NMR Liquid Saturation via Endpoint Interpolation
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Solution Overview
Problem
Existing NMR data analysis methods face challenges in accurately determining liquid saturation from overlapping T2 distributions of water and hydrocarbon components in geological formations, which complicates hydrocarbon exploration and production decisions.
Innovation Solution
A method and system that identify distinct endpoints for water and hydrocarbon T2 peaks in NMR data, allowing for the calculation of liquid saturation by interpolating in logarithmic space, thereby distinguishing between overlapping T2 distributions and determining water saturation accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional NMR data analysis methods are used to measure overlapping T2 distributions of water and hydrocarbon components, then the measurement process is simple and direct, but the measurement precision of liquid saturation determination deteriorates due to overlapping distributions
Solution Approach 1:
The patent segments the overlapping T2 distribution into distinct water and hydrocarbon components by identifying separate endpoints (T2w and T2h) that represent pure water and pure hydrocarbon signals. This segmentation allows independent analysis of each fluid type despite their overlapping distributions, thereby improving measurement precision of liquid saturation without requiring complex additional hardware.
2Measurement precision
If endpoints are identified from mixed NMR data containing both water and hydrocarbon components, then the analysis is straightforward, but the measurement precision deteriorates due to mutual interference between components
Solution Approach 1:
The patent performs preliminary action by first identifying the water endpoint (T2w) and hydrocarbon endpoint (T2h) from the mixed NMR data before calculating liquid saturation. By establishing these reference endpoints first, the method creates a foundation for accurate component separation and saturation determination, reducing the difficulty of detecting and measuring individual components in the overlapping distribution.
3Reliability
If liquid saturation is calculated without separating overlapping T2 distributions, then the calculation process is simple, but the reliability of hydrocarbon exploration decisions deteriorates
Solution Approach 1:
The patent changes the parameter representation by working with T2 distribution parameters (endpoints T2w and T2h, and their amplitudes) rather than directly processing the raw overlapping signals. By transforming the problem into parameter space, the method achieves reliable liquid saturation determination while maintaining reasonable data processing efficiency, as the parameter-based approach simplifies the mathematical operations required for separation and calculation.
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 precise determination of water saturation, leading to improved accuracy in hydrocarbon exploration and production decisions by effectively separating overlapping T2 distributions in NMR data, enhancing the interpretation of well log data.
Implementation Method 1
One type of downhole well-logging tool uses nuclear magnetic resonance (NMR) to measure the response of nuclear spins in formation fluids to applied magnetic fields
Implementation Method 2
The static magnetic field produces an equilibrium magnetization in the fluid that is aligned with a magnetization vector along the direction of the static magnetic field
Implementation Method 3
A transmitter antenna produces a time-dependent radio frequency magnetic field that is perpendicular to the direction of the static field. The radio frequency magnetic field produces a torque on the magnetization vector that causes it to rotate about the axis of the applied radio frequency magnetic field
Implementation Method 4
This causes the magnetization vector to align with the component perpendicular to the direction of the static magnetic field, and to precess around the static field. This produces NMR measurements which contains data indicative of multiple components within the well
Data Source
AI summary
A liquid saturation may be identified from nuclear magnetic resonance (NMR) data having overlapping peaks indicative of two liquids by, generally, identifying a first endpoint based at least in part on the T2 NMR data for the first liquid, and identifying a second endpoint based at least in part on the T2 NMR data for the second liquid. Then, the liquid saturation is identified by relating a composition of the first liquid for an overlapping distribution region based at least in part on the first endpoint and the second endpoint. In some embodiments, the liquid saturation is identified based on an interpolation between the first endpoint and the second endpoint.