Seismic Source Element Actuation Sequencing for Bubble Contamination
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Solution Overview
Problem
In marine surveying, simultaneous actuation of seismic source elements leads to complex and unpredictable effects due to air bubbles, causing distortion in the wavefield and reducing the quality of seismic images.
Innovation Solution
Arranging source elements in specific geometries and actuating them in a sequence based on their relative positions and the towing velocity of the source subarray, with time intervals between actuations minimized to less than a second to avoid contamination from previous actuations, thereby stabilizing the deconvolution of the source wavefield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If source elements are actuated simultaneously, then productivity is improved, but measurement precision deteriorates due to air bubble contamination and wavefield distortion
Solution Approach 1:
The source array is divided into multiple source subarrays, each containing multiple source elements. This segmentation allows independent control and actuation sequencing within each subarray, enabling the system to maintain high productivity while avoiding air bubble contamination through coordinated sequential actuation of elements across subarrays.
Solution Approach 2:
Source elements are actuated in a periodic sequence rather than simultaneously. The actuation sequence is designed with specific time intervals between elements to allow air bubbles from previous actuations to clear, maintaining measurement precision while achieving continuous or near-continuous data acquisition through the periodic cycling of source element actuation.
2Measurement precision
If source elements are actuated in sequence to avoid air bubble contamination, then measurement precision is improved, but productivity deteriorates due to increased time between actuations
Solution Approach 1:
By segmenting the source array into multiple subarrays with multiple elements each, the system can actuate elements in a sequence across subarrays rather than waiting for complete clearance between individual elements. This maintains measurement precision while reducing total actuation time and improving productivity.
Solution Approach 2:
The actuation sequence is pre-planned and optimized based on source element positions, towing velocity, and desired time intervals. This preliminary arrangement of the actuation pattern allows the system to achieve continuous or near-continuous acquisition while maintaining adequate separation to avoid air bubble contamination.
3Measurement precision
If time intervals between actuations are increased to allow bubble separation, then measurement precision is improved, but loss of time increases
Solution Approach 1:
Dividing the source array into multiple subarrays allows the system to overlap the actuation cycles of different subarrays. While one subarray is waiting for bubble clearance, another subarray can be actuated, effectively utilizing the time intervals and reducing overall loss of time while maintaining measurement precision.
Solution Approach 2:
The system achieves continuous or near-continuous data acquisition by coordinating actuation across multiple subarrays. The useful action of seismic data collection continues without interruption as elements from different subarrays are actuated in an overlapping sequence, minimizing idle time while maintaining adequate separation for bubble clearance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for continuous or near-continuous actuation of source elements, reducing the impact of air bubbles and improving the quality of seismic data acquisition by minimizing the time between actuations and stabilizing the wavefield, leading to enhanced resolution in marine surveys.
Implementation Method 1
The source control may cause the one or more sources, which can be air guns, marine vibrators, electromagnetic sources, etc., to produce signals at selected times. Each signal is essentially a wave called a wavefield that travels down through the water and into the subterranean formation.
Implementation Method 2
simultaneous actuation of seismic source elements leads to complex and unpredictable effects due to air bubbles, causing distortion in the wavefield
Implementation Method 3
At each interface between different types of rock, a portion of the wavefield may be refracted, and another portion may be reflected
Implementation Method 4
At each interface between different types of rock, a portion of the wavefield may be refracted, and another portion may be reflected
Data Source
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Figure 3~4
AI summary
Source element of a source subarray can be individually actuated according to an actuation sequence. The actuation sequence can be at least partially based on a relative position of each of the source elements within a particular geometry of the source subarray with respect to a previously actuated source element and a towing velocity of the source subarray.