B41oa oil and Gas Processing Section a flow Assurance Heriot-Watt University

3.7.3 Chemical Methods 
Chemical methods are based on injecting a chemical for preventing or 
removing wax deposits. The chemical control methods are divided into the 
following categories: 
•
Solvents: these methods dilute the deposit forming materials and/or 
dissolve the deposit. For example, injection of toluene can dissolve 
wax deposits. 
However, the solvents are generally expensive and, in order to reduce 
the costs, it is important to place the solvent in the vicinity of wax 
deposits. 
For wax deposits inside a wellbore, the chemicals could be placed on 
the top of wax deposits (by wireline bailers or coiled tubing). 

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TOPIC 3: Wax Deposition 
 
 
 
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•
Wax crystal modifiers: these methods alter and/or inhibit wax crystal 
growth. These chemicals prevent wax crystal growth and are generally 
used as preventive techniques. 
•
Wax particle dispersants: these methods retard and/or prevent the wax 
solids from agglomerating and depositing. Again, they are most 
effective as a preventive technique. 
Other methods suggested for wax control, include microbial (e.g. SPE 80529) 
and magnetic treatment (e.g., SPE 68749). The former is based on microbial 
degradation of heavy paraffinic hydrocarbons (especially normal alkanes) to 
reduce the apparent molecular weight of the crude oil. The latter is based on 
applying magnetic field to the crude oil and affecting wax crystallisation.
Clearly, where appropriate, a combination of some of the above techniques 
could be used for more effective and economical removal of wax deposits. 
N I N E 

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TOPIC 4: Asphaltenes 
 
 
 
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