Guara Oilfield, Santos Basin, Brazil

The Guara oilfield is located in block BM-S-9 of the Santos basin, about 310km off the coast of Rio de Janeiro, Brazil. The field is situated at a water depth of 7,065ft and is estimated to contain about 1.1 billion to two billion barrels of light oil and natural gas.

Discovered in June 2008, Guara is being developed by a consortium consisting of Petrobras (45%), BG Group (30%) and Repsol-Sinopec (25%). Petrobras is the main operator of the field. The first oil from the south discovery field is expected in 2013 and from the north discovery in 2016.

Stena DrillMAX I rig

The Stena DrillMAX I drilling rig, which was built by Samsung Heavy Industries in South Korea, has been leased for four years to drill the Guara field. It arrived in Brazil in February 2008 and features a dynamic positioning system and can operate at depths of about 10,000ft of water.

The DrillMAX I has a storage capacity of 62,810 barrels of crude oil and 72,231 barrels of fuel oil. Its facilities include a helicopter deck, three 85t electric-hydraulic Knuckleboom cranes and one 40t riser handling gantry. The rig can accommodate a crew size of 180.

Guara FPSO

In January 2010, the Guara field consortium signed an agreement with the Schahin / Modec consortium to lease and operate an FPSO on the Guara oilfield for a period of 20 years. The very large crude carrier (VLCC) Radiant Jewel will be converted into FPSO Cidade de Sao Paulo MV23 for use at the field.

In May 2011, Modec (34%), Mitsubishi (33%) and Mitsui (33%) agreed to invest in the FPSO construction. Schahin is yet to finalise its participation in the investment. Modec will be responsible for the engineering, procurement, construction, mobilisation, operation of the FPSO. The vessel is scheduled to be moored at the field in the fourth quarter of 2012. The spread mooring will be provided by Sofec.

The FPSO will be designed to process 120,000bopd of oil and 180 million cubic feet of gas per day. It will have oil storage capacity of 1.6 million barrels.

The FPSO will be capable of receiving up to ten producers, ten injectors and spare wells. It will have a capacity to inject 150,000 barrels of water per day. The first wells of the field will be vertical to ensure effective reservoir management.

Field development

Initial tests conducted on the Guara oilfield revealed that it contained huge quantity of high quality reserves. Considering the high potential of the oil field, a 120,000boe per day platform is to be installed.

Although Petrobras discovered the field in 2008, the amount of reserves it contains could not be revealed until 2009. In September 2009, production tests indicated the potential reserves contained. Complex technologies were required to explore the field and estimate the reserves.

The DrillMAX I drilled the oilfield up to a depth of 20,134ft. The first discovery well, 1-SPS-55, was situated at a depth of 7,024ft and flowed at 7,200boe per day. The discovery well is neing used in the extended well test (EWT).

Petrobras is planning to carry out further tests to determine the size of the oilfield. In December 2010, it began a five-month EWT at the field. The output during the test was expected to reach 15,000bopd. The data collected during this test was expected to assist in developing the pilot production system.

In March 2011, however, Petrobras halted the EWT due to a rupture in the riser connecting the well to the production platform.

Guara geology

The Guara oilfield is located in the pre-salt Santos basin. The pre-salt region spans 800km along Brazil’s coast and contains huge deposits beneath the layer of salt. These deposits are situated about 3,000m under the ocean surface and another 3,000-5,000m under the seabed. The latest discovery of Guara has confirmed that the pre-salt region contains large quantities of oil.

Exploration and production of the pre-salt region, however, is complicated because of the type and petrophysical features of the reservoir rocks, which include alternating microbialites and volcaniclastics.

Considering the potential of the region, Petrobras has been investing in a range of new technologies to develop the reserves and make them commercially viable.

Contracts for the Guara field

In April 2010, Aker Solutions was awarded the contract to supply 14 trees for the Guara field. The scope of work includes fabrication and engineering the trees, which will be supplied in the next four years.

Keppel FELS won the contract for fabricating the topsides of the FPSO in February 2011. In April 2011, Subsea 7 was awarded the contract for supplying the riser systems.

Petrobras awarded an engineering, procurement, construction and installation contract to Saipem in May 2011 for gas export pipelines and related infrastructure.

Parker Hannifin Corporation was subcontracted by Subsea 7 in June 2011 to supply sheathed tethering lines measuring 6,000ft in length. The lines will moor submerged buoys to the seabed at the field.

In October 2011, Dresser-Rand was awarded a $700m contract by TUPI, a Petrobras operating company, to supply compression equipment for eight FPSO vessels, of which two vessels will be located at Guara field.