Marlim Field: The Utilization of Floating Production Units

Abstract

Abstract Petrobras has utilized different types of units in Marlim Field development. From converted Semi-Submersibles to turret-equipped FPSOs, many different options were made. This paper describes the main reasons for choosing the different types of production units, the conversion approach, and the process plant automation and control system - showing the evolution from one unit to another. The paper also presents the actual performance of each production unit, analyzing the operational results-opex-the main causes of production losses and the efficiency levels reached by the wells and also the process plants. Finally, the paper shows a host of new technologies applied in this development and describes the future units that are on their way to Marlim Field. Introduction The use of pilot systems and step by step development is a default procedure at Petrobras. By these means future problems or adjustments in the development plans are foreseen and theirs solutions can be provided for the next step. For the development of the Marlin field, this modular conception was adopted, utilizing subsea completions and floating production systems, and five modules were planned in addition to a pre-pilot and a pilot system. The Marlim field is located at the Northeast of Campos Basin, approximately 105 km from shore with water depths varying from 650 to 1050 meters. The field was discovered in February 1985 by the wildcat 1-RJS-219. Its approximate area is 132 km2. Estimated recoverable reserves are 1.504,3 Mm3 of 19.5° API oil and 18.3 GNm3 of associated gas. The well's water depth varies from 700 to 1050 meters, with flow lines length up to 19 km. Water injection and gas lift is required to improve the field recovery and wax removal operation is a must due to oil characteristics and low water temperature at sea bed. Until December 1998 the Marlim Field has shown an accumulated production of 36.9 Mm3 of oil and 3.1 billion Nm3 of gas. The average daily production in December 1998 was 49827 m3 /d Choice of the Units and conversion approach The experience with floating production systems, associated with the technology developed by PROCAP (Deep Water Capability Program) and PROCAP-2000 (Technological Innovation Program on Deepwater Exploitation Systems) led Petrobras to use floating production systems for the development of Marlim field. The Pre-Pilot and Pilot systems were set offside the field at shallower water depths in order to avoid further interferences with the main development. For this purpose, semi-submersible units were chosen, due to its flexibility. The Petrobras 13, priory a drilling unit operating in Campos Basin, was adapted for a long-term production test and became the pre-pilot unit. Its oil production came on stream on Mars 1991. The oil was exported to a tanker on a monobuoy and the gas was burned. In that time Petrobras had purchased some floating units available in the market. One of these units, specifically the Fortune Ugland, a former flotel, was converted into a floating production system and became the pilot system of the Marlim field. The unit was renamed as Petrobras 20 and its production came on stream on July 1992. The oil production is exported through a monobuoy system to tankers and the gas production send to shore through pipelines.