Downhole Fluid Viscosity via NMR Relaxation Ratio
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Solution Overview
Problem
Existing methods for determining the viscosity of downhole fluids using nuclear magnetic resonance (NMR) technologies are unreliable.
Innovation Solution
A method involving performing an NMR survey to determine the longitudinal relaxation time (T1) and apparent transverse relaxation time (T2app) for the fluid, forming a ratio R of T1/T2app, and using this ratio to calculate the viscosity (η) of the fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NMR technologies are used to determine viscosity of downhole fluids, then viscosity estimation capability is provided, but the determination is unreliable
Solution Approach 1:
The patent transforms the NMR measurement approach by changing from single relaxation time measurement to measuring multiple relaxation times at different temperatures. This parameter change enables the determination of activation energy and improves viscosity determination reliability through the Arrhenius relationship.
Solution Approach 2:
The patent adds the temperature dimension to the NMR measurements. By measuring relaxation times across a range of temperatures rather than at a single temperature, the method extracts additional physical parameters (activation energy) that improve viscosity determination accuracy and reliability.
2Reliability
If traditional NMR methods are used for viscosity determination, then the measurement process is simple, but the results are unreliable
Solution Approach 1:
The patent performs preliminary temperature-dependent relaxation time measurements before calculating viscosity. By collecting T1 and T2 data at multiple temperatures first, then using these data to determine activation energy and calculate viscosity, the method improves reliability while keeping the overall process systematic and manageable.
Solution Approach 2:
The patent introduces activation energy as an intermediary parameter that connects NMR relaxation time measurements to viscosity determination. This intermediary allows the transformation of simple relaxation time data into reliable viscosity estimates through the Arrhenius relationship, bridging the gap between measurement and target parameter.
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 reliable and effective means to estimate the viscosity of downhole fluids, enabling better characterization of hydrocarbon quality and differentiation between light and heavy oils based on the correlation between the relaxation time ratio and viscosity.
Implementation Method 1
performing a nuclear magnetic resonance (NMR) survey of the fluid; determining a longitudinal relaxation time, T1, and an apparent transverse relaxation time, T2app
Implementation Method 2
performing a nuclear magnetic resonance (NMR) survey of the fluid
Data Source
AI summary
A method for determining viscosity, η, of a fluid downhole, calls for performing a nuclear magnetic resonance (NMR) survey of the fluid; determining a longitudinal relaxation time, T1, and an apparent transverse relaxation time, T2app, for the fluid; forming a ratio R of T1/T2app for the fluid; and determining the viscosity, η, according to the ratio, R. A computer program product for implementing the method is provided.