Sediment-Basement Velocity Model Using Seismic and Potential Fields
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Solution Overview
Problem
Current techniques for creating velocity models for sediment-basement interfaces in subsurface formations are inaccurate due to limitations in seismic velocity analysis and well penetration, leading to poor imaging and time-depth conversion results.
Innovation Solution
A data processing system integrates seismic and potential fields data to generate a velocity model by estimating coefficients for a time-depth relationship, using weighted time-depth data pairs and optimizing velocity coefficients to improve the accuracy of sediment-basement interface imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If classical seismic velocity analysis and well data techniques are used, then velocities are reliable in shallow sedimentary sections, but velocities become inaccurate for imaging the sediment-basement interface
Solution Approach 1:
The patent combines potential fields data (gravity or magnetic surveys) with surface seismic data to create a hybrid velocity model. The potential fields data provide depth estimates for the sediment-basement interface, which are then integrated with seismic travel times to derive accurate velocities at the interface, resolving the contradiction between shallow reliability and deep accuracy.
Solution Approach 2:
The patent introduces potential fields data as an intermediary to bridge the gap between surface seismic data and the sediment-basement interface. The depth estimates from potential fields act as a mediator to constrain and improve velocity estimates at depths where direct seismic measurements are unreliable.
2Device complexity
If velocities are derived from surface seismic data alone, then the process is simple, but resolution and sensitivity deteriorate at depth
Solution Approach 1:
The patent merges surface seismic data with potential fields data to maintain simplicity in data acquisition while improving depth resolution. The combination allows the use of existing surface seismic data without requiring complex deep-earth measurements, thereby improving velocity resolution without proportionally increasing complexity.
3Measurement precision
If more wells are drilled to penetrate basement structures, then velocity accuracy improves, but cost and complexity increase significantly
Solution Approach 1:
The patent uses potential fields data as an intermediary to obtain depth information without requiring wells to penetrate the basement. The potential fields surveys provide the necessary depth constraints to calculate velocities at the sediment-basement interface, avoiding the need for complex and expensive deep well surveys.
Solution Approach 2:
The patent replaces the mechanical approach of drilling deep wells with a geophysical approach using potential fields surveys. Instead of physically penetrating the basement with wells, the method uses gravity or magnetic field measurements to infer depth and velocity information, significantly reducing complexity and cost.
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
The approach enhances the accuracy of seismic images and time-depth conversions, providing a more precise estimation of the sediment-basement interface by combining depth and time estimates from potential fields data with surface seismic data.
Implementation Method 1
seismic data including acoustic data generated by an acoustic source and received by one or more receivers in a subsurface
Implementation Method 2
Examples of potential fields data include gravimetry, magnetometry and electromagnetic data
Implementation Method 3
Examples of potential fields data include gravimetry, magnetometry and electromagnetic data
Implementation Method 4
Examples of potential fields data include gravimetry, magnetometry and electromagnetic data
Data Source
AI summary
A process for generating a velocity model for a sediment-basement interface of a subsurface region includes receiving seismic data representing acoustic signals that are reflected from regions of the subsurface. The process includes receiving potential fields data comprising potential field values that are mapped to locations in the subsurface. The process includes generating weighted time-depth data pairs. The process includes selecting a velocity model that relates a velocity value to a depth value in a time-depth relationship. The process includes optimizing velocity coefficients of the velocity model by determining, for each velocity model of a set, a set of depth estimates for corresponding time values and comparing the set of depth estimates to depth values of the weighted time-depth data pairs. The process includes adjusting the velocity coefficients of the velocity model. The process includes generating a seismic image of the sediment-basement interface.