There is no doubt that as you have shown there is a differential for general Wyoming crude but I suspect ELK is in a unique position for the sale of its Grieve oil and hence the stated premium. Apart from quality of the oil , the main reasons crudes sell at differing prices are regional dynamics, being transportation and storage costs. Grieve oil is classified as premium light sweet 37 API oil , so the quality is excellent, but it is the fact that it 100% owns the 32 mile Grieve Oil Pipeline from the field to Casper, where it sells the crude to the 25000 BOPD Sinclair refinery in the town which may eliminate the differential. Indeed, it will charge Denbury US$ 3 a barrel to transport their oil to Capser.
If this is a critical point for you I will be happy to contact the company to clarify.
Cheers
Dan
ELK Price at posting:
7.9¢ Sentiment: Buy Disclosure: Held