Flow Assurance and Multiphase flow - part 2 By Prof ... - Aker Solutions
Flow Assurance and Multiphase flow - part 2 By Prof ... - Aker Solutions
Flow Assurance and Multiphase flow - part 2 By Prof ... - Aker Solutions
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WAX<br />
Definitions<br />
What is wax?<br />
Mainly long-chain alkanes with 20-50 carbon atoms, but also contain minor quantities of<br />
branched <strong>and</strong> cyclic hydrocarbons. Typical content t in North Sea oils is 1-15 15 weight%.<br />
What is cloud point?<br />
Cloud point is the first temperature where wax starts to precipitate when an oil is cooled.<br />
It is often referred to as the wax appearance (or precipitation) temperature. Cloud point is<br />
typically 30-40°C, but may be as high as 50-55°C.<br />
What is wax melting point?<br />
The melting point of wax deposits is normally about 20°C higher than the cloud point.<br />
What is pour point <strong>and</strong> yield stress?<br />
Pour point is the temperature where sufficient amount of wax (about 4 weight %) is<br />
precipitated to make the oil take on a solid-like (gel) structure. The pour point of North<br />
Sea oils may be as high as 35°C <strong>and</strong> lower than -50°C. Below the pour point, the oil has a<br />
yield shear stress, i.e. the oil cannot <strong>flow</strong> unless it is subjected to a certain minimum<br />
shearing force (shaking or pumping). p Figure 3 shows a typical relationship between yield<br />
stress <strong>and</strong> restart pressure.<br />
23<br />
Seminar at <strong>Aker</strong> <strong>Solutions</strong>, Stavanger - May31st, 2011
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