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Bend Formation Study

Kurt Rucker
Pioneer Natural Resources

In the Midland Basin, the Pennsylvanian Atoka Bend formation sits between the overlying Strawn carbonate and underlying Atoka Detrital intervals, both of which are productive targets in Spraberry Trend wells. Until recently, the Atoka Bend was not considered a target in itself, other than to note that it would be a low cost incremental completion with low water saturation and subsequent minimal risk. Core and wireline logs indicate the low-porosity, heavily recrystallized carbonate ramp deposit is composed of sub-wavebase crinoid meadows, shallow brachiopodal bioherms, muddy bioturbated algal mats, and shoal deposits. Clastic shedding, primarily off the Big Lake Fault to the south and secondarily off the Central Basin Platform to the west, intermittently washes over the background carbonate ramp facies and provides the only observed permeability and porosity in the system. Limited production indicates an active and productive petroleum system, but one that is historically restricted to structural fields to the south, where clastic deposits are a more significant Bend component than in most of Pioneer's acreage. Mapping of the Strawn Detrital, between the Strawn and Bend intervals, suggests the Bend and Strawn can be completed as a single frac stage along the eastern margin of the basin. Further South and West the Bend requires a separate frac stage, but off-structure productive capability is not yet sufficiently described to assess whether the potential value of a Bend-specific completion stage warrants the cost and time of the completion.


AAPG Search and Discovery Article #90164©2013 AAPG Southwest Section Meeting, Fredericksburg, Texas, April 6-10, 2013