Roncador Field Early Production System - A 2000m Water Depth Challenge
Authors: Henriques Carlos C. 
Published: October 2008

Roncador is a giant field located in the northernmost part of Campos Basin, offshore Brazil, in water depths ranging from 1,500 to 2,000m. The field was discovered in October 1996 and is composed by light and heavy oil reservoirs. Due to the reservoir complexity, Petrobras decided, at the beginning of 1998, to implement an early production system in this field. The main objectives were to acquire more data from the field and to test new technologies.

An FPSO (Floating, Production, Storage and Offloading) unit, a rigid production riser and a wet Christmas tree compose the Roncador EPS. The Seillean FPSO that was operating in 140m waters in the North Sea was upgraded to work in water depths up to 2,000m. Seillean is a unique production unit, that it is equipped with a Dynamic Positioning System and is able to install the production riser and the Christmas tree by itself.

The FPSO entered operation by the end of 1998, and the first oil was achieved less than one month later braking two records: the world's deepest subsea well completion and the stationary unit producing in the greatest water depth in the world (1853m). It was the first time when the ANM-2000, a wet Christmas tree designed to operate in up to 2,000m, was used. It was also the pioneer utilization of the DPR-2000, a Drill Pipe Riser designed for completion and production in 2,000m waters.

This paper describes the upgrade of the FPSO Seillean, giving an overview of the whole production system. The challenge to develop a fast-track project that incorporates so many new technologies is highlighted here.

Introduction

Roncador Field was discovered by the wildcat 1-RJS-436 in October 1996, that showed the presence of Cretaceous sandstone saturated with good quality oil (31° API). The field is located in the northernmost part of the Campos Basin (see Figure 1), 20 km north of Albacora field, at 130 km from shore, in water depth ranging from 1,500 to 2,000m, covering an area of 132 km2.

In October 1997 it was drilled the second exploratory well in the field, the 1-RJS-513, located in the Southwest part of the field, in 1559m waters. The oil characteristics in this well were different (18° API) from the characteristics found in RJS-436. This well also indicated the presence of a gas cap in the reservoir, what was not expected.

A third well was drilled in February 1998, and a forth one in the next month. The last one, located in the northern part of the field, detected an oil-water contact in a different elevation from the contact verified in the RJS-436. The information gathered from the exploratory wells confirmed the geological complexity of Roncador field.

This geological complexity was an important factor in the decision to implement Roncador EPS, that is composed by main three parts: the FPSO, the x-mas tree and the production riser, as can be seen in Figure 2. This paper is complemented by another one that will be presented by Petrobras at OTC'99, which focus on the development and installation of the x-mas tree and production riser for Roncador EPS (ref. 3).

Seillean FPSV

Seillean was originally built as an FPSV (Floating, Production and Storage Vessel) in 1990. The ship was owned and operated by BP up to 1996 when it was bought by Reading&Bates Corporation (now R&B/Falcon). The ship worked in the North Sea in shallow waters (less than 200m) up to 1997 in a concept called SWOPS (Single Well Oil Production System). In this system the ship stays over the production well using its Dynamic Positioning capability and deploys the production riser that is mated to the wellhead. The ship is provided with a derrick (see Fig. 3) to handle the riser joints and a heav