Permeability Evaluation for Hydrate-Bearing Sediment via Complex Conductivity
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Solution Overview
Problem
Current methods for evaluating the permeability of hydrate-bearing sediment are time-consuming, costly, and have a limited measuring range, failing to accurately reflect the micro-pore structure of hydrate-bearing sediment, which is crucial for natural gas production and reservoir evaluation.
Innovation Solution
A permeability evaluation method based on complex conductivity parameters, including impedance spectrum measurement, induced polarization well-logging, and calculations using Archie's law, formation factor, and fractal characteristics to determine hydrate saturation and permeability, allowing for a large measuring range and low-cost, high-accuracy assessments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional permeability measurement methods are used, then measurement accuracy may be adequate, but the measurement process is time-consuming and costly
Solution Approach 1:
The patent replaces traditional mechanical permeability measurement systems with an electrical measurement system based on complex conductivity. Instead of using physical flow measurements through the sediment, the invention uses electrical impedance spectroscopy to infer permeability parameters, thereby eliminating time-consuming mechanical measurement processes while maintaining measurement capability.
Solution Approach 2:
The invention changes the measurement parameter from direct permeability measurement to complex conductivity measurement. By measuring electrical conductivity at different frequencies and deriving permeability information from these electrical parameters, the method achieves faster measurement without sacrificing the ability to obtain accurate permeability data.
2Adaptability or versatility
If traditional permeability evaluation methods are used, then some measurement capability is provided, but the measuring range is small and cannot effectively reflect micro-pore structure
Solution Approach 1:
The patent employs dynamic frequency sweeping to measure complex conductivity across a wide range of frequencies. This dynamic measurement approach allows the system to adapt to different pore size scales and structures, effectively expanding the measuring range to capture micro-pore characteristics that static single-frequency measurements would miss.
Solution Approach 2:
The invention adds the frequency dimension to the measurement process by conducting impedance spectroscopy across multiple frequencies. This dimensional expansion enables the measurement system to probe different pore size ranges and structural features, thereby significantly increasing the measuring range and improving the ability to reflect micro-pore structure.
3Adaptability or versatility
If complex conductivity method is used, then measuring range is large and cost is low, but measurement precision must be verified
Solution Approach 1:
The patent incorporates feedback mechanisms through the use of equivalent circuit modeling and iterative fitting processes. The measured complex conductivity data is continuously compared with theoretical models, and parameters are adjusted to achieve the best fit, thereby ensuring measurement precision while maintaining the advantages of wide measuring range and low cost.
Solution Approach 2:
The invention creates a universal measurement framework that can handle various sediment types and pore structures through a single complex conductivity methodology. The multi-functional approach uses the same basic measurement technique across different applications, with precision maintained through model-based interpretation rather than requiring multiple specialized measurement systems.
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 method enables accurate and cost-effective permeability evaluation of hydrate-bearing sediment, effectively reflecting its micro-pore structure and improving the assessment of hydrate reservoirs for natural gas production.
Implementation Method 1
impedance spectrum measurement is performed on the sample and an electrical impedance spectrum is obtained; using a relationship between electrical impedance and complex resistivity
Implementation Method 2
based on an induced polarization well-logging method, supplying AC to current electrodes in a well by using ground equipment, the complex conductivity spectrum is obtained by changing frequency f of the AC
Implementation Method 3
calculating the formation factor based on Archie's first law; calculating the permeability of the hydrate-bearing sediment based on relaxation time in combination with the hydrate saturation and the formation factor
Data Source
AI summary
The present application relates to a permeability evaluation method for hydrate-bearing sediment, including a complex conductivity spectrum obtaining step, a hydrate saturation calculating step based on the spectrum, a formation factor calculating step based on Archie's first law or from the complex conductivity real part, imaginary part and a conductivity of pore water; and a permeability calculating step based on relaxation time, hydrate saturation, hydrate occurrence mode correction factor and formation factor, or based on the polarization amplitude, hydrate saturation, occurrence mode correction factor and formation factor, or based on the CEC, hydrate saturation and occurrence mode correction factor, or based on the pore radius, fractal dimension, hydrate saturation and occurrence mode correction factor. The application allows a large measuring range, low cost and high accuracy, and can accurately obtain the permeability of hydrate-bearing sediment and effectively reflect the micro-pore structure thereof.