Field Development Planning and Floating Platform Concept Selection for Global Deepwater Developments

Abstract

Abstract Successful deepwater field development planning requires close collaboration between the subsurface, drilling and completions, surface facility, operation and business teams that jointly constitute the development planning team. The reservoir is the main driver of the development plan. Despite significant technological advances in reservoir characterization, there remains a high degree of uncertainty in predicting well performance and recovery. This is attributable largely to the very high cost of deepwater drilling exploration and appraisal of deep reservoirs which limits the data set of key parameters required to construct the reservoir and geologic models. The development planning team must quantify and manage this uncertainty to mitigate the potential for an over or under designed surface facility. In this paper, important factors that drive the selection of a deepwater field development and floating platform are identified. Linkages between key reservoir and fluid characteristics and surface facility parameters are established. Strategies to manage reservoir and well performance uncertainty, particularly in deeper, subsalt reservoirs with few production analogs, are discussed. The focus of this paper is on mature deepwater basins in the GoM, West Africa and Brazil. These are principally oil fields with associated gas and account for over 90% of total deepwater production. Regional drivers play an important role in field development planning and platform selection. A high level overview of deepwater platform selection in the GoM is presented. Deepwater Field Development Selection Drivers The process of selecting a field development plan following a discovery involves a complex iterative interaction of its key elements (subsurface, drilling and completions, surface facilities) subject to regional and site constraints (Figure 1). The objective is to select a development plan that satisfies an operators' commercial, risk and strategic requirements. The selection occurs while uncertainty in critical variables that determine commercial success (well performance, recoverable reserves) is high. The challenge is to select a development plan that manages downside reservoir risk (considering the very large capital expense involved) while having the flexibility to capture its upside potential. Selecting a floating production platform is a subset of the overall field development plan. A brief description of the more significant field development selection drivers follows. Reservoir Geology and Geometry Reservoir geology, geometry, fluid properties and flow rates of trapped hydrocarbons have the greatest impact on the field development plan. Table 1 summarizes relative impacts of key reservoir characteristics on primary field development parameters. Geologists and reservoir engineers create geological and reservoir models from seismic and well log data obtained from exploration and appraisal activities. Permeability and porosity of the reservoir rock are the principal determinants of well performance, (well rates and recovery) and well count. Generally, higher rock permeability and porosity yields better well performance, and fewer development wells.