Material Balance Calculator

Havlena-Odeh Analysis, Drive Mechanism Identification, and OOIP/OGIP Estimation

Initial Reservoir Conditions

Reservoir Parameters
PVT Properties at Initial Conditions
Compressibilities
m = GBgi / NBoi (0 for no gas cap)

Production & Pressure History

Enter cumulative production data and average reservoir pressure at each time step

Time
P (psi)
Np (MSTB)
Gp (MMscf)
Wp (MSTB)
Wi (MSTB)
PVT Data Table (Optional)

Enter pressure-dependent PVT data or use correlations

Havlena-Odeh Analysis Settings

Plot Type
Straight Line Analysis
OOIP (N)
-
MMSTB
R-Squared
-
Slope
-
Intercept
-
Drive Mechanism Interpretation
Enter production data to analyze drive mechanism
Data Points
Time F (RB) Et (RB/STB) Eo (RB/STB)

Havlena-Odeh Plot

A straight line through the origin with slope = N indicates volumetric depletion. Upward curvature indicates water influx or gas cap expansion.

Drive Index Calculation

Energy Source Contributions
Oil Expansion Index (DDI)
-
%
Gas Cap Expansion Index (SDI)
-
%
Water Drive Index (WDI)
-
%
Rock/Fluid Compressibility (CDI)
-
%
Drive Mechanism Breakdown
DDI
SDI
WDI
CDI
Oil Expansion
Gas Cap
Water Influx
Rock/Fluid
Primary Drive Mechanism
-

Drive Index History

Drive Index Data

Time P (psi) DDI (%) SDI (%) WDI (%) CDI (%)

Tank Model Parameters

Volumetric Estimates
Prediction Settings
Recovery Predictions
Ultimate Recovery
-
%
EUR Oil
-
MMSTB
EUR Gas
-
Bscf
Total Water Influx
-
MMSTB

Tank Model Predictions

Prediction Table

P (psi) Np (MMSTB) Gp (Bscf) RF (%) We (MMSTB)

Aquifer Model Selection

Schilthuis Parameters
We = J * integral(delta_P * dt)
Calculated Values
Total Water Influx
-
MMSTB
Aquifer Constant
-

Water Influx Analysis

Water Influx History

Time P (psi) Delta P (psi) We (MSTB) Cum We (MMSTB)

Material Balance Summary

Original Hydrocarbons In Place
OOIP (N)
-
MMSTB
OGIP (G)
-
Bscf
Gas Cap (mNBoi)
-
MMRB
Aquifer Size Est.
-
MMSTB
Current Recovery
Oil Recovery Factor
-
%
Gas Recovery Factor
-
%
Cum. Oil Produced
-
MMSTB
Cum. Gas Produced
-
Bscf
Drive Mechanism Analysis
DDI
SDI
WDI
CDI
Dominant Drive
-

Analysis Quality Metrics

Havlena-Odeh Fit
R-Squared
-
Data Points
-
Confidence
-
Reservoir Characterization
Enter production data to generate reservoir characterization
Recommendations
  • Enter production history data
  • Run material balance analysis
  • Review drive mechanism indicators
  • Validate OOIP estimate with volumetrics