Acquisition scheme for vibroseis marine sources

Abstract

Control mechanisms, computer software and methods for driving vibrational source arrays underwater. An incoherent acquisition scheme drives individual source elements simultaneously and incoherently while a coherent acquisition scheme drives high-frequency individual source elements simultaneously and incoherently and low-frequency individual source elements simultaneously and coherently. Thus, denser coverage and an increased energy input is achieved for the source arrays.

What is claimed is: 
     
         1 . An incoherent acquisition method for driving vibrational source arrays under water, the method comprising:
 towing with a vessel a first source array and a second source array underwater, wherein the first source array includes plural first individual source elements and the second source array includes plural second individual source elements; and   activating simultaneously the first source array and the second source array so that incoherent coded driving signals drive the first and second source arrays,   wherein the coded driving signals include corresponding signatures so that during a processing phase, seismic signals from the first source array are separated from seismic signals of the second source array.   
     
     
         2 . The method of  claim 1 , wherein the incoherent coded driving signals of the first and second source arrays include multiple frequencies and coded driving signals for the first source array are not correlated to coded driving signals for the second source array. 
     
     
         3 . The method of  claim 1 , wherein the plural first individual source elements and the plural second individual source elements are configured to emit a frequency lower than about 32 Hz. 
     
     
         4 . The method of  claim 3 , wherein the first source array and the second source array include plural third individual source elements that are configured to emit a frequency higher than about 32 Hz. 
     
     
         5 . The method of  claim 4 , further comprising:
 towing the plural first and second individual source elements at a depth larger than a depth of the plural third individual source elements.   
     
     
         6 . The method of  claim 1 , wherein the plural individual first and second source elements are electro-mechanical sources. 
     
     
         7 . The method of  claim 6 , further comprising:
 activating an electro-magnetic actuator system to generate a first seismic wave; and   activating a pneumatic mechanism to generate a second seismic wave,   wherein the electro-magnetic actuator system and the pneumatic mechanism are part of an individual source element.   
     
     
         8 . A control mechanism configured to implement an incoherent acquisition method for driving vibrational source arrays under water, the control mechanism comprising:
 a processor configured to activate simultaneously a first source array and a second source array so that incoherent coded driving signals drive the first and second source arrays,   wherein the first source array includes plural first individual source elements and the second source array includes plural second individual source elements, and   wherein the coded driving signals include corresponding signatures so that during a processing phase, seismic signals from the first source array are separated from seismic signals of the second source array.   
     
     
         9 . The control mechanism of  claim 8 , wherein the incoherent coded driving signals of the first and second source arrays include multiple frequencies and codded driving signals for the first source array are not correlated to codded driving signals for the second source array. 
     
     
         10 . The control mechanism of  claim 8 , wherein the plural first individual source elements and the plural second individual source elements are configured to emit a frequency lower than about 32 Hz and the first source array and the second source array include plural third individual source elements that are configured to emit a frequency higher than about 32 Hz. 
     
     
         11 . An incoherent acquisition method for driving vibrational source arrays under water, the method comprising:
 towing with a vessel first and second source arrays, the first source array having first high-frequency and first low-frequency source elements and the second source array having second high-frequency and second low-frequency source elements; and   activating simultaneously the first high-frequency, first low-frequency, second high-frequency and second low-frequency source elements with incoherent coded driving signals.   
     
     
         12 . The method of  claim 11 , wherein the coded driving signals include corresponding signatures so that during a processing phase, seismic signals from the first source array are separated from seismic signals from the second source array. 
     
     
         13 . The method of  claim 11 , wherein the incoherent coded driving signals of the first and second source arrays include multiple frequencies. 
     
     
         14 . The method of  claim 11 , wherein coded driving signals for the first source array are not correlated to coded driving signals for the second source array. 
     
     
         15 . The method of  claim 14 , further comprising:
 towing the first and second high-frequency source elements at a depth larger than a depth of the first and second low-frequency source elements.   
     
     
         16 . The method of  claim 11 , wherein the first high-frequency and first low-frequency source elements and the second high-frequency and second low-frequency source elements are electro-mechanical sources having pistons that simultaneously move in opposite directions to generate seismic waves. 
     
     
         17 . The method of  claim 16 , further comprising:
 activating an electro-magnetic actuator system to generate a first seismic wave; and   activating a pneumatic mechanism to generate a second seismic wave,   wherein the electro-magnetic actuator system and the pneumatic mechanism are part of an individual source element.   
     
     
         18 . A control mechanism configured to implement an incoherent acquisition method for driving vibrational source arrays under water, the control mechanism comprising:
 a processor configured to activate simultaneously a first source array and a second source array so that incoherent coded driving signals drive the first and second source arrays,   wherein the first source array has first high-frequency and first low-frequency source elements and the second source array has second high-frequency and second low-frequency source elements.   
     
     
         19 . The control mechanism of  claim 18 , wherein the coded driving signals include corresponding signatures so that during a processing phase, seismic signals from the first source array are separated from seismic signals from the second source array. 
     
     
         20 . The control mechanism of  claim 18 , wherein coded driving signals for the first source array are not correlated to coded driving signals for the second source array.