Exploration • Drilling • Field Services
Maintaining power to the people
A major interruption of gas supplies to millions of people was avoided by a complex subsea pipeline re-routing operation. Paul Boughton looks at this high-pressured operation to avoid a power crisis.
Con una operación de redireccionamiento de una tubería compleja subacuática, se evitó una importante interrupción de los suministros de gas a millones de personas. Paul Boughton observa esta operación de alta presión para evitar una crisis energética.
Eine schwerwiegende Unterbrechung der Gasversorgung von Millionen Menschen konnte durch eine komplexe Umleitung über Unterseeleitungen vermieden werden. Paul Boughton untersucht diesen Einsatz unter Hochdruck zur Vermeidung einer Energiekrise.
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Fig. 1. Lowering the hot tapping machine offshore into the sea.
akarta, the capital and largest city of Indonesia, is one of the most densely populated urban areas in the world. Located on the north-west coast of Java, it has a population of about 9,761,407. Gas is supplied to the city from the Lima Flow Station, in the Java Sea, which has been slowly subsiding into the seabed since 1997. It was, therefore, vital that subsidence
remediation work was carried out at the Lima Flow Station, which was built in the early 1970s, and consists of compression, service and process platforms, as well as a platform bridge, flare bridge and tower. However, a complete shutdown of this station would have severely disrupted the flow of natural gas from the Lima field. “Nine million live in Jakarta; half of
whom rely upon natural gas supplied from Lima field, so the stakes were extraordinarily high,” said Edward Sinaga, execution lead for Pertamina EP, the Indonesian state-owned oil and natural gas corporation. “Without gas from Lima field, much of the city would have been thrown into chaos, without power and in some cases, electricity, which was utterly unacceptable. It was critical that supply to the city remain steady while jacking operations took place.”
Stabilising the platform on the seabed by lifting and consolidating it made it necessary to shutdown several lines connected to it. A complete shutdown would have severely disrupted the flow of natural gas from the field. To ensure that production and supply would continue uninterrupted during remediation works, several lines were to be installed to bypass the 14-inch and 20-inch MGL pipelines that extend from the TLA and TLD platforms to the Lima Process Stations (L-PRO) and the 24-inch MGL pipeline that extends between the L-PRO and Cilamaya, where the pipelines make landfall. Pertamina EP engaged pipeline
services and equipment TD Williamson (TDW), headquartered in Oklahoma, USA, to isolate the affected lines so that temporary bypass lines could be installed through which gas would flow, ensuring uninterrupted supply to Jakarta. Te Lima intervention would prove to
be TDW’s largest, most demanding subsea hot tap and Stopple plugging operation. Hot tapping – or pressure tapping – is the method of making a connection to existing piping or pressure vessels without the interruption of emptying that section of pipe or vessel. Tis means that a pipe or tank can continue to be in operation. Pertamina EP gave TDW only five months to plan, gather resources and execute this subsea project. Each phase preparation, engineering assessment, fabrication, simulation, mobilisation and execution had to be carried out to perfection in order to meet the demanding deadline.
Hot taps To maintain flow and facilitate the installation of the bypass lines, TDW developed a solution that required an intricate series of subsea activities: nine hot taps followed by simultaneously executing Stopple plugging operations in six different locations. Because Pertamina EP required that all intervention work be completed within
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