ABSTRACT
The oil fields of the Minneola complex in southwest Kansas produce from northwest-southeast-trending marine sandstones of Morrowan age. Reservoir quality stratigraphic traps developed at the intersection of sandstone trends and topographic lows or channels on the underlying eroded Mississippian surface.
The discovery well, Ladd 1-8 Norton, was drilled in Sec. 8, T30S, R25W, Clark County, Kansas, on a seismic anomaly recognized on 12-fold Vibroseis data. Eleven feet (3 m) of productive Morrowan sandstone at 5,280 ft (1,609 m) was completed for 157 BOPD. Electric logs in the discovery well revealed that an expanded (up to 100 ft or 30 m) Morrow section consisting of sandstone and shale had been deposited in lows on the underlying eroded Mississippian surface. Modeling indicated that the addition of this low-velocity clastic material within these channels caused a variety of seismic anomalies, the distribution of which guided subsequent exploration and development drilling. These seismic anomalies are associated with topographic lows on the Mississippian unconformity surface rather than the productive sandstones.The anomalies vary in character and consist of (1) diffractions, (2) high amplitude bright spots, (3) brealcs in seismic continuity of tlie Mississippian reflector (polarity reversals), (4) sagging of the Marmaton reflector, and (5) possible faulting of Viola-Arbuclde reflectors. These anomalies vary according to the thickness of sediment deposited within the erosionally low areas, the varying geometry and lithologies of these deposits, variations in overlying sediments, and the angle at which the seismic line is shot across the lows. Subsurface control and seismic data can be used to trace the paleodrainage pattern and to interpret the distribution of the overlying productive Morrowan sandstones.
