SemCrude vs Murphy Oil Prices

Earlier today I posted the historical prices for Williston Sweet using SemCrude's prices/web site.

Subsequently, I was told that Murphy Oil also had a site for oil prices. A quick check revealed that the prices at Murphy and SemCrude were significantly different; Murphy Oil was generally significantly higher the few dates I checked.

It seemed Murphy was about $10 higher when oil was in $50 to $70 range and $20 higher when price range was closer to $90 to $100. That's a huge spread and I can't explain it. Hopefully I'm not misreading something.

Check it out for yourself; see if I'm missing something.

Murphy oil website.

SemCrude oil website.

Note: the Williston Herald said the same thing -- Empire Oil reporting $102/bbl of oil.