Permeability Logging via Wideband EM Inversion
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Solution Overview
Problem
Current methods for predicting formation permeability and generating permeability logs from conductivity measurements are limited by the need for core sampling, which is time-consuming and expensive, and rely on assumed formation factors, leading to potential errors due to variations in these factors.
Innovation Solution
The use of wideband electromagnetic (EM) measurements and models that evaluate hydraulic permeability with minimal input parameters, allowing for continuous permeability logging and the determination of permeability as a function of formation depth, enabling informed reservoir completion and simulation strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If core sampling is used to measure formation factor for permeability prediction, then measurement accuracy is improved, but time consumption and cost increase significantly
Solution Approach 1:
The patent replaces the mechanical core sampling process with electromagnetic measurement technology. Instead of physically extracting and analyzing core samples, the system uses electromagnetic waves to measure formation properties directly in situ, eliminating the time-consuming mechanical extraction and laboratory analysis process while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces electromagnetic waves as an intermediary to indirectly measure formation factor and permeability. Rather than directly sampling the formation, electromagnetic measurements serve as a mediator that provides formation properties through physical field interactions, enabling non-intrusive and rapid assessment.
2Measurement precision
If core sampling is used to measure formation factor for permeability prediction, then measurement accuracy is improved, but operational complexity and cost increase
Solution Approach 1:
The patent replaces the complex mechanical core sampling system with a simpler electromagnetic measurement system. The electromagnetic approach eliminates the need for core extraction equipment, handling mechanisms, and laboratory analysis apparatus, significantly reducing operational complexity while maintaining measurement precision.
3Ease of operation
If assumed formation factor values are used for permeability prediction, then operational simplicity is improved, but measurement accuracy deteriorates due to formation variations
Solution Approach 1:
The patent creates a universal electromagnetic measurement system that can determine formation factor and permeability across different formation types without requiring formation-specific assumptions. The electromagnetic method provides a multi-functional approach that works for various lithologies and fluid conditions, eliminating the need for formation-specific lookup tables or assumptions while maintaining operational simplicity.
4Productivity
If continuous permeability logging is implemented using wideband EM measurements, then productivity is improved, but measurement complexity increases
Solution Approach 1:
The patent segments the wideband electromagnetic spectrum into multiple frequency bands, each optimized for specific measurement objectives. By dividing the broad frequency range into manageable segments (e.g., low frequency for conductivity, high frequency for permittivity), the system achieves continuous permeability logging through coordinated use of simpler frequency-specific measurements rather than requiring a single complex wideband system.
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
Enables accurate and efficient evaluation of hydraulic permeability without the need for core sampling, reducing errors associated with assumed formation factors and providing robust petrophysical parameter characterization, thus supporting optimal reservoir management decisions.
Implementation Method 1
complex conductivity spectra of a formation are measured utilizing an electromagnetic logging tool
Implementation Method 2
a wideband EM model is inverted with the measured data and determined values as inputs for dominant grain size, and optionally pressure and temperature, in order to obtain a determination of permeability
Data Source
AI summary
A permeability log is generated by running borehole tools in a borehole traversing a formation, including at least electromagnetic (EM) tool providing at least a low-frequency complex conductivity measurement at least one frequency. Data from the EM tool and other data obtained from other tools are provided to a wideband EM model, where a data inversion is conducted to provide a plurality of outputs from which a cementation exponent may be calculated. The cementation exponent is used to find a formation factor at each depth of interest in the borehole, and the formation factor is used to find a permeability value which is used for the permeability log. The permeability log may be generated without the use of core data.