Westerngeco L.l.p.

Schlumberger Technology Corporation

Remco Muijs

Johan Olof Anders Robertsson

Dirk-Jan Van Manen

Johan O A Robertsson

Johan Robertsson

Andrew Curtis

Aslaug Strommen Melboe

A method of processing multi-component seismic data acquired at a receiver station comprises determining a calibration filter that calibrate a first component of the seismic data relative to a second component of the seismic data in order to compensate for differences in coupling between the two components. The determination of the calibration filter comprises processing the data in the common shot domain. This allows optimisation criteria to be applied to the up- and down-going constituents of particle velocity, and this is simpler than prior art methods of applying optimisation criteria to the up-going and down-going constituents of the pressure.

Processing seismic data

The invention provides a method of determining the orientation of a seismic receiver () from seismic data acquired at the receiver (). The determined orientation can be taken into account in subsequent analysis of the seismic data. This avoids inaccuracies that can occur if the receiver orientation is estimated. In a preferred embodiment the horizontal spatial derivatives of the pressure measured at the receiver are used in the determination of the orientation of the receiver. These may be calculated on either the source side or the receiver side. These are combined with horizontal components of the particle displacement, velocity or acceleration (or a higher time-derivative of the particle displacement). Alternatively, horizontal spatial derivatives of the particle displacement measured at the receiver may be used in place of the horizontal spatial derivatives of the pressure. The invention also provides a seismic receiver () having three or more closely-spaced, non-collinear pressure sensors (). The provision of three or more pressure sensors enables the horizontal spatial derivatives of the pressure to be determined accurately.

Determining the orientation of a seismic receiver, a seismic receiver, and a method or seismic surveying

A method for estimating near-surface material properties in the vicinity of a locally dense group of seismic receivers is disclosed. The method includes receiving seismic data that has been measured by a locally dense group of seismic receivers. Local derivatives of the wavefield are estimated such that the derivatives are centered at a single location preferably using the Lax-Wendroff correction. Physical relationships between the estimated derivatives including the free surface condition and wave equations are used to estimate near-surface material properties in the vicinity of the receiver group. Another embodiment of the invention is disclosed wherein the physical relationships used to estimate material properties are derived from the physics of plane waves arriving at the receiver group, and the group of receivers does not include any buried receivers.

System and method for estimating seismic material properties

A method of processing multi-component seismic data acquired at a receiver comprises determining a suitable decomposition scheme to use. This makes use of the existence of pairs of wavefield components that are uncoupled from one another. If there is no physical coupling between first and second wavefield components, the first and second components should not arrive at a receiver location at the same time. The method comprises decomposing a first portion, for example a test portion, of the seismic data into a plurality of wavefield components using an initial decomposition scheme. First and second wavefield components of the decomposed data that should be uncoupled from one another are then selected, and their product is determined. Since the first and second wavefield components of the decomposed data should be uncoupled from one another, their product should be zero or close to zero and a product that is significantly different from zero indicates that the decomposition scheme is inaccurate.

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Zurich, Switzerland

Remco Muijs