--> Abstract: The La Rosa Basal Sand, Block I, Lake Maracaibo, Venezuela. Expectations and Strategies, by A. Leon, J. Casas, X. Bengochea, N. Agostini, L. Salamanca, M. Medina, P. Munoz, and N. A. Parra; #90942 (1997).

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Abstract: The La Rosa Basal Sand, Block I, Lake Maracaibo, Venezuela. Expectations and Strategies

LEON, A., J. CASAS, X. BENGOCHEA, N. AGOSTINI, L. SALAMANCA, M. MEDINA, P. MUNOZ, N. A. PARRA

The La Rosa Basal Sand (Miocene), best known in some areas as the Santa Barbara Member, was discovered in 1945 with a relatively poor success during the next 45 years of production. Since 1992 however, an aggressive policy of drilling and workovers has increased by over 300% the total oil production of medium and light oil. These activities were based upon the recommendations of several multidisciplinary team projects. The La Rosa Basal Sand is a 1-50-ft thick sandstone deposited in a fluvio-deltaic environment overlying an unconformity which truncated Eocene successions (Misoa Formation). Lateral continuity varies from south to north, and there is the feasibility not only to observe new sand bodies but also a coalescing effect below Eocene productive sands. La Rosa Basal Sand is overlain by a thick (100-2000) marine mudstone (the La Rosa Shale). The majority of the expectations are as a consequence of the results of well VLA-1185 upon the west flank of the Block which changed the paradigms of the area, and also demanded a revision of the petrophysical parameters. Its initial production of 1300 BPP and 0.3% water, was difficult to explain considering resistivity values of only 10 Ohm-m; a parameter which had been long considered to indicate high water saturation. Such a wrong parameter calculated a reduction of remanent reserves and rejection of some well locations. Also taking new cores has helped to better understand reservoir behavior and predict future activities. During the last years new 3D seismic interpretation, stratigraphic well by well correlation, history matching and structural and isopach maps being updated by information from recent wells has acted as a support for a slim holes campaign. Consequently, geologically optimized wells and no conventional workovers, increased production from 4000 BPD to 18400 BPD.

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