Abstract
The Lagomar production Unit covers Blocks I, II and XII of Maraven's concession in the Lake Maracaibo basin, Western Venezuela. The Unit consists of 114 reservoirs mostly of Eocene age, it has 740 wells drilled to date and has been on production for more than 40 years. The combined total OOIP of these reservoirs stands in excess of 8,487 MMSTB and at the end of 1996, 663 MMSTB remain as proven and 44 MMSTB as probable reserves. These substantial volumes of remaining reserves make the Lagomar Unit as one of the most attractive producing areas within Maraven's operating plan.
Until 1992, the Lagomar Unit had been on a steady decline mostly because of primary depletion and with limited efforts of secondary recovery. Detailed characterization of the reservoirs was lacking up to this time and the reservoir mechanism and the fluid movements, specially in terms of secondary recovery were not well understood. A revitalization program for increasing production and ultimate recoveries was undertaken at this time in the form of a multidisciplinary team effort. The team was charged with increasing the production and reserves over the following five years. The strategies included, a) recompletion of old wells, b) drilling of new wells including the re-entry and horizontal wells, c) commingled production of multiple horizons, d) slimhole, geologically targeted infill and appraisal drilling, e) reactivation of Basal La Rosa reservoir.
Implementing the revitalization strategies increased the drilling activity to 82 wells and 109 recompletions during 1992-1996. Directional drilling technology was successfully applied in the development well VLA-1035 and in the reentry sections of the wells, VLA-780 and VLA-807 in the VLA-6, C-7 reservoir. The productivity of Basal La Rosa increased from 3,000 to 19,000 STB/D. Commingling the production of C-2 and BLR reservoirs increased the production fourfold. The application of geologically targeted infill drilling (19 wells) and slimhole drilling (18 wells) increased the production output by another 20,000 STB/D.
The implementation of these technological alternatives favorably impacted the Lagomar production rate with an increase from 59,000 STB/D in 1992 to 81,000 STB/D in mid-1996. This paper describes the various strategies of revitalizing the Lagomar Segregation Unit and how these were implemented in a multidiscilplinary manner for achieving optimum results.
