response signal may be differentiated prior to scaling and summing. A method is also disclosed for overcoming phase errors that might be introduced, for example, by the use of a transformer-coupled hydrophone. In another embodiment of the invention, a linear adaptive filter is applied to the hydrophone and geophone response signals to obtain an output signal having attenuated noise characteristics.

Method for seismic exploration in artic regions

In dual-sensor, bottom-cable marine seismic exploration where hydrophone/geophone pairs are deployed on the marine bottom, coupling imperfections between the geophones and the marine bottom contribute to differences between the impulse response of the geophones and the impulse response of the hydrophones. To correct for the coupling imperfection, a filter is designed which compensates for the inherent impulse response differences as well as response differences caused by the imperfect coupling. Preferably, the filter is designed using a calibration procedure prior to production shooting. First, the response of a hydrophone and geophone to a seismic wave is recorded. Then, these recorded responses are transformed into the frequency domain. Once transformed, the response of the hydrophone is divided by the response of the geophone to produce a filtering function. When the filtering function is applied to geophone signals during production shooting, the filter compensates the geophone signals to alleviate differences in response characteristics between the geophone signals and the hydrophone signals.

Method for correcting impulse response differences of hydrophones and

In dual-sensor, bottom-cable marine seismic exploration where hydrophone/geophone pairs are deployed on the marine bottom, coupling imperfections between the geophones and the marine bottom contribute to differences between the impulse response of the geophones and the impulse response of the hydrophones. To correct for the coupling imperfection, a filter is designed which compensates for the inherent impulse response differences as well as response differences caused by the imperfect coupling. Preferably, the filter is designed using a calibration procedure prior to production shooting. First, the response of a hydrophone and geophone to a calibration wave is recorded. The calibration wave has a magnitude that is similar to the magnitude of a reflected wave that hydrophone and geophone would detect during normal production shooting. These recorded responses are transformed into the frequency domain. Once transformed, the response of the hydrophone is divided by the response of the geophone to produce a filtering function. When the filtering function is applied to geophone signals during production shooting, the filter compensates the geophone signals to alleviate differences in response characteristics between the geophone signals and the hydrophone signals.

A marine seismic reflection prospecting system reduces coherent noise by applying a scale factor to the output of a pressure transducer and a particle velocity transducer positioned substantially adjacent one another in the water. The transducers can be positioned at a point in the water above the bottom and, thereby, eliminate downgoing components of reverberation, or they can be positioned on the water's bottom and, thereby, eliminate both upgoing and downgoing components of the reverberation. The scale factor, which derives from the acoustical impedance of the water or water-bottom material, can be determined both deterministically and statistically. The former involves measuring and comparing the responses of the pressure and velocity transducers to a pressure wave induced in the water. The latter involves comparing the magnitude of the pressure signal autocorrelation to the pressure and velocity signal crosscorrelation at selected lag values or, alternatively, comparing the magnitude of the pressure signal autocorrelation to the velocity signal autocorrelation at selected lag values.

System for attenuation of water-column reverberations

A method and apparatus are disclosed for carrying out the seismic exploration of the strata which surrounds a borehole during the drilling of that borehole. A compressional mode jar mechanism is disposed in a drill string above a drill bit. Sufficient weights to cock and actuate the jar are disposed both below and above the jar mechanism respectively. A telescoping joint above the jar prevents the impact on the drill bit from propagating up the drill string and multiple geophones at the surface are utilized to receive the seismic waves generated by the impact of the drill bit within the borehole. In a preferred mode of the present invention, an additional geophone is disposed within the drill string proximate to the drill bit to detect the 'first break' of the impact thus generated.

Growing community of inventors

Houston, TX, United States of America

Frederick J Barr