Roncador Field Development with Subsea Completions

Abstract

Abstract The development of the offshore industry introduced subsea completions as a means to produce hydrocarbons under the water in an economic way. Since the first subsea completion in the beginning of the 60's, an increasing number of installations occurred around the world during the incoming decades and particularly offshore Brazil after 1979, when the first installation was made at 189 meters of water. Different needs led Petrobras to use subsea completions in increasing water depths what called for different projects which surpassed important milestones, like the installation in water depths deeper than the diving limit and over 1,000 meters. Nowadays the deepest installations of subsea trees in the world are being performed in Roncador field where up to date 5 subsea trees, including the well 7 RO 8 RJS at 1,877 meters, were made in the range of 1,850 meters of water. The technical solutions developed in house for subsea completions in ultra deep water showed to be reliable and became a standard operation. Moreover, improvements in the overall time spent for these completions were also made. As other subsea trees will be installed in Roncador field, the analysis of the efficiency of the installations performed so far will improve future results. This paper will show the evolution of the subsea completions offshore Brazil in order to explain the solutions used in ultra deep waters field and then show a comparison of the time spent in different subsea completions in Roncador field. It will also anticipate proposed solutions for even deeper waters. As ultra deep water exploration is surpassing the 2,000 meters barrier, reliable and efficient subsea completions hardware and techniques are a must in order to economically develop future discoveries. A Brief History of Subsea Completions Subsea completions were introduced in the beginning of the 60's in the Gulf of Mexico as a means to produce hydrocarbons under the water in locations far from the existing platforms and as a test for production in deeper waters, since at that time offshore production was only achieved with the use of fixed platforms. Soon later subsea completions were also introduced offshore California to produce gas directly to shore. During the 60's all subsea trees installations were done in the USA, and the Through Flowline Concept (TFL) was widely used as it allowed tools like a pressure gauge, to be pumped downhole and recovered after the job was accomplished. Other features of these subsea trees were the diverassisted flowlines pull in and direct hydraulic operated subsea valves. By the end of the 60's, the number of installed subsea trees was 68, at a maximum water depth (WD) of 130 meters, all of them in the USA. With the discovery of hydrocarbons in the North Sea, subsea trees were also used as a means to accelerate production, to acquire more reservoirs information as well as to get an earlier cash flow.