The next step was an offshore test led by DDI. It was planned to demonstrate two installation scenarios:
- the down-line technique conceived by DDI and supported by the deployment system developed; and
- draping the flying leads from the cage of the ROV.
The test was performed on Stolt’s Defender and it was a race against time as a hurricane slipped into the gulf. Confident in the down-line method, DDI chose to proceed first with the draping technique which consumed much time and effort, and caused the umbilical to hockle (twist in the water on itself). This proved that the flying leads could be handled, but the draping idea was not the team’s first choice. Due to the weather and damage to the prototype from the twisting, the down-line method could not be fully tested. The initial test was successful, but more testing was required to confirm the down-line method.
The first SFL installation campaign would follow installation of the umbilicals for the Macaroni and Angus projects. The Seaway Condor had the umbilical installation contract. Between the Macaroni and Angus main umbilical installations, a second wet-test was conducted using the down-line method. This test was a complete success and demonstrated that the straightener was not necessary. SFLs were installed on these two projects then quickly followed by Shell Europa and Shell King. DDI wrote the procedures and set up the flying lead installation system. Shell provided the Stolt Defender and the Legend. Approximately a dozen flying leads were installed along with steel tube jumper assemblies (UTAJ) from the stab and hinge-over j-plates to the high density metal (HDM) of the UTA. The flying leads were not as easy as HFLs to fly, but definitely easier to deploy as they were already spooled and service personnel did not have to dig them out of crates and wind them onto deployment frames. The SFL era had begun.
Phase 2
The second phase of the SFL evolution began on Amerada Hess projects. While the Shell team and KOS were testing SFLs, Amerada Hess requested that KOP make an SFL for the Penn State project. The design was loose super duplex tubes inside an overhose. They were successful during their installation, but they struggled. DDI, together with KOP, conceived the KOP cobra which was more compact and stronger than the Phase 1 design and could transfer the strength of the tubes into the cobra bracket. The tube count increased along with stiffness from 15,000 pounds per square inch (psi) tubes. Using the same compliant section, two 450ft SFLs and one 5,900ft SFL single tie back from the two-well cluster were installed. This eliminated the installation complexity of an infield umbilical with UTAs on both ends and some flying lead connections. A small electrical lead was strapped to the flying lead during the installation as it was going over the chute. Plastic baskets were strapped to both cobras with the excess in the baskets and the ODI connector tie wrapped in for easy manipulation by the ROV.
Phase 3
The third phase includes DDI and KOP. After the Conger project and three years after the original development of the SFL, KOP project engineers and DDI management were together for the start of two simultaneous projects – Canyon Express and BP King. A brief discussion between the two of them resulted in the next phase, loose tube steel flying leads (LSFLs), where loose tubes are in an overhose as on Penn State, but connected to cobra terminations on the end to get the benefits of a cobra’s righting moment, seafloor proximity, and angle of attack. Both KOP and DDI began manufacturing the LSFLs. Canyon Express installed 39 KOP LSFLs and were supported by both KOP and DDI labour testing and deployment systems. BP King used KOP LSFLs and the DDI deployment system. BP Marlin used KOP LSFL and a DDI LSFL with KOS cobras and a DDI strength pot to transfer the axial strength.
At this point, DDI developed the Moray® which is a cobra-type connection but designed to host all control supplier J-plates for installation loads and ease of connectivity.
This phase also produced the compliant Moray® . The system consists of an electrohydraulic (EH) umbilicaljoining to 20ft of compliant 1/2” loose tubes via a strength termination (capable of full installation loads), then to a Moray® hosting two fibre transfer and test system (FITAS) and two electrical connectors parked on the Moray® bracket. Two 25ft long electrical flying leads (EFLs) are parked in the basket and the connectors are parked on the Moray® bracket. This design is for unlimited length of single well step-outs with only a tree connection required and has been successfully used on the Kerr McGee Navajo and BHP Boris projects. Cameron is using the system for five infield umbilicals for the ExxonMobil Erha project. This system is ideal for connecting one field to another, connecting to single well tie-backs, and for distances beyond the installation range.
Phase 4
Phase 4 was the future, but is already the present. DDI is making LSFLs 4,000ft and 5,000ft long and up to as many tubes as requested. When installing flying leads through a field, around trees, UTAs and manifolds, the LSFL with Moray® terminations is recommended. If connecting two fields or a single tie back and without meandering inside and around the field, the infield umbilical with a compliant Moray® on the ends is recommended.
In the past, the length of an LSFL was limited by EFL installation limits. That length was about 600ft. DDI is now offering either the infields, as in Erha, which are 244m to 317m long and contain hydraulic, electrical and fibre optic components, or a preferred option of LSFLs with the EFL strapped to the flying lead with excess housed in the DDI ‘doughnut’ buoyancy with electrical storage.
DDI is also in the process of manufacturing the new Mini-Moray® which is a DDI LSFL connected to the new DDI J-plates which are more compact, simpler to install and less expensive. The cobra and the Morays® were developed to compensate for the limitations of existing J-plates. The DDI Mini-Moray LSFL can be manufactured up to 6,000ft long and with the new DDI integral j-plate, more flying leads can be stacked on the stackable baskets and be installed in a single mobilisation. DDI continues developing and refining the SFL in all its forms to further broaden the reliable choices for subsea distribution systems for the industry.
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Drilling & Well Services
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