It is possible to record data continuously by using a recording length that is longer than the time interval between consecutive shots. This can be useful for imaging deep targets with long offsets, for example in salt-prone areas. Continuous recording can improve source sampling and have a positive impact on efficiency, particularly in the presence of strong currents.
By overlapping shot records, the recording length chosen for a survey can be longer than the time interval between consecutive shots. This is comparable to continuous recording as a continuous data stream can be extracted.
This technique was utilized for the wide-azimuth Triton survey in the Gulf of Mexico, where it increased the recording period without increasing the shot interval between consecutive signals. Longer recording lengths are better for imaging of deep sub-salt targets with long offsets, a common feature in the Gulf.
Combining continuous recording and overlapping shot records also speeds up acquisition, as well as improving efficiency in the presence of strong currents. Recently, PGS has applied this technique in deep water off the west coast of Africa to maintain good average speed despite strong currents.