Water and aqueous thermodynamics

Oil and gas systems contain water - and the water may cause many problems!

Scale formation / salt precipitation



Release of acid gases (CO2 and H2S)

Hydrates formation

It is therefore important to be able to track water through the process and calculate propterties of the water phase correctly.

Most process simulation tools use Equations Of State (EOS) such as the SRK or the PR EOS, and they are not able to simulate the properties of the water phase correctly. For example, solubility of gases in the water phase is not simulated correctly with most EOS. This can have serious implications for the process design and operation. Also, most process simulators do not include salts/ions, acids/bases and pH is not calculated.

With the ScaleSim software, Scale Consult can simulate compositions and properties of the water phases through the process. This includes:

  • Concentrations of dissolved salts/ions at any location
  • pH at any location, including effects of acids/bases
  • Solubility of gases in produced water and where the gas is flashed off
  • Concentration of CO2 and H2S in released gas streams
  • Water content in gas streams, and where this water will condense (potential hydrate formation)

Results from a process simulation using a ordinary process simulation tool (for example HYSYS), can be used to build the same process in ScaleSimPro and re-simulate the process with an accurate model for the water phase.

Example: Low GOR HP field. Process simulations indicated very little gas - just enough for fuel gas. Re-simulating the process with ScaleSim, including produced water and gas released from the water, showed that the gas rate increased 100%, but the fuel gas will contain up to 25% CO2 and will not burn.

Release of H2S at different locations in a process. Simulations are based on production profiles over 17 years.