Abstract
Feasibility studies for development of offshore fields must satisfy both technical capability and economic success. To accomplish these objectives, feasibility studies are subdivided into a number of specific tasks to provide a systematic, sequential approach to developing an optimum design. The primary tasks to be performed are selection of a project team, selection of criteria, performed are selection of a project team, selection of criteria, description and evaluation of alternative concepts, preliminary design of the selected conceptual costing and economic evaluations. The method of approach to such studies, the requirements for each task and its objective are discussed.
Introduction
The objective of a feasibility study for development of any field, onshore or offshore, is to select an optimum production system for the operator. Feasible by definition is that which is capable of being done, carried out, used or dealt with successfully. To be feasible, the plan must be suitable, reasonable and practical within the limits of ability or capacity. Thus, any practical within the limits of ability or capacity. Thus, any feasibility study must satisfy both technical capability and economic success. Onshore development does not generally require indepth feasibility assessment, because the fields are usually more easily accessible and options are numerous. Exceptions would be locations in harsh environment areas such as arctic or very remote areas with nonexistent infrastructure. However, both technical and economic feasibility must be carefully determined for offshore development, because the locations are not easily accessible and development costs are exceptionally high in comparison to onshore development.
To accomplish its objectives, such a study is divided into a number of specific tasks. Initially, the criteria and field development concepts are established. The various concepts are then studied both qualitatively and quantitatively to assess technical feasibility and arrive at cost and schedule estimates. The various concepts can then be ranked for selection of a preferred case which is studied in more depth. The preferred preferred case which is studied in more depth. The preferred case design focuses on preliminary design and inplace analysis of operational requirements. Installation, hookup and commissioning are included in this phase of the study. Definitive costs and schedules can then be developed for budget purposes and, more importantly, for economic projections and a final decision.
This paper will describe the method of approach to feasibility studies for offshore field development, discuss the requirements for each task and its objectives.
METHOD OF APPROACH
Feasibility studies can be subdivided into a number of discrete tasks to provide a systematic, sequential approach to development of an optimum system. The level of effort in these studies is less than a detailed design, capable of being implemented in a shop or fabrication yard, but should provide a technically superior system defined to a level where an accurate cost estimate can be produced and a detailed design can proceed. Evaluation of the various concept alternatives should be flexible and when any concept is clearly not technically feasible or cost-effective, further effort on that concept should be discontinued. If no concept is feasible, the study should identify those aspects which require either modification to existing or development of new technology.
MAJOR TASK DESCRIPTIONS
The general tasks to be performed in a feasibility study are given in Table 1. Each task is usually, subdivided into further tasks for a study plan similar to the one shown in Figure 1.
Project Team Project Team Feasibility studies require input from a wide range of professional disciplines and experience. The project team professional disciplines and experience. The project team should preferably be headed by a project manager with a broad experience in developing and operating offshore fields. Figure 2 shows a typical project team organization. Engineering skills include structural, geotechnical, marine, facilities and petroleum. Input from individuals having construction, petroleum. Input from individuals having construction, installation and operating experience is essential.