Hydrates

Hydrates are solid ice-like compounds of water and light gases and hydrocarbons. They can form at temperatures above the ice point and are therefore a serious concern in oil and gas processing operations.

• the Fluid phases (CPA or RKSAINFO)
• the hydrate phases (structures I, II and H)
• the freezeout model for ice and halite scales
• the hydrate nucleation model

Model parameters are available to predict inhibition by methanol, ethanol, isopropanol and the glycols - MEG, DEG, TEG, propylene glycol and glycerol . The CPA model is particularly good for calculating methanol partitioning between the aqueous and hydrocarbon phases.

Hydrate Inhibition by salt can also be modelled by converting a salt analysis into a sodium chloride equivalent. The sodium chloride can be handled either as a "salt component" with the properties of NaCl or as an electrolyte with Na+, K+, Ca++, Cl- and Br- ions.

Typically thermodynamic hydrate models predict the hydrate dissociation boundary, usually within ±1K. This is the most conservative set of conditions at which hydrates may form. The nucleation model predicts the least conservative hydrate boundary where hydrates will definitely form. Between the two boundaries is the region of hydrate risk.

For more information see our Hydrates , Hydrates Inhibitor Partitioning leaflets, case studies or publications .