Isothermal Compressibility

Introduction

The basic mathematical description of Isothermal Compressibility is:

Generally speaking, petroleum reservoirs are considered to be isothermal (constant temperature), except for scenarios such as Thermal Stimulation.

Basic observations are:

• Increasing pressure causes volume of material to decrease (compression)

• Decreasing pressure causes volume of material to increase (expansion of reservoir fluids)

• Formation/rock compressibility can have a significant impact on production performance

Types of Compressibility:

The broad groups of compressibility used in AFA are:

• Fluid Compressibility

  • Oil Compressibility

    • Above Bubble Point

    • Below Bubble Point

  • Gas Compressibility

  • Water Compressibility

• Conventional https://predico.atlassian.net/wiki/pages/createpage.action?spaceKey=AFAUM&title=Rock%20%28Formation%29%20Compressibility&linkCreation=true&fromPageId=58064928

  • Sandstone

  • Limestone/Dolomite

• Sorption Compressibility

• Cleat Compressibility

See Also

Total System Compressibility:

In a generic scenario, the total system compressibility for:

where:

c_t = Total system compressibility, 1/psia or 1/kPaa

c_g = gas compressibility, 1/psia or 1/kPaa

c_o = oil compressibility, 1/psia or 1/kPaa

c_w = water compressibility, 1/psia or 1/kPaa

c_f = formation compressibility (or Cleat Compressibility or CSG Cleat Compressibility Examples in CSG applications), 1/psia or 1/kPaa

c_s = Sorption Compressibility , 1/psia or 1/kPaa

S_w, S_g, S_o refer to Fluid Saturations