Theory & Background
Petroleum engineering equations, correlations, and methodology
73 articles
Decline Curve Analysis
Decline Curve Analysis Overview
OverviewComprehensive guide to decline curve models for production forecasting and reserves estimation
Ansah-Knowles-Buba (AKB) Decline Model
Semi-analytical decline model for gas wells under boundary-dominated flow, derived from material balance principles
Arps Decline Curve Analysis - Exponential, Hyperbolic, and Harmonic Models
Complete theory and equations for classical Arps decline curves including exponential, hyperbolic, and harmonic models for production forecasting and EUR estimation.
Decline Curve Statistics
Objective functions for evaluating decline curve model fit quality including SSE, log-space SSE, and weighted variants
Duong Decline Model for Unconventional Wells
Theory and equations for the Duong decline model designed for multi-fractured horizontal wells in shale and tight reservoirs with extended linear flow.
Field Production Profiles
Aggregate production modeling for multi-well field development using parametric and discrete convolution approaches
Modified Hyperbolic Decline Model
Hybrid decline model combining hyperbolic and exponential decline with a terminal decline rate for realistic long-term production forecasting.
Power Law Exponential (PLE) Decline Model
Theory and equations for the Ilk et al. Power Law Exponential decline model for tight gas and unconventional reservoirs, capturing transient-to-BDF transition.
Stretched Exponential Production Decline (SEPD) Model
Theory and equations for the Valkó-Lee Stretched Exponential decline model based on statistical physics, ideal for shale and unconventional reservoir analysis.
Electric Submersible Pump
ESP System Design Overview
OverviewComprehensive guide to Electric Submersible Pump system design, component selection, and calculation workflow for artificial lift optimization
ESP Pump Performance - Head, Staging, Efficiency, and Horsepower
Theory and equations for ESP pump performance including head-capacity curves, total dynamic head, staging calculations, brake horsepower, and best efficiency point analysis
ESP Gas Handling - Free Gas, Void Fraction, and Gas Separation
Theory and equations for gas interference in ESP systems including free gas volume at pump intake, void fraction calculations, gas separator efficiency, and Turpin-Dunbar correction factors
ESP Viscosity Corrections - Turpin and Stepanoff Methods
Theory and equations for correcting ESP pump performance curves for viscous fluid effects, including Turpin and Stepanoff correction factor methods for head, efficiency, and flow rate derating
ESP Motor and Cable Sizing - Horsepower, Amperage, and Voltage Drop
Theory and equations for ESP motor horsepower selection, amperage calculations, load factor analysis, cable voltage drop, cable size selection, and power loss estimation
Equation of State
Equation of State Overview
OverviewGuide to cubic equations of state for compositional modeling, flash calculations, and phase behavior prediction
Peng-Robinson Equation of State
Theory and equations for the Peng-Robinson cubic equation of state including mixing rules, alpha functions, and volume translation
Flash Calculations
Theory and methods for PT flash calculations, Rachford-Rice equation, stability analysis, and K-value estimation
Phase Envelope
Theory and construction of phase envelopes showing bubble point and dew point curves, cricondentherm, and cricondenbar
C7+ Characterization
Methods for estimating critical properties, splitting heavy fractions, and lumping components for equation of state modeling
Compositional Viscosity Models
Viscosity prediction methods for compositional EoS modeling including Lee-Gonzalez-Eakin, Lorentz-Bray-Clark, and Pedersen models
Field Production Profile
Field Production Profiles Overview
OverviewGuide to field-level production forecasting including buildup-plateau-decline profiles and multi-well schedule aggregation
Drilling Schedule and Multi-Well Forecasting
Multi-well production aggregation methods, drilling schedule impact on field profiles, and schedule-based cumulative production forecasting
Flow Assurance
Flow Assurance Overview
OverviewComprehensive guide to flow assurance calculations including hydrate prevention, corrosion management, and erosion control for oil and gas production systems
Hydrate Prevention
Gas hydrate formation conditions, Hammerschmidt equation for temperature depression, and thermodynamic inhibitor calculations for methanol and MEG
Corrosion and Erosion
CO2 corrosion prediction using the de Waard-Milliams model, NACE severity classification, and erosional velocity calculations per API RP 14E
Gas Lift
Gas Lift Overview
OverviewGuide to gas lift design including continuous gas lift, valve mechanics, injection pressure, and gas lift optimization
Gas Lift Valve Mechanics
Theory and calculations for gas lift valve operation including dome pressure, opening and closing pressures, spread, and gas throughput
Hydraulic Fracturing
Hydraulic Fracturing Overview
OverviewComprehensive guide to hydraulic fracturing theory, fracture geometry models, leakoff, fluid efficiency, and proppant transport for well stimulation design
Fracture Geometry Models - PKN, KGD, and Radial
Complete theory and equations for classical 2D hydraulic fracture geometry models including PKN, KGD, and Radial (penny-shaped) with Carter leakoff and fluid efficiency
Proppant Transport in Hydraulic Fractures
Theory and equations for proppant settling velocity, wall effects, hindered settling, power-law fluid corrections, and transport ratio calculations in hydraulic fractures
Inflow Performance Relationship
Well Flow Overview
OverviewComprehensive guide to well inflow performance, productivity index calculations, and flow rate estimation for oil and gas wells
Gas Well Deliverability
Darcy and non-Darcy gas flow equations for vertical gas well performance and deliverability testing
Horizontal Well Productivity
Productivity index and drainage area correlations for horizontal and deviated wells
Vogel Inflow Performance Relationship
Dimensionless IPR curve for solution-gas drive wells producing below bubble point pressure
Well Productivity Index
Productivity index calculations for vertical and horizontal wells under steady-state, pseudosteady-state, and transient flow conditions
Material Balance Equation
Material Balance Overview
OverviewGuide to material balance methods for reservoir engineering including drive mechanism identification, OOIP/OGIP estimation, and aquifer modeling
Gas Reservoir Material Balance
p/z method for volumetric gas reservoirs, modified p/z for geopressured reservoirs, and OGIP estimation techniques
Oil Reservoir Material Balance
Havlena-Odeh straight-line method for oil reservoir analysis, OOIP estimation, gas cap ratio determination, and Campbell plot interpretation
Aquifer Models
Theory and application of aquifer models for water influx calculation: Pot, Schilthuis steady-state, Fetkovich pseudo-steady-state, and Van Everdingen-Hurst unsteady-state
Underground Withdrawal and Expansion Terms
Calculation of underground withdrawal F, expansion terms Eo, Eg, Efw, effective compressibility, and two-phase formation volume factor Bt
Monte Carlo Simulation
Monte Carlo Simulation Overview
OverviewGuide to Monte Carlo methods for uncertainty quantification in petroleum engineering including probabilistic reserves, risk analysis, and sensitivity studies
Probability Distributions for Monte Carlo
Common probability distributions used in petroleum engineering Monte Carlo simulation including normal, lognormal, triangular, uniform, PERT, and truncated distributions
Pressure Transient Analysis
Pressure Transient Analysis Overview
OverviewComprehensive guide to well testing models and interpretation methods for reservoir characterization
Bounded Reservoir Solutions for Pressure Transient Analysis
Method of images for modeling boundary effects including sealing faults, constant pressure boundaries, and combinations in well test analysis.
Dimensionless Variables for Pressure Transient Analysis
Definitions and equations for dimensionless pressure, time, radius, distance, and wellbore storage used in well test analysis and type curve matching.
Infinite Acting Reservoir Solutions for Pressure Transient Analysis
Line source solution, Ei function, Stehfest numerical inversion, and wellbore storage/skin effects for infinite homogeneous reservoir well testing.
PVT Properties
PVT Properties Overview
OverviewComprehensive guide to selecting and applying PVT correlations for crude oil, gas, and water properties
Bubble Point Pressure Correlations
Empirical correlations for predicting the saturation pressure of crude oil from surface-measured fluid properties
Formation Water PVT Properties
McCain correlations for formation water density, formation volume factor, compressibility, viscosity, and solution gas-water ratio
Gas PVT Properties
Comprehensive correlations for natural gas compressibility factor, viscosity, density, formation volume factor, and pseudo-critical properties
Interfacial Tension Correlations
Gas-oil interfacial tension correlations for wellbore hydraulics calculations
Oil Compressibility Correlations
Empirical correlations for predicting isothermal compressibility of crude oil at saturated and undersaturated conditions
Oil Formation Volume Factor (Bo) Correlations
PVT correlations for oil formation volume factor including Standing, Vazquez-Beggs, Glasø, Al-Marhoun, Petrosky-Farshad, and Dindoruk-Christman methods.
Oil Viscosity Correlations
Empirical correlations for predicting crude oil viscosity at dead, saturated, and undersaturated conditions
Solution Gas-Oil Ratio (Rs) Correlations
PVT correlations for solution gas-oil ratio including Standing, Vazquez-Beggs, Glasø, Al-Marhoun, Petrosky-Farshad, and Dindoruk-Christman methods.
Rod Pump
Rod Pump Overview
OverviewGuide to sucker rod pumping system design including pump displacement, rod string analysis, polished rod loads, and counterbalance
Rod Pump Displacement and Efficiency
Pump displacement calculation, fillage analysis, volumetric efficiency, effective stroke length, and pump intake pressure for sucker rod pumping
Rod String Analysis
Sucker rod string design including rod weight, stretch calculations, polished rod loads, stress analysis, and API 11L dynamic factors
Special Core Analysis
SCAL Overview - Relative Permeability Correlations
OverviewComprehensive guide to selecting and applying relative permeability correlations based on rock type, wettability, and fluid system
Corey and LET Relative Permeability Models
Analytical relative permeability models using power-law (Corey) and three-parameter (LET) formulations
Honarpour Relative Permeability Correlations
Empirical relative permeability equations for consolidated rocks based on regression analysis of laboratory data
Ibrahim-Koederitz Relative Permeability Correlations
Comprehensive linear regression relative permeability equations for all rock types, wettability states, and fluid systems
Rock Compressibility Correlations
Pore volume compressibility correlations for sandstone and limestone reservoirs
Surface Facilities
Surface Facilities Overview
OverviewComprehensive guide to surface facility calculations including choke models for flow control and pipeline equations for fluid transport
Choke Models for Multiphase, Gas, and Liquid Flow
Theory and equations for critical and subcritical choke flow including Gilbert-type correlations, Sachdeva, Ashford-Pierce, and single-phase choke models
Pipeline Flow Equations for Gas, Liquid, and Two-Phase Systems
Theory and equations for pipeline pressure drop and flow capacity including Weymouth, Panhandle A/B, Darcy-Weisbach, and two-phase correlations
Utilities
Utilities Overview
OverviewGuide to utility functions including unit conversion, interpolation methods, and mathematical tools for petroleum engineering calculations
Interpolation and Integration Functions
Numerical methods for interpolating, differentiating, and integrating tabular data using spline techniques
Unit Conversions and Special Functions
Utility functions for unit conversions, gravity transforms, and mathematical special functions used in petroleum engineering
Vertical Flow Performance
Pipe Flow Overview
OverviewComprehensive guide to single-phase and multiphase pipe flow correlations for wellbore and pipeline calculations
Beggs and Brill Multiphase Flow Correlation
Comprehensive correlation for predicting pressure drop and liquid holdup in multiphase flow through pipes at any inclination angle
Single-Phase Pipe Flow
Reynolds number, friction factor, and pressure drop calculations for single-phase liquid and gas flow in pipes
Vertical Multiphase Flow Correlations
Hagedorn-Brown and Gray correlations for predicting pressure gradients in vertical and near-vertical wells
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