Seismic Image Correction Using Fiber Optic DAS Speed Profiles
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Solution Overview
Problem
Current seismic imaging techniques face challenges in accurately correcting for speed of sound variations in water and water column height changes, leading to noise and compromised image quality in marine seismic surveys, especially in 3D and 4D imaging.
Innovation Solution
The use of fiber optic sensing systems configured for distributed acoustic sensing (DAS) to detect seismic excitations and determine the function of speed of sound in water, allowing for correction of digital seismic images and improved image accuracy by accounting for variations in water column properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional seismic imaging techniques are used without fiber optic sensing correction, then the processing is simpler and faster, but the image quality is compromised due to uncorrected speed of sound variations and water column height changes
Solution Approach 1:
The patent applies preliminary action by measuring speed of sound and water column height variations before seismic imaging using fiber optic sensing. This pre-measurement allows correction factors to be established in advance, which are then applied during image processing to eliminate noise artifacts caused by environmental variations.
Solution Approach 2:
The patent introduces fiber optic sensing as an intermediary system that independently measures environmental parameters (speed of sound, water column height) affecting seismic imaging. This intermediary measurement system provides correction data that mediates between the raw seismic data and the final corrected image, improving accuracy without requiring fundamental changes to the imaging process.
2Measurement precision
If fiber optic sensing is used to measure speed of sound and water column height variations, then correction accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies universality by using fiber optic sensing technology that can simultaneously measure multiple parameters (speed of sound, water column height, temperature) along the entire water column. This multi-functional approach consolidates what would otherwise require multiple separate measurement systems into a single integrated solution.
Solution Approach 2:
The patent replaces traditional mechanical measurement systems (such as physical sound velocity profiles and water level sensors) with fiber optic sensing that uses optical principles. This substitution eliminates complex mechanical moving parts and calibration requirements while providing continuous, high-resolution measurements along the entire survey area.
3Productivity
If speed of sound and water column height are not corrected, then the survey is faster and less resource-intensive, but noise artifacts appear in the seismic images compromising hydrocarbon identification
Solution Approach 1:
The patent implements feedback by continuously monitoring speed of sound and water column height variations during the seismic survey using fiber optic sensing. This real-time feedback allows for dynamic correction of seismic data as environmental conditions change, ensuring consistent image quality throughout the survey without requiring repeated measurements.
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 generates more accurate digital seismic images, enhancing hydrocarbon exploration and production by better delineating subsurface features and improving decision-making in well placement and reservoir management.
Implementation Method 1
DAS data representing the detected seismic excitations are received. The DAS data are determined using fiber optic sensing systems configured for distributed acoustic sensing (DAS).
Implementation Method 2
A function of speed of sound in water as a function of depth is determined using the DAS data. This involves analyzing seismic wave travel times through the water column to derive velocity profiles.
Implementation Method 3
A digital seismic image associated with the area of interest is corrected using the function of speed of sound in water. P waves typically travel faster than S waves, and variations in physical properties of the geological medium change the properties of the seismic waves.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
One embodiment includes receiving distributed acoustic sensing (DAS) data for responses associated with seismic excitations in an area of interest. The area of interest includes a sea surface, the water column, a seafloor, and a subseafloor. The seismic excitations are generated by at least one seismic source in the area of interest. The responses are detected by at least one fiber optic sensing apparatus configured for DAS that is in the 0 water column, on the seafloor, in a wellbore drilled through the seafloor and into the subseafloor, or any combination thereof. The embodiment includes determining a function of speed of sound in water using the DAS data, and correcting a digital seismic image associated with the area of interest using the function of speed of sound in water to generate a corrected digital seismic image.