🧪 PETE 665 — PR EOS Mini Simulator

Peng-Robinson Equation of State (1978) simulator for black oil phase behavior — bubble point, CCE, and differential liberation, running entirely in the browser.

Spring 2026 · Individual Project · 100% Client-Side

Live Demo · Source Code

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Overview

A browser-based PVT simulator that implements the Peng-Robinson Equation of State (1978) to model black oil phase behavior. Input a multicomponent hydrocarbon composition, and the simulator calculates saturation pressure, runs Constant Composition Expansion (CCE), and performs stepwise Differential Liberation (DL) — all with interactive charts and Excel export. No backend, no installation required.

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Simulation Capabilities

1. Saturation (Bubble Point) Pressure

Calculates Psat via successive substitution using fugacity equilibrium (φᵢᴸ = φᵢⱽ). Starting from Wilson's K-value correlation for initial estimates, the algorithm iterates until ΣKᵢxᵢ = 1 within tolerance of 10⁻⁷.

2. Constant Composition Expansion (CCE)

Simulates a PVT cell expansion at constant temperature and overall composition:

• Above Psat — single-phase liquid; computes Z-factor, molar volume, and oil density directly from the cubic EOS
• Below Psat — two-phase flash using Rachford-Rice with Newton-Raphson; computes liquid/vapor splits, phase densities, and total relative volume (V/Vsat)

Output properties: Relative Volume (Vrel), Oil Density (ρo), Gas Density (ρg)

3. Differential Liberation (DL)

Stepwise liberation simulating laboratory DL at reservoir temperature:

1. Flash the current liquid at each pressure stage
2. Remove all liberated gas
3. Flash residual liquid to standard conditions (14.7 psia, 60°F) to obtain Vo,sc
4. Compute all volumetric properties referenced to stock-tank barrel

Output properties: Oil FVF (Bo), Total FVF (BtD), Gas FVF (Bg), Solution GOR (RsD), Cumulative Released Gas (RsDb)

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Thermodynamic Engine

Peng-Robinson EOS (1978)

$$P = \frac{RT}{V-b} - \frac{a\alpha}{V(V+b) + b(V-b)}$$

With the 1978 κ correlation:

$$\kappa = 0.379642 + 1.48503\omega - 0.1644\omega^2 + 0.016667\omega^3$$

Implementation Details

Component	Method
Cubic solver	Cardano's method — handles 1-root and 3-root regimes; selects min(Z) for liquid, max(Z) for vapor
Mixing rules	van der Waals one-fluid (kᵢⱼ = 0)
Fugacity coefficients	Analytical derivation from the PR EOS with component-specific partial derivatives
Flash convergence	Successive substitution on K-values; Rachford-Rice solved by Newton-Raphson; convergence criterion: Σ(Kᵢⁿ⁺¹/Kᵢⁿ − 1)² < 10⁻⁹
DL gas removal	Moles of liberated gas tracked cumulatively; residual liquid recomposed at each stage
Standard conditions	Final flash of residual oil to 14.7 psia / 60°F for Bo and RsD normalization

Constants

Symbol	Value	Unit
R	10.73146	psia·ft³/(lb-mol·°R)
Ωa	0.45724	—
Ωb	0.07780	—

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Default Composition

Component	zᵢ	Tc (°R)	Pc (psia)	ω	MW
Methane	0.19962	343.00	666.40	0.01142	16.043
Ethane	0.10010	549.76	706.50	0.09950	30.070
Propane	0.18579	665.68	616.00	0.15230	44.097
n-Butane	0.09036	765.29	550.60	0.20020	58.124
n-Pentane	0.18851	845.37	488.78	0.25150	72.150
Pseudo C6+	0.23563	913.32	436.29	0.29600	86.177

All values are editable in the UI. Reservoir temperature defaults to 129.7°F.

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Project Structure

├── eos.ts           # PR EOS class — parameters, cubic solver, fugacity coefficients
├── simulator.ts     # MiniSimulator — Psat, CCE, and DL algorithms
├── App.tsx          # React UI — input panel, charts (Recharts), Excel export
├── utils.ts         # Tailwind utility helpers
├── index.css        # Global styles and CSS theme variables
├── main.tsx         # React entry point
└── vite.config.ts   # Vite build configuration

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Tech Stack

Layer	Technology
Language	TypeScript
Framework	React 19
Build	Vite 6
Styling	Tailwind CSS 4
Charts	Recharts
Animations	Framer Motion
Export	SheetJS (xlsx)
Deployment	Vercel

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Getting Started

git clone https://github.com/jairam25/PETE-665-Mini-Simulator.git
cd PETE-665-Mini-Simulator
npm install
npm run dev
# → http://localhost:3000

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Export

Click Download Results (.XLSX) after running a simulation. The Excel workbook contains three sheets:

1. Fluid Properties — component table with zᵢ, Tc, Pc, ω, MW
2. CCE Results — pressure, V/Vsat, ρo, ρg, Z-factor
3. DL Results — pressure, Bo, BtD, Bg, RsD, RsDb, ρo

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References

1. Peng, D.-Y. & Robinson, D.B. (1976). A New Two-Constant Equation of State. Industrial & Engineering Chemistry Fundamentals, 15(1), 59–64.
2. Peng, D.-Y. & Robinson, D.B. (1978). The Characterization of the Heptanes and Heavier Fractions for the GPA Peng-Robinson Programs. GPA Research Report RR-28.
3. Pedersen, K.S., Christensen, P.L., & Shaikh, J.A. Phase Behavior of Petroleum Reservoir Fluids, Ch. 4.
4. Rachford, H.H. & Rice, J.D. (1952). Procedure for Use of Electronic Digital Computers in Calculating Flash Vaporization Hydrocarbon Equilibrium. JPT, 4(10), 19.

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Live Demo

👉 pete-665-mini-simulator.vercel.app

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Built for PETE 665 — Advanced Reservoir Fluid Properties