The waxes present
in most crude oils include n-alkanes, iso-alkanes, alkyl cyclic
compounds and alkyl aromatics. In most crude n-Alkanes are
the predominant species. The amount and distribution of these
n-Alkanes is crude specific. Short-branched chains are the
next most common. These have a significant impact on wax deposition
There is no standard
definition for wax content but it is generally accepted that
n-alkanes from C18 to C40 represent waxy material. Paraffin
solubility not only depends on the composition of the crude
but also the temperature and pressure.
The wax appearance
temperature (WAT) is the temperature at which, on a cooling
cycle, the crude oil first precipitates solid wax. This is
arguably the single most important characteristic in examining
wax deposition potential in crude oil. The deposition of wax
leads to several problems in reduced production and impaired
flow assurance. Severe deposition can lead to loss of production
and pipeline blockage etc.
The main options
for removing deposits are as listed below:
- Pigging –
A cleaning pig launched into a pipe to mechanically scrape
wax from the pipewall and distribute it within the crude
in front of the pig.
- Thermal Techniques
– if the temperature of the oil can be maintained
or increased above the WAT e.g. by increasing the flow
rate the wax deposits will either not be laid down or
will be softened and removed.
- Chemical Solvents
and Dissolvers – a wide range of solvents are available,
the most popular being substituted aromatics (HAN etc)
blended with gas oil. Chlorinated solvents are now precluded
from use due to environmental concerns. A preferred and
unique product to Roemex is RX 49LT, a proprietary blend
with good environmental characteristics and excellent
wax dispersion and dissolution properties.
- Wax Inhibitors
– there are four main categories of such chemical additives:
- Crystal Modifiers
- Pour Point Depressants
Series - The RX-7000 series is a complete range of Wax
Inhibition / Pour Point Depressant chemicals, successfully
developed by Roemex.
RX-7491 - RX-7495
Wax Dissolver Range - designed specifically for the removal of wax with varying characteristics.
Questionnaire - If you would like us to investigate a
wax problem, please complete the questionnaire and return
to Roemex Limited.
|For further detailed product
information and case histories please contact Duncan Baillie
or e-mail: Enquiries@roemex.com