NMR Probe for Pore Fluid Phase Behavior in Shale
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Solution Overview
Problem
Conventional PVT measurement techniques are inadequate for characterizing the phase behavior of hydrocarbon fluids in unconventional resources like nano-confined shale systems, as they cannot probe the true phase behavior and fluid composition inside shale nanopores, leading to uncertainties in hydrocarbon storage and recoverability.
Innovation Solution
A system and method using a nuclear magnetic resonance (NMR) probe to measure phase behavior by loading a fluid into an NMR sample cell with a porous medium, controlling pressure and temperature, and deriving NMR parameter distributions to determine the presence or absence of fluid phases and estimate phase boundaries, enabling characterization of phase behavior in porous media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PVT measurement is used, then bulk fluid phase behavior can be characterized, but phase behavior inside shale nanopores cannot be accurately measured
Solution Approach 1:
The patent replaces conventional mechanical PVT measurement systems with nuclear magnetic resonance (NMR) technology. The NMR system uses magnetic fields and radiofrequency pulses to detect fluid phase behavior non-invasively, enabling direct measurement of phase behavior inside shale nanopores without requiring bulk fluid extraction or complex pressure-volume-temperature equipment.
Solution Approach 2:
The invention specifically addresses porous media (shale formations) by using NMR techniques that can probe fluids confined within nanopores. The method characterizes phase behavior of hydrocarbons trapped in the porous structure of shale, accounting for the unique confinement effects that differ from bulk fluid behavior.
2Loss of information
If numerical simulations are used to assess phase behavior, then phase behavior can be estimated, but the equation of state remains controversial and no direct measurement is available
Solution Approach 1:
The NMR system performs self-contained measurements directly on the shale samples with pore fluids present. The technique uses the intrinsic magnetic properties of hydrogen nuclei in the hydrocarbon fluids to detect phase behavior, eliminating the need for external assumptions or controversial equations of state. The measurement is self-calibrating and provides direct observational data.
3Loss of information
If bulk phase PVT data are collected, then conventional phase behavior information is obtained, but true phase behavior and fluid composition inside nanopores remains unknown
Solution Approach 1:
The invention transitions from macroscopic bulk phase measurements to nanoscale pore-level measurements by using NMR's unique ability to probe magnetic properties at different spatial scales. The technique resolves fluid composition and phase behavior dimensions that are inaccessible to conventional PVT methods, providing information about fluids confined within individual nanopores rather than averaged bulk properties.
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 allows for the accurate characterization of phase behavior in shale nanopores, providing detailed insights into hydrocarbon storage and recoverability, which cannot be achieved with conventional PVT methods, and helps in optimizing reservoir production strategies.
Implementation Method 1
a nuclear magnetic resonance (NMR) probe that collects NMR signal measurements from nuclei of the fluid and porous medium in the sample cell
Data Source
AI summary
To measure the phase behavior of a fluid in a porous medium such as a tight gas shale, one illustrative method involves: (a) loading the fluid into a sample cell containing the porous medium; (b) setting a pressure and a temperature for the fluid in the sample cell; (c) applying an RF pulse sequence to the fluid in the sample cell to acquire an NMR signal; (d) deriving from the NMR signal an NMR parameter distribution that depends on the pressure and the temperature; (e) determining whether a fluid phase is present based on the NMR parameter distribution; (f) repeating operations (c) through (f) to determine the presence or absence of the fluid phase at multiple points along a pressure-temperature path that crosses a phase boundary; and (g) providing an estimated location of the phase boundary based on the presence or absence of the fluid phase at said points.