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Workflow collections

Well control calculatorsDrilling hydraulics calculatorsPVT calculatorsPetroleum engineering formula guide

Topics with multiple in-depth references

Drilling Hydraulics (3)Fluid Flow in Porous Media (2)Hydraulic Fracturing (2)Inflow Performance (2)PVT and Rock-Fluid Properties (2)PVT Properties (3)Resistivity Logs (2)Well Control (6)Well Performance (2)

Engineering guides

Well Control Calculation WorkflowA source-checked well control calculation workflow for hydrostatic pressure, kill mud weight, initial circulating pressure, final circulating pressure, and MAASP checks.Drilling Hydraulics FormulasA drilling hydraulics formula guide for ECD, annular pressure loss, annular velocity, pump output, and pressure-window checks.Reservoir Engineering Formula GuideA reservoir engineering formula guide for Darcy flow, straight-line productivity index, Vogel IPR, material balance, and original oil in place checks.Petroleum PVT Calculator GuideA petroleum PVT calculator guide for gas formation volume factor, oil formation volume factor, real-gas density, API gravity, and reservoir-to-surface volume conversion checks.Joshi Horizontal Well Productivity GuideA source-backed guide to the Joshi horizontal well productivity equation, drainage geometry, anisotropy, effective radius, skin, and the limits of steady-state inflow screening.Shaly Sand Water Saturation GuideA practical comparison of Indonesian, Archie, and Simandoux water-saturation calculations for resistivity logs, with input checks for shale volume, shale resistivity, porosity, and water resistivity.Annular Hydraulics and Velocity GuideA drilling annular hydraulics guide connecting flow rate, annular geometry, average velocity, hole-cleaning limits, pump output, pressure loss, and equivalent circulating density.Black-Oil PVT Correlation GuideA black-oil PVT correlation guide for Vasquez-Beggs solution gas-oil ratio, bubble point, formation volume factors, gas properties, and Beggs-Robinson oil viscosity checks.API RP 14E Erosional Velocity GuideA careful API RP 14E erosional-velocity workflow covering mixture density, empirical C factor, actual velocity, utilization, pipe sizing, and the equation's documented screening limitations.Hydraulic Fracture Carter Leakoff GuideA hydraulic-fracturing leakoff guide for Carter square-root-time fluid loss, spurt loss, exposed area, time basis, fluid balance, fracture efficiency, and model limitations.
In-depth calculator directory

Calculators with published engineering guidance

These records include a functioning calculator, formula and variables, a reproducible default result, individually written assumptions and limitations, common error checks, and source context.

Drilling Engineering

9 in-depth calculators

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Annular Velocity from Pump Output

Annular velocity from pump output estimates the average drilling-fluid velocity in the annulus from flow rate and annular area.

Equivalent Circulating Density

Equivalent circulating density converts annular pressure loss into an effective mud-weight value at depth during circulation.

Final Circulating Pressure

Final circulating pressure estimates circulating pressure after kill-weight mud reaches the bit at the planned kill rate.

Hydrostatic Pressure from Mud Weight

Hydrostatic pressure from mud weight calculates the pressure exerted by a drilling-fluid column at true vertical depth using the standard oilfield 0.052 conversion factor.

Initial Circulating Pressure

Initial circulating pressure estimates the pump pressure required at the start of a well-control circulation using slow circulating pressure and shut-in drillpipe pressure.

Kill Weight Mud Determination - Moore Equation

Kill weight mud determination estimates the mud density required to balance formation pressure after a kick using original mud weight, shut-in drillpipe pressure, and true vertical depth.

Maximum Allowable Annular Surface Pressure from Shoe EMW

Maximum allowable annular surface pressure estimates the casing-shoe pressure limit by comparing shoe equivalent mud weight with current mud hydrostatic pressure.

Pore Pressure Gradient - Rehm and McClendon

The Rehm and McClendon pore pressure gradient relationship estimates formation pore-pressure gradient from drilling or formation-evaluation indicators used in well planning.

Velocity of Fluid in Annulus

Fluid velocity in an annulus converts circulating flow rate and concentric annular geometry into an average linear velocity between the hole or casing and the drillpipe or tubing.

Geomechanics and Fracturing

1 in-depth calculator

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Fracture Gradient - Zoback and Healy

Fracture gradient estimates the pressure gradient required to initiate or propagate a fracture under a stated stress model.

Petrophysics

2 in-depth calculators

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Archie Water Saturation from Resistivity Logs

Archie water saturation estimates formation water saturation from resistivity-log measurements, porosity, formation-water resistivity, and Archie exponents.

Indonesian Water Saturation from Shaly Sand Logs

The Poupon-Leveaux Indonesian equation estimates water saturation in shaly formations by combining formation-water and shale conductivity terms with effective porosity, shale volume, true resistivity, and saturation exponents.

Phase Behavior and Thermodynamics

4 in-depth calculators

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Beggs-Robinson Live Oil Viscosity Correlation

The Beggs-Robinson live-oil correlation estimates saturated oil viscosity from dead-oil viscosity and solution gas-oil ratio through correlation coefficients that capture the viscosity-reducing effect of dissolved gas.

Real Gas Density

Real gas density estimates gas density at pressure and temperature using gas molecular weight or gravity and the real-gas z-factor.

Standing Oil Formation Volume Factor

Standing oil formation volume factor estimates the reservoir-barrel volume occupied by stock-tank oil and dissolved gas at reservoir pressure and temperature.

Vasquez-Beggs Solution Gas-Oil Ratio from Pressure

The Vasquez-Beggs correlation estimates solution gas-oil ratio from pressure, temperature, oil API gravity, gas specific gravity, and the coefficient set selected for the oil-gravity range.

Production Engineering

5 in-depth calculators

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API RP 14E Erosional Velocity

The API RP 14E erosional velocity equation divides an empirical C factor by the square root of flowing mixture density to produce a screening velocity for gas-liquid production piping.

Carter Leakoff Volume for Hydraulic Fracturing

The Carter leakoff equation estimates hydraulic-fracturing fluid volume lost to the formation from leakoff area, Carter leakoff coefficient, exposure time, and instantaneous spurt-loss thickness.

Productivity Index and Straight-Line IPR

Productivity index relates stabilized liquid production rate to reservoir-to-wellbore pressure drawdown and defines a straight-line inflow-performance relationship for a producing well.

Treatment Fracture Gradient - Hydraulic Fracturing

Treatment fracture gradient estimates the pressure gradient associated with hydraulic-fracturing treatment pressure at depth.

Vogel Inflow Performance Relationship

The Vogel IPR estimates oil well inflow rate under two-phase flow conditions using flowing bottomhole pressure and average reservoir pressure.

Reservoir Engineering

7 in-depth calculators

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API Gravity

API gravity converts oil specific gravity into the API gravity scale used to classify crude oil density in petroleum engineering workflows.

Capillary Number

Capillary number compares viscous forces with capillary forces and is commonly used as a rock-fluid screening parameter in displacement and recovery calculations.

Darcy's Law for Linear Single-Phase Flow

Darcy's law for linear single-phase flow estimates volumetric flow rate through porous rock from permeability, flow area, pressure drop, viscosity, and flow length.

Gas Formation Volume Factor

Gas formation volume factor converts gas volume between reservoir conditions and standard surface conditions using pressure, temperature, and gas z-factor.

Joshi Horizontal Well Productivity Index

The Joshi horizontal well productivity index estimates steady-state oil deliverability for a centered horizontal well by combining horizontal and vertical flow resistance, drainage geometry, anisotropy, well length, fluid properties, and skin.

Original Oil in Place from General Oil Material Balance

Original oil in place from general oil material balance estimates OOIP by reconciling produced fluids, pressure change, expansion terms, and water influx in a reservoir material-balance relationship.

Steady-State Radial Liquid Flow Rate

Steady-state radial liquid flow rate estimates oil or liquid inflow toward a well from permeability, thickness, pressure drawdown, viscosity, formation volume factor, drainage radius, wellbore radius, and skin.