Multi-Step Inversion for Electromagnetic Well Logging
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Solution Overview
Problem
Current inversion schemes for well logging are time-consuming, require vast amounts of data, and are specific to single downhole tools, limiting real-time operation and increasing operational costs, which hinders efficient drilling and production decisions.
Innovation Solution
A method of preselecting initial guesses for multi-step inversion using shallow electromagnetic resistivity logging tools, where high-confidence shallow inversion results are used to create initial pools for deep inversions, preserving fine resolution around the wellbore while extending depth of investigation with deep measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current inversion schemes are used, then formation characteristics can be determined, but the process is time-consuming and requires vast amounts of data
Solution Approach 1:
The patent applies preliminary action by performing a shallow inversion first to obtain initial guesses, which are then used as starting points for the subsequent deep inversion. This preliminary step reduces the computational burden of the full inversion process by providing informed initial estimates, thereby reducing the time required while maintaining formation characteristics determination accuracy.
Solution Approach 2:
The inversion process is segmented into multiple steps: a shallow inversion step followed by a deep inversion step. Each step focuses on specific depth ranges and uses results from previous steps. This segmentation allows the complex full-depth inversion to be broken into manageable portions that can be computed more efficiently, reducing overall processing time.
2Measurement precision
If current inversion schemes are used, then formation characteristics can be determined, but vast amounts of data are required
Solution Approach 1:
The data processing is segmented by depth, with shallow measurements used in the first inversion step and deep measurements used in the second step. This segmentation allows the system to determine formation characteristics using smaller subsets of data at each stage rather than requiring all data simultaneously, reducing the effective data volume needed at any given time.
Solution Approach 2:
The shallow inversion performed as a preliminary step uses only shallow measurement data to generate initial guesses. This preliminary action reduces the data requirement for the subsequent deep inversion, as the initial guesses provide a head start that reduces the need for extensive data processing to converge to a solution.
3Measurement precision
If single-tool specific inversion schemes are used, then tool-specific accuracy is achieved, but operational costs increase
Solution Approach 1:
The patent implements a universal inversion framework that can accommodate multiple downhole tool types and measurement configurations. The multi-step inversion approach with shallow and deep measurements can be applied regardless of the specific tool used, making the methodology adaptable to various tools while maintaining accuracy. This universality reduces operational costs by eliminating the need for separate inversion schemes for each tool type.
Solution Approach 2:
The inversion scheme is designed to be dynamic and adaptable to different tool configurations. The framework can adjust the shallow and deep measurement components based on the specific tool being used, allowing a single versatile methodology to replace multiple tool-specific schemes, thereby reducing operational costs while maintaining the adaptability needed for different measurement systems.
4Manufacturing precision
If shallow measurements are used, then fine resolution around the wellbore is achieved, but depth of investigation is limited
Solution Approach 1:
The investigation space is segmented into shallow and deep zones, with each measurement type optimized for its respective depth range. Shallow measurements provide fine resolution for near-wellbore formation characteristics, while deep measurements extend the investigation depth. The segmented multi-step inversion process combines results from both segments to achieve both fine resolution and deep investigation capability simultaneously.
Solution Approach 2:
The patent merges shallow and deep measurement results through a multi-step inversion process. The shallow inversion results are combined with deep measurements in the second step, creating a comprehensive formation model that achieves both the fine resolution of shallow measurements and the extended depth of investigation of deep measurements, effectively combining the strengths of both approaches.
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 faster, more cost-effective inversion processes that can support real-time drilling decisions, maintaining high resolution and confidence in formation evaluations, thereby improving operational efficiency and reducing costs.
Implementation Method 1
An electromagnetic transmitter may be disposed on the wellbore and operable to transmit electromagnetic fields into a formation
Data Source
AI summary
A system and method for electromagnetic measurements. The system may comprise an electromagnetic transmitter, wherein the electromagnetic transmitter is an antenna and is operable to transmit a low frequency electromagnetic field into a formation or a high frequency electromagnetic field into the formation. The system may further comprise an electromagnetic receiver, wherein the electromagnetic receiver is an antenna and is operable to record the high frequency electromagnetic field or the low frequency electromagnetic field. The method may comprise transmitting a high frequency electromagnetic field, recording a high frequency electromagnetic field, transmitting a low frequency electromagnetic field, recording a low frequency electromagnetic field, performing a shallow inversion on the low frequency electromagnetic field and the high frequency electromagnetic field to form a formation resistivity model, and running the deep inversion with the random initial guesses that have the misfit.