METHOD AND DEVICE COMPENSATING FOR WATER VELOCITY VARIATION FOR 4D DATA SETS

摘要

Methods for determining a seismic wave's propagation velocity in water for monitor seismic data of a 4D data set analyze a relationship between seafloor time-shifts and source-receiver offsets. The time-shifts are differences of normal move out corrected seafloor source-receiver travel times for pairs of traces. Each pair includes a base trace extracted from base seismic data of the 4D data set and a monitor trace extracted from the monitor seismic data, the traces corresponding to the same seafloor bin and having the same source-receiver offset.

主权项

1. A method for determining a monitor velocity in water related to monitor data of a 4D data set, the method comprising:
extracting monitor traces from the monitor data, and base traces from base data included in the 4D data set, the monitor and the base traces being associated with a same surface bin; selecting pairs of traces so that each pair includes a first trace from the monitor traces and a second trace from the base traces, with traces in a pair belonging to the same offset class; determining, for each of the pairs, a time-shift which is a difference of normal move out (NMO) corrected seafloor source-receiver travel times, according to the first trace and according to the second trace, respectively; and ascertaining the monitor velocity in water by analyzing a relationship between time-shifts of the pairs of traces and corresponding source-receiver offsets.