February 24, 2019 - Nom Geo
Brazil’s Presalt Oil Revolution
It is hard to think of any area in our society, especially by those of us in the energy and petroleum patch, that hasn’t undergone big changes since 2000. Am I right or am I wrong?
Back in the year 2000 the idea of reaching ultra-deep reservoirs laying below thick salt-layers offshore Brazil was for dreamers. For a start, seabed infrastructure construction at depths of over 1,300 metres was risky and very costly. In addition, the high-pressure, high-temperature drilling conditions for very deep reservoirs were at the limits of drilling competency. Sure, the Russians (Soviets) and some intrepid explorers had previously tested some of the depth limits, and a pre-salt discovery occurred in Angola in 1983 but these efforts were a long way from commercial viability.
Along with the typical challenges of going deep was the task of drilling through 2,000 metres of salt, a reactive type of geological formation that requires salt-saturated drilling fluids and specific well-control measures. Adding to the challenge were hazardous high-sulphur bearing compounds found in reservoir fluids. Although the safe handling of these contaminants was already well established, it was not so clear how this could be managed in ultra-deep environments.
It was not until 2006 that Brazil’s Petrobras made the first commercial discovery of pre-salt oil and first production was from the Jubarte field in 2008, a relatively recent feat that completely busted previous assumptions about the non-viability of these types of reservoirs.
World beating developments in deep and challenging reservoirs in the Caspian Basin and in the Gulf of Mexico have also been instrumental in increasing the technical abilities for conventional extraction of oil and gas.
The major change is that investors, who can see Brazil’s industrial scale pre-salt developments, no longer regard ultra-deep conventional, sour oil reservoirs as being out of bounds. In fact, they increasingly (and optimistically) assume that development of large hydrocarbon resources is technically possible no matter how hostile the subsurface environment.
Another major change was the economics of natural-gas which in many places was an uneconomical by-product of oil production. But infrastructure growth, especially in LNG and changes in energy consumption have transformed natural gas into a globally significant energy source.
And I haven’t even touched on solar, wind, geothermal and biofuels.
Please feel free to let us know via comments on changes from your corner of the energy patch?