Patent ID: 6256589
Filing Date: 2001-07-03
Classification: G01V

Abstract:
A method for the measurement of the multidirectional far-field source array signatures from marine seismic surveys which comprises the steps of:a) providing a vertical cable technique for vertical cable seismic acquisition;b) acquiring seismic data according to a given geometry of vertical cable with receivers equally distributed along each of a set of vertical cables in different levels, obtaining a data set volume which is made up of seismic traces generated for each shot point location at the surface;c) from said data-set, specifying the receivers located below the far-field region of the utilized seismic source array and above the sea bottom such as any other seismic events do not arrive during the recording of the complete length of the seismic signature;d) sorting the data from c) into common selected-receiver gathers CSRG, such as the seismic traces inside the CSRG are related to the shot points at the surface active for that specific receiver;e) windowing the data along the direct wave of the data obtained in d), such as the length of the window has the same length as the length of the signature to be measured;f) computing from the windowed direct wave the azimuth and incident angles related to the sea surface of each signature from the navigation position of the center of the seismic source at each shot point and from the positioning of each single receiver of each cable, so as each seismic trace in the CSRG will have azimuth and incident angle information;g) normalizing the amplitude of each signature obtained in each CSRG from f) as if said signature was measured at a distance (geometric spreading correction) of one meter to the center of the source array by multiplying the signature amplitude values by the source-receiver distance; andh) obtaining the far-field multidirectional signature for each seismic source array location.