Pgs Geophysical As

Tilman Kluver

Stian Hegna

Jostein Lima

Anthony James Day

Noise can be attenuated in marine seismic data from a marine seismic survey. A first near-continuous measurement of a wavefield and a second near-continuous measurement of the wavefield recorded from a marine seismic survey can be equalized, a coherent portion of the equalized second near-continuous measurement can be collapsed, and a noise model can be derived. The noise model can be subtracted from the second near-continuous measurement.

Noise attenuation

Techniques are disclosed relating to performing marine surveys with non-uniform spacing of survey elements in a cross-line direction. This may include, for example, performing a survey pass in a multi-pass survey by towing a plurality of sources and sensors in a towing pattern with non-uniform spacing between adjacent ones of the sources. In some embodiments, the non-uniform spacing between adjacent ones of the sources is determined based on a common mid-point (CMP) spacing parameter for the survey pass in the cross-line direction. The spacing parameter may relate, for example, to difference in average CMP spacing for different parts of the survey spread, variance in CMP spacing, and/or width of the survey spread for which a threshold CMP spacing distance is satisfied. In various embodiments, the disclosed techniques may improve survey resolution and/or accuracy and may require a smaller number of survey passes and/or a reduced amount of survey equipment relative to traditional techniques.

Non-uniform towing patterns in marine geophysical surveys

Estimating an earth response can include deconvolving a multi-dimensional source wavefield from near-continuously recorded seismic data recorded at a receiver position. The deconvolving can include spreading the near-continuously recorded seismic data across a plurality of possible source emission angles. The result of the deconvolution can be the earth response estimate.

Estimating an earth response

Source element of a source subarray can be individually actuated according to an actuation sequence. The actuation sequence can be at least partially based on a relative position of each of the source elements within a particular geometry of the source subarray with respect to a previously actuated source element and a towing velocity of the source subarray.

Individual actuation within a source subarray

This disclosure is directed to systems and methods of wavefield separation based on matching operators that represents the relationship between co-located pressure and particle motions sensors. A pressure wavefield and a particle motion wavefield emitted from a subterranean formation are measured using co-located pressure and particle motion sensors located along one or more streamers of a seismic data acquisition system. A matching operator that relates pressure sensor and particle motion sensor responses for co-located pressure and particle motion sensors is computed based on depth of the co-located pressure and particle motion sensors and on the measured pressure and particle motion wavefields. The matching operator and the measured pressure and particle motion wavefields may then be used to compute up-going and down-going wavefields.

Wavefield separation based on a matching operator between sensor responses in multi-component streamers

At least some embodiments are directed to a system. The system includes a processor and a memory coupled to the processor. The memory stores a program that, when executed by the processor, causes the processor to calculate a pressure response of a first sensor, and correct pressure wavefield data obtained from the first sensor responsive to a first acoustic wavefield. The correction is based on the calculated pressure response of the first sensor. The pressure response of the first sensor is responsive to a second acoustic wavefield having a propagation path between a source of the second acoustic wavefield and the first sensor, in which the propagation path includes no reflection from a subsurface formation.

Separation of up-going and down-going wavefields including the direct arrival

Computational systems and methods that combine global frequency-wavenumber-domain ('f-k domain') filters with localized eigenimage based event selection to generate a resulting wavefield with reduced filter imprints on gather edges, reduced noise, and correct treatment of aliased energy are disclosed. The methods are executed by applying filters to the full set of seismic gather data in the f-k domain in order to obtain a resulting wavefield from recorded pressure and/or particle velocity data. The output of the filter is iteratively decomposed according to local dip values using eigenimage processing based on singular value decomposition ('SVD'). The same sample locations are extracted using SVD from the input in addition to generating input for a subsequent iteration with already processed data removed. Eigenimage processing methods allow for correct treatment of spatially aliased energy in f-k domain filtering.

Growing community of inventors

Oslo, Norway

Tilman Kluver