Sentence:  The initial capacity of the Alaskan pipeline was 1.7 million barrels per day. With the addition of a chemical nicknamed “<WSD>slickem</WSD>,” which reduced drag within the pipeline and thus improved the ease of flow, the pipeline's capacity was boosted to 2.1 million barrels per day. 
Meaning of the word marked with <WSD> tags:  A long-chain polymer that is injected into oil pipelines to reduce turbulent flow.