Monthly Luncheon

Speaker: William Stephens

Company: Delta Oil & Gas

Presentation: Strawn Clastic Depositional Systems of the Northern Eastern Shelf, with Observations on Regional Petroleum Sourcing, and an Update on JC (Strawn Upper) Field

About William Stephens:

During the Desmoinesian stage a regional shelf along the northern “Eastern Shelf” had not yet developed. Large-scale carbonate buildups, such as the King Platform and Anson Bank, ultimately link together to create the true Eastern Shelf by mid-Missourian time.

Regional sedimentation was controlled by a low-angle ramp dipping west-southwest at approximately 1-2 degrees towards the incipient Midland Basin. Ouachita and Muenster-Wichita-derived clastics rapidly prograded westward as elongate deltas, depositing fluvio-deltaic, mixed nearshore, and deeper marine facies. Deeper deposits, up to 100M water depths, have been observed in atypical restricted depressions and, as suspected, submarine channels. The strong cyclicity observed in both clastic and carbonate deposits was likely driven by glacioeustasy. Individual cycles are postulated to represent 200,000-400,000 years of sedimentation.

For Atoka through Strawn reservoirs, there are two primary petroleum source provinces: an eastern, Fort Worth Basin Barnett source, and a western, Midland/Permian Basin source. These two systems are not observed to overlap. There are additional, localized source provinces that have been demonstrated to source Atoka and Cisco-Canyon reservoirs.

This discussion will briefly review the two primary petroleum provinces sourcing Strawn-age reservoirs, analyze specific Strawn cyclical elements studied in King County, and examine the change in depositional vectors for Strawn sandstone cycles through time along the west-southwest pivoting Bend Arch.

Additionally, the NBX-operated JC (Strawn Upper) Field, the largest conventional oilfield discovered on the Eastern Shelf this century, will be reviewed and discussed.

Members and guests are welcome. Meal prices are $15 with or without a reservation but reservations are encouraged!