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MDA Technologies 5/2016

MDA Technologies 5/2016

Innovative drive systems

Innovative drive systems for underwater oil pumping operations Stefan Obst Tailored for complex application requirements like the ones in underwater pumping of oil, the high-tech and customizable drive system from Siemens offers one of the most efficient drive designs, featuring interchangeable modules. The oil and gas industry is continuously on the search for ever increasingly efficient processes. Tar sands, fracking, deep-sea drilling – the demand for reliable solutions grows as the demand for energy increases. In 2015, the Norwegian company, Aker Solutions embarked on an underwater pumping pilot project, with Siemens as its technology partner to provide a reliable drive system well suited for oil and gas industry’s complex application requirement. Six MW installed 1 000 meters below the water surface to pull through one of the most important raw materials in the world. To pump oil from the ocean floor, powerful pumps operated from large oil rigs are required. These floating high-tech islands are indispensable when it comes to pumping oil from the seabed. The Johann Sverdrup oilfield is the largest in the North Sea. Exploitation of this oil field is to start in 2019 – and Aker Solutions is incharge to equip Author: Stefan Obst, Process Industries and Drives, Siemens AG the rigs. This Norwegian company developed the ‘MultiBooster’ underwater pump, which is also suitable for use in deep-sea drilling operations. “With this project, our customers will be able to achieve a higher degree of efficiency and reduce their costs”, explained Jarle Skjetne, Project Manager for the new Aker Solutions test station. “One of the new pumps can replace two existing ones, and further, reduce the pressure in the borehole”, continued Skjetne. A new milestone for underwater drive systems The pump is driven from a liquid-cooled motor, which must provide 6 MW at a speed of 6 000 rpm – representing a new milestone for underwater drive systems. The pressure-power combination – which has not been possible up until now – means that these pumps can be used in deep-sea environments. Aker Solutions is developing the motor and pump prototype for its customers – large international oil corporations. “This pump not only allows customers to pump a mixture of oil and gas to a rig, but also to land. What’s more, it can also be used to inject water in order to increase the pressure in the bore hole and increase the rate at which oil is pumped”, explains Skjetne. The motor and pump prototype was tested in Aker’s new test station in Tranby, Norway. Here, solutions are put through their paces to address some of the most complex challenges in the oil and gas domain. The new Sinamics SM120 CM converter from Siemens is an important component of the station. “In order to carry out tests with a motor as load, a motor that can handle this load is required. The most effective way of testing the system is to have a test stand equipped with two converters”, explained Skjetne. “We are using the Perfect Harmony GH180 converter from Siemens as drive for our submersible motor – and the new Sinamics SM120 CM, to simulate the pump load.” The power generated by the Sinamics MACHINE ELEMENTS MDA Technologies 5/2016

01 Aker Solutions Engineering Project Manager Jarle Skjetne and the Siemens commissioning team SM120 CM converter can be injected back into the supply line. The energy recovery capability of the Sinamics SM120 CM means that Aker can operate the test stand with low associated losses. Tackling the most difficult challenges in the sector With its new Sinamics SM120 CM converter, Siemens has simultaneously addressed several challenges for one of the most innovative suppliers to the oil and gas industry. The converter has enjoyed considerable interest in the oil and gas industry as a result of its low weight when compared to other models and its compact dimensions. The transformer and control unit of the Sinamics SM120 CM are not integrated in the converter itself, which allows them to be separately mounted. This boosts the degree of flexibility for applications where space and weight represent critical factors. The transformer can be located outside engine rooms that tend to be narrow. Besides saving space, this has another advantage – expensive measures to cool the room are not required as the transformer is placed outside. The Sinamics SM120 CM has a modular design, employing multilevel converter technology (M2C) where several low-voltage cells are connected in series. The customer decides how many of these cells are connected in series. The concept is scalable and can be adapted to the power required. The modular design also facilitates a redundant configuration. If one of the cells develops a fault, then it is automatically bypassed and can be replaced the next time maintenance is carried out. This means that a sudden defective cell does not negatively impact converter functionality. Further, Sinamics S120 CM is equipped with modular multilevel technology. The voltages are superimposed on one another so that the output voltage waveform is similar to a sinusoidal waveform. This results in low-line harmonics and reduces the load and stress on the motors and cables. 03 Sinamics SM120 Cabinet Modules frequency converter 02 Sinamics SM120 CM showing the cell frame for uninterrupted operation Three weeks of testing in Tranby, Norway The commissioning of the Tranby Technology Manufacturing Center was scheduled for summer 2015 – and checking out the various systems was completed on time before the actual test was to commence. Jarle Skjetne, the project test manager at Aker Solutions, explained that preparations for the test represented a real challenge. It had to be ensured that everything functioned satisfactorily before the actual test could commence. “Commissioning was successful. We carried out an extensive test program for the motor: Vibration levels, torques, motor power and temperatures were measured to ensure that none of the limit values were violated”, explained Skjetne. The test lasted three weeks. Several customers, who were also involved in the development project itself, participated in the test. Based on this test, Aker was able to demonstrate to customers that the company can supply the solutions that it had committed to. “The positive feedback clearly indicated that with Sinamics SM120 CM, we are on the right track. The next development steps will mean that this drive will perfectly supplement our medium voltage portfolio”, explains, Stefan Obst, Product Manager for Sinamics SM120 CM in Germany. Photographs: lead Aker solutions www.siemens.com About Siemens Siemens is a global powerhouse focusing on the areas of electrification, automation and digitalization. One of the world’s largest producers of energy-efficient, resource-saving technologies, Siemens is a leading supplier of systems for power generation and transmission as well as medical diagnosis. In infrastructure and industry solutions the company plays a pioneering role. As of September 30, 2015, Siemens had around 348,000 employees in more than 200 countries. In fiscal 2015, the company generated revenues more than € 75 billion. MDA Technologies 5/2016