Portal de Periódicos da CAPES

Presalt Propels Brazil into Oil's Front Ranks

2010; Society of Petroleum Engineers; Volume: 62; Issue: 04 Linguagem: Inglês

10.2118/0410-0040-jpt

1944-978X

Joel Parshall,

Marine and Offshore Engineering Studies

In an industry whose scale and character have arisen so much from great discoveries of vast fields, the recent oil discoveries in the deepwater presalt layers off Brazil could rank as some of the biggest, most important globally in several decades. At the center of the expansive presalt play is Petrobras, the Brazilian national oil company, which operates most of the concession acreage that has been awarded and has drilled most of the discoveries. With the discoveries made in the presalt, Petrobras President Sergio Gabrielli has said Brazil will rise to eighth place in oil and gas reserves among the world’s producing countries. Based on current rankings, this would place it above Nigeria and below Venezuela. To optimize the development of the presalt, a host of major challenges—geological, engineering, commercial, and financial among them—will need to be met. Until the discoveries of 2007–09, there had been little drilling in Brazil’s presalt structures for many years. A number of shallow-water presalt discoveries had been drilled and developed in the Campos Basin during the 1970s and 80s. However, giant discoveries in post-salt reservoirs at that time shifted most attention toward those strata. Major questions remained about the suitability of presalt targets and the risks of drilling through salt layers as thick as 6,600 ft. The difficulties of seismic imaging beneath salt also were a considerable barrier, not to mention the challenges of deepwater drilling and development pertaining to some potential future targets. Over the following 10 to 15 years, however, the industry’s deepwater capabilities progressed, along with the realization that the largest remaining prospects lay in deeper and deeper waters. In bidding rounds during 2000–01, Petrobras acquired a cluster of deepwater and ultradeepwater presalt leases in the Santos Basin—acreage that in total was larger than the entire Campos Basin to the north. The company then launched one of the largest seismic programs in industry history to image and interpret the geology of the lease acreage.