Production System Modeling

Nodal Analysis, IPR/VLP Curves, and Decline Analysis

Well & Reservoir Data

Reservoir Properties

Reservoir Pressure (psi)

Bubble Point (psi)

Temperature (F)

Productivity Index (STB/d/psi)

IPR Model

Fluid Properties

Oil API Gravity

Water Cut (%)

GOR (scf/STB)

Gas SG (air=1)

Well Geometry

Well Depth TVD (ft)

Tubing Shoe MD (ft)

Tubing ID (in)

Wellhead Pressure (psi)

VLP Correlation

Multiphase Flow Correlation

IPR / VLP Curves

Sensitivity:

IPR/VLP Data Points

Rate (STB/d)	Pwf IPR (psi)	Pwf VLP (psi)	Delta P

Operating Point

Operating Rate
0
STB/d

Flowing BHP
0
psi

Drawdown

psi

% Drawdown

IPR Analysis

AOF (q_max)

STB/d

% of AOF

System Analysis

Fluid Velocity

ft/s

Flow Regime

GLR Total

scf/STB

Liquid Holdup

Production Status

Natural Flow

Well is flowing naturally with adequate pressure support.

IPR Model Comparison

Reservoir Data

Reservoir Pressure (psi)

Bubble Point (psi)

PI at Pb (STB/d/psi)

Test Rate (STB/d)

Test Pwf (psi)

Fetkovich Parameters (Gas Wells)

C Coefficient

n Exponent (0.5-1.0)

n=1.0 for laminar flow, n=0.5 for turbulent flow

IPR Comparison Chart

Model Equations

Linear PI: q = J * (Pr - Pwf)

Vogel: q/qmax = 1 - 0.2(Pwf/Pr) - 0.8(Pwf/Pr)^2

Fetkovich: q = C * (Pr^2 - Pwf^2)^n

Composite: Linear above Pb, Vogel below Pb

AOF Comparison

Linear AOF

STB/d

Vogel AOF

STB/d

Composite AOF

STB/d

Fetkovich AOF

STB/d

Model Selection Guide

Drive Mechanism	Recommended
Undersaturated (Pr > Pb)	Linear PI
Solution Gas Drive	Vogel
Mixed (Pr near Pb)	Composite
Gas Wells	Fetkovich
High Rate / Turbulent	Fetkovich (n<1)

VLP Parameters

Well Geometry

TVD (ft)

Tubing ID (in)

Surface Conditions

Wellhead Pressure (psi)

Wellhead Temp (F)

Fluid Properties

Oil API

Water Cut (%)

GOR (scf/STB)

Gas SG

BHT (F)

VLP Correlation Comparison

Correlation Details

Hagedorn-Brown: Best for high GOR wells, liquid holdup correlation

Beggs-Brill: Accounts for inclination angle, most versatile

Gray: Developed for gas condensate wells

Flow Analysis

At Rate: 1000 STB/d

Hagedorn-Brown

psi

Beggs-Brill

psi

Gray

psi

Avg Difference

Flow Regime Analysis

Superficial Vsl

ft/s

Superficial Vsg

ft/s

Predicted Flow Regime

Slug Flow

Production Data

Initial Conditions

Initial Rate qi (STB/d)

Initial Decline Di (%/yr)

Decline Type

b Factor (Hyperbolic)

0 = exponential, 0.3-0.5 = oil, 0.5-0.8 = gas, 1 = harmonic

Economic Limits

Economic Limit (STB/d)

Forecast Period (yrs)

Historical Data (Optional)

Paste Production History (Time,Rate per line)

Format: days,rate - one per line

Decline Curve Analysis

Reserves Estimate

EUR
0
MSTB

Economic Life
0
years

Cum @ 1 yr

MSTB

Cum @ 5 yr

MSTB

Decline Parameters

Decline Type	Hyperbolic
b Factor	0.5
Nominal Di	25%/yr
Effective De	22.1%/yr

Rate Forecast

Year	Rate (STB/d)	Cum (MSTB)