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British-Borneo Exploration Inc.'s Morpeth export system introduces two industry firsts -- the use of a diverless piggableb tie-in sled installed in a stacked orientation through a stinger and the installation of the first dynamic steel catenary riser (SCR) employing Slay techniques. Careful design and installation planning resulted in successful on-bottom positioning of the sleds within 5° of vertical without any rectification. The pipeline and SCR Slay work was performed from a conventional, moored barge in water depths ranging from 360 to 1650 feet along the 19.5-mile route. Introduction The Morpeth field is located in Ewing Banks Block 965. The field layout is illustrated in Figure 1. Oil and gas from the field are produced from three subsea wells in 1750 feet of water via flexible catenary risers to the Atlantia-designed SeaStar® mini-TLP located in EW 921 in 1650 feet of water. Product is then exported through a 12" and 8" gas steel catenary riser and pipeline system to a conventional platform in GI 115 in 360 feet of water. The subsea facilities are operated remotely from the TLP. The installation of the export system was performed with J. Ray McDermott's combination lay/crane barge DB28 in two phases to maintain the 21-month fast-track schedule. The bulk of the pipeline was laid in the first phase in the Slay configuration, terminating at the piggable tie-in sled location. The sled, the remaining 2 miles of each pipeline, and the SCRs were laid in the second phase in the S-lay and the J-lay configurations, completing the export system installation. Figure 1 Morpeth Field Layout (Available in full paper)

This paper provides an overview of the Liuhua infield production and test pipelines, focuses on new technologies used to tie the pipelines into a subsea manifold, and reviews the basis for selection of flexible pipe in preference to steel pipelines. The infield pipelines consist of two 13.5 -in.-ID flexible pipes for production and one 6. O-in.-ID flexible pipe for well test. Each pipeline riser is approximately 10,300 ft (3, 130 m) long and runs from the subsea manifold below the FPS, Nanhai Tiao Zhan, to the FPSO tanker, Nanhai Sheng Li. The technologies used to tie the pipelines into the subsea manifold involved:A transition tie-in base into which the flexible pipe was pulled using ROV-assisted tooling to make up the first end connectorA rigid pipe long jumper from the manifold to the tie-in baseThe survey and measurement tools to set up the jumper welding jigs Each new pipeline tie-in technology was proven through field tests of actual components before completion of manufacturing and installation. Flexible vs. Rigid Pipelines An overview of the manifold-to-pipeline system is provided in Fig. 1. Amoco uses two subsea connection techniques for the Liuhua subsea connection system. To understand how this occurred, a brief history on the Liuhua pipelines is presented. A more detailed discussion of the history and economics of the flexible pipeline selection has been presented previously (Refs. 1 and 2). During the defining stage, the Liuhua pipeline system consisted of three pipelines - two production and one test. The pipelines were to be of all-steel construction, fabricated either onshore or in shallow water and towed to site prior to the arrival of the vessels. Once the FPS was on site, the pipelines and manifold would be connected via a long jumper that spanned up to 150 ft between the manifold and the lead tow sled. At Coflexip's (now Coflexip Stena Offshore) request, Amoco agreed to reconsider the use of flexible pipelines. An all-flexible pipeline system was previously rejected due to its perceived higher cost. Full-cycle economics - including the rental of riser reels, risk of damage to the pipelines and communication cables during tow, and cost of cable crossings, corrosion inhibition chemicals, maintenance, and corrosion monitoring - was performed after receipt of installation bids. The economic result favored two 13.5-in,-ID flexible pipes for production and one 6,0-in, ID-flexible pipe for well testing. In addition, this solution outperformed the rigid pipeline option with respect to risk of damage or failure. Once awarded the work, Coflexip Stena worked with Amoco to develop an acceptable method to tie the pipelines into the manifold. The designed for steel pipelines, did not permit significant horizontal loads on the manifoldduring a flexible pipe lay away. Pile-founded tie-in bases were selected to resist lay-away loads with rigid-pipe long jumpers connecting them to the manifold.

Industry interest in floating production systems in the Gulf of Mexico and elsewhere is increasingly pointing toward deeper water depths ranging to 10000 ft. In these waters, the moorings are an increasingly significant factor in the overall system cost. This paper presents important design considerations for deepwater mooring systems for permanently moored floating platforms. The engineering of feasible and cost-effective deepwater moorings requires substantive departures from conventional design and installation techniques. These include rethinking commonly accepted design criteria, the use of synthetic materials, alternatives to conventional catenary systems, increasing use of deeply submerged buoys, and innovative ideas for system installation. Issues addressed include: design criteria; the use of lightweight, high-strength materials such as aramid fiber rope in lieu of wire rope; analysis methods and procedures indicating the importance of quasistatic, dynamic, fatigue and probabilistic analyses; installation options and the benefits of maximizing deployment vessel options; the use of alternatives to a conventional chain/ wire catenary system; and design considerations and construction options of large-buoyancy, deeply submerged buoys.

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