Abstract

Flaxton field produces oil from a structural-stratigraphic trap in the Mississippian Mission Canyon and Charles Formations. The field was discovered in 1956 with completion of the Texota 1 Sorum. This and other early wells in the field were completed in the Midale and Nesson intervals of the Charles. The field was rediscovered in 1981 with completion of the Monsanto 1 Bird in the Coteau interval of the Mission Canyon.

The Mission Canyon Formation in the more recently developed part of the field is a limestone with variable, but generally low porosity and permeability (usually less than 15% and 1 md). Most of the reservoir rocks were deposited in shallow-marine shoals which were sometimes exposed subaerially. Diagenetic changes, especially cementation, have had an important effect on the reservoir.

The structure at the top of the Mission Canyon is a southwest-plunging anticline. Much of the structural relief at this horizon results from differential compaction of the upper part of the Mission Canyon. The trap is formed by a combination of structural reversal and an updip loss of reservoir due to stratigraphic and diagenetic changes.

There are presently 70 wells completed in the Flaxton field, of which 48 have been completed since 1981. The field has an estimated ultimate reserve of 4 million bbl of oil (6.4x10⁵m³).