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What are olefins?

The term 'olefins', also known as alkenes, refers to a large number of compounds that contain carbon and hydrogen and have at least one double bond in their structure. Short-chain olefins, like ethylene, are cracked from naphtha or natural gas. Ethylene is then oligomerised into longer chain linear alpha olefins, ranging from 4 to 24 carbons in length.

Alpha olefins (1-alkenes) are characterised by their high purity, high degree of linearity, and a double bond between the first and second carbon atom. For drilling fluid applications, alpha olefins in the C14 to C18 range are used because they have the right mix of physical properties like viscosity, pour point and flash point.

Internal olefins are produced from linear alpha olefins by catalytically moving the double bond to different positions in the molecule. As a result, the pour point of the fluid decreases significantly, thus enabling these materials to be used successfully in cooler deep-water applications. Internal olefins used as base fluids for drilling muds typically have carbon chain lengths in the C15 to C18 range.

How do Shell chemicals companies resolve the alpha versus internal olefin challenge?

What are paraffins?

Paraffins, also known as alkanes, refers to a large number of compounds that contain carbon and hydrogen and have single bonds only (fully saturated). They may be linear (normal), branched (iso) or cyclic (ring structures). Since both the carbon number and the linearity impact the physical properties substantially, the carbon range used for drilling fluid applications may vary widely from C10 to C22. Unlike linear alpha olefins, several processes exist for producing paraffins. They include refinery extraction, Fischer Tropsch synthesis, and hydroformylation of linear alpha olefins.