深海工程技术的挑战(有采油树采油树介绍)Deep_Sea_Challenges

Clauss G.F., Hoog S.: …Deep Sea Challenges of Marine Technology and Oceanographic Engineering“, published in …Science-Technology Synergy for Research in Marine Environment: Challenges for the XXI Century“, multi-authors work, Paolo F., Giuseppe S., Laura B. (Editors), Elsevier Science Ltd., Oxford, England, 2002.Deep Sea Challenges of Marine Technology and Oceanographic Engineering Günther Clauss a and Sven Hoog ba Prof. Dr.-Ing. Günther Clauss is head of the Institute of Naval Architecture and Ocean Engineering at the Technische Universität Berlin.b Dipl.-Ing. Sven Hoog is research engineer at the Institute of Naval Architecture and Ocean Engineering at the Technische Universität BerlinSymbiosis is the close relationship of members of a different species from which both derive some advantages. Good and reliable relationships between competent partners gain the best and longest lasting advantages for both sides - not only for animal or plant symbiotic structures but also for symbiotic relations in the technical world of marine sciences and marine technology.A challenging focus in marine science lays in the possibility to gain multidisciplinary geophysical and oceanographic data from long-term observations at deep-sea plains. These data should be analysed near real-time.The intention of conquering deep seas is a present task and future challenge for marine science and offshore technology. Consequently, some impulses for symbiotic structures in the field of deep-sea data acquisition and observation between marine sciences and offshore technology are identified in this paper.1. IntroductionLike in the maritime living space, marine science has an intensive - symbiotic - relationship to marine technology:Marine science is a methodically oriented branch with major fields like meteorology, physical oceanography as well as marine chemistry, biology, geology and geography.Marine technology is related to maritime engineering, with major fields like naval architecture, coastal engineering, mining, process technology, materials technology, electronics and food technology. Marine technology as problem-oriented branch also delivers traditionally the technical support for marine science applications. This co-operative field of marine technology is called ‚oceanographic engineering‘, and aims for the development of equipment, methods and procedures for all kinds of oceanographic and meteorological studies in an environmental protecting manner. One major task is the exploration and exploitation of the deep seas, widely supported by ‚man in the sea‘ operations in shallow waters and by Remotely Operated Vehicles (ROVs) in deep waters. With GEOSTAR [1], a new specialized ROV with high payload capacity and a multidisciplinary, autonomous benthic station is introduced in this paper.Address: TU Berlin • Secretary SG 17 • Salzufer 17-19 • 10587 BerlinTel. +49 30 314 23105 (direct) • +49 30 314-24657 (Secretary) • Fax +49 30 314 22885E-Mail Clauss@ism.tu-berlin.de• Web: http://www.ism.tu-berlin.de/• E-Mail hoog@ism.tu-berlin.de2. The deep sea frontier is descendingRecent increase of crude oil prices at the world market allows oil companies to develop even marginal and deep-sea hydrocarbon deposits. Fig. 1 illustrates the latest deep-water records of offshore production facilities in the North Sea, the Gulf of Mexico (GoM) and the Campos Basin in Brazil. Other promising deep-sea areas are found in the waters off West Africa and Southeast Asia / Australia.The related technical developments are based on both the intensive and consequent redesign and adaptation of existing oil production systems and on the invention of new concepts. Of course, environmental protection is a major condition.An overview of currently established oil production structures in the deep-sea reveals three major development lines [2]:• Tension Leg Platforms (TLPs), e.g. the Ursa TLP reaches in 1998 the water depth of 1190 meters in the GoM• Sub-sea completions, e.g. a FPSO (Floating Production, Storage and Offloading vessel) in the Roncador field (Campos Basin) is operating since 1998 at depth of 1863 meters • SPAR buoys with surface trees, e.g. a SPAR buoy started in 1999 to operate in the Diana field (GoM) in 1420 meters w. d.World wide leasing activities for ultra-deep sea areas are promising and will further enhance this challenging trend.Fig. 1: Increase in water depth of offshore production facilities [3]2.1. Going into the deep in the offshore oil and gas industry2.1.1 Manifolds and Christmas TreesAn essential issue for the successful development of deep-sea oil deposits is the new sub-sea completion technology. Fig. 2a shows the deployment of the central manifold for the Troika field in the Gulf of Mexico. It looks like a giant cage. A manifold ties together the produced fluid flows from satellite wells, and pumps it up to the storage vessel or directly to an export pipeline network. A key technology is the ROV (Remotely Operated Vehicle) to be used for guidelineless deployment, installation and maintenance of sub-sea structures. This technology comprises the deployment and connection of risers and control umbilicals at ‚easy access interfaces‘ between the sub-sea structures.Christmas Trees as shown in Fig. 2b are integral components of sub-sea developments. A great number of these trees cover a hydrocarbon deposit allowing simultaneous production from up to 59 satellite wells (Asgard field, North Sea) [2]. Christmas Trees provide blowout prevention, pressure and temperature monitoring as well as data read back from downhole instrumentation through control umbilicals. By umbilicals, some of these parameters are interactively controlled from the central producing vessel. In addition, electrical power is transmitted to the sub-sea installations.The entire sub-sea development must be especially prepared and proved to be remotely operable. For this reason the development of standardized - or universal - interfaces and automated, task-based intervention methods is necessary to advance to the next step. Enhancements in the ROV field as well as in the field of remote, online data acquisition will lead to safe and cost effective sub-sea operations improving deep sea activities of the oil companies.2.1.2 Sub-sea developments cover huge hydrocarbon deposit areasThe size and depth of hydrocarbon deposits as well as water depth and environmental conditions are initial criteria to choose the optimum technology for development.Fig. 2c gives an impression of these criteria. Crude oil or gas production from marginal fields or deep-sea areas need the application of all deep-sea technologies mentioned previously. It includes drilling with semi-submersibles or drill ships, production with FPSOs, SPARs or similar vessels, and crude oil transfer with shuttle tankers or pipelines. Theproduction vessel is held on location with a mooring system or by dynamic positioning. Flexible or steel risers provide the necessary connections to the sub-sea equipment on the ocean floor. Satellite wells are spread over the whole deposit area. The dimension of the covered sub-sea area can easily be several hundred square kilometers, while the monitoring and control of any fluid flow parameter is possible due to bi-directional umbilicals. Thus, the online connection to different satellite stations is a key factor for safe and effective operation of these ‘out of human reach’ facilities.2.2. Going into the deep in marine sciencesInstallation and maintenance of sub-sea developments in the offshore oil and gas industry are major tasks for ROV interventions, which led to an increasing role of ROV technology in deep seas. Due to increasing demands on capability, productivity and reliability of remote intervention tools and techniques ROV technology is continuously improving. Key issues of future developments are high depth rates, equipment modularity, reduced size, universal interfaces and automation of intervention tasks.Currently about 90 companies and institutions are involved in the development of the next ROV generation worldwide that led to about 300 different ROV types and almost 3000 units presently on the market [4]. Although these numbers imply a high grade of coverage of most demands, the market of specialized and prototype ROVs for the relatively low budgets of marine scientific programs is still growing. A recent example is the development of the MODUS ROV, which has been developed in co-operation with the authors.2.2.1 GEOSTAR: A new toolset for marine sciences deep sea operationsFunded by EU in the framework of Marine Science and Technology (MAST3), GEOSTAR (GEophysical and Oceanographic STation for Abyssal Research) is a current example of a successful co-operation between marine science and marine technology. Participating companies and institutions come from Italy (ING, Tecnomare), France (Ifremer, LOB, IPG, Orca) and Germany (TU Berlin, TFH Berlin).The GEOSTAR system consists of two main components - the deep-sea intervention tool named MODUS (MObile Docker for Underwater Sciences) designed and built at the University of Applied Sciences (TFH) Berlin and the Technical University Berlin (TUB), and the innovative deep-sea observatory, designed and built in Italy and France. This benthic station is capable to perform autonomous, long-term geophysical, geochemical and oceanographic observations in abyssal depths. It is deployed, recovered and serviced by the MODUS via an electro-mechanical umbilical - winch - ship system. The concept of GEOSTAR has been evaluated during the European ABEL and DESIBEL projects (MAST 2) in the early 90th. As one result the MODUS was specified to be frequently able to deploy and recover heavy payload stations to abyssal depths.A successful demonstration mission in August 1998 in the Adriatic Sea has proven the basic functionality of the GEOSTAR system in shallow waters (GEOSTAR phase 1: water depth 40 m). The second phase of GEOSTAR (GEOSTAR 2) has led to the overall upgrade of main components as the MODUS and the benthic laboratory (up to 4000 m w. d.). Utilizing the services of the Italian R/V Urania in September 2000, sea trials of the upgraded system have proven the GEOSTAR deep water capabilities, and led to the successful deployment of the benthic station in 2000 m w. d. in the Tyrrhenian Sea near Ustica Island north of Sicily (Fig. 3).Fig. 3: GEOSTAR system with umbilical-tethered MODUS ROV and the benthic station(left: dummy, right: prototype) with A-Frame of R/V Urania. Tyrrhenian Sea, September 2000.MODUS and Benthic StationMODUS is responsible for the exact positioning and retrieval of the benthic station at/from the seafloor: Fig. 3 shows the enhanced deep-sea version of MODUS latched with the frame of the benthic station. The ‘catch’ operation is aided by a 2 m diameter wide-open funnel, which fits exactly on top of the benthic station. A flexible pin provides the electromechanical connection. Ascent and descent operations down to 4.000 m are managed by the ship-mounted winch and umbilical. This umbilical supplies the vertical movements and provides power and data transmission to the submerged devices. Horizontal movements are driven by brush-less DC thrusters (2x700 N thrust) by aid of a ship mounted dynamic Global Positioning System (dGPS) and an Ultra-Short-Base-Line (USBL) system, while the final approach to the station is supported by sonar and a video system mounted on the MODUS. To stabilize the horizontal position adjustment during coupling procedures, two vertically oriented thrusters are installed. All remote operations and data transfers are monitored and stored on videotapes or log files supplied by the operation control unit on board the ship.Once deployed at location, the benthic station is capable to stay 6 months up to one year on the ocean floor. During this time the extensive multidisciplinary sensor equipment like seismometers, scalar and vectorial magnetometers, gravity meter, ADCP (Acoustic Doppler Current Profiler, 300kHz), CTD (Conductivity-Temperature-Depth), transmissiometer, hydrophone, electrochemical package (pH, H2S) and water sampler (48x500 ml) are autonomously surveying the location. The frame of the station also hosts all necessary equipment for the missions such as battery pack, Data Acquisition and Control System (DACS) as well as a communication system.The GEOSTAR system is a modular design: Properties of prototypes MODUS Benthic StationPurpose Umbilical driven frequent operations Long term missions(6-12 months) in deepocean watersMaterial Aluminium / Stainless Steel / Titanium (pressure boxes) Aluminium / StainlessSteel / Titanium(pressure boxes)Weight in air (kg) 1070 2942Weight in water (kg) 730 1416Total length (mm) 2878 3500Total width (mm) 2348 3500Total height (mm) 1700 (without cable termination) 2900(without docking pinand magnetometerbooms)Thrust lateral (N) 2x700 -Thrust vertical (N) 2x700 -Depth rated (m) 4000 4000Table 1: Properties of the GEOSTAR 2 system main componentsThe acquired data are transmitted via pop-up buoys and - in addition - by acoustic telemetry. For near real-time transmission the use of a dedicated mooring system and INMARSAT infrastructure is foreseen. Due to its moderate dimensions and the need of only three operators for deployment and recovery, the MODUS ROV is a very cost effective tool. In addition, two persons are required to check functionality of the sensors and to start operation of the benthic laboratory. For reliability and cost reduction reasons, the GEOSTAR system uses deep sea proved ‘out of the shelf’ components like thrusters, sonar, altimeter, underwater lights and cameras or acoustic releases.Taking advantage of the multitude of theoretical and experimental investigations for ‘standard’ ROVs published in the literature since 25 years, the design process for a special configuration still has to face both the environmental and especially the inner space requirements and constraints of the specific application. In various project stages the hydrodynamic and hydroelastic behaviour of the tethered GEOSTAR system has been investigated and further developed ([5], [6], [7]). Computational Fluid Dynamics (CFD) analysis is utilized to optimize structural induced drag losses of MODUS with respect to power consumption and thruster arrangement, while simulations of the system dynamics are performed to prevent slack conditions with dangerous snap loads during operation: The analysis comprises various research ship headings for the prevailing sea during the many hours deployment and recovery procedures. The response of the ship to sea spectra (calculated with the Response Amplitude Operators - RAOs of the ship) is the input of a non-linear dynamic time-domain analysis of motions of the submerged system with umbilical, ROV and benthic station at its end. Simulations for the operation with R/V Urania result in a limiting significant wave height of H s =0.5 m for paying out 3.500 m of cable in beam seas. Different values are achieved for shorter cable length and different ship-wave headings [5]. This short excursion should only give an idea of the global considerations made during the development procedure of the GEOSTAR system. The dynamics of MODUS is similar to other vertically umbilical-tethered systems like caged ROVs, stand alone CTDs, drill strings,water sampling rosettes, piston corers and therefore the analytical approach is highly developed (e.g. [8], [9], [10]). In the next section the paper focuses on some specific aspects concerning the ability of the modular GEOSTAR system to be part of a symbiotic structure with ‘conventional’ offshore sub-sea facilities like manifolds, templates and satellite wells. 3. Symbiosis is possibleSymbiotic structures require the consensus between two partners having equal rights. The knowledge of each starting point allows articulating common goals. Consequently, our suggestions concerning symbiotic structures in the field of marine science and offshore technology are based upon the technical and scientific status quo in the outgoing 20th and beginning 21st century described in this paper.Fig. 4: Sketch of symbiosis scenarios between sub-sea oil and gas production facilities and multidisciplinary benthic laboratories (here: Symbolic open frames of GEOSTAR lab and MODUS) The possibility to combine state-of-the-art deep-sea data collection systems for long-term applications with sub-sea structures, which are presently used in the offshore industry, is convincing. As a first approach, the main components developed during the GEOSTAR project - the MODUS ROV, the benthic laboratory with its deep ocean proved sensor modules (or other systems) and the Data Acquisition and Control System (DACS) - are proposed for the following applications:Deployment of specifically equipped benthic stations for exploration purposes at pre-determined locations to evaluate time dependent environmental data starting before exploitation activities. Durability: Autonomous up to one year. Deployment, service and recovery of a variety of different bottom stations with just one MODUS ROV.Deployment of benthic stations to a location nearby an already operating sub-sea development for various purposes, e.g. for environmental quality control or monitoring of actual working conditions for service ROVs. Durability: Not terminated due to direct power supply and online data connection via umbilicals with sub-sea structures.Deployment, service and recovery of the benthic stations with the MODUS ROV.Installation of the newly developed and deep sea proved GEOSTAR sensor packages including DACS in or on existing or new sub-sea developments as standard data collection units. Durability: Same as the hosting structures due to direct power and data interconnection. Service and Recovery with aid of conventional maintenance ROVs.Interactive real-time Internet connection to the DACS for data retrieval and/or reconfiguration of mission control is possible. Access to all available data for the oil and gas company in charge and for the marine scientists community.The range of collectible data meets the increasing demand of marine scientists and offshore engineers for reliable long-term site surveying and observation for a better understanding of deep ocean processes. As sub-sea developments in offshore hydrocarbon production are actually continuously controlled and managed, data collection and real-time transmission for marine science and offshore technology purposes offers a great opportunity for safe and cost effective symbiotic structures – now and in the near future.4. Conclusions➘The status quo in offshore technology offers opportunities to a wide range of national and international co-operations in geological and oceanographic data collection systems➘The deep sea frontier is descending: Latest water depth records in exploration and production of hydrocarbons are pointing on further developments➘Long-term data collection from deep seas offers a reliable basis for geological and oceanographic archives and improved sub-sea designs➘Feasibility studies for symbiotic structures should be promoted to guarantee maximum performance of sensors and undisturbed operation of sub-sea facilities➘Symbiotic structures for marine science and offshore technology are promising to be safe, reliable and cost effective, and comply strictly with safety and environmental standards5. AcknowledgementsThe GEOSTAR project is carried out under contracts EU/DG XII Mast III-CT95-0007 (GEOSTAR 1) and Mast III-CT98-0183 (GEOSTAR 2). The present partnership includes:Istituto Nazionale di Geofisica (Coordination) ITecnomareSpA IUniversity of Applied Sciences Berlin DDBerlinTechnicalUniversityIfremer FOrca Instrumentation FLaboratoire d’Océanographie et de Biogeochimie - CNRS FInstitut de Physique du Globe de Paris F6. 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