Integrated Subsurface Model Using Seismic and Transient Electromagnetic Data
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Solution Overview
Problem
Current frequency domain controlled source electromagnetic (f-CSEM) surveying techniques are limited to relatively great water depths and struggle to distinguish between oil and gas bearing formations due to similar electrical conductivity, necessitating a method to combine seismic and electromagnetic data for a more accurate subsurface model.
Innovation Solution
A method that integrates transient controlled source electromagnetic (t-CSEM) and seismic data by generating initial models for both, optimizing parameters, and ensuring consistency between them to produce a more representative subsurface model, capable of resolving structure and fluid content of oil, gas, and water-bearing formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency domain controlled source electromagnetic (f-CSEM) surveying is used, then electromagnetic data can be obtained, but the method is limited to relatively great water depths and cannot reliably distinguish between oil and gas bearing formations
Solution Approach 1:
The patent combines transient controlled source electromagnetic (t-CSEM) surveying with seismic surveying to create an integrated evaluation method. By merging these two different surveying techniques, the method overcomes the limitations of f-CSEM in distinguishing oil and gas bearing formations while maintaining effectiveness across various water depths. The integration allows for complementary information extraction from both electromagnetic and seismic data.
Solution Approach 2:
The patent transitions from frequency domain (f-CSEM) to transient domain (t-CSEM) electromagnetic surveying, which involves changing the temporal parameters of the electromagnetic signal. This parameter change enables the method to effectively operate at greater water depths while improving the ability to distinguish between different formation types based on their transient electromagnetic response characteristics.
2Measurement precision
If separate seismic and electromagnetic data interpretations are used, then each data type can be processed independently, but the overall accuracy of subsurface modeling is limited
Solution Approach 1:
The patent merges seismic and electromagnetic data processing into an integrated evaluation method. By combining these data types and their respective inversion models, the method achieves higher accuracy in subsurface characterization. The integration allows for consistent modeling of both structural and physical properties of subsurface formations.
Solution Approach 2:
The patent employs iterative inversion processes where the seismic and electromagnetic models are repeatedly adjusted and refined. The feedback mechanism involves comparing the modeled responses with actual survey data and adjusting the models accordingly, leading to progressively more accurate subsurface representations.
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 integrated approach enhances the accuracy of subsurface modeling, improving the ability to identify and differentiate between oil, gas, and water-bearing formations, overcoming the limitations of separate seismic and electromagnetic data interpretations.
Implementation Method 1
measuring voltages and/or magnetic fields induced in electrodes, antennas and/or magnetometers disposed on or near the Earth's surface or the sea floor. The voltages and/or magnetic fields are induced in response to the electric current and/or magnetic field imparted into the Earth's subsurface by the source.
Data Source
AI summary
A method for determining spatial distribution of properties of the Earth's subsurface includes obtaining seismic data over a survey area of the Earth's subsurface. Controlled source electromagnetic survey data are obtained over substantially the same survey area. An initial model of the Earth's subsurface for each of the seismic data and the electromagnetic data is generated. Further data may include gravity, magnetics, seismics any type and borehole data. Each model is optimized on at least one model parameter. Consistency is determined between the models; and the at least one model parameter is adjusted and the optimizing and determining consistency are repeated until the models are consistent. Constraints are successively derived from the data sets and also cross checked against reservoir data where available.