Resistivity Logging Boundary Detection via Multi-Spacing Inversion
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Solution Overview
Problem
Current resistivity logging techniques face challenges in accurately detecting multiple subsurface layer boundaries in real-time during drilling operations, leading to uncertainties in geosteering and formation evaluation.
Innovation Solution
The implementation of robust inversion techniques using multi-spacing and multi-frequency directional logging data to calculate distances to upper and lower bed boundaries, enabling accurate identification of subsurface layer profiles and boundaries through iterative analysis of resistivity measurements from multiple transmitter-receiver spacings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional resistivity logging techniques are used, then the logging process is simpler, but the accuracy in detecting multiple subsurface layer boundaries deteriorates
Solution Approach 1:
The patent segments the resistivity logging process into multiple independent inversion operations, each handling a specific transmitter-receiver spacing. This allows the complex multi-layer boundary detection to be broken down into manageable segments that can be processed separately and then combined, improving accuracy without overwhelming system complexity.
Solution Approach 2:
The patent introduces an additional dimension by using multiple transmitter-receiver spacings simultaneously. Instead of relying on a single measurement configuration, the system performs independent inversions for each spacing, effectively adding a spatial dimension to the measurement approach. This enables more accurate detection of multiple subsurface layer boundaries by capturing information at different depth scales.
2Reliability
If multiple transmitter-receiver spacings are used for independent inversion, then the detection of subsurface layers is more accurate, but the computational complexity increases
Solution Approach 1:
The patent divides the formation evaluation into multiple independent inversion segments, each corresponding to a specific transmitter-receiver spacing. By segmenting the inversion process, the system can process each spacing independently, reducing the overall computational complexity while maintaining high reliability through the combination of multiple independent results.
Solution Approach 2:
The patent changes the measurement parameter by varying the transmitter-receiver spacing. Each inversion operation uses a different spacing parameter, allowing the system to probe different depth ranges and formation characteristics. This parameter variation enables reliable formation evaluation across multiple scales without requiring a single overly complex inversion model.
3Productivity
If real-time boundary detection is implemented, then drilling decisions can be made faster, but the measurement accuracy may deteriorate
Solution Approach 1:
The patent performs preliminary independent inversions for each transmitter-receiver spacing before combining the results. This preliminary action allows the system to quickly process each spacing independently and identify potential boundary locations, which are then refined through combination. This approach enables real-time processing while maintaining accuracy by preparing results in advance rather than performing a single complex inversion.
Solution Approach 2:
The patent performs multiple independent inversions, which is more than the single inversion traditionally used. This excessive action of performing redundant inversions at different spacings provides multiple independent estimates of boundary locations, which can be combined to improve overall accuracy. The partial results from each inversion contribute to the final accurate determination, enabling both speed and precision.
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 allows for precise and timely detection of subsurface layer boundaries, enhancing geosteering accuracy and enabling more informed drilling decisions by providing reliable and real-time formation information.
Implementation Method 1
electromagnetic resistivity logging tools have been used to explore the subsurface based on the electrical resistivity (or its inverse, conductivity) of rock formations. Some resistivity logging tools include multiple antennas for transmitting an electromagnetic signal into the formation and multiple receiver antennas for receiving a formation response.
Data Source
AI summary
Systems, methods, and software for detecting boundary locations of multiple subsurface layers are described. In some aspects, the boundaries of multiple subsurface layers in a subterranean region are identified based on measurements associated with multiple different transmitter-receiver spacings. The measurements are generated based on operating multiple transmitters and multiple receivers of a resistivity logging tool at a tool depth in a wellbore in the subterranean region. A first pair of the subsurface boundary locations are determined based on a first measurement associated with a first transmitter-receiver spacing. A second, different pair of the subsurface boundary locations are determined based on a second measurement associated with a second, longer transmitter-receiver spacing. The first pair of subsurface boundary locations reside between the second pair of subsurface boundary locations in the subterranean region.