Redevelopment of mature oil fields is becoming increasingly important, both in Ecuador and worldwide. This paper describes the results of the integration of disciplines in the Palo Azul mature field where leading edge techniques were applied to develop high-definition static and dynamic models, change previous interpretations, and improve the understanding and characterization of the Hollin reservoir to estimate the remaining reserves.
An advanced 3D method was developed that integrates the well log signature, petrophysical analysis, seismic calibration with well logs, horizon correlation, and structural mapping using seismic attributes. Based on this approach, an area of high potential in the northern side of the structure was defined. The Hollin formation was subdivided into three depositional environments: fluvial, tidal-dominated, and marine. For each environment, three primary static parameters were modeled in detail. These parameters include net sand distribution, geometry of the sandstone bodies, and reservoir connectivity.
The static model was critical in providing more meaningful structural information, opening up adjoining areas, and identifying new pay horizons and bypassed reserves. A simulation model was developed to demonstrate the potential of the Hollin formation in Ecuador. Within this formation, defining the location of vertical transmissibility barriers and seal zones was a critical factor in the achievement of good history matching. Based on integrated work between the geology and reservoir engineering teams, several wells were reviewed and updated in the geostatistical model to reproduce, as closely as possible, the historical field behavior. This approach provided a better understanding of reservoir distribution. It enabled the optimization of new drilling locations in the northern area and infill drilling plans for the southern Palo Azul field, reduced the cost of new wells, improved the recovery factor, and enhanced reservoir management.