Variable Sweep Length Vibratory Sources for Crosstalk Reduction
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Solution Overview
Problem
Simultaneous and blended seismic surveys using swept frequency vibratory sources face significant interference issues due to crosstalk, which can be severe due to the elimination of listening time and near-simultaneous sweeps, affecting the quality and efficiency of seismic imaging.
Innovation Solution
The method involves deploying multiple vibratory source groups with each group operating at unique frequency bandwidths and sweep lengths, minimizing crosstalk by ensuring that frequency sweeps from different sources do not overlap, allowing them to be positioned in close proximity while reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blended acquisition with near-simultaneous sweeps is used to improve productivity, then source productivity increases and acquisition time reduces, but crosstalk interference between sources increases
Solution Approach 1:
The patent applies parameter changes by varying the sweep length of different vibratory sources. Specifically, sources are assigned different sweep lengths (e.g., 6 seconds, 8 seconds, 10 seconds) rather than using uniform sweep lengths. This parameter variation ensures that sources operating in close proximity or simultaneously do not produce identical frequency-time signatures, thereby reducing crosstalk interference while maintaining high productivity through blended acquisition
Solution Approach 2:
The patent implements local quality by assigning unique frequency bandwidths and sweep lengths to individual sources or source groups. Each source operates with locally optimized parameters tailored to its specific location and operational context. This localized parameter assignment allows sources to coexist in the same survey area with minimal interference, as each source's energy emission pattern is distinctly characterized
2Productivity
If sources are positioned in close proximity to reduce survey area, then survey efficiency improves, but crosstalk between sources increases
Solution Approach 1:
The patent uses parameter changes by assigning different sweep lengths to sources positioned in close proximity. For example, one source may use a 6-second sweep while another nearby source uses an 8-second or 10-second sweep. This parameter differentiation allows sources to operate simultaneously in the same or adjacent locations without generating interfering crosstalk, as their frequency-time signatures remain distinct
Solution Approach 2:
The patent applies segmentation by dividing the survey area into sectors with assigned source groups, where each group operates with unique sweep length parameters. This segmentation strategy allows multiple source groups to operate concurrently in different sectors or even within the same sector, maintaining survey efficiency while minimizing inter-source interference through parameter-based differentiation
3Ease of operation
If uniform sweep length is used for all sources, then operational simplicity is maintained, but crosstalk interference increases
Solution Approach 1:
The patent implements parameter changes by varying sweep lengths across different sources (e.g., 6s, 8s, 10s) to reduce crosstalk. While this introduces some operational complexity compared to uniform sweep lengths, the patent maintains ease of operation through automated parameter assignment and centralized control systems that manage the differentiated sweep patterns without requiring manual coordination between sources
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 significantly minimizes recorded crosstalk, enabling effective deblending of seismic data and reducing acquisition time while maintaining high productivity and image quality.
Implementation Method 1
emission of seismic energy by a plurality of vibratory source groups
Implementation Method 2
concurrently performing frequency sweeps to emit seismic energy from each seismic energy source
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An array of seismic energy receivers is deployed at fixed locations across the length and width of a land surface area of interest. A land fleet composed of a number of vibratory swept frequency or vibroseis seismic energy sources is deployed at predetermined initial locations within the receiver array. The sources are arranged in groups which at their initial locations are spaced from other groups of the source fleet by an intergroup spacing distance representing a segment of the receiver array. Each of the vibratory sources in a source group is assigned within that group a designated specific length for its energy emissions and a frequency sweep band different from the other sources in the group. The sources in all groups concurrently emit energy at a succession of spaced, assigned locations as they are moved incrementally over their respective intergroup spacings. The responses of subsurface formations to the emissions from the sources are recorded as a blended seismic record by the fixed array of processors and made available for processing.