The LL-04 reservoir is located in the northeastern section of Lake Maracaibo and is part of the prolific Bolivar Coastal Field (BCF). Since its discovery in the late 1920's, this reservoir has produced over 520 MMSTB of oil from shallow (<3000 feet), unconsolidated fluvial and fluvial deltaic sandstones of the Miocene Lagunillas and La Rosa formations. Production is complicated by the heterogeneous nature of the sediments, low oil gravity (12° -19° API) and water coning and channeling. A multidisciplinary team consisting of engineers, geologists, geophysicists and petrophysicists was assembled to characterize and simulate the field. The objective of the team was to develop a reservoir management plan for the LL-04 Field that would increase daily production and ultimate recovery. Available data included 3-D seismic, openhole logs from over 600 wells, four cores and production and pressure measurements. All available data were used and honored in the interpretation process. Pressure measurements and production history were integrated with the seismic interpretation, log analysis, core descriptions, log correlations and deterministic mapping to define the reservoir compartments. Seven reservoir regions were defined. The original oil in place (OOIP) was increased by 44% as a result of this rigorous study. Also, 80 workover/recompletion candidates and 25 areas for infill drilling were identified. Introduction The mature LL04 reservoir, located along the Bolivar Coast of Lake Maracaibo, Venezuela, was discovered in 1926, and has produced over 520 MMSTB of oil as of December 2000. Producing mechanisms are natural depletion, water support from aquifer and injection, gas and LPG injection and compaction. Cyclic "huff'n'puff" steam injection has been used in 70 wells, as a stimulation mechanism. The main objective of the study was to address the numerous production problems in order to optimize the recovery of the substantial remaining reserves within the exploitable area.

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