Basic Reservoir Engineering

Program Objectives

This 5-day course presents important material-balance techniques to analyze reservoir performance. The course covers the full scope of reservoir producing mechanisms: solution-gas drives, gas-cap drives, gas drives, water drives, and compaction drives. Attendees learn a mechanistic and physical understanding of the factors affecting fluid production.  The course also covers the full spectrum of reservoir fluids: dry gases, wet gases, gas condensates, volatile oils, and black oils. Generalized methods of analysis are presented.  Attendees learn how material balance is used to history-match reservoir performance.  They learn techniques to estimate OOIP and OGIP, confirm producing mechanisms, estimate gas-cap sizes, estimate water influx, estimate aquifer size and conductivity, and compute drive indices. The techniques range from simple graphical methods to sophisticated optimization methods.  Actual field cases are presented.  Attendees reinforce their learned skills with several in-class exercises.  In addition, the course includes a special project where attendees build their own spreadsheet model and then use it to analyze an example reservoir.
Course Outline
Day 1
  • Reservoir producing mechanisms 
  • Reservoir energies 
  • Fluid properties 
    • Fluid classes
      • Dry gases
      • Wet gases
      • Gas condensates
      • Volatile oils
      • Black oils
    • Fluid characteristics
    • Producing characteristics
    • p-T diagrams
    • Standard PVT parameters (Bo, Rs, Bg, and Rv)
Day 2 
  • Material balance 
    • Assumptions
    • Physical interpretation
    • Equations
  • Expansion mechanisms 
    • Gas expansion and expansivities
    • Oil expansion and expansivities
    • Water expansion and pore-volume contraction
  • Fluid withdrawal

Day 3
  • Material-balance applications 
    • Drive indices 
    • Analyzing wet- and dry-gas reservoirs 
Day 4
  • Material-balance applications (continued)
    • Analyzing black-oil reservoirs
    • Algebraic versus graphical (regression) methods
    • Analyzing gas-cap reservoirs
    • Material balance surveillance 
Day 5
  • Analyzing water-drive reservoirs
    • Van Everdingen-Hurst water-influx model
    • McEwen Method
  • Case study: Simultaneously determining water-influx constants, OOIP, and OGIP in a water-drive reservoir