Holographic Inversion With Spectral Analysis for Hydrocarbon Detection
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Solution Overview
Problem
Current surface seismic surveys face challenges in accurately determining the presence of hydrocarbons in subsurface reservoirs due to the similarity in seismic reflections between hydrocarbon and water-saturated formations, making it difficult to generate precise images and characterize rock types and fluid contents.
Innovation Solution
The method involves holographic inversion by redatuming seismic gathers to a target horizon, analyzing the spectrum of seismic reflections, and using spectral measures like FSR and CF to differentiate between hydrocarbon and water-saturated reservoirs based on differences in high and low frequency amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface seismic surveys are used to image subsurface geology, then subsurface structures can be visualized, but the ability to accurately differentiate between hydrocarbon and water-saturated formations is compromised due to similar seismic reflection characteristics
Solution Approach 1:
The patent transforms the seismic data from the time domain to the frequency domain through spectral analysis. By examining frequency spectra and calculating attributes like spectral centroid and bandwidth, the method identifies subtle frequency-domain differences between hydrocarbon and water-saturated formations that are not apparent in conventional time-domain seismic images, thereby improving detection accuracy and characterization reliability
Solution Approach 2:
The patent introduces a new dimension of analysis by applying holographic inversion techniques that reconstruct seismic wavefields in both spatial and frequency domains. This multi-dimensional approach allows simultaneous visualization of subsurface structure and fluid content, enabling differentiation of formations based on their spectral signatures rather than relying solely on amplitude and timing information
2Manufacturing precision
If conventional seismic processing is applied to surface seismic data, then subsurface images can be generated, but the precision of rock type and fluid content characterization is insufficient
Solution Approach 1:
The patent performs preliminary redatuming of seismic gathers to a target horizon before conducting spectral analysis. This preprocessing step positions the seismic events of interest at a consistent time location across all traces, ensuring that subsequent spectral measurements are made at the optimal point in the waveform where fluid-related attenuation effects are most pronounced, thereby preserving critical fluid content information
Solution Approach 2:
The patent replaces conventional mechanical seismic processing workflows with a spectral-domain approach using holographic inversion. Instead of relying on traditional amplitude-based imaging, the method substitutes frequency-domain analysis and spectral attribute calculation to extract fluid content information, achieving higher precision in subsurface characterization without losing critical information
Data Source
AI summary
A method of determining a presence of hydrocarbons is disclosed. The method includes obtaining a surface seismic dataset, composed of a plurality of seismic gathers, determining a redatumed gather for a target horizon based on the seismic gather, determining a time window of the redatumed gather around the target horizon, and determining a spectrum of a portion within the time window. The method further includes determining a hydrocarbon indicator based, at least in part, on an amplitude of a higher-frequency portion and lower-frequency portion of the spectrum of the plurality of seismic gathers, determining a geographic map of values of the hydrocarbon indicator from the plurality of seismic gathers, and determining a presence of hydrocarbons based, at least in part, on at least one anomalous value on the geographic map. A system including a seismic acquisition system and a seismic processor for executing the method is disclosed.