Beginning The Pre-Salt Conquest
With the first few weeks as of the May 1 start-up of the Tupi prospect Long Duration Test (LDT) now under its belt, Petrobras can savor some good practical results being chalked up by the first production system in the Santos Basin’s pre-salt layer. Even though it is operating with a controlled outflow, the RJS-646 well, which is connected to the FPSO Cidade de São Vicente, has been able to maintain production of 14,000 barrels/day, a volume that is compatible with the early projections.
Although a fuller assessment requires more time extracting from the reservoir, the first responses that have been collected up to now indicate that the initial estimates regarding the field made by the company’s technicians are being confirmed. Despite water depth of 2,140 meters, the high oil/gas ratio (OGR) of 230 m3/day and the 12% CO2 content in the oil, the behavior of the reservoir has been shown to be homogenous and stable.
Control of the production outflow is in compliance with a decision by the National Petroleum Agency (ANP) to limit the volume of associated gas that can be flared off. The regulatory agency approved the coming on stream of the system operation and the condition that the maximum amount of gas could be flared was 500,000 m3/day.
Located in the central part of the Santos Basin at a cost of US$ 500 million, the Tupi TLD will operate for 15 months at the Sagui Verizon, the carbonatic reservoir with a salt layer 2,000 meters thick. The reservoir is 5,000 meters in length and has 28º API oil. Initially the system will exploit the RJS-646 well, to be disconnected in a second stage and reconnected to a new well, the RJS-660.
According to Petrobras’ schedule, the RJS-646 will remain in operation for about six months. The RJS-660 is expected to operate for the same amount of time. The distance between the two wells is nearly 3.9 km. Once it has concluded the tests in these two locations, the FPSO Cidade de São Vicente will again be connected to the RJS-646. In both cases, the production unit will be located approximately four km from the wells themselves.
The drilling of RJS-660 was begun in March by the West Eminence rig, interrupted before it was finished. The unit will return to the location in June to conclude the work.
Logistics
Located about 290 km off the coastline, the Tupi LDT required the setting up of a special logistical system, never before used in the region. Support of the operation has been through two distinctive locations in Rio de Janeiro: Macaé and Jacarepaguá. All of the offshore logistics are being handled out of Macaé, whereas the air operations are through the Jacarepaguá airport.
The distance to the coastline is, in fact, one of the main challenges of the project. The flying time to Tupi is one hour and 20 minutes, whereas by boat trip lasts no less than 17 hours. Both Macaé as well as Jacarepaguá are being used as provisional bases for the development of Tupi. The definitive logistical configuration for the pre-salt layer is being studied, to be eventually decided upon between Rio and São Paulo
In order to put the LDT into operation on May 1, Petrobras went on virtual wartime footing for the location. For the first time, a number of field activities were carried out nearly simultaneously, which caused some maritime traffic jams in the region.
During the month of April, a peak time for activities in the field, vessels were fighting for space at the location. These included support, anchoring and pipe laying vessels finalizing their work campaigns and dividing space with the FPSO Cidade de São Vicente.
At the peak of the work, some 350 persons were laboring on the location. The FPSO Cidade de São Vicente alone had 120 persons aboard, requiring Petrobras to request special authorization from the Brazilian Navy because the vessel has approved capacity for only 99 persons. Besides those on the vessels, another 100 persons worked on it from shore-based facilities.
Less than two years passed between the confirmation of the oil strike, made official in 2007, and the first production of oil. The Tupi wildcat well, the RJS-628, was drilled in 2006, and the confirmation of the results only came about the following year, in 2007, through the 2007 by the RJS-646, drilled by the Paul Wolf semi-submersible rig belonging to Noble Drilling.
The letter of the intent for the conversion of the FPSO was signed with BW Offshore in mid-April 2008. The unit arrived on location in March — that is, less than one year after the contract was signed.
Unit
Converted in Singapore, the FPSO Cidade de São Vicente has the capacity to produce 30,000 barrels/day of oil and 1 million m3/day of gas, and can store up to 500,000 barrels of oil. The work on the project was based on an already existing plant, and in order to speed up the procedures to authorize the platform, the Navy inspected the unit in South Africa, making it possible for the FPSO to move out directly from the dockyard to its final location.
“We broke the mold with the installation of the Tupi long duration test. Our technicians and partners responded extremely well to the challenge of the deadline that was established, even though it was a system that was located nearly 300 km off the coastline,” said José Luiz Marcusso, general manager of the Santos Basin Business Unit (UN-BS).
Besides BW Offshore, among the main partners at Tupi are Acergy, responsible for launching the flexible lines; Wellstream, the company that produced the lines and risers in Rio de Janeiro; MFX, responsible for the electrical-hydraulic umbilical; and Cameron, supplier of the Wet Christmas Tree (WCT).
Read Also: 'Tests In 18 Santos Areas' and 'Pipeline Laying Record'
