Downhole Fluid Compositional Analysis Using NMR and Optical Data Inversion
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Solution Overview
Problem
Current methods for compositional analysis of hydrocarbon-containing fluids using NMR and optical data face challenges in accurately determining chain length distributions due to noise-induced non-uniqueness in inversion processes and limited resolution, especially when dealing with dissolved gases like methane and ethane.
Innovation Solution
Combining NMR data with optical and other downhole measurements to constrain and enhance the inversion process, utilizing forward models and empirical interpolation schemes to improve the accuracy and resolution of chain length distributions, and incorporating additional data from tools like viscometers and pressure measurements to address noise and resolution issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NMR inversion process is used to determine chain length distribution, then compositional analysis is obtained, but noise-induced non-uniqueness and limited resolution occur
Solution Approach 1:
The patent combines NMR data with optical data and other downhole measurements into a unified inversion framework. By merging multiple data sources that provide complementary information about fluid composition, the system resolves the non-uniqueness problem inherent in standalone NMR inversion while enhancing overall measurement precision and reliability
Solution Approach 2:
The patent implements an iterative inversion process where initial compositional estimates are refined through feedback loops. The system uses forward models to predict expected measurements from estimated compositions, compares these predictions with actual measurements, and adjusts the composition estimates accordingly to minimize discrepancies and improve uniqueness
2Quantity of substance
If optical tools are used to determine weight percent of components, then compositional data is obtained, but resolution is limited for individual components
Solution Approach 1:
The patent segments the compositional analysis into distinct component groups (C1-C5, C6+, and water/CO2) that can be analyzed with specialized techniques. By dividing the complex mixture into manageable segments and applying appropriate analysis methods to each, the system achieves both comprehensive quantity measurement and high resolution for individual components
Solution Approach 2:
The patent merges optical measurement data with NMR relaxation and diffusion data to achieve superior component resolution. The optical data provides accurate weight percentages for component groups, while the NMR data provides detailed molecular-level information that resolves individual component contributions within those groups
3Measurement precision
If multiple data sets are integrated to constrain inversion, then accuracy and resolution improve, but device complexity increases
Solution Approach 1:
The patent implements a universal inversion framework that can accommodate multiple data types (NMR, optical, viscosity, pressure) through a single integrated processing system. This multi-functional approach allows the same computational infrastructure to handle diverse measurement modalities, reducing overall system complexity compared to separate analysis systems for each data type
Solution Approach 2:
The patent introduces forward models and empirical interpolation schemes as intermediary computational layers between raw measurements and final compositional results. These intermediaries translate diverse measurement data into a common compositional framework, simplifying the integration process and reducing the complexity of directly combining multiple data sets
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 provides a more robust and accurate determination of chain length distributions across a wider range of carbon numbers, improving the resolution and consistency of compositional analysis by integrating multiple data sets and constraining inversion processes with physical properties.
Implementation Method 1
NMR relaxation and diffusion measurements can be made with a downhole fluid analysis logging tool. The NMR tools measure the magnetization Mi at a series of echo times ti.
Implementation Method 2
The optical tools measure the optical densities {ODi} at a set of wavelengths λ1.
Data Source
AI summary
Methods and apparatuses are provided for analyzing a composition of a hydrocarbon-containing fluid. The methods include using a nuclear magnetic resonance (NMR) tool to conduct an NMR measurement on the hydrocarbon-containing fluid to obtain NMR data. A non-NMR tool, such as an optical tool, is used to conduct additional measurements on the hydrocarbon-containing fluid and to obtain non-NMR data on the fluid. An indication of the composition of the fluid can be determined by using the NMR data and the non-NMR data in an inversion process.