Print this pageControl of Reservoir Architecture on Remaining Oil in Mixed-Load Fluvial and Bay-Fill Systems in the Upper Laguna and Lower Bachaquero Members in the Lagunillas Formation, Mioceno Norte Area, Lake Maracaibo, Venezuela
AMBROSE, W. A., M. SALEEM AKHTER, MILTON MENDEZ and REGULO ALVAREZ
An integrated reservoir-characterization study by the Bureau of Economic Geology and Lagoven, S.A., targets multiple areas for strategic oil recovery in the Upper Laguna and Lower Bachaquero Members in the 30-km2 Mioceno Norte Area in northern Lake Maracaibo. Considerable volumes of remaining oil (400 to 800 MSTB/20 ac) occur in narrow fluvial- and distributary-channel sandstones uncontacted at the current 300-m well spacing. Detailed lithofacies maps document the control of sandstone architecture on hydrocarbon distribution and demonstrate that the current well spacing on a grid pattern is too large to efficiently recover the remaining oil.
This study identifies a variety of recompletions, infill wells, and water-injection wells to target reservoir sandstones, efficiently recover the remaining oil resource, and offset the current production decline. These development wells are estimated to recover more than 100 MMSTB, an additional 10 to 15 percent of the original oil in place.
The Upper Laguna and Lower Bachaquero Members in the Mioceno Norte Area were deposited on a low-gradient coastal plain in a foreland-basin setting. Fine-grained meanderbelt deposits, having a northwestern source in the region of the present-day Perija Mountains, merge southeastward into mud-rich bay-fill deposits updip of an inferred wave-dominated coastline. Genetic units in these members are 50 to 150 ft (15.2 to 45.7 m) thick and are bounded by continuous paleosol marker beds that record climate changes or shutoff in sediment supply.