US 8,898,020 B2Granted

Method for time picking and orientation of three-component seismic signals in wells

AssigneeIfp Energies Nouvelles

InventorsCharles Naville, Sylvain Serbutoviez, Jean-Claude Lecomte

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Abstract

A method, having application to petroleum exploration or production, for picking the arrival time of seismic waves and use thereof for orienting the components of a multi-component sensor. After acquisition of seismic data using a VSP type method, with a multi-component sensor, a module signal is constructed by calculating the square root of the sum of the squares of at least two orthogonal seismic components. Arrival times of a direct seismic wave are then picked on an amplitude extremum of this module signal. Based on this picking, the seismic components can then be oriented in a unique reference frame whatever the depth of the sensor. A time window is defined on either side of the picked arrival times and the azimuthal direction is determined by maximizing the energy of the horizontal components within this time window. Finally, the three components are oriented in a reference frame defined with respect to the azimuthal direction, which is identical for each depth.

Claims45

Dependent claims

A method of pre-processing seismic data acquired by seismic prospecting using vertical seismic profiling comprising emitting seismic waves and receiving the seismic waves by at least one multi-component sensor positioned in a well at least at two depths with the at least one sensor comprising at least three orthogonal geophones recording as a function of time a first seismic component in a known vector direction, and at least two other seismic components in two directions orthogonal to the known vector direction, comprising:

a) providing a module signal by calculating a square root of a sum of squares of the at least two other orthogonal seismic components and picking arrival times of a direct seismic wave which is an amplitude extremum of the module signal;
and
b) orienting the two other seismic components in a unique reference frame regardless of a depth of the at least one sensor, by repeating for each depth defining a time window on either side of the arrival times, determining an azimuthal direction by maximizing an energy of the two other seismic components orthogonal to the known vector direction within the time window and orienting to within 360° the two other seismic components orthogonal to the known vector direction in a unique reference frame defined with respect to the azimuthal direction which is identical for each depth.

Dependencies are inferred from the claim text.