Albacora Leste Field - Subsea Production- System Development

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 18044, "Albacora Leste Field - Subsea Production System Development," by C.E.C.V. Longo, S.J.A. Neto, and M.T.R. de Paula, Petrobras; F.M. Lopes Jr., Technip; and C.A.F. Godinho, SPE, Prysmian, prepared for the 2006 Offshore Technology Conference, Houston, 1–4 May. The Albacora Leste field-development plan comprises 30 horizontal wells tied back to a floating production, storage, and offloading (FPSO) platform moored by use of an innovative spread mooring system (SMS). All risers are flexible and installed in a free-hanging configuration. Environmental conditions and FPSO motion were factors in flexible-riser design. All flexible lines were anchored by means of torpedo piles. The full-length paper describes field development, including planning, design, qualification, manufacturing, and installation activities. Introduction The Albacora Leste field is in the deep north area of the Campos basin approximately 120 km off the coast of Brazil. Water depths in this field range from 800 to 2000 m, and oil densities range from 17 to 21°API. The field development comprises 30 horizontal wells (16 production wells and 14 injection wells, three of which are in a piggyback configuration) tied back to a host FPSO, P-50 by flexible risers and flowlines. Bending-stiffener and top riser accessories development and qualification represented an important and challenging success factor for the project. Three test benches were designed and assembled to perform the long-term fatigue tests for the gas-export flexible riser and to validate the new concept of the stiffener hanging systems. The FPSO will be moored in 1230 m of water by use of an innovative differential-compliance anchoring system. The oil, after treatment and storage on the FPSO, is pumped to a shuttle tanker. The produced gas then is cleaned and compressed, and a fraction of the total volume is used for power generation, gas lift, and internal consumption; the remaining volume is exported to shore by way of Platform PGP-1 in the Garoupa field, Campos basin. During the design phase, continuous gas lift and electrical-submersible-pump (ESP) artificial-lift methods were selected as potential candidates for the wells. However, at the time of the design phase, an ESP that could handle the high oil flow rates expected was not available, so the decision was made to use continuous gas lift as the artificial-lift method for the production wells. The approved gas lift design strategy eliminated pressure-operated valves and adopted a very simple and reliable well completion that included a single gas lift orifice valve. A high-discharge-pressure gas compressor was installed topside to guarantee continuous gas injection through the orifice valve at normal well-operation conditions and kickoff.