Seismic Multiples Attenuation via Well Data Modeling
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Solution Overview
Problem
Seismic images often contain contamination from multiples, particularly peg-leg multiples, which are difficult to filter out due to their similarity to primary signals, leading to inaccurate time readings and interference with deeper layer signals.
Innovation Solution
A method that identifies and quantifies multiples contamination by modeling data from well sites, flattening specific layers to isolate interference, and determining spatial areas of contamination in seismic images, allowing for accurate marking and attenuation of multiples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-stack filtering is used to remove multiples, then primary signals are preserved, but peg-leg multiples are difficult to filter out due to their similarity to primary signals
Solution Approach 1:
The method segments the seismic signal analysis into distinct processing stages: pre-stack filtering for obvious multiples, post-stack analysis for peg-leg multiples, and iterative refinement. This segmentation allows different filtering strategies to be applied to different types of multiples based on their characteristics.
Solution Approach 2:
The method performs preliminary flattening of seismic layers before multiple attenuation to establish a common reference framework. This preliminary action enables more effective identification and removal of peg-leg multiples that would otherwise be difficult to distinguish from primary signals.
2Object-affected harmful factors
If aggressive filtering is applied to remove all multiples, then multiple contamination is reduced, but primary signals may also be attenuated
Solution Approach 1:
The method applies different filtering strengths to different spatial and temporal regions of the seismic data. In areas where peg-leg multiples are identified through flattening analysis, stronger filtering is applied locally, while primary signal-rich regions maintain more aggressive preservation.
Solution Approach 2:
The method uses an iterative feedback process where initial multiple attenuation results are analyzed, flattening is adjusted based on observed effects, and subsequent filtering is refined. This feedback loop ensures that filtering continues to remove multiples while preserving primary signals that were inadvertently affected.
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 effectively isolates and attenuates multiples contamination, improving the accuracy of seismic images by distinguishing between primary and multiple signals, even in areas with high dip angles and complex geology.
Implementation Method 1
A portion of the wave proceeds downward, into the ground, until a portion thereof is reflected back upward by a 'reflector' due to impedance changes, according to Snell's law.
Implementation Method 2
Multiples occur as a returning, reflected signal encounters a boundary between two rock layers of different impedance.
Data Source
AI summary
Methods, systems, and computer-readable media for identifying multiples contamination in a stack are provided. The method includes identifying spatially an area of potential multiples contamination in the stack. The method also includes constructing, using a processor, a model of multiples contamination using well data, and evaluating a degree of contamination in the area of potential contamination using the model of multiples contamination. The method further includes attenuating multiples contamination in the areas of multiples contamination, and validating the stack after attenuating.