RIO DE JANEIRO – Petrobras says it deployed its first wet christmas tree at the end of last year using cables in the presalt area of the Santos basin.
The main innovation was the use of a subsea equipment support vessel (SESV) to install the equipment on the Sapinhoá field, instead of a costlier drilling vessel. This resulted in a time saving of around 10 days, leading to a gain of more than $5 million.
The 7-SPH-2D-SP well is in a water depth of 2,130 m (6,988 ft).
Petrobras says the operation, which involved lowering the christmas tree into position and installing it on the wellhead using a suspended cable, was carried out from an SESV using a subsea equipment guidance system.
A drilling vessel, the company added, usually takes around 10 hours to lower a riser 1,000 m (3,280 ft) into the sea, so the time taken to lower a christmas tree onto a well in 2,300 m (7,546 ft) of water is typically 40 hours.
SESVs, it claims, can perform the same maneuver in less than four hours, due to the cable launch and return speed.
Petrobras already had used this technology at depths of up to 2,000 m (6,562 ft). Following engineering studies, adaptations to the SESV Skandi Santos allowed the vessel to install equipment deeper, in water depths of up to 2,300 m (7,544 ft).
The company has now chartered a second SESV, which is being adapted to deploy equipment down to 2,500 m (8,202 ft), and this should start operations during the second half of 2016.