Cross-line Source Separation for Marine Seismic Surveys
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Solution Overview
Problem
Marine seismic surveys face limitations in subline coverage due to the configuration of seismic source elements and streamers, leading to prolonged survey times and incomplete data collection, especially in large underwater areas.
Innovation Solution
Increasing the cross-line source separation between seismic source elements and streamers, allowing for shorter near offsets and improved subsurface sampling, which enhances the resolution of seismic data and aids in predicting multiples by positioning seismic source elements outside the innermost streamers and using a specific configuration based on integer multiples of the streamer separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cross-line source separation is increased by positioning seismic source elements outside the innermost streamers, then the subline coverage is improved and survey time is reduced, but the device complexity increases due to the specific configuration requirements based on integer multiples of streamer separation
Solution Approach 1:
The patent applies parameter changes by modifying the cross-line source separation distance to be greater than the cross-line streamer separation, specifically positioning sources outside the innermost streamers. This parameter change enables shorter near offsets and improved subsurface sampling, directly resolving the contradiction between productivity and device complexity by optimizing the geometric configuration rather than adding complex equipment.
Solution Approach 2:
The patent utilizes the cross-line dimension (perpendicular to the sail line direction) to position seismic sources outside the streamer array boundaries. This dimensional approach allows the sources to be distributed in a broader spatial footprint, increasing subline coverage without requiring additional streamers or complex source configurations within the existing streamer spread.
2Measurement precision
If the cross-line source separation is increased, then shorter near offsets are achieved and data resolution is improved, but the survey area coverage becomes more limited requiring more sail lines
Solution Approach 1:
The patent changes the cross-line source separation parameter to be greater than the cross-line streamer separation, positioning sources outside the innermost streamers. This parameter optimization achieves shorter near offsets for improved measurement precision and resolution, while the systematic configuration minimizes the impact on survey area coverage by optimizing the geometric efficiency of each sail line.
3Reliability
If seismic source elements are positioned outside the innermost streamers, then incomplete data collection is prevented and image quality is improved, but the device complexity increases due to navigation and positioning requirements
Solution Approach 1:
The patent establishes specific parameter relationships where cross-line source separation is greater than cross-line streamer separation, and sources are positioned outside the innermost streamers. These parameter definitions provide clear navigational targets and positioning criteria, reducing the complexity of navigation control by providing explicit geometric constraints rather than requiring complex real-time optimization algorithms.
Solution Approach 2:
The patent applies preliminary action by pre-defining the optimal source-streamer geometric configuration based on integer multiples of streamer separation. This preliminary design establishes the navigation targets and positioning requirements before the survey begins, allowing for simpler execution and reducing the complexity of real-time navigation control during the actual survey operation.
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 increases the subline coverage, reduces survey time, and improves the quality of seismic data by providing shorter near offsets and better resolution, particularly at the edges of sail lines, allowing for more comprehensive and efficient data collection in marine seismic surveys.
Implementation Method 1
Each signal is essentially a wave called a wavefield that travels down through the water and into the subterranean formation
Implementation Method 2
At each interface between different types of rock, a portion of the wavefield may be refracted
Implementation Method 3
another portion may be reflected, which may include some scattering, back toward the body of water to propagate toward the water surface
Data Source
AI summary
A method for a marine seismic survey can include towing streamers that are spaced apart in a cross-line direction by a streamer separation (L) and towing seismic source elements that are spaced apart in the cross-line direction by a source separation based on an integer (k), an inverse of a quantity of the seismic source elements (1/S), and the streamer separation as represented by (k+1/S)L. The seismic source elements can be actuated and seismic signals can be detected at each of a plurality of receivers on the streamers.