Fairfield Industries, Inc.

Fairfield Geotechnologies

Kenneth Craft

Carsten Udengaard

Josef Paffenholz

Bryan C Keller

A system to improve calibration of geophone and hydrophone pairs is described. The system generates first and second phase shifted data by applying a first and second phase shift to first seismic data acquired by the geophone. The system generates a first upgoing wavefield by summing the first phase shifted data and second seismic data acquired by the hydrophone, and a second upgoing wavefield by summing the second phase shifted data and the second seismic data. The system generates a first downgoing wavefield from a difference of the first phase shifted data and the second seismic data, and a second downgoing wavefield from a difference of the second phase shifted data and the second seismic data. The system determines ratios of the upgoing wavefields and the downgoing wavefields for each phase shift to identify the highest ratio, and selects the phase shift corresponding to the highest ratio for calibration.

Calibration of geophone and hydrophone pairs

Methods and systems for minimizing RMS travel time error in a seismic data acquisition. Field measurements of source and receiver coordinates, speed of sound in water as a function of depth and time, receiver timing, and clock drift are first collected. The seismic data is then examined to measure travel time from each source to each receiver. A model travel time is computed based on the field measurements. By iteratively perturbing at least one of the field measured data using a look-up table and calculating the travel time after each perturbation until an acceptable RMS error has been achieved, conditioned seismic data that takes into account the dynamic nature of the water column will provide the basis for creating an accurate seismic map that is unaffected by the changing water conditions.

Seismic data analysis using ocean bottom node data collection

Methods and apparatus for processing dual sensor (e.g., hydrophone and vertical geophone) data that includes intrinsic removal of noise as well as enhancing the wavefield separation are provided. The methods disclosed herein are based on a decomposition of data simultaneously into dip and frequency while retaining temporal locality. The noise removed may be mainly coherent geophone noise from the vertical geophone, also known as V(z) noise.

Geophone noise attenuation and wavefield separation using a multi-dimensional decomposition technique

Methods and apparatus for removing noise from signal traces collected during a seismic gather, particularly removing the aliased energy in the time-slowness (tau-P) domain so that aliasing noise does not lead to high noise levels in the inverse transformed data are provided. Removal of the aliasing noise may provide for quieter seismic traces and may increase the likelihood for successful three-dimensional (3-D) tau-P interpolation and detection of seismic events.

3-D TAU-P interpolation

Coherent wave noise energy is removed from seismic data by modeling both the P-wave primary energy and the coherent wave noise energy. The P-wave primary energy is modeled first and then subtracted from the input data. The data with the P-wave primary energy removed is used as the input for coherent wave energy removal. The coherent wave energy is modeled and subtracted from the original input data, i.e. the data input into P-wave primary removal. This leaves a dataset with P-wave primary energy and noise energy not related to coherent waves. This method can be utilized to remove all types of coherent noise with a velocity difference to the desired P-wave primary energy or with a different type of moveout (change of time of arrival with source-receiver distance) such as, for example, linear moveout.

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Missouri City, TX, United States of America

Kenneth Craft