Method of processing seismic data
AssigneeWesternGeco L.L.C.
InventorJohan O. A. Robertsson
Life of this patent
Estimating the term…
Abstract
A method of de-ghosting seismic data acquired in a marine seismic survey comprises estimating ∂zp (where p is the fluid pressure) from a time-derivative of p and a derivative of p in a horizontal direction such as the x-direction. The time-derivative of p and the derivative of p in the horizontal direction can be readily obtained from the acquired seismic data, and are used to provide an improved estimate of ∂zp which, in general, cannot be directly determined from the acquired seismic data. Once ∂zp has been estimated it can be used to de-ghost the acquired seismic data.
Claims22
A method of de-ghosting seismic data, the method comprising the steps of:
- a) obtaining seismic data using a seismic source and a seismic receiver disposed within a fluid medium;
- b) determining a derivative with respect to time of the fluid pressure at a point in the vicinity of a selected one of the seismic source and the receiver;
- c) determining a derivative with respect to a first direction of the fluid pressure at a point in the vicinity of the selected one of the seismic source and receiver;
- d) determining a derivative with respect to a second direction of the fluid pressure at a point in the vicinity of the selected one of the seismic source and receiver from the results of steps (b) and (c);
- and
- e) processing the seismic data using the derivative with respect to a second direction of the fluid pressure, thereby to reduce the effects in the processed seismic data of seismic energy reflected and/or scattered at the sea surface.
A method of calibrating a seismic receiver, the method comprising the steps of:
- a) measuring the particle velocity using a seismic source and a seismic receiver disposed within a fluid medium;
- b) determining a derivative with respect to time of the particle velocity at a point in the vicinity of the receiver;
- c) determining a derivative with respect to a first direction of the particle velocity at a point in the vicinity of the receiver;
- d) determining a derivative with respect to a second direction of the particle velocity at a point in the vicinity of the receiver from the results of steps (b) and (c);
- and
- e) determining a measure of the quality of the measurement of the particle velocity using the derivative with respect to a second direction of the particle velocity.
A method of determining the depth of a seismic receiver, comprising the steps of:
- disposing a seismic receiver in a fluid medium;
- measuring the fluid pressure and the particle velocity using the seismic receiver;
- determining the distance between the fluid surface and the seismic receiver using an extra degree of freedom resulting from the measured values of the particle velocity and the fluid pressure;
- and
- determining the shape of the seismic receiver using the extra degree of freedom.
Dependencies are inferred from the claim text.