Abstract In the current and future scenario of an increasing demand for hydrocarbons, many companies have oriented their efforts to maximize the recovery in mature fields. This paper presents the implementation and results of an integrated reservoir management strategy that allowed revitalizing a field, which was previously considered as a marginal and currently is one of the main assets of the company.
Yarigui-Cantagallo Field, Colombia, is a compartmentalized, varying-dip monocline, with three main tertiary reservoirs. The field was discovered in the 1940's and reached its production peak of 20,400 STB/day in 1962 after two aggressive drilling programs. A third drilling campaign in the 1980's had poor results and no additional wells were drilled. At 1999 production declined to 5,000 STB/day. In order to mitigate production decline, and maximize final recovery, integrated reservoir characterization including structural, stratigraphic, and petrophysical reinterpretation, geostatistic modeling, advanced production analysis, PVT and pressure reinterpretation, and reservoir simulation have been conducted.
An effective reservoir management has been implemented, including infill drilling, optimized well completion, hydraulic fracturing and production optimization. As a result, production levels had increased up to 13,000 STB/day and 40 MMSTB of reserves have been incorporated. Future implementation of a waterflooding project and additional infill program will incorporate 35 MMSTB of reserves.
Introduction Yarigui-Cantagallo field is located in the Middle Magdalena River Basin in Colombia, 290 Km NW from Bogota and 20 Km NE from Barrancabermeja, below the Magdalena River. (Figure 1).
Figure 1. Yarigui-Cantagallo field location map.
The structure is a faulted monocline, with dips varying from 50° to 9°, and an extension of 7 Km by 2 Km. Structural features have been identified based on pressure, fluid contacts and production performance, since the seismic information is sparse. There are five compartments or blocks, I to V, where block V accounts for 80% of OOIP (Figure 2). Oil production is from tertiary, fluvial, stacked channel sands, divided in three reservoirs: B sands, C sands and Cantagallo sands. The sands are poor selected, friable, and interbedded with shales (Figure 3). Oil is 20° API, asphaltenic, and viscous (20 cp @ reservoir temperature, 140°F). The main reservoir is Cantagallo sands, with 600–1000 ft of oil column. Drive mechanism in blocks I to III is gas expansion; block IV has a strong water drive; block V has a combination of gravity drainage, partial water drive, and expansion of a secondary gas cap.