Compliant Platform Guyed tower platform Tension Leg Platform (TLP) The relatively light weight jacket of a guyed-tower platform … A guyed tower may be applicable in deep hostile waters where the loads on the gravity base or jacket-type structures from the environment are prohibitively high. Tension leg platforms installed as of 2002 . 7.20) and a suspension cable tangent tower where three phases are arranged in horizontal configuration (as shown in Fig. Don E. Lennard, in Encyclopedia of Energy, 2004. Subrata Chakrabarti, ... Cuneyt Capanoglu, in Handbook of Offshore Engineering, 2005. This type of rig structure can be configured to adapt to existing fabrication and installation equipment. Several issues have to be pointed out: The structural behavior of fixed jacket platforms is different compared with others. The articulated tower is considered as amplification of tension leg platform. Yet to be installed are the first full–scale tension–leg (TLP) and guyed–tower types of installations. A double-circuit tower usually has three or four cross-arms arranged in an umbrella or drum form and can significantly narrow the line corridors by arranging the three-phase conductors vertically. The former Soviet Union, Japan, the United States, Italy, Canada, Brazil, and other countries have constructed pilot sections of UHV transmission lines of various scales, and launched extensive theoretical and experimental studies on UHV transmission lines including tower types. Remotely operated sea floor production systems have been designed for very deep waters (beyond 600 meters). A 1000-kV double-circuit steel tubular tangent tower in Japan. Some of the promising concepts are tension leg platforms, guyed and articulated tower platforms which take advantage of the effect of compliance, i.e., yield to the environmental forces. But unlike in sea star, the tension legs dont go all the way to the sea floor. Articulated towers belong to the class of compliant towers which have been found quite suitable for deep water applications. The guy wires also restrain the platform motion during typical operating weather conditions without lifting the clump weights off the bottom. Schematic diagram of 1000-kV cat-head tower. The CT design is more flexible (hence the name) than conventional land structures to cope better with sea forces—it can deflect (sway) in excess of 2% of height. Discussions in chapter “Disciplines Involved in Offshore Platforms Design,” Section 2.10 are related to fixed jacket platforms. Fig. The Petronius Platform is a compliant tower in the Gulf of Mexico modeled after the Hess Baldpate platform, which stands 2,000 feet (610 m) above the ocean floor. However, guyed towers are unfavorable for operation and maintenance due to measures taken to protect guys against looseness and theft; meanwhile, guyed towers have large root span for the guys, large footprints, and limited choice of sites for tower positions, which usually leads to higher overall costs than self-supporting towers. At present the deepest is the Chevron Petronius tower in waters 623m deep. The former Soviet Union has abundant land resources and the transmission lines run through plain, hilly, and grassland areas that are sparsely inhabited, making it possible to use guyed towers. Tension leg platform. Schematic diagram of ±800-kV claw tower. Although based on well-established heat engine cycles, the OTEC energy extraction process has an overall practical efficiency of some 2.5% due to the relatively small operating temperature differential, which has to be compared with a figure of typically 30% or more for a fossil fuel power station. There are other structures which span greater depths to the ocean floor (eg. The concepts differ mainly in the means by which the loadings are transmitted to the seabed and in the form of the anchorage to the sea floor. A compliant tower is disclosed having a foundation connected to a wide-bodied compliant framework with a plurality of vertically extending legs a minimum of horizontal bracing. The rig consists of narrow, flexible (compliant) towers and a piled foundation supporting a conventional deck for drilling and production operations. 9 tons. Various deepwater concepts have been employed worldwide, including compliant towers, floating production storage and offloading vessels, semisubmersibles, spars, tension leg platforms… The jacket of a compliant tower has smaller dimensions than those of a fixed platform. Although the thermal resource is particularly relevant to developing countries, there are many other factors to be considered before it can be said that a particular country or location is suitable for an OTEC installation. These include distance from shore to the thermal resource, depth of the ocean bed, depth of the resource, size of the thermal resource within the exclusive economic zone (EEZ), replenishment capability for both warm and cold water, currents, waves, hurricanes, sea bed conditions for anchoring, sea bed conditions for power cables of floating plants, present installed power and source, installed power per head, annual consumption, annual consumption per head, present cost per unit (including any subsidy), local oil, gas, and/or coal production, scope for other renewables, aquaculture potential, potable water potential, and environmental impact. A guyed tower consumes less steel but occupies a large area. Fixed Platforms: Compliant Towers 8 A compliant tower is similar to a traditional jacket platform and extends from surface to the sea bottom, and it is fairly transparent to waves. 1.1 Introduction 1. The articulated tower is considered as amplification of tension leg platform. Topic. Compliant Tower . Therefore, practical realization—engineering of the system—is a key issue in considering the future of OTEC and is a major element in its economics. In the 1000-kV Jindongnan–Nanyang–Jingmen UHV AC pilot and demonstration project, both types are used. An essential component of a tilt-up system is the “gin pole” or a fixed section to use as a lever arm to provide leverage to lift the tower weight. 4 . Figure 4. Approximately 60,000 barrels of oil and 100 million cubic feet of natural gas are produced daily by the Petronius platform. Exxon is further researching use of this type of platform in water depths to 5,000 feet. In 1150-kV single-circuit transmission lines constructed by the former Soviet Union, the cost of towers and foundations accounted for 31% of the total construction cost, and steel consumed by towers for each kilometer of lines was 68. Compliant Tower Deck Fw (t) Tower Frame Ungrouted pile sliding inside the tower leg or pile guides Pile top weld connected to the tower at top. It can be seen that the options for OTEC plants are considerable and that optimization for a particular site involves the review of many variables. The tower is installed in the middle opening of the four leg TLP. Because the flexible cables replace massive rigid legs, this design may extend the production to water even deeper than 2,500 feet. By continuing you agree to the use of cookies. Schematic diagram of 1000-kV cup tower. 1.5.4 Friction Dampers 27. In Japan, UHV AC transmission lines use double-circuit towers which typically have three or four layers of cross-arms supporting conductors vertically (as shown in Figs. Compliant Tower Deck Fw (t) Tower Frame Ungrouted pile sliding inside the tower leg or pile guides Pile top weld connected to the tower at top. Compliant towers are designed to sustain significant lateral deflections and forces, and are typically used in water depths ranging from 1,500 to 3,000 ft. 3. In such a case a floating production system is more appropriate, even with the increased cost of risers and mooring. Naeim Nouri Samie MSc Hydraulic Structures, in Practical Engineering Management of Offshore Oil and Gas Platforms, 2016. A compliant tower (CT) is a fixed rig structure normally used for the offshore production of oil or gas. A Tension-leg platform is a vertically moored °oating structure normally used for the ofishore production of oil or gas, and is particularly suited for water depths around 1000m to 1200 metres (about 4000 ft). Thus, CTs are designed to sustain significant lateral deflections and forces, and are typically used in water depths ranging from 1,500 to 3,000 ft. 1.5.3 Passive Control Algorithm 26. Spar Subsea Infrastructure . Compliant structure concepts may be classified in one of four categories: Articulated towers . 15 - Wood Group Mustang Deepwater Systems Global Distribution . There are several types of oil platforms and rigs: 1, 2) conventional fixed platforms; 3) compliant tower; 4, 5) vertically moored tension leg and mini-tension leg platform… Single-circuit self-supporting tower. are out of this book discussion. Most single-circuit angle towers are of a “干” type. Lattice towers are not designed to withstand side-lifting loads as well as monopoles. The cost of the tower itself is low, but the land cost is increasing; therefore, the total cost may be higher than that for self-supporting towers. Compliant Tower A compliant tower is a flexible structure with flex elements (principally flexible legs or axial tubes) to control mass and stiffness characteristics so as to mitigate the effects of periodic wind, wave and current forces. TENSION-LEG PLATFORM 29. We use cookies to help provide and enhance our service and tailor content and ads. Compliant towers are designed to sustain significant lateral deflections and forces, and are typically used in water depths ranging from 1,500 to 3,000 feet (450 to 900 m). In order to reduce right-of-way, UHV AC transmission lines in Japan use double-circuit towers. Compliant structures, e.g., the guyed tower and tension-leg platform, are being developed; they can extend production capabilities to water depths of 600 meters, and possibly beyond. Compliant-tower rigs are similar to fixed platforms, since both are anchored to the seabed and hold most of their equipment above the surface. MTLP- Mini Tension Leg Platform. [2]. tension leg platforms), but compliant towers still demonstrate static stability albeit with greater degrees of lateral deformation (up to 2.5%) compared to land-based structures (usually 0.5% or less). MINI TLP 32. Due to this the platform experiences more horizontal motion due to the jerks from the rough weather. However, the latter has larger height and member weight than the former. Figure 7.26. Spar Subsea Infrastructure . … Figures 8.1 and 8.2 show a cat-head tower and cup tower, respectively. These towers function on the basic idea of fixed platforms. Guyed towers can be assembled on the ground and the small wind turbine attached before lifting with a crane. This platform allows drilling at an amazing depth of 7000 feet. Abundant experience with this tower type has been accumulated. Figure 18.17. In addition, the former Soviet Union also developed a 1150-kV V-shaped guyed tower where three phases are arranged in triangular configuration (as shown in Fig. Tension-leg platform. Figure 7.23. Guyed towers are featured by consumption of less steel materials and are the preferred choice for UHV AC transmission lines in some countries. Double-circuit tower. Tower history The compliant tower concept has essentially progressed through an evolution of three configurations. Process design, power generation/distribution, control systems, piping, and installed equipment more or less follow the same concepts as explained in this book. A Tension Leg Platform (TLP) consists of a structure held in place by vertical tendons connected to the sea floor by pile-secured templates. Tension- leg platform – Tension- leg platform are floating platforms, ususally the giant version of the Sea Star platforms, except the tension legs extend from the ocean floor to the platform itself. 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