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Abstract: How to Revitalize a Mature Reservoir: New Development Strategy--An Integrated Study in Petroleum Engineering

L. Rondon, C. Coll, P. Cordova, H. Gamero, L. Hernandez, Z. Jimenez, K. Leon, I. Bryant, B. Baygun, M. Herron, A. Matesson, R. Ramamoorthy, S. Tario, I. Stewart

The results from a 3-D, 3-Phase numerical simulation model of Lower Lagunillas reservoir in Block IV Lake Maracaibo indicate the possibility of additional recovery from this mature field by drilling infill horizontal wells. The simulation model was the final outcome of an integrated work effort by a team of specialists. The field has produced approximately 920 MMSTB or 43% of OOIP to date and the remaining reserves are estimated to be 270 MMSTB. The reservoir pressure has declined from 4200 psi to 1400 psi, well below the bubble point pressure of 4000 psi. The objectives of an integrated reservoir study were to understand the reservoir heterogeneity and dynamics, evaluate the efficiency of the gas injection started in 1966 and the strength of the active aquifer as pressur support mechanisms.

The new model shows the presence of layers with bypassed oil and higher pressures between layers that show greater pressure depletion and high GOR. This situation demonstrates the need to formulate a new development strategy for efficiently recovering the remaining reserves.

The study indicates that the drilling of horizontal wells or infill deviated wells in some of these layers offers the best solution for maximizing recovery from this reservoir taking full advantage of the reservoir heterogeneity, aquifer support and secondary gas cap to optimize well locations.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela