What Is the Reservoir Material Balance Drive Index Calculator?
Drive indices determine the proportion of reservoir voidage replacement supplied by each natural energy source.
How Does the Reservoir Material Balance Drive Index Calculator Work?
Normalizes individual expansion volumes against total expansion, ensuring the sum of all indices equals 100%.
Reservoir Material Balance Drive Index Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
ext{DDI} + ext{SDI} + ext{WDI} + ext{CDI} = 1.0 quad (100%)
Schilthuis material balance drive index normalization.
How to Use the Reservoir Material Balance Drive Index Calculator
- Input calculated expansion volumes for oil, gas-cap gas, net water influx, and formation compaction in MMbbl.
Step-by-Step Example Calculation
Active Water-Drive Offshore Reservoir
Input Values:
oilExpansionMmbl:12.5
gasCapExpansionMmbl:8.2
waterInfluxNetMmbl:24
formationCompactionMmbl:1.8
Worked Steps: Water Drive (WDI) = 51.6%, Depletion Drive (DDI) = 26.9%, Gas-Cap Drive (SDI) = 17.6%, Compaction (CDI) = 3.9%.
Understanding Your Result
Identifies the primary drive mechanism (e.g. Water Drive, Gas-Cap Drive, or Depletion Drive) and percentage split.
Factors That Affect the Result
- Aquifer size, permeability, and continuity determine water drive strength; initial gas cap size dictates gas drive.
When Should You Use This Calculator?
- Reservoir management, pressure maintenance planning (water injection vs gas reinjection), and reserve booking.
Assumptions & Limitations
- Assumes thermodynamic equilibrium and accurate historical production/injection accounting.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Havlena-Odeh material balance formulation.