NMR Reservoir Evaluation for Helium-Rich Gas Accumulation Efficiency
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Solution Overview
Problem
The existing methods lack effective evaluation of the accumulation efficiency of helium-rich natural gas, particularly in terms of geological structure, lithological distribution, and genetic sources, with a lack of qualitative and quantitative characterization parameters.
Innovation Solution
A method involving obtaining geological data through NMR spectral signals of rock samples, calculating gas driving efficiencies under different pressures, and determining accumulation pressure and rate to evaluate helium-rich natural gas reservoir efficiency, using a system comprising a vacuuming and saturating device, simulation test device, gas supply device, and control and display device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional geological methods are used to study helium-rich natural gas, then research can be conducted on geological structure and lithological distribution, but there is a lack of quantitative characterization parameters for accumulation efficiency
Solution Approach 1:
The patent replaces conventional geological field survey methods with NMR (Nuclear Magnetic Resonance) technology to measure helium-rich natural gas accumulation efficiency. The NMR instrument detects hydrogen proton signals from fluids in rock pores, providing quantitative data on fluid distribution and accumulation efficiency without complex mechanical field operations.
Solution Approach 2:
The patent uses NMR technology as an intermediary method to indirectly measure accumulation efficiency. Instead of directly observing helium accumulation, the system measures hydrogen proton signals from associated fluids (water, hydrocarbons) in the rock pores, which correlate with helium-rich gas accumulation patterns, providing quantitative characterization parameters.
2Measurement precision
If NMR spectral signals are used to measure fluid volume in rock samples, then accumulation rate can be calculated, but multiple measurements under different conditions are required
Solution Approach 1:
The patent performs preliminary saturation of rock samples with target fluids (water or hydrocarbons) under controlled vacuum conditions before NMR measurement. This preliminary action ensures complete fluid saturation of pore spaces, establishing a known baseline state that accelerates subsequent measurements and reduces the need for repeated conditioning experiments.
Solution Approach 2:
The NMR measurement system is designed to perform multiple functions: measuring fluid volume in saturated samples, determining gas driving efficiency under different pressures, and calculating accumulation rates. This multi-functional approach consolidates what would otherwise require separate measurement protocols into a single integrated system, reducing total measurement time.
3Measurement precision
If gas driving efficiency is measured under multiple different gas driving pressures, then accumulation pressure can be determined, but the evaluation process becomes more complex
Solution Approach 1:
The patent employs dynamic gas driving experiments where gas pressure is progressively increased to displace fluids from rock pores. By measuring NMR signal changes at multiple pressure stages, the system captures the dynamic displacement process, allowing determination of accumulation pressure as the point where gas driving efficiency reaches optimal values. This dynamic approach simplifies operation compared to static multi-point measurements.
Solution Approach 2:
The system uses real-time NMR signal feedback during gas driving experiments to monitor fluid displacement. The NMR instrument continuously provides signals indicating fluid volume changes, which feed back to determine gas driving efficiency at each pressure stage. This feedback mechanism automates the identification of accumulation pressure, reducing operational complexity despite multiple pressure measurements.
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
The method provides accurate, objective, and scientifically sound evaluation of helium-rich natural gas accumulation efficiency, applicable to various rock types, unaffected by external factors, and easy to operate, with clear principles and results.
Implementation Method 1
an NMR device (3a), wherein the geological data comprises an NMR spectral signal of the rock sample
Data Source
AI summary
A method for evaluating accumulation efficiency of helium-rich natural gas includes: obtaining geological data of a rock sample of a stratum reservoir to be evaluated where the geological data includes a first and a second NMR spectral signal of the rock sample and a slope obtained by linearly fitting first volumes of a target fluid and NMR signal intensities of the rock sample imbibing the target fluid of the first volumes, calculating a second volume of the target fluid in the rock sample saturated with the target fluid in vacuum environment, determining gas driving efficiencies of the rock sample under different gas driving pressures, determining an accumulation pressure of the rock sample, and evaluating an accumulation efficiency of the stratum reservoir to be evaluated according to the accumulation pressure of the rock sample and the second volume of the target fluid.