Exploration • Drilling • Field Services
three months, TDW quickly mobilised equipment from North America, Europe and Asia Pacific, accompanied by a team of experienced technicians, to the hot tap and Stopple plugging operation site. Following the installation and commissioning of the temporary bypass lines upon the successful completion of nine hot taps, the TDW team could commence with setting the Stopple plugs in six different locations. Working from the dive support vessels (DSVs) at depths up to 131ft (4m), the five-member team used a full complement of specialist machines to hot tap the pipelines, and Stopple plugging systems
“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.”
Edward Sinaga, Pertamina EP
with Lock-O-Ring Plus fittings to plug them for final completion. Once the line has been safely isolated, cold-cutting of the isolated pipeline for the installation of subsea in-line ball valve commenced. In just 25 days, all of the lines were hot tapped, Stopple plugs set and successfully isolated, making it the fastest such operation in TDW history. For 22 days, the lines remained safely isolated at a pipeline pressure of 13.78bar (200psig). Te entire operation was completed in just 63 days. Natural gas flowed continuously through the temporary bypass lines to Jakarta, allowing the city to function without missing a beat.
“Te sheer scale and complexity of this subsea operation posed many challenges for Pertamina EP, so we are very pleased that it was completed so quickly and effectively,” said Edmund Ang, operations manager Asia Pacific for TDW. “Te fact that we were able to simultaneously carry out six Stopple plugging operations at different subsea locations meant that every step of the process had to be precisely orchestrated. But our efforts paid off. By completing them in a matter of days instead of weeks, the lines were properly isolated in time for Pertamina EP to divert flow through the temporary bypass lines to Jakarta.” l
Fig. 2. Coupons are the sections of pipe removed to establish service. It is very highly desirable to ‘retain’ the removed during pipeline pressure intervention.
Improving data recovery options A
collaboration between Sonardyne International, Shell and ocean data services provider Liquid Robotics has
seen the development of a Liquid Robotics Wave Glider autonomous marine vehicle configured for unmanned data retrieval from seafloor sensors. For the past three years, an array of Sonardyne’s autonomous sensors has been recording pressure data for monitoring seafloor subsidence in a Shell-operated deepwater field. Now, using a Wave Glider fitted with a Sonardyne high- speed acoustic modem, multiple data harvesting operations have demonstrated the ability to retrieve logged data on demand without requiring a conventional survey vessel. Seabed settlement monitoring is a surveillance tool used to constrain dynamic reservoir models and is
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undertaken as a part of a comprehensive reservoir surveillance campaign.
Te sensor logging nodes designed and manufactured by
Sonardyne operate autonomously and are able to remain deployed for several years without intervention. Te data stored within each sensor node is available
for recovery on demand at the surface via the integrated high-speed acoustic modem and during the early stages of the monitoring project, data was conventionally retrieved using acoustic modem technology onboard a vessel of opportunity. However, the new innovative Wave Glider removes the need for such a vessel as it is capable of remaining at sea for many months in all weather conditions, autonomously transiting between each node’s location to collect data. l
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