Abstract: Application of Sequence Stratigraphy in an Integrated Reservoir Characterization Study of the Miocene Laguna Member, Lagunillas Formation, Blocks III and IV, Lake Maracaibo, Venezuela

GOMEZ, E., M.A. MUNOZ, R. A. RIPPLE, B. A. LUNEAU, I.D. BRYANT, GAMERO DE VILLARROEL, H., C. M. COLL, Z. JIMENEZ, K. LEON, R. PADRON, and L. RONDON

The Miocene Laguna reservoir was discovered in the 1950s and has produced over 300 MMBO. The Laguna had been initially subdivided into three homogeneous reservoir sandstone units that were interpreted as part of a coastal/barrier bar complex and assumed to be in fluid communication. Subsequent engineering studies showed that this simplistic geological model did not adequately address the heterogeneities of the reservoir.

A new sedimentological model consisting of sixteen (16) distinctive, correlatable units (XIII-XXVIII) was developed using sequence stratigraphy and tied to eight (8) cores. Sequence stratigraphic techniques proved to be invaluable in unraveling the complex stratigraphy of the Laguna reservoirs. The lower Laguna is the highstand system tract of a third-order sequence that includes the underlying Lower Lagunillas Member. The upper Laguna represents a complete third-order sequence bounded by two type 1 sequence boundaries. Several thick sandstones that had traditionally been interpreted as barrier bars are actually incised valleys that are part of the overlying Bachaquero Member.

The sedimentological model was then integrated with 210 well logs, 3D seismic data, petrophyical evaluations, production and pressure data to produce a new, more accurate geological model. This model indicates that the numerous thin shales associated with flooding events in the Laguna act as partial barriers to vertical communication resulting in relatively complex reservoir hydrodynamics. This knowledge permitted better simulation of reservoir performance and has identified new opportunities to optimize recovery through horizontal drilling and recompletions supported by an improved water injection program.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria