Lower Hackberry (mid-Frio) reservoirs are highly unpredictable in the subsurface due primarily to variations in sand thickness and sand distribution. Most exploration for lower Hackberry reservoirs has been limited to turbidite sand-filled channels cut between sea-floor paleotopographic highs, and lower Hackberry sands on the northern flanks of salt domes, where excellent stratigraphic traps exhibit north dip--in places with significant closure. Two other existing types of reservoirs have received little attention, both in the literature and in exploration. The suprafan lobe in the midfan position lying at the base of the slope is a prime exploration target, where massive lower Hackberry sands should be found. Several wells in northwestern Cameron Parish, Louisiana, penet ated thick lower Hackberry sands in a downdip position from the channel plays, suggesting that a mechanism for large-scale downslope movement was present during Hackberry deposition.

Another potential reservoir that deserves more exploration is the interdomal sediment "pondering" of lower Hackberry sands into topographic lows created by the scouring of the sub-lower Hackberry surface. These sands generally are concentrated in the center of the pond and may not be present in either the traditional lateral or updip pinch-out positions. Many of the ponds occur independently from ideal structural location, commonly with a pinch-out of the sands serving as the trap. Ideal prospect locations are where the sub-lower Hackberry unconformity and top of the lower Hackberry marker diverge, indicating the presence of a sand-filled scour feature. Southwestern Calcasieu Parish provides excellent examples of this ponding feature in the subsurface. Successful exploration efforts d pend on careful attention to paleontological information,

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which is critical in identifying and establishing the placement of the sublower Hackberry unconformity that records erosion of the early Frio surface.

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