System for sorting seismic data in marine surveys

• US 4,561,073 A
• Filed: 05/13/1982
• Issued: 12/24/1985
• Est. Priority Date: 05/26/1981
• Status: Expired due to Term

• Current Assignee: Geophysical Company of Norway As (Schlumberger NV)
• Original Assignee: Geophysical Company of Norway As (Schlumberger NV)
• Inventors: Brandsaeter, Helge, Ommundsen, Tor A., Mjoen, Oyvind
• Primary Examiner(s): Jordan, Charles T.
• Assistant Examiner(s): Steinberger, Brian S.
• Application Number:
  US06/378,015
• Time in Patent Office: 1,321 Days
• Field of Search: 367/7, 367/19, 367/21, 367/88, 367/106, 367/23, 367/38, 367/68, 367/72, 367/107, 367/111, 367/116
• US Class Current: 367/19
• CPC Class Codes: G01V 1/3808 Seismic data acquisition, e.g. survey design

Abstract

A system for sorting data from seismic surveys at sea. The data are acquired by signal transmission/receiving by streamer cables, which streamers are equipped with position-defining instruments. For the sorting, the area to be surveyed is subdivided into squares of defined size and position. The data provided through the measurements is sorted, and accepted data is processed further and transferred to the individual squares in the grid pattern. On the basis of the data, the configuration and position of the streamer is also computed, and information regarding this is displayed on a screen. On the basis of these results, the coverage of the measurement area may be determined, and an adjustment of the vessel'"'"'s steering can be carried out to allow one to obtain the best coverage of the area. The acquired data is stored for later treatment.

Claims

1. In a system for measuring and collecting data from seismic surveys at sea with the aid of a vessel including at least one seismic signal transmitter operatively connected to the vessel to be towed thereby, at least one acoustic streamer cable operatively connected to the vessel to be towed thereby having means located along said cable for measuring reflection signals produced by said at least one transmitter, and position defining means at the locations of said reflection signal measuring means, the improvement comprising:

means to subdivide an area to be surveyed into a grid of individual rectangles of a defined size and geographical position;

said at least one streamer cable being divided along its length into a plurality of subgroups of said reflection signals measuring means and respective position defining means so that the subgroups provide seismic data of near-traces from the subgroup closest to the vessel, distant-traces from the subgroup farthest from the vessel and middle-traces from at least one subgroup between said nearest and farthest subgroup;

control means to continuously receive and sort independently and simultaneously data from said near-traces, middle-traces and distant-traces to obtain and transmit the measured reflection and position defining data therefrom;

a computing unit for receiving and processing said measured reflection and position defining data and transferring it to the respective individual rectangles of said grid and computing from said measured reflection and position defining data the configuration and position of the subgroups of the streamer cable;

display means to continuously during the surveying operation display control data, recording data and streamer cable position on a grid of individual rectangles corresponding to the rectangles formed by subdividing the area being surveyed to show the coverage of said data in the individual rectangles of the grid;

means to evaluate said displayed data operatively connected to the vesses'"'"'s navigation system for use in navigating the vessel;

means to compare said measured reflection and position defining data with known data to determine the degree of coverage in the area being surveyed so that a single pass of the vessel over said area produces a substantially complete survey; and

means to store said data.

2. A system as claimed in claim 1 wherein, said plurality of subgroups comprises three subgroups, and further comprising a tail buoy attached to the outer end of said streamer cable, and a position-defining means on said tail buoy.

3. A system as claimed in claim 1 wherein, said position-defining means comprises a magnetic compass.