Method and device to acquire marine seismic data

Abstract

The invention concerns a method to acquire seismic waves by means of a streamer towed by a vessel and comprising a plurality of seismic receivers. The streamer comprises a head portion that is slanted relative to the water surface and a tail portion having at least one section with a different slant.

1 . A method for acquiring seismic waves in water, the method comprising:
 towing a streamer having a head portion and a tail portion;   adjusting a set of head birds attached to the head portion to obtain a head slope for the head portion;   adjusting a first set of birds, attached to a first section of the tail portion, to obtain a first slope for the first section;   adjusting a second set of birds, attached to a second section of the tail portion, to obtain a second slope for the second section; and   recording the seismic waves with seismic receivers distributed along the head portion, the first portion and the second portion of the streamer,   wherein the head slope is different from the first slope and the first slope is larger than the second slope.   
     
     
         2 . The method according to  claim 1 , wherein the tail portion has a third section having a third slope different from the first and second slopes. 
     
     
         3 . The method according to  claim 2 , wherein the second slope is larger than the third slope. 
     
     
         4 . The method according to  claim 1 , wherein the head slope is larger than the first slope. 
     
     
         5 . The method according to  claim 1 , wherein the seismic receivers of the streamer include hydrophones. 
     
     
         6 . The method according to  claim 1 , wherein the seismic receivers of the streamer comprise a combination of hydrophones and geophones. 
     
     
         7 . The method according to  claim 1 , further comprising:
 shooting a seismic source to generate the seismic waves.   
     
     
         8 . A method for acquiring seismic waves in water, the method comprising:
 towing a streamer having a head portion and a tail portion, the tail portion including first and second sections;   adjusting birds on the head portion and the tail portion to achieve different slopes for the head portion and the first and second sections of the tail portion; and   recording the seismic waves with seismic receivers distributed along the head portion, the first portion and the second portion of the streamer,   wherein the slope of the first section is larger than the slope of the second section.   
     
     
         9 . The method according to  claim 8 , wherein the tail portion has a third section having a different slope than the slopes of the first and second sections. 
     
     
         10 . The method according to  claim 9 , wherein the slope of the second section is larger than the slope of the third section. 
     
     
         11 . The method according to  claim 8 , wherein the slope of the head portion is larger than the slope of the first section. 
     
     
         12 . The method according to  claim 8 , wherein the seismic receivers of the streamer include hydrophones. 
     
     
         13 . The method according to  claim 8 , wherein the seismic receivers of the streamer comprise a combination of hydrophones and geophones. 
     
     
         14 . The method according to  claim 8 , further comprising:
 shooting a seismic source to generate the seismic waves.   
     
     
         15 . A method for acquiring seismic waves in water, the method comprising:
 towing a streamer having a head portion and a tail portion, the tail portion including first and second sections; and   adjusting birds on the head portion and the tail portion to achieve different slopes for the head portion and the first and second sections of the tail portion,   wherein the slope of the first section is larger than the slope of the second section.   
     
     
         16 . A seismic system configured to acquire seismic waves related to a subsurface to be surveyed, the system comprising:
 a vessel towing a seismic source and a streamer;   the streamer having a head portion and a tail portion and the tail portion having first and second sections;   a plurality of seismic receivers distributed along the head and tail portions of the streamer; and   depth control devices spaced along the head portion and the tail portion,   wherein the depth control devices are adjusted on the head portion and the tail portion to achieve different slopes for the head portion and the first and second sections of the tail portion, and   wherein the slope of the first section is larger than the slope of the second section.   
     
     
         17 . The system according to  claim 16 , wherein the tail portion has a third section having a different slope than the slopes of the first and second sections. 
     
     
         18 . The system according to  claim 16 , wherein the slope of the second section is larger than the slope of the first section. 
     
     
         19 . The system according to  claim 16 , wherein the plurality of seismic receivers include hydrophones. 
     
     
         20 . The system according to  claim 16 , wherein the plurality of seismic receivers comprise a combination of hydrophones and geophones.