--> Abstract: Approaches to Identifying Reservoir Heterogeneity and Reserve Growth Opportunities from Subsurface Data: A Case Study of Successful Infill Drilling in the Mature Budare Field, Venezuela, by D. S. Hamilton, S. K. Raeuchle, M. H. Holtz, M. Uzcategui, and T. Jimenez; #90942 (1997).
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Abstract: Approaches to Identifying Reservoir Heterogeneity and Reserve Growth Opportunities from Subsurface Data: A Case Study of Successful Infill Drilling in the Mature Budare Field, Venezuela

HAMILTON, D.S., S.K. RAEUCHLE, M.H. HOLTZ, M. UZCATEGUI, and T. JIMENEZ

Despite being a mature oil producer, the Budare field in the Eastern Venezuela Basin offers considerable reserve growth potential because of stratigraphic and structural complexity. Our ability to resolve these complexities was significantly advanced following the acquisition in 1995 of a Previous Hit3-DNext Hit seismic data set over the field. We applied an integrated geologic, geophysical, and engineering approach devised to identify heterogeneities in the subsurface that might lead to reserve growth opportunities. The approach involved 4 key steps: 1) determining geologic reservoir architecture, 2) investigating trends in reservoir fluid flow, 3) integrating fluid flow trends with reservoir architecture, and 4) estimating original oil-in-place, Previous HitresidualTop oil saturation, and remaining mobile oil, to identify opportunities for reserve growth.

The integrated analysis revealed that Oligocene-Miocene oil-producing reservoirs (Oficina Formation) at Budare were deposited in a bed-load fluvial system, an incised valley-fill, and a barrier-strandplain system. Reservoir continuity is complex because, in addition to lateral facies variability, the major Oficina depositional systems were internally subdivided by high-frequency stratigraphic surfaces. These surfaces define times of intermittent lacustrine and marine flooding events that punctuated the fluvial and marginal marine sedimentation, respectively. Syn- and post-depositional faulting further disrupted reservoir continuity. Trends in fluid flow demonstrated the effectiveness of reservoir facies pinchout, flooding shale markers, and faulting, as barriers to lateral and vertical fluid flow.

Numerous reserve growth opportunities were identified in the study because the complexities trapped mobile oil in compartments smaller than current well spacing could access and, to date, the first 4 well proposals were all successfully completed as oil producers, each averaging more than 1,000 bopd.

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