Performing geophysical surveys using unmanned tow vessels

摘要

A system comprising a plurality of unmanned tow vessels 302a-d including a first vessel towing one or more source element (116, fig 1) and a second vessel towing one or more streamers (120, fig 1). Vessels traverse a first sail path 316 in an ordered formation, actuating the source(s) and collecting data via the streamer(s). Vessels turn towards a second sail path 318, which they traverse in a second, differently ordered formation, actuating the source element(s) and collecting data via the streamer(s). During the first formation vessels may be aligned in a direction perpendicular to the sail path. First and second formations may be mirror images. Fig 4 shows another aspect wherein unmanned tow vessels 402 are positioned in a crossline direction, having one or more streamers and source elements 404, comprising different numbers of, but at least one low (404c) and at least one high frequency source (404a). Fig 4 shows another aspect wherein there is at least one mid (404b), high (404a) and low (404c) frequency source(s), which are towed at different source densities with the low-frequency source(s) being towed at a lower source density than at least one of the mid or high frequency sources.