Abstract

The design development plan for the Barracuda and Caratinga fields was initially conceived to operate a Production Pilot System with eleven production vertical wells tied back to a host FPSO platform. This Pilot System, in addition to an oil production anticipation, granted important information regarding reservoir parameters, fluid properties and flow assurance, providing a good support to obtain a better design of the Definitive Production System. Considering the opportunity to implement technical modifications to the Definitive System after the design phase is concluded, the production engineering team will continue the flow sensitivity analysis aiming to increase the oil production curve. This paper presents cases of attempts to improve the subsea well design of the Definitive System, with the objective of obtaining increased oil production taking economic aspects into account to support the decision of such technical modifications. When a technical modification is proposed to increase the oil well production curve, it is important to consider in the study the effect of the whole field production curve, in order to conclude the analysis. In this paper, it is also discussed the design criteria adopted to the well artificial lift method and the actions proposed to improve flow assurance in order to minimize production losses. This paper reinforces the importance of considering the analysis of the whole field production curve before an alternative of technical modification is implemented.

Introduction

The Barracuda and Caratinga fields are located in the central position in Campos Basin offshore Brazil, approximately, 160 km east of Macaé in Rio de Janeiro (Figure 1). Water depths in these fields range from 600 m to 1100 m in Barracuda and from 850 m to 1350 m in Caratinga. Considering the relatively physical proximity of these fields, the Design Development Plan scheduled for these areas comprised two distinct stages: The Pilot System and the Definitive System. The Pilot System produced its first oil in September 1997 and the operation extended along five years through eleven production vertical wells (eight from Barracuda and three from Caratinga) tied back to a host FPSO P-34 (Floating Production Storage and Offloading) anchored at 835 m water depth. The P-34 topsides processing plant was designed to handle liquid and gas volume capacities by 45,000 bpd and 950,000 std m3/d respectively (Figure 2). In addition to oil production anticipation, the Pilot System provided important information regarding the characteristics of the field's reservoirs, the fluid properties and also data regarding multiphase flow and flow assurance. The Definitive Production System comprised two FPSOs (P-43 and P-48) converted from two twins VLCCs (Very Large Crude Carriers). The topsides processing plant capacities for each FPSO are 150,000 bpd for the liquid, 6,000,000 std m3/d for the gas and 40,000 m3/d for water injection. After processing and storage in the FPSO tank, the oil is pumped to a shuttle tanker. The produced gas is processed, treated in a glycol dehydration plant, compressed and utilized as power generation, gas lift injection, internal consumption and the remaining volume exported onshore via platform PNA-1 (Namorado field, Campos Basin).

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