Seafloor deposits are a very promising source of mineral ore for the near future, discovered over the last 40 years. In particular, Seafloor Massive Sulphides (SMS) are very high grade hydrothermal mineral deposits distributed on the mid ocean ridges, arc and back arc basins in the deep confines of the world oceans. The most commercially attractive minerals are copper and gold, combined with large quantities of lead, zinc and silver. The first deposits that will be developed are located in 1600 to 2000 m water depth. Production will start on a commercial level by 2011.Applicable cutting and lifting technologies must be defined and tested rapidly so that the full production system can be engineered and built in a very short time frame. Existing oil and gas deep water developments is a proven source of technology that can be used as the basis of knowledge and experience to meet this challenging schedule.As a company at the forefront of deepwater developments, Technip is deeply committed to this new industry. A strong and comprehensive R&D effort has been put together to characterize the ore, its behaviour under load, its effect on the lift system and all related flow behaviour within the riser system.The R&D effort is split in four topics, all closely inter-related:A -Rock characterization performed in cooperation with Ifremer which has made available its SMS samples gathered over 30 years of deepsea exploration campaigns to determine mechanical and chemical behaviour of the SMS.B -Crushing test in hyperbaric conditions to evaluate the effect of pressure on cutting forces and determine rock size distribution.C -Slurry transportation models were performed using state of the art CFD modelling, both in two-phase and three-phase flow. This will be confirmed through large scale test loop experiments. D -Abrasion tests have been performed to select the preferred liner material for jumpers and risers. These liners will be tested in the test loop to confirm their behaviour over time.This paper describes the test program, provides the main available results and identifies the way forward to meet this technological challenge.

This paper builds on the experience of designing, and building production and drilling risers for oil and gas fields and extends into deepwater mining. With the recent discovery of high grade seafloor massive sulphides (SMS) in Papua New Guinea, New Zealand and elsewhere, there is a resurgence of interest in deep ocean mining. This renewal of interest has been spearheaded by Nautilus Minerals through its Solwara 1 project; in 1,700 m of water, with a production rate of 2.0 million tons per annum. Neptune Minerals Plc also endeavors to produce SMS with a similar production rate. This paper describes the two different deepsea SMS lifting concepts being developed by the two projects and the design challenges encountered during the course of the project executions for the two mining companies.

Seafloor deposits are a very promising source of mineral ore for the near future, discovered over the last 40 years. In particular, Seafloor Massive Sulphides (SMS) are very high grade hydrothermal mineral deposits distributed on the mid ocean ridges, arc and back arc basins in the deep confines of the world oceans. The Technip Subsea Mining R&D program is now entering its 6 th year with a clear goal of developping the necessary technologies to recover these sea deposits in an economical, safe, and environementally friendly way. The current paper describes the current field development that Technip is focussing on. This concept is based on the use of flexible riser anchored to the sea bed and positionned into a wavy shape in order to allow production in rough seas. This concept also focuses on the use of a grabber able to cut and collect the SMS chemineys from top to bottom. The innovative aspect of this concept is to maintain the pumping system on the topside vessel for efficiency and maintenance purposes. One the key unit to be developped is the Subsea Crushing and Feeding Unit (SCFU) that will allow collecting and crushing the material from the grabber content, as well as feeding the crushed material into the high pressure flow circulating inside the riser and jumper network. On this task, Technip has teamed up with ith MMD sizers, a leading crushing equipment supplier for the Mining Industry, to integrate into a subsea structure a sizer and a feeding unit self regulating the transfer of crushed material into the high pressure flow.

Subsea Flowlines blockage due to hydrate or paraffin plugs, resulting from pour point issues or deposition, is a frequent concern in subsea production requiring expensive remediation methods. The expenditures associated with subsea flowlines unplugging can increase very quickly, especially when considering the associated loss of production as well as the various investigations needed to define the appropriate remediation strategy. Such investigations cover the identification of the plug's nature, its location, the assessment of the appropriate dissociation method as well as the flowline restart strategy. In some scenarios, the plug dissociation method, like depressurization for hydrate plug and chemical soaking or pigging for paraffin plug, may take a long time ranging from several days to several months. Often, the remediation cannot be performed from the topside facility and will require the mobilization of an external drillship vessel to carry manifold or Xmas tree work over. Ultimately, the plug removal method may fail and therefore lead to flowline abandonment and/or replacement. From these observations, there is room for the development of a more efficient, predictable and reliable method to unplug subsea flowlines. With this regard, the development a new subsea flowline intervention system named Electrically Trace Heated Blanket (ETH Blanket) has been initiated. The ETH-Blanket is a compact and modular system, with length adaptable typically up to 2km. The system is equipped with trace heating cables relying on Joule's Effect for heat generation to dissociate the plug and distributed temperature sensing (DTS) to monitor the flowline's bore temperature in order to identify the location of the plug, characterize its nature and follow-up the temperature and pressure profiles during plug dissociation. The ETH Blanket can be deployed onto any kind of existing flowlines (flexible or rigid) and in any condition (buried or not) from a Light Construction Vessel. The power required to dissociate the plug is low (typically <1MW) and once the dissociation is completed, the ETH Blanket can be recovered onto the intervention vessel and relocated. This paper describes into details the ETH-Blanket assembly and its operating principles, its anticipated thermal performances determined using CFD modeling, as well as and its deployment method and spread. To illustrate the ETH-Blanket efficiency, a typical multiple hydrate plugs dissociation operation will be presented and compared to a conventional topside depressurization. As a conclusion, the on-going fast-track qualification programme for the development of the Electrically Trace Heated Blanket Technology will be presented.

Placid Oil Company has installed the first floating production system in the Gulf of Mexico using unprecedented technology. The technology includes a complex rigid-flexible combination riser system. The riser allows production and surface control of each subsea completed well, as well as export of separated oil and gas between a subsea production template and a semi-submersible drilling rig that was modified to allow simultaneous drilling and production operations. Flexible pipe segments, suspended between the semi-submersible's pontoons and the top of the free standing rigid riser, are essential components of the combination riser. The flexible pipes accommodate significant differential motion between the floater and the upper connector of the free standing riser. They are designed to withstand hurricane extreme environmental conditions while enabling the riser to remain connected to the rig. This paper presents the various phases of engineering, manufacturing and installation of the flexible pipe elements. Particular emphasis is placed on engineering methodology used in this frontier development to design a system that accommodates large differential motions in an extremely confined space. INTRODUCTION Placid Oil has installed a subsea production template capable of supporting 24 subsea wells in 1530 feet of water on Green Canyon Block 29. Three satellite trees, one located in adjoining Ewing Bank Block 999 and two in Green Canyon Block 31, are tied back to the template. Two export pipelines, one 16 inch for gas export and one 14 inch for oil, enable production to be sent to shore. Top side process facilities and drilling capability are provided by Penrod 72, a semi-submersible rig converted to drilling, workover and production modes. Flowpaths between the floating production system and the template are provided by a buoyant, self standing rigid/flexible combination riser. The rigid segment of the riser is made buoyant by the use of syntactic foam modules and pressurized air cans (Figure 1). This paper addresses various aspects related to the engineering, manufacturing and installation of the flexible pipe elements of the rigid/flexible combination riser. Flexible pipe is an essential element that renders the concept feasible. PROJECT START UP The contract for engineering and manufacture of the flexible pipe jumpers of the riser system was awarded in February 1986 for a planned installation in February 1987. The contract called for delivery of 27 lines, including a spare 8 inch export line. The 27 lines consisted of:24 production/annulus flowlines: 2.3 inch I.D., 7500 psi working pressure, 11250 psi test pressure, 300 ft long.2 oil export lines: 8 inch I.D., 2160 psi working pressure, 3240 psi test pressure, 300 ft long.1 gas export line: 12 inch I.D., 2160 psi working pressure, 3240 psi test pressure, 300 ft long. The gas export jumper and 12 of the production jumpers were suspended between a porch installed on the port side pontoon of Penrod 72 and the top of the free standing riser.