ABSTRACT

Accumulation of oil in the Lignite field is controlled by stratigraphic changes which occur over low order structural noses. This is the first significant oil field to produce from the Midale beds of the Charles formation of Mississippian age in an area where the accumulation is. not affected by the truncation of porosity at the Paleozoic unconformity.

Lithology of the Charles indicates probable deposition of the entire formation in a predominantly penesaline environment. The pay unit may be easily divided into four major lithotopes which are illustrated and described. A structure map contoured on the top of the Midale Pay shows that the main producing portion of the field is located on a broad, gentle, southwest plunging nose.

The reservoir is characterized by relatively high connate water saturation and slightly sulphurous crude. As of February 1, 1958, twenty wells had produced 90,000 barrels of oil and no dry holes had been drilled in the main field area.