Fieldbus and FPSOs
Fieldbus is an ideal fit for Floating Production, Storage, and Offloading operations, otherwise known as FPSOs. As the name states, FPSOs are floating vessels that can collect, process, and store oil from offshore platforms, templates, or other sources. The oil can later be pumped to a tanker or pipeline for transportation. FPSOs are an ingenious solution for offshore applications. They are cheaper and easier to build than offshore platforms. Old oil tankers can be converted into FPSOs, but there are also FPSOs built from the ground up in various shapes and sizes. Most people are probably familiar with the oil tanker conversion units. Various research firms have estimates on FPSO spending, with estimates ranging as high as $10 billion for the current market. Oil companies love a cost effective solution, however, and spending on FPSOs is expected to increase well into the double digits for the foreseeable future.
|The Terra Nova FPSO Operated by Petro Canada
Photo: AlfvanBeem (Own work) [CC0], via Wikimedia Commons
FPSOs are cramped places where real estate for anything, much less automation equipment, is scarce. Fieldbus, particularly when using H1 cards with integrated power, significantly reduces the footprint and weight of the process automation system. Devices these days are no longer are integrated with just one signal each. A control valve, intelligent on/off valve, flowmeter, or level transmitter, for example, may have 3 signals each. This means that system I/O counts are higher than in years gone by. With FOUNDATION fieldbus, however, you work with device count, not I/O count. This means that a 6,000 I/O conventional system turns into a 2,000 device system with a huge reduction in I/O hardware.
This is what we refer to as “Virtual Marshalling” at the Fieldbus Foundation. You simply don’t need anywhere near as much hardware to get the job done, and many of the traditional I/O functions that were once handled by purpose built hardware are instead handled in the software.
Since the “topsides”automation of FPSOs consists of process modules fabricated in different yards, FOUNDATION fieldbus enables these modules to be connected with the rest of the ship using only a few cables. This makes fieldbus Ideal for fast track projects, and what project isn’t fast track these days?
No I/O cards are installed on the process modules out on deck. Fieldbus runs from small simple junction boxes back to the H1 cards inside the rack room. Couplers in the field junction boxes are rugged and encapsulated and are suitable for Zone 1. With Fieldbus Intrinsically Safe Concept (FISCO) the junction boxes are passive.
Then there are also FLNG vessels being built using FOUNDATION fieldbus as we speak. One of these is Shell Prelude FLNG