Pictures of the Future Spring 2008
Energy for Everyone – Oil & Gas Systems
Pumping from the Floor
The oil and gas industry plans to build production facilities on the ocean floor. Siemens engineers are helping it to achieve this ambitious goal.
Fully automatic deep water production systems (bottom right) are increasingly replacing expensive surface platforms. Deep sea facilities require particularly resistant compressors (left)
In November 2007 off the icy coast of Norway it took a robot half a day to position a yellow box on a deep sea oil installation, bolt it down, and connect it to a power cable. The box was a SISOG DPM broadband modem developed by Siemens Oil and Gas, and the installation is part of the Snorre UPA subsea oil production facility, which lies 350 meters below the surface of the North Sea.
The modem now transmits data about bore holes—temperature, pressure, oil flow rate, and sand content—to a platform control system located at the Snorre A platform 6 km away. "StatoilHydro uses the data to continually update its oil reservoir model," says Roy Skogsrud, Vice President of Oil and Gas Offshore at Siemens in Oslo. "StatoilHydro can now monitor the quantity of sand that has been pumped and calculate flow directly on screens in the control room. This feature will help to optimizing production and extend the field’s lifetime."
Instrumentation and monitoring systems with these properties weren’t available when Snorre UPA was put into operation in the 1990s, but the pressure in the reservoirs has decreased over time, and it’s becoming difficult to pump oil out from underground. The oil is generally found in tiny pores and tends to adhere to the bedrock. As a result, only 40 % of a well’s production potential is generally recoverable. StatoilHydro plans to increase this figure to 55 % in the North Sea. But this will require precise knowledge of the physical conditions inside the reservoir. "Interrupting production to upgrade existing systems would be too expensive," says Skogsrud. The SISOG SSC monitoring system from Siemens is therefore the ideal solution, as it can be quickly installed at existing facilities and can use their power lines to transfer data at rates as high as three megabits per second.
To exploit deep-water deposits, producers need technologies that can withstand extreme conditions for long periods. "Most of today’s subsea production facilities are located a few kilometers from conventional offshore platforms," says Skogsrud. The trend is, however, to replace expensive platforms with automatic subsea processing facilities. Several components of these systems are now available, including devices that separate water and sand from oil, and then inject the water underground, where it increases reservoir pressure.
Under Pressure. Among the devices still needing further development are underwater compressors—machines that compress natural gas directly at the seabed. Such compressors would increase the amount of gas extracted and could also channel it into underwater pipelines several hundred kilometers long at pressures of up to 100 bar. Siemens has many years of experience as a manufacturer of compressors for the oil and gas industry, so the development of an underwater compressor represents the next logical step for the company. In cooperation with subsea specialists at FMC Technologies, Siemens engineers are preparing their innovative Eco II compressor for use at a depth of up to 1,000 m. Later, applications at depths of up to 3,000 m and water pressures of up to 300 times atmospheric pressure are conceivable.
Siemens developed the Eco II jointly with Shell and the Dutch petroleum company NAM. The unit is capable of compressing natural gas as it comes out of a bore hole. "The Eco II is especially robust," says Tore Halvorsen, Senior Vice President of FMC Technologies. Adds Gerold Hake, Sales Director at Siemens Oil & Gas, "A robust machine needs to have as few components as possible."
ECO-II employs a high-speed induction motor equipped with a variable speed drive. The motor rotor is cooled by the extracted gas, as are its maintenance-free magnetic bearings. "The unprocessed natural gas mixture must not come into contact with the windings of the electric coil that drives the rotor," explains Hake. "That would quickly corrode the copper wires."
The rotor is therefore housed in a gas-tight casing made of a specially developed, fiber-reinforced plastic. The innovative ECO-II design has also eliminated the need for shaft seals, which are essential in conventional gas compression technology and require periodic replacement. The Eco II thus requires little maintenance, resulting in dramatically improved productivity and environmental performance.
A prototype system installed in the Netherlands has already proved itself in field operations that began in the fall of 2006. The machine, which has an output of six megawatts, is expected to operate for five years with no maintenance, which would be ideal for use in an underwater environment. Eco II will be put to the test with wet, impure natural gas at StatoilHydro’s K-Lab in the fall of 2008. The Norwegians plan to install the first underwater compressor units in the Åsgard field to the north of Trondheim by 2013 to maintain production levels there.
A further milestone on the road to underwater oil production facilities will be a deep-water electrical power distribution system, for which frequency converters and transformers will be needed. Frequency converters regulate the degree of compression. "The great challenge is to dissipate the heat," says Skogsrud. Also not an easy task is to transmit several megawatts of electricity over distances above 100 km. "As an electronics specialist, Siemens already has most of the components required," says Skogsrud. "What we need to do now is to get them ready for deep sea operations."
Ute Kehse
Raw Materials from Oil Sand Waste
Luck and exasperation sometimes go hand in hand in the life of an inventor. "The best ideas often come in the darkest moments," says Chad Felch, a chemist at Siemens’ Water Technologies division in Rothschild, Wisconsin. Felch, a specialist in wastewater, experienced such a dark hour four years ago while attempting to come up with a process that would dehydrate a viscous, black, soot sludge waste product that results from a process for creating synthetic gas in the oil sands of Canada. "The soot particulates accounted for only 15 % of the mixture’s weight: the rest was water," says Felch. Due to its heavy metal content, the sludge required disposal in a hazardous waste landfill. To make the process cost effective, the quantity of waste had to be cut drastically. A Siemens team led by Felch unsuccessfully experimented with different methods for months. However, the soot particulates and water simply could not be separated. The researchers finally attempted a completely new approach. "We tried to destroy the soot particulates rather than separating them," Felch recalls. They did this by treating the soot sludge using Zimpro wet-air oxidation—a patented Siemens process for eliminating what are usually difficult-to-treat pollutants—such as sulfides, phenols, and pesticides from wastewater. To do so, the sludge is pressurized, heated, and brought into contact with air or pure oxygen. The process was very successful, as it was able to break down the stubborn soot particulates. In fact, Felch’s team succeeded in oxidizing 90 % of the carbon into carbon dioxide. "The soot contains metals such as vanadium and nickel, which have a catalytic effect," says Felch. So by manipulating the process conditions, the Siemens team was able to use the metals as a reaction catalyst, which in turn made it possible to lower process pressure and temperature, thereby reducing costs. The left over metal-rich sludge can easily be dehydrated, and potential customers for its use have already been identified—so a problematic waste product has been turned into a new raw material. Such processes for preparing oil sands are ever-more important, as specialists estimate that two-thirds of the world’s current oil reserves are contained in this type of deposit. Felch’s ingenious innovation, which won him the Siemens Inventor of the Year award, isn’t his sole achievement, however. Over the last two years alone, he has come up with 28 inventions, two of which have been patented.