Abstract

The Dean and Spraberry formations in north-central Irion County are more carbonate-rich and proximal to the Eastern Shelf than the stratigraphic equivalent produced in the axis of the Midland Basin. Located more than 10 miles to the east of the existing Spraberry Field, this carbonate-rich Dean and Spraberry is productive but relatively underdeveloped near the shelf edge. Recent completions in this interval currently produce at a daily rate exceeding 900 BOPD in the study area, with an average peak rate of 80 BOPD per well.

Production characteristics in the Dean and Spraberry are more favorable in the carbonate-rich facies in the northern part of the study area, than in the siliceous shale-rich facies to the south. This indicates that the production profile is facies dependent. Dean and Spraberry completions in the northern, carbonate-rich portion of the field have had an average 30-day IP of 80 BOPD, while wells completed in the southern, shale-rich facies had an average 30-day IP of 25 BOPD.

This suggests a potentially significant expansion of the existing Spraberry field, proving up a band of productive carbonate-rich “Detrital” Dean and Spraberry that covers hundreds of square miles near the shelf margin. The trend likely extends north and south along the Eastern Shelf where depositional characteristics are similar.

Similarly, the Wolfcamp section in the study area has a carbonate-rich detrital section proximal to the shelf edge, and becomes more shale-rich to the southwest in the developing Wolfcamp Shale play. More work is needed to determine if production characteristics seen in the carbonate-rich Dean and Spraberry apply to the Wolfcamp Shale and its carbonate-rich equivalent.