Kerr-McGee's and Devon Energy's Red Hawk spar was installed at GB 876 in approximately 5,300 ft water depth (WD) in April 2004. This is the first use of Technip's third generation spar (cell spar) and is one of the first permanent deepwater floaters in full production to use a passive polyester Taut Leg Mooring (TLM) in the Gulf of Mexico (GOM). This paper describes the planning and installation of the Red Hawk cell spar and the polyester mooring system using a Construction and Anchor Handling Tug (CAHT).

Polyester taut-leg mooring systems (TLMs) promise superior stationkeeping and reduced cost (compared to conventional systems using wire and chain) for drilling and production applications in deep water. The Brazilians have successfully proven use of polyester moorings anchored with Suction Embedment Anchors (SEAs) or Vertically Loaded Anchors (VLAs), yet several technical and cost issues are evident with the approaches taken to date. GOM acceptance of this important technology, and possibly other areas of the world, requires demonstration and recognition of existing, improved components and installation techniques by both regulatory authorities and deepwater industry players. In late 1998, a JIP was sponsored by (now BP Amoco), BHP, Chevron, Mobil, Aker Marine Contractors and Marlow Ropes attempting to achieve these objectives. The intent was to prove a new anchor design (Suction Embedded PLate Anchor --SEPLA) and torque matched polyester rope (suitable for connection to conventional sixstrand wire). Two preset moorings using these components were to be used as part of an eight leg preset mooring attached to the semisubmersible Ocean America.While several objectives and lessons were established in this initial test, use of the polyester components and a SEPLA was not realized due to unrelated equipment failures; however, important lessons about polyester handling and deployment equipment, SEPLA installation and recovery, and preset mooring benefits were achieved. Further development was undertaken by Aker Marine Contractors, Inc. (AMC) and Marlow, culminating in a second component test with the semisubmersible Ocean Victory to be moored in 4,500 ft of water late in 1999. Vastar joined the JIP for the second test by providing the rig and an installation vessel.This paper describes the development and testing processes, installation and equipment techniques, test results and lessons learned and makes an assessment of how the technology can be used for future drilling and production applications. The work will provide a critical benchmark for industry acceptance of the technology.

Two recent conversions of semisubmersibledrilling units to floating productionfacilitieswere governed by a differentset of design requirements and operator philosophies. This paper compares them and illustrates how fabrication philosophies were chosen to produce a cost-effective project for each. OTC 7S33 HARVEV E. McBEE, RICHARDS. Hll& PEIER G.S. DOVE 7

WOPyrIGM 19% OFFSHORE TECHNOLOGY CONFERENCE nw$ papaf was pmpafad w pfesenlabm al ha Offshore Techc@Y Confererca kkl m HwstcfI, Texas, 6-9 May 19% TM papa was salauad for presantalm by an OTC Prcgmm Commit-folknwng rav!ew c+ mlcwnattof ontaned m an abstracl submrtted by the autkf(s) Ccmtents of the P&PC as wwanmd me nol been revwed by the OIWWe T@WWWY @ WE S* tO W*M by U-m author(s) The materkl as presmtad tis nd recassaniy rafkd my POsrbcn ot ttw 0iT5P0re TechmMgy Ccdarenm c+ m o%cm PanmssIwI to cmpy @ feemchd to an Astrad d nd mcfe man 303 words lllustfat~s may cot b-a copwd TM *SW sti cmiam CZXMPKUMIS aduwu-ent of~re and by whom W p-ape IS pfesanted AbstractAn Operator wanted to drill one or two additional delineation wells in 3,200 feet of water at Green Canyon 254. Because there were no MODUs capable of this water depth available to fit the Operator's schedule, the Operator elected to increase the water depth capability of an existing Ocean Victory Class MODU. The modification consisted of increasing the number of riser tensioners, installing longer BOP control hoses, guidelines and television cable, and using pre-laid moorings to enhance the mooring capability. This paper describes the pre-laid mooring procedures. Each prelaid mooring leg consisted of one 10 metric ton anchor, 1,000 feet of ground wire, 2,500 feet of dip-zone chain and 3,@30 feet of catenary wire. Prior to the arrival of the MODU, each leg also had 3,500 feet of 2 inch riser wire and a surface buoy. The moorings were laid using a single 6,140 brake-horsepower, anchor-handling, towing, supply vessel with a large A-frame at the stern. This same vessel was used to connect the chain from the MODU to the pre-laid moorings.Using pre-laid moorings to extend water depth capability gives the Operator greater flexibility in selecting MODU'S for deep water drilling and can solve scheduling problems. The use of an A-frame and a ground wire adjacent to the anchor allowed use of a smaller vessel than would otherwise be required. The MODU can be moved to nearby deepwater locations without fully recovering the pre-laid moorings.This operation demonstrates that the water depth capability of an all chain MODU, normally capable of 2,000 feet of water, can lx. extended to over 3,000 feet by using wire inserts and pre-laid moorings.

Spread moored floating production platforms are employed worldwide in the exploitation of offshore hydrocarbons. To date they have all employed catenary spread mooring systems (CSMS) using chain or combination wire/chain components. In water depths to 1500 feet and beyond, such simple wire/chain systems become increasingly inefficient and costly. To improve cost efficiency, tighten watch circles and 10wer vertical load on the platform several innovations have been introduced such as the use of submerged spring buoys (Ref. I), ground wire, and ropes made from synthetic aramid fiber. An aramid rope has yet to be employed in a permanently spread moored production platform as industry awaits a better understanding of the long term behavior of this material (Ref. 2). The installed cost of a deep water (XM remains high despite these innovations and a need exists for even more efficient spread moorings as industry looks to water depths of 3000 feet and beyond. The most promising alternative to the (XM to emerge in recent years is the Taut Leg Spread Mooring (TLSM) system, with short scope legs (Fig. 1) and where vertical uplift on the anchors is permitted (Ref 3, 4). This paper explains the operating principles of a TLSM, its performance sensitivity to variations of key parameters and shows the cost benefit versus a CSM by specific case studies. FUNDAMENTAL BEHAVIOR EXPLAINED To develop a cost efficient design, it is essential to understand the basic mechanisms by which a TLSM resists platform mean loads and wave induced motions. The behavior is most easily grasped by studying the simple taut leg system shown in Figure 2. k consists of a light weight, elastic mooring leg in water depth D stretched between the anchor point A and the fairlead point F separated by a horizontal distance L. The anchor point is fixed and resists horizontal and vertical forces. As the fairlead point translates away from the anchor point in response to an applied mean load, tension is induced in the leg as it stretches elastically between the points. An equilibrium position is attained when the moment created by the horizontal force components (H *D) is balanced by the moment created by the vertical force couple (V*L) between the anchor and fairlead points. As the line slope angle relative to the horizontal decreases, distance L increases requiring a smaller vertical force and therefore smaller line tension to resist a given horizontal force. However, line scope and therefore cost also increases. If horizontal force per unit of line volume is used as a measure of cost efficiency, it can be demonstrated that the most cost efficient line slope of a simple TLSM to resist a horizontal mean load is 450 (scope/depth ratio of 1.414). In a catenary system, mean offset is controlled by line weight and pretension. Lines composed of materials with lighter weights and with larger pretensions produce.