Deepwater Completion Challenges in Brazil

The pre-salt is still in its infancy, the only thing that´s guaranteed is that a lot of light oil is down there under a massive viscous salt crust over 2km deep in places. We know its recovery is viable and economically feasible (Oil companies don´t play to lose). How much O&G there actually is down there, may be a whole lot more than people are led to believe. Some people do have a reasonable idea of the magnitude of the deepwater pre-salt, mostly they are or one day were, Petrobras geologists, yet no one really knows the full extension of the Brazilian pre-salt reservoirs. It´s massive anyway, it´ll take 5 more years for the picture to become clearer but the deepwater challenges are here, they are many, and time is not on Brazil´s side.

Pure deepwater challenges for oil and gas E&P in Brazil abound. Recently the multiplex wellhead systems being used at one of the Tupi (Lula) wells failed to pass control tests. The hydraulic commands from the surface didn´t have enough power to open and close key valves when they arrived at over 2,000 meter water depth. This was explained by the fact that the hydraulic commands were losing power along the way. The same equipment installed only a hundred or so meter shallower was working fine.

That may give you an idea of the thin line that separates success from failure in the deep. Well completions in the pre-salt are becoming a problem and according to deepwater completion specialists, the full electric subsea wellheads may be the only solution for safe deepwater production. This is a vital problem as you really want to be able to close that valve.

We are talking about new reservoirs with a lot of pressure, untapped for over 100 hundred million years, over 6,000 meters under in final well depth. Serious pressure spikes will occur and the demand on subsea equipment will be harsh as will the consequences of equipment or human failure. Somehow, these and other important deepwater challenges will have to be sorted out within the next couple of years. 

Petrobras should really be praised for their foresight in indentifying the need to immediately address these deepwater challenges and for building a very solid deepwater technology research base, at this point in time making Brazil the world leader in deepwater O&G recovery research. However, for the perfect deepwater wellhead we´ll depend on the efforts of subsea systems manufacturers such as Cameron, Aker, FMC, VetcoGray and Dril-Quip.

Claudio Paschoa