Equation of State Correlation for Gas Condensates
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Solution Overview
Problem
Current methods for reservoir engineering analysis, particularly in unconventional shale plays, face challenges in accurately correlating gas condensates and wet gases due to the limitations of existing oil correlations and the need for extensive PVT data, which are time-consuming and costly to obtain.
Innovation Solution
The method involves calculating condensate gas-ratio (CGR) and separator pressure-temperature values using a reduced pseudo-component fluid model, creating a fluid database, and determining the mole fraction of components heavier than heptane (C7+) through established relationships, enabling efficient correlation and simulation without requiring extensive PVT data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial PVT simulation software is used to obtain mathematically recombined composition and fit data to an equation of state model, then accurate PVT data files can be created for numerical reservoir simulation, but the process becomes time consuming and expensive
Solution Approach 1:
The patent extracts only the essential parameters needed for PVT analysis (condensate gas ratio, separator pressure, separator temperature) from the complex PVT simulation process, eliminating the need for full commercial software execution while retaining the core functionality for creating accurate PVT data files
Solution Approach 2:
The patent creates a simplified correlation model that copies the essential functionality of commercial PVT simulation software by using established equation of state relationships to generate PVT data files, providing a cheaper and faster alternative that replicates the accuracy of full simulation
2Productivity
If extended black oil correlations are used for gas condensates and wet gases, then some PVT properties can be calculated, but the results are prone to errors and inconsistencies
Solution Approach 1:
The patent changes the input parameters from standard black oil correlation inputs to specific parameters better suited for gas condensates and wet gases (condensate gas ratio, separator pressure, separator temperature), improving both the reliability and applicability of the correlations for these fluid types
Solution Approach 2:
The patent develops a unified correlation approach using equation of state relationships that works for both gas condensates and wet gases, providing a universal method that eliminates the need for separate correlation sets and improves consistency across different fluid types
3Device complexity
If reduced compositional models are created by combining components together, then the complexity and cost of simulation is reduced, but the model must still be matched with full compositional models which requires extensive PVT data
Solution Approach 1:
The patent performs preliminary calculations of condensate gas ratio, separator pressure, and separator temperature that establish the reduced compositional model parameters in advance, eliminating the need for subsequent matching with full compositional models and reducing the overall data requirements
Data Source
AI summary
Systems and methods for correlating gas condensates and wet gases in unconventional shale plays based on an equation of state using a condensate gas-ratio, a separator pressure and a separator temperature.