Abstract

In the western Anadarko Basin, the Lower Pennsylvanian Lower Morrow sands are an elusive exploration target. These transgressive marine sands produce on both paleo structural highs, (southeast Lipscomb field), and in paleo structural lows, (CNB field).

The seismic expression of the southeast Lipscomb field and the CNB field, Lipscomb county, Texas Panhandle are shown. Several interpretation techniques used in the exploration for the Lower Morrow sands are demonstrated.

One-dimensional merged log modeling, two-dimensional log interpolation modeling, color seismic inversion processing, seismic facies mapping, traditional structural, and isochronal mapping techniques have been applied to two Lower Morrow fields.

In the southeast Lipscomb field, the productive sand is deposited on a paleo high. Structural mapping of the Mississippian Chester and isochronal mapping between the Des Moines carbonate and the Mississippian Chester demonstrate the presence of the structural high during sand deposition.

On the structural seismic section and the color seismic inversion data, the sand is represented by a single reflector. The sand is within the thin-bed regime (below the tuning point) so that there is a correlation between the amplitude of the reflector and the thickness of the sand. The productive sand can be mapped using seismic facies mapping techniques and its general thickness and areal extent determined.

In the CNB field, the productive sand is just one thin sand among many on the downthrown side of a lower Pennsylvanian fauLt, in an anomalous paleo low. Structural mapping of the Mississippian Chester and isochronal mapping between the Des Moines carbonate and the Mississippian Chester demonstrate the presence of the faulted structural tow during sand deposition.

The geometry of the various lower Morrow sands in the CNB field make it impossible to differentiate the individual pay sand from other non productive sands. The constructive and destructive interference between the various sands preclude isolating and mapping the pay sand separately. However, it is possible to delineate and map the areal extent of the entire depositional sequence on the downthrown side of the fault on seismic inversion data, thereby delineating the areal extent of the field.