Reservoir Architecure of the Vla-6/9/21 Area, Lake Maracaibo, Venezuela

Abstract

Reservoir sandstone geometry of tide-dominated depositional sequences in the Lower Misoa Formation (lower Eocene), together with multiple northwest-trending normal faults, exerts a strong influence on fluid distribution and poorly swept areas in the VLA-6/9/21 Area in north-central Lake Maracaibo. An integrated reservoir-characterization study by the Bureau of Economic Geology (BEG) and Maraven, S. A., identifies depositional and structural controls on bypassed oil in poorly swept areas adjacent to elongate pathways of water encroachment along depositional axes within sparsely drilled, fault-bounded compartments. The upper C6 to C3 Members consist of multiple tide-dominated depositional sequences, 30.5 to 91.5 m (100 to 300 ft) thick, bounded below by tidal-ravinement surfaces and capped by flooding surfaces. Each sequence contains multiple parasequences composed of 50- to 100-ft (15.2- to 30.5-m), predominantly upward coarsening, pervasively burrowed sandstones, eroded by cross bedded sandstones. Limited accommodation space resulted in tidal ravinement and erosion of older genetic stratigraphic units. Detailed depositional modeling of these depositional sequences provides a framework for understanding and predicting reservoir drainage patterns and distribution of remaining oil.