ResToolbox3

ResToolbox3 is a petroleum engineering calculator built for engineers who need answers fast - on a rig floor, in a meeting, or on a plane. PVT analysis, nodal analysis, gas hydrate prediction, production forecasting, volumetric calculations, and well testing, all from your iPhone or iPad.

FLUID PROPERTIES (PVT)

• Gas PVT: Z-factor, viscosity, compressibility, pseudo-pressure, water content, and thermal properties via 5-component Peng-Robinson EOS. Handles CO2, H2S, N2, H2, and hydrocarbon mixtures including pure and high-concentration cases
• Oil PVT: Bubble point, solution GOR, formation volume factor, viscosity, and compressibility using Valko-McCain and Velarde correlations. Three solve modes with scaling factors for GOR and viscosity
• Brine & Rock: Soreide-Whitson mutual solubility with Spivey brine correlations. Gas composition from Gas PVT flows through automatically

GAS HYDRATES

• Hydrate formation prediction via Motiee and Towler-Mokhatab correlations
• Thermodynamic inhibitor dosing for MEG, DEG, TEG, methanol, and ethanol
• Interactive P-T stability curves with inhibited and uninhibited envelopes
• Water content mass balance between reservoir and operating conditions

NODAL ANALYSIS

• Gas and oil well inflow performance (IPR) with non-Darcy flow and Vogel
• Outflow performance (VLP) via four methods: Woldesemayat-Ghajar, Hagedorn-Brown, Beggs & Brill, and Gray
• 3x3 sensitivity matrix or real-time Explorer mode with interactive sliders
• Water cut modelling with physics-based two-phase flow
• Injection well support

PRODUCTION FORECASTING

• Single-well decline profiles: hyperbolic, exponential, and harmonic
• Two-stage decline with continuous slope matching
• Multi-well field development with drilling schedule, plateau constraints, and abandonment rate

VOLUMETRICS

• Deterministic OGIP and OOIP with combined gas/oil mode
• Monte Carlo probabilistic analysis with Normal, Log-Normal, and Triangular distributions
• Exceedance probability curves with P90, P50, and P10 reporting

WELL TEST & TOOLS

• Choke flow: gas mode (Gilbert, Norsok, TAM, SLB) and oil mode (Gilbert, Ros, Baxendell, Achong)
• AGA-3 orifice metering for gas and ISO 5167 for liquid
• Gas flowline pressure drop: 30-segment Darcy-Weisbach with PR-EOS properties at each segment, plus Weymouth and Panhandle B empirical methods
• Petrophysics: Archie equation with density, sonic, and direct porosity methods, Pickett plot
• Gas heating value and composition
• Pipe capacities database (tubing, casing, drill pipe)
• Unit converter with HC equivalents, reciprocal GOR/CGR, and density-gradient conversions

DESIGNED FOR THE FIELD

• iPhone-first interface with iPad responsive layouts
• Oilfield and Metric unit systems with one-tap toggle
• Share results and charts via email or messaging
• Available in English, Norwegian, French, Chinese, Spanish, and Arabic
• Works fully offline - no internet connection required
• PVT properties flow between modules automatically

All calculations use published, peer-reviewed methods from SPE literature and industry-standard references. No proprietary correlations, no curve-fitted shortcuts. Tabular data exports let you paste results directly into Excel or Google Sheets.