|Deepest Oil: Part 2|
|Energy & Enterprise|
|Monday, 28 February 2011 16:38|
The¬†technology and logistics of deepsea¬†prospecting
by Norman Gall
Developing deep-water discoveries in the Santos Basin is forcing Petrobras to wrestle with frontier challenges in technology and logistics on a scale without precedent in the oil industry as it leaps into the future.
Scientists and engineers at Cenpes, the research center of Petrobras in Rio de Janeiro, are trying to find a way of placing automated processing plants to separate oil, gas and water on the seabed, some 2,000 meters beneath surface waters. The plants would be powered by undersea electrical generators that also would pump oil and gas through pipelines laid along the bottom of the South Atlantic to gathering stations and terminals hundreds of kilometers away.
"Our target for the next 10 years is not to need production platforms," Carlos Tadeu Fraga, director of Cenpes, told the newspaper Valor Econ√īmico. "In innovation, there is a way of reasoning that changes the capacity of people to realize something new, depending on the question asked. In presenting an idea, there are two ways of reacting. One is to ask: ‚ÄėWhy?' The other is to ask: ‚ÄėWhy not?' Our role is to ask: ‚ÄėWhy not?' Why should it not be possible some day to operate a pre-salt platform remotely, from a base on land where a technician can monitor functions on a screen?"(1)
There are plenty of "why nots" as Petrobras struggles with obstacles to extracting oil and gas 7,000 meters below the surface of the South Atlantic. Beneath the seabed, huge amounts of petroleum are said to lie beneath 3,000 meters of rock that overlay salt beds 2,000 meters thick, trapping fossilized microbes transformed over millions of years by heat and pressure into oil and gas.(2)
Petrobras technicians have spoken of creating unmanned platforms, totally automated. But in the oil industry until now, unmanned platforms have been located mainly in older fields and shallower waters, much closer to shore than in the Santos Basin, as in the Gulf of Mexico, BP's Valhall field in the Norwegian North Sea and Shell's Champion West in runei.¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬† photo Ricardo Azoury
Moving production equipment onto the seabed has become a goal of the global oil industry as it moves into deeper waters. Other companies with deep-water projects include Shell, BP, Chevron, Exxon Mobil, Statoil and ConocoPhillips as well as the independent Anadarko. Salt plays havoc with seismic sound waves, which travel much faster through salt than through surrounding sediments, distorting images the way a pencil seems bent when placed inside a glass of water, "like a blurry, snowy TV picture," said one geophysicist.(3)
Anadarko's innovation in processing of 3D seismic probes by supercomputers led to the discovery of the subsalt Mahogany field by Phillips in 1993 and to a new wave of subsalt exploration in the Gulf of Mexico. Anadarko now is the only independent exploring Brazil's pre-salt formations. "We are at the dawn of the global subsalt play," said Clint Moore, who pioneered Anadarko's seismic processing in the 1990s. "Now that we have a new tool to see under and within the salt basins of the world, it will make a huge difference in the amount of oil and gas that can be discovered in these complex geological basins."(4) Petrobras absorbed these new techniques in its deep-water discoveries.
Petrobras generates only 6% of its daily production from international projects in the Gulf of Mexico, West Africa, South America and offshore Australia, but gains geological and tecnhical knowledge from its ventures in partnership with other companies. In this way, Petrobras thrived in the crosswinds of nationalism and internationalism, incorporating both technology and personnel as needed from abroad and sending hundreds of Brazilians to universities in other countries to create a world-class corps of petroleum technicians.
The industry's biggest conquest so far in installing production equipment on the seabed is Shell's $3 billion Perdido platform in the Gulf of Mexico, mounted atop a moored floating steel cylinder at roughly the same distance from the coast as the Tupi dicoveries. "Perdido opens up a whole new frontier in deep-water oil production," said Tyler Priest, an oil industry historian at the University of Houston. "It is the most technologically advanced facility in the world."
Perdido drills, gathers and separates oil and gas from some 35 wells spread over 80 square kilometers on the sea floor, housing sensitive equipment in a pressurized shed the size of a football field that is planted on the seabed to protect against undersea currents and avalanches.(5) Data from the metabolism of the Perdido complex, as well as from Shell's BC-10 project in Brazil's Campos Basin, is monitored and analyzed at a remote control center in New Orleans.(6) In the deep-water Parque das Conchas field in he Campos Basin, Shell in 2009 installed the first full-field development using subsea oil and gas separation and subsea pumping, even before this technology was incorporated in the Perdido complex that began operations in 2010.(7)
TO PRODUCE¬†OIL from deep waters at up to 350 kilometers from the coast in the Santos Basin, Petrobras must overcome technical and logistical problems more severe than those faced by companies in the Gulf of Mexico, now the source of one-fourth of U.S. oil production, where underwater salt deposits cover 85% of the continental shelf.
The salt beds in the Santos Basin are very thick, in some places reaching 5,000 meters. They are plastic, mobile and heterogeneous, containing different kinds of salt, shifting position as drilling proceeds. "Drilling into the subsalt reservoir presents daunting challenges," Petrobras engineers observed at the Offshore Technology Conference (OTC) in Houston.(8) "Of all these challenges, salt creeping is the most common and difficult to manage."
The salt beds are unstable and can engulf the drill bit and collapse the casing that encloses the drill pipe. "Microcarbonate reservoirs still are poorly known," said one veteran reservoir engineer. "The oil emerges from the reservoir very hot into a cool environment at only 40 centigrade, congealing as wax to clog the pipe unless special chemicals are added and the pipe is continuously lubricated." The instability of salt beds impedes horizontal drilling to increase recovery from reservoirs immediately below the salt.
At the surface of the South Atlantic, there are more engineering and logistical problems. "In the pre-salt discoveries, we have two kinds of logistical problems," Petrobras President Jos√© S√©rgio Gabrielli explained in an interview. "The first is about people, which is a problem of distance. In the Campos Basin, currently our main producing area, we transport more than 60,000 people to the platforms 150 kms. offshore by helicopter. But the pre-salt clusters in the Santos Basin can be 300 kms away, too far for large-scale helicopter transportation."
"So first," Gabrielli continued, "we have to reduce the number of people working on the platforms by intensifying automation. We have to build offshore platforms midway between the coast and the pre-salt discoveries to serve as logistical hubs with sleeping quarters, so that workers arriving aboard boats can be distributed by helicopter to the operating rigs and platforms after overnight stays on the logistical hub. The second logistical problem is the delivery of supplies to offshore operations. You need transportation of chemicals, machines, electricity. We probably will have specialized platforms dedicated to generating electricity and others to mix chemicals for drilling fluids."(9)
One difficulty of creating these hubs is assuring enough stability in rough seas to permit efficient mooring, landing and departure of ships and helicopters. "Everyone thinks it's easy, but it isn't," said Jos√© Formigli, Petrobras's manager of pre-salt operations. "And what's the price? We even were offered the use of aircraft carriers as hubs. But aircraft carriers have the bad habit of swerving from side to side. They have thin hulls that they need for speed, so when they stop forward motion they sway and helicopters can't land on them."(10)
Petrobras faces engineering challenges in scaling up production from the 20,000 BD extended well test begun in 2009 at its Tupi/Lula discovery and from the 100,000 BD pilot from the drillship Cidade de Angra dos Reis that started operating in October 2010, with further development of this cluster calling for another 10 platforms to be installed by 2016. A seabed pipeline would send gas 300 kms. to a treatment plant at Cabi√ļnas in Rio de Janeiro State.(11) These are gigantic undertakings, yet the Lula cluster is only one of several discoveries being evaluated. "We lack barges to lay 50-inch diameter pipe," said one engineer. "Big barges to do this are not available on world markets. The pipeline walls must be very thick and soldered every 15 meters, supported by buoys."
At the OTC Conference in Houston in 2009, Formigli explained why Petrobras must innovate to develop the pre-salt cluster, given the scale of production and the "unique characteristics" of the area: "ultradeep water, remote location, contaminants in producing fluids, high gas-oil ratio, etc." The main contaminants are carbon dioxide and hydrogen sulfide. One major obstacle, Formigli said, is the lack of space on the decks of converted supertankers (FPSOs) used as production hubs, because of the amount of specialized equipment needed to separate and process the natural gas contained in the crude oil, removing contaminants and reinjecting large volumes of gas, carbon dioxide and water back into the reservoir to maintain well pressure. This is one reason why the industry is seeking to place more production equipment on the seabed.
Formigli compared the scale of production in the supergiant Lula field with the giant Marlim field in the nearby Campos Basin further north, which produces 645,000 BD in 2002 but then declined to less than 300,000 BD in 2010.(12) While Marlim was developed with seven platforms or FPSOs producing from 130 wells, Lula would need from 15v to 25 FPSOs fed by 2,000 wells using the development concepts applied in Marlin, "which would result in non-economic projects."(13)
A skeptical report from Credit Suisse, an investment bank, warned of diminishing returns from new discoveries, since the resource base of Petrobras "has grown to a level where marginal discoveries have a very low value, given that existing fields are already enough to guarantee a reserve life of over 50 years."(14)
Yet reserve estimates from very sketchy data for these new Santos Basin discoveries vary widely. They are based on reports by two international consultants released just before Petrobras's US$67 billion stock market capitalization last September in a highly politicized environment. Independent observers point out that the Tupi/Lula discovery, which receives the most attention, still is in the exploration phase.
The pre-salt discoveries have bred myths of their own. These myths hide disturbing questions. Gabrielli has announced at public meetings that Petrobras's US$224 billion investment program for 2010-14 is absorbing annually one-tenth of Brazil's gross fixed capital formation in a nation with one of the lowest rates of public investment in Latin America.
Does Brazil really need to invest in pre-salt development at this speed and scale? Will these accelerated investments create distortions of their ogwn? Are these investments in oil more important to the future of Brazil than more investment in schools, ports, airports, electricity generation and transmission, communications basic sanitation and transport infrastructure? Future articles in this series will address some of these issues