Remote Hydrocarbon Source Rock Identification via Seismic and Electromagnetic Data
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Solution Overview
Problem
Current methods for identifying and characterizing hydrocarbon source rocks in untested or poorly explored basins are uncertain and lack the ability to accurately detect source rocks with moderate vertical resolution and accuracy, especially at depths of 3000 meters or more, due to limited commercial access to sedimentary basins.
Innovation Solution
A method combining seismic and electromagnetic geophysical data to remotely assess hydrocarbon source rock potential by obtaining electromagnetic field data and seismic reflection data, extracting resistivity and transit time profiles, and evaluating depth intervals for source rock potential, allowing for the identification and characterization of source rocks without the need for well data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If geological interpretation of seismic reflection patterns is used to map source rocks in untested basins, then the method can be applied without well data, but the identification accuracy and reliability are large uncertainties
Solution Approach 1:
The patent combines seismic reflection data with electromagnetic (EM) data to create a hybrid identification method. The seismic data provides structural information and stratigraphy, while the EM data provides resistivity information that is sensitive to organic content. This merging of complementary datasets improves both the adaptability to unexplored areas and the reliability of source rock identification.
Solution Approach 2:
The patent uses an intermediary approach by introducing a calibration layer that links remote geophysical measurements to well-log based Delta Log R methodology. The calibration layer translates seismic and EM data into TOC and LOM estimates that are comparable to traditional well-based measurements, thereby bridging the gap between exploration methods.
2Measurement precision
If traditional well-based Delta Log R method is used, then accurate TOC and LOM assessment is achieved, but the method requires physical well access which is limited in unexplored basins
Solution Approach 1:
The patent creates a remote copy of the well-based measurement process by using seismic and electromagnetic data to replicate the information that would be obtained from well logs. The seismic data provides a copy of the acoustic velocity profile while the EM data provides a copy of the resistivity profile, allowing Delta Log R analysis without physical well access.
Solution Approach 2:
The patent substitutes the mechanical well-drilling and logging process with a non-contact geophysical measurement system. Instead of physically inserting tools into the ground to measure acoustic velocity and resistivity, the method uses surface-based seismic and electromagnetic surveys to remotely obtain the same physical parameters.
3Length of stationary object
If source rock identification is attempted at depths of 3000 meters or more, then deeper exploration capability is achieved, but the vertical resolution and detection accuracy deteriorate
Solution Approach 1:
The patent segments the deep subsurface into distinct depth intervals and uses different geophysical methods optimized for each depth range. The seismic data is processed to provide structural context at deep levels, while the EM data is processed to provide resistivity information with enhanced vertical resolution through inversion techniques that account for depth-dependent attenuation.
Solution Approach 2:
The patent changes the physical parameters being measured and their corresponding wavelengths to optimize penetration depth and resolution. By adjusting the frequency content of the seismic data and the source characteristics of the electromagnetic data, the method achieves both deep penetration (3000+ meters) and adequate vertical resolution through parameter optimization.
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 enables accurate identification and characterization of hydrocarbon source rocks, providing moderate vertical resolution and depth investigation capabilities, thereby enhancing exploration opportunities in unexplored areas and overcoming the limitations of existing methods.
Implementation Method 1
obtaining electromagnetic field data representative of the subsurface region from a survey conducted above the subsurface region
Implementation Method 2
obtaining reflection data from a surface seismic survey of the subsurface region
Implementation Method 3
extracting a vertical profile of resistivity or its reciprocal, conductivity, from the electromagnetic data
Implementation Method 4
extracting a vertical profile of acoustic velocity or its reciprocal quantity, transit time, from the seismic reflection data
Data Source
AI summary
Method for assessing hydrocarbon source rock potential of a subsurface region without well log information. The method uses surface electromagnetic (121) and seismic (122) survey data to obtain vertical profiles of resistivity and velocity (123), which are then analyzed in the same way as well log data are analyzed by the well known Delta Log R method (124).