An Overview of the GA-SP Project: Field Applications and Economics

Abstract

Abstract "GA-SP" was a joint industry project supported by the European Community and eight major oil companies. The project was in three phases which culminated in testing a prototype system in a drydock. The system enables manifolding of products, separating gas from produced liquids and transporting them along separate lines. The produced liquids are pumped using a single phase pumping system. The system is highly modularized for ease of installation and retrieval of key components. GA-SP is suitable for deepwater application and development of marginal fields which are a long distance away from the mother platform. The economics of developing marginal fields using GA-SP system looks very attractive, making the system viable both technically and economically. In this paper, work carried out under GA-SP project is reviewed. 1. lNTRODUCTION Goodfellow Associates Subsea production (GA-SP) project was a joint industry project supported by the European community (EC) and eight major oil companies, namely; Agip (UK), Chevron (UK), Conoco (UK), Elf(UK), Norsk Hydro, Phillips Petroleum (UK), Statoil and Texaco (UK). The project was developed under three phases as follows:Phase I. Nov 1986-Nov 1987. Conceptual development of the subsea production/process system.Phase II. Nov 1987-Feb 1989. Detailed Design of Prototype system and material Procurement.Phase III. Jan 1989-May 1990. Installation and Testing of the prototype system in a dry dock. 2. OBJECTIVES The main purpose of the project was to develop a subsea production system with the following objectives:To develop a subsea production/processing system suitable for development of marginal fields.To identify the key components of the system, their requirements and the state of the art for their application.To address all major operational aspects in order to establish the viability, applications and limitations of the system.To prepare a cost estimate for the development of a field, using the GA-SP system, and to establish the economic viability of the system.To demonstrate the operation and control of a prototype system in order to confirm system viability and to identify any particular areas which would require further development or modifications for future field applications. WHY SUBSEA PRODUCTION AND PROCESSING? Development of marginal fields using conventional bottom supported jackets and floating production systems is, in majority of cases, uneconomical because of their high capital cost. The economics become further affected by the development of fields which are located in deep waters and have one or more of the following characteristics:Reservoir conditions demanding several satellite wells for recovery of the field reserves.Low production rates associated with low Productivity Index (PI)Limited total recoverable reserves, typical range being between 10 to 100 million barrels of oil.Low production pressure and rapid pressure decline, requiring water injection and gas lift as an additional aid to enhance recovery.High water cut, reaching 70 to 80% of the production near the end of the field life. These conditions can further be aggravated by uncertainties in reservoir behavior, presence of H2S and C02, waxy crude oil and production of sand.