CO2-Oil Miscibility Evaluation via Volume Expansion Curve
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Solution Overview
Problem
Current methods for evaluating the miscibility aiding effect of CO2 oil-displacing agents are time-consuming and labor-intensive, making it difficult to quickly screen the best mixing aid for specific oil reservoirs, especially in China where heavier oil and higher viscosity pose challenges for CO2 miscibility pressure reduction.
Innovation Solution
A method involving measuring the volume expansion of CO2-oil interfaces at different pressure levels to plot a miscibility percentage-pressure curve (δ-P curve), allowing for rapid and accurate comparison of miscibility aiding effects among different mixing aids, thereby facilitating the selection of appropriate agents for specific oil reservoirs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard slim tube test method is used to determine minimum miscibility pressure, then measurement accuracy is improved, but time consumption and experimental workload increase significantly
Solution Approach 1:
The patent creates a simplified copy of the slim tube test system using a constant volume pressure container with observation window. This copy replicates the essential measurement function (tracking oil-CO2 interface position) while eliminating time-consuming operations, reducing evaluation time from over one month to just a few days while maintaining measurement accuracy through the same fundamental measurement principle
Solution Approach 2:
The patent segments the complex slim tube test into a simplified constant volume pressure system. By separating the measurement function (interface position observation) from the complex test apparatus, the method retains the core measurement capability while removing unnecessary complexity and time requirements
2Reliability
If multiple candidate mixing aids are screened using standard methods, then reliable evaluation results are obtained, but experimental workload becomes excessively heavy
Solution Approach 1:
The patent creates a simplified copy of the standard test system that can be rapidly executed. By using a constant volume pressure container with direct observation capability, multiple mixing aids can be screened in parallel or sequence without the burden of complex apparatus setup and lengthy test durations, dramatically improving screening productivity while maintaining result reliability
Solution Approach 2:
The patent enables preliminary screening of multiple mixing aids through a simplified rapid test method. By performing preliminary evaluations using the constant volume system, researchers can quickly identify promising candidates before investing time in more detailed analysis, thereby improving overall screening efficiency
3Loss of time
If theoretical prediction models are used to estimate minimum miscibility pressure, then time consumption is reduced, but measurement accuracy and reliability decrease
Solution Approach 1:
The patent creates a physical copy of the measurement process that captures actual experimental data rather than relying on theoretical predictions. The constant volume pressure system with direct observation provides real experimental evidence, ensuring measurement precision while maintaining rapid evaluation through the simplified apparatus design
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 method significantly reduces the time and workload required for evaluating miscibility aiding effects, enabling rapid screening of mixing aids and providing stable, reliable results, which is essential for advancing CO2 miscibility oil-displacing research and industrial applications.
Implementation Method 1
measuring the extent of oil volume expansion at different CO2 pressure levels
Data Source
AI summary
Provided in the present invention a method for evaluating the mixing effect of a CO2 oil-displacing and mixing agent, characterized in measuring the volume expansion of a CO2-oil interface when pressure is gradually increased, drawing a mixed-phase percentage-pressure curve (δ-P curve), and evaluating the mixing effect of the CO2 oil-displacing and mixing agent by means of comparing the characteristics of the δ-P curve. Further provided in the present invention is a method for initially screening a CO2 oil-displacing and mixing agent.