An Integrated and Systematic Revitalization of a Mature Asset

Abstract

The Vizcacheras License in Mendoza Province, Argentina, is a complex multi-reservoir asset within YPF's mature asset portfolio. Facing a current recovery factor averaging 46+% between the producing reservoirs, YPF embarked on a program to enhance recovery and maximize asset value. Vizcacheras, discovered in 1962, stands with 400 wells in 2 structures with homogenous and heterogenous reservoirs and operated by 4 different organizations. Peak production was 38,000 bopd; currently producing 10,000 bopd with water cut of 97%. Beyond the geologic complexity, was the commercial challenge rejuvenating the field under mounting operating costs. YPF decided to respond by assessing: if the field had stranded value; the magnitude of stranded value; and, method(s) to deliver value. A multi-disciplined YPF and Arthur D. Little team was formed to assess the Vizcacheras license from subsurface through surface employing innovative technical systems analysis to build a risk-based field development plan. The focus of revitalizing a mature field is to define a customized asset evaluation approach to quickly manage large amounts of data and identify key mechanisms for stranded value and value-added solutions, while minimizing costs. The team captured this through innovative systems planning and operation, displacing the traditional lab-to-field R&D search in that multiple options were generated from within functional technology contributions. The result is convergence toward multiple enhanced recovery and operational changes that are anticipated to yield increased recoveries and more efficient management of the asset. Diagnostic analyses of production profiles from individual wells and patterns of wells identified zones of poor reservoir sweep and bypassed oil, guided by large-grid simulation models aimed to reduce risks. Uplift opportunities from pump optimization, infill drilling, injection and adjusted secondary recovery patterns were identified using a risk-based value analysis, with an anticipated increase in recoverable oil of 3%. EOR strategy work is currently underway in which YPF envisions up to three times the recent optimization results. Use of a ground up approach to gather, quality check, and integrate data to build models of the geological framework and to conduct quantitative engineering analysis of the system's performance is showing added recovery benefits from the integrated workflow as it is implemented. Introduction Faced with an expiring lease, and mounting costs for water handling and disposal, YPF needed to assess: if the Vizcacheras license had stranded value; the magnitude of stranded value; and method(s) to deliver value. In 2007 YPF commenced a 2 year study to evaluate and recommend various scenarios to revitalize production from the Vizcacheras license located in the northern part of the Cuyo Basin, Figure 1. Currently the license is producing 10,000 bopd with a water cut of 97%. Two fields, Canada Dura and Vizcacheras lie within the license. Vizcacheras began production in 1965 and is a north plunging anticline on which the Papagayos and Barrancas formations are stratigraphically trapped, Figure 1. Canada Dura is a faulted domal structure producing from the Barrancas sands and has been producing since 2000. The Papagayos is homogeneous sand whereas the Barrancas sands are heterogeneous. The sands range from fine grained to coarse sand to pebble conglomerates. Most wells have artificial lift using Electric Submersible Pumps. The Papagayos reservoir is producing under an active natural water drive and the Barrancas reservoirs have been supported by water injection in their more recent production life cycle. The field was initially developed with a 600 m well spacing. Later, core areas were infilled at 300 m spacing. There are approximately 400 wells within the license area.