Part of the Shell standardized deepwater subsea system is the standardized tubing head, shown here being installed on Macaroni.
Shell recently rolled out its latest subsea development, Macaroni, which will tie back 12 miles to the Auger TLP. Macaroni is located in 3,700 ft water depth, in Garden Banks Block 602, about 235 miles southeast of Houston. The subsea system will consist of three subsea satellite wells clustered around a four-well subsea manifold.
Production will flow through dual 6-in. by 10-in. pipe-in-pipe flowlines to Auger. Peak production rates are expected to reach 35,000 b/d and 65 MMcf/d by later this year.
While no deepwater subsea system can be called "routine", that is exactly how Shell and its alliance partner FMC would some day like to view such projects. Shell, which has a number of record assets in deepwater and more than its share of subsea developments, would like to see the fixed costs of a deepwater subsea development come down so that the technology could be applied to a broader range of fields. Shell quoted statistics that show 34% of the cost of a subsea well can be attributed to the fabrication and installation of the flowlines, while an additional 21% is spent on the subsea hardware. The remaining 45% covers drilling and completion costs. Shell and FMC focused their attention on the fixed costs of the subsea hardware.
To this end, Shell and FMC are working on a program of standardization that could use the same basic components to construct a variety of subsea systems. Doug Peart, manager of subsea projects for Shell, said Shell has learned a lot about deepwater subsea systems over the years. Peart said there are a handful of basic concerns a standardized deepwater subsea system should address. The chief concerns are high pressures of 10,000-15,000 psi, cold flow temperatures due to long offsets, high flow rates, resource availability, and the frequency with which intervention is necessary.
Reviewing deepwater prospects in the future, the company set out to distill what it had learned into a suite of systems. Shell and FMC worked together to design a standard system that meets all of the functionality requirements of the bulk of Shell's deepwater portfolio.
This standardization of the hardware means Shell and FMC can optimize every stage of construction from building to testing to installation. Peart said that Shell has learned much from early reliability challenges in their subsea systems. He said that although the long-term reliability of these systems is still an unknown, applying the previous learnings to a standardized system means that these components are tested in the field in early applications, and any weaknesses can be compensated for in later designs. Beyond reliability, there are a variety of efficiencies Shell can draw from with this standardized system. The way they are designed, the components of the subsea system do not have to be assembled in any particular order. This allows a lot of flexibility when a rig needs to be on site.
Because the trees, manifolds, jumpers, and other components are standard from one project to the next, rig schedule changes can be better managed due to the ability to swap equipment from one project to another, thus saving costly rig downtime.
Shell would eventually like to see this standardization lead to a wider application of subsea technology. In the future, the company hopes to be working on several subsea projects simultaneously. Currently, there are four in the works, all using different versions of this standardized system. The fields are Angus, Green Canyon 113, in 2,000-ft water depth; Macaroni, Europa, Mississippi Canyon 934, in 3,900-ft water depth; and King, Mississippi Canyon 764, in 3,285-ft water depth. Angus and Macaroni will be completed this year; Europa and King are due on-line in 2000.
Elgin/Franklin avoids high-cost lifts
At the Barmac Nigg yard near Inverness, Scotland, workers are putting the final touches on the massive Elgin/Franklin production platform. The facility will go on line with first production from the two fields in the year 2000. The platform will be located on the Elgin field although it will also handle production from Franklin, which is nearby. The 27,400-ton platform is large by any standards, but is distinguished by the fact that it is a jackup style vessel, rather than the conventional jacket and topsides design.
The platform is referred to by designer Technip as a production, utilities, and quarters facility or PUQ. The main advantage to this design is that it is fabricated and assembled into one piece onshore. The entire platform is towed onto station and self-installed. This avoids the expense of heavy offshore lifts. In addition, most of the hookups and commissioning work will be carried out onshore before the sailaway.
The platform, called TPG 500, will be towed to the Elgin Field in block 29/5b of the central Graben area of the UK North Sea. Once the TPG 500 is maneuvered into position, in 93 meters water depth, the legs will be extended, lifting the platform to 34 meters above the surface. Once in place, six pilings will be installed in each of the three legs. It is estimated the platform will operate until at least 2022 when it will again save the operator money by not requiring heavy lifts for field abandonment.
Pipefreeze unit offers isolation alternative
BJ Process and Pipeline Services has developed a controlled temperature mobile pipefreeze unit that provides temporary isolations at controlled temperatures in the range of 0-60°C. This innovation will help operators who require temporary isolations for pipework with specifications that differ from traditional freezing techniques. Unlike traditional pipefreezing methods, the only consumables this method requires are electricity and water. As a result, it is a more cost-effective method than conventional freezing applications since the refrigerant is self-contained and there is no requirement for additional shipping or use of consumables. In addition, BJ says there are fewer risks than those associated with other methods, and the unit can be used in enclosed spaces.
