**Source**

**Theme**

**Author**

- Aas, Per Magne (1)
- Abe, Nobuharu (2)
- Abu Sharkh, S.M. (1)
- Abugihalia, Y. (1)
- Adachi, Katsushige (1)
- Ailliot, P. (1)
- Akagawa, Satoshi (3)
- Akakura, Yasuhiro (1)
- Akazawa, Katsufumi (1)
- Al Harash, Mohamed Thabet (1)
- Al-Mhaidib, Abdullah I. (1)
- Alcorn, R.G. (1)
- Aleksandersen, Jostein (2)
- Allersma, H.G.B. (1)
- Amdahl, Jorgen (1)
- Amdahl, JØrgen (1)
- Amin, Jayesh (1)
- Amitani, Yasutaka (1)
- Anam, Iftekhar (1)
- Andersen, Glen R. (1)
- Anelli, E. (1)
- Ansari, A.R. (1)
- Anson, T.I' (1)
- Anurudran, G. (1)
- Aoki, Taro (3)
- Aoshima, Mitsunobu (1)
- Araki, Susumu (1)
- Arambel, Pablo (1)
- Arami, M. (1)
- Aranha, José A.P. (1)
- Arena, Felice (1)
- Arena, G. (1)
- Arita, Yoichi (1)
- Arkchipov, Boris V. (1)
- Arntsen, Ø. (2)
- Asada, Tsuyoshi (1)
- Ashmawy, Alaa K. (1)
- Askheim, D.Ø. (1)
- Astafyev, V.N. (1)
- Astrup, O.C. (1)
- Aubeny, CP. (1)
- Aya, L. (3)
- Baba, S. (1)
- Bai, Yong (1)
- Bajeet, E. Sheik (2)
- Bajeet, E.S. (1)
- Bakis, R. (1)
- Bal, Sakir (1)
- Bando, Akiyoshi (1)
- Bang, Sangchul (1)
- Barltrop, Nigel (2)
- Bea, Robert G. (1)
- Beattie, W.C. (1)
- Bekker, Alexander T. (2)
- Bentley, Doug (1)
- Bereznitski, A. (1)
- Berg, S. (2)
- Berge, Gunnar (1)
- Berhault, C. (1)
- Berstad, A. (1)
- Berti, D. (1)
- Bhattacharyya, S.K. (1)
- Bijker, R. (1)
- Bilgin, M. (1)
- Biolley, F. (2)
- Birk, L. (1)
- Birkelund, Yngve (1)
- Birkinshaw, M. (1)
- Birknes, Jorn (1)
- Birknes, JØrn (1)
- Bjarte-Larsson, T. (1)
- Bjertness, Erik (1)
- Bjorkum, Per Arne (1)
- BjØrnoy, O.H. (1)
- BjØrnØy, O.H. (2)
- Blagovidov, Lev B. (1)
- Bolshev, A. (1)
- Bonmarin, Pierre (1)
- Boon, B. (1)
- Borgman, L.E. (1)
- Bornes, Atle Harald (1)
- Bostan, T. (1)
- Botros, Fikry R. (1)
- Brandes, Horst G. (1)
- Brandini, Carlo (1)
- Breda, JØren (1)
- Brooker, D.C. (1)
- Bruu, Hans H. (1)
- Bryndum, Mads (1)
- Buchannon, Robin C. (1)
- Buchner, Bas (1)
- Buffington, Sharon (1)
- Bughi, Sabrina (1)
- Burgess, James J. (1)
- Burman, Philip (1)
- Cao, ZD (1)
- Capanoglu, C.C. (1)
- Cassidy, M.J. (2)
- Chan, H.H. (2)
- Chang, Chih-hsin (1)
- Chang, Hsien-Kuo (2)
- Chang, Mei (1)
- Chaplin, J.R. (2)
- Chart, Andy T. (1)
- Chaudhuly, Gautam (1)
- Chen, Gung-Rong (1)
- Chen, Hamn-Ching (4)
- Chen, W. (1)
- Chen, Xiaohong (1)
- Chen, Yao-Chung (1)
- Chen, Yu-Chin (1)
- Chen, Z. (1)
- Cheng, Xiaohua (1)
- Cheng, Yo-Ming (1)
- Cheung, Kwok Fai (1)
- Chien, Lien-kwei (1)
- Chiew, S.P. (1)
- Cho, Yeongki (1)
- Choi, Hang S. (1)
- Choi, S.B. (1)
- Choi, Yoon R. (1)
- Chou, Chung-Ren (1)
- Chuang, Jiun-Chi (1)
- Chucheepsakul, Somchai (1)
- Chung, Jin S. (1)
- Chung, P.Y. (1)
- Chwang, Allen T. (1)
- Clamond, Didier (1)
- Clark, Charles (1)
- Clark, James H. (1)
- Clausen, Carl J.F. (1)
- Clausen, Terje (1)
- Clauss, G.F. (1)
- Clauss, Günther F. (5)
- Clément, Alain H. (1)
- Collberg, L. (1)
- Colleluori, D. (1)
- Colmard, Christophe (1)
- Colombo, Adalberto (1)
- Cook, H. (1)
- Correa, S.H.S. (1)
- Corsini, S. (1)
- Costa, Luís Cláudio S. (1)
- Coutermarsh, Barry A. (1)
- Cumino, G. (1)
- Das, B.M. (1)
- Das, Samrat (1)
- Datta, Manoj (1)
- De León, D. (1)
- de Wilde, J.J. (2)
- Degenkamp, Gijs (1)
- Deguchi, Ichiro (2)
- Delauré, Y.M.C. (1)
- Deleuil, G. (1)
- Dessi, Daniele (1)
- Devlin, P.V. (1)
- Di Natale, M. (1)
- Dilzas, Konstantinos P. (1)
- Dissanayake, U. I. (1)
- Dolez, Patricia (1)
- Dong, C.M. (2)
- Dong, Guo-hai (2)
- Dong, Guohai (1)
- Dong, Sheng (2)
- Donguy, B. (1)
- Drago, Michele (1)
- Draper, G. (1)
- Dretvik, Svein (1)
- Duan, Meng-Lan (1)
- Duclos, Gaelle (1)
- Dutta, Piyush K. (3)
- E, Xuequan (1)
- Eide, Svein Inge (1)
- El Mesmary, M.A. (1)
- El Rayes, Magdy (1)
- El-Kelesh, Adel M. (1)
- Ellinas, C.P. (2)
- Ellwanger, Gilberto B. (1)
- Elsanadedy, Hussein M. (1)
- Embong, Mohamad Bin (1)
- Endal, Geir (1)
- Enomoto, Hiroyuki (1)
- Ersdal, Gerhard (2)
- Etienne, S. (1)
- Eto, H. (1)
- Falzarano, Jeffrey (2)
- Fisher, John W. (2)
- Fontaine, E. (3)
- Francescutto, Alberto (2)
- Frawley, P. (4)
- Fujikubo, Masahiko (2)
- Gardiner, C.P. (2)
- Grilli, Stéphan T. (2)
- Gudmestad, Ove Tobias (3)
- Habel, Rolf (2)
- Hayer, Sverre (2)
- He, Juwen (2)
- Heurtier, J.M. (2)
- Hiraishi, Tetsuya (3)
- Hirose, Yukio (2)
- Huang, C.J. (2)
- Huang, Erick T. (2)
- Huijsmans, R.H.M. (2)
- Hyakudome, Tadahiro (2)
- Inoue, M. (2)
- Jo, Chul H. (3)
- Kamio, Zenji (3)
- Kaneko, K. (2)
- Kawano, Kenji (2)
- Khaleeq, H.B. (4)
- Kim, M.H. (4)
- Kim, T.H. (2)
- Kirkemo, Finn (2)
- Kojima, R. (3)
- Koterayama, Wataru (2)
- Kubo, Masayoshi (3)
- Kuboki, E. (2)
- Kurokawa, Akira (2)
- Kvitrud, Arne (2)
- Kyozuka, Yusaku (3)
- Le Cunff, C. (2)
- Leonhardsen, Roger L. (2)
- Li, Guangwei (2)
- Li, Hua Jun (2)
- Li, Zhijun (2)
- Liagre, P.F. (2)
- Lotsberg, I. (2)
- Luo, Y.H. (2)
- Maddox, S.J. (2)
- Marley, M.J. (4)
- Martin, C.M. (2)
- Massie, W.W. (2)
- Matsui, T. (2)
- Matsui, Tamotsu (5)
- Matsushita, Hisao (3)
- McGee, Thomas M. (2)
- Meling, Trond Stokka (3)
- Moe, G. (2)
- Morikawa, Katsuyoshi (2)
- Moros, T. (2)
- Murakawa, Hidekazu (2)
- Murashima, Takashi (2)
- Nagai, Toshihiko (3)
- Nagata, S. (2)
- Nakajoh, Hidehiko (2)
- Nakamura, Toshiaki (2)
- Nakazawa, Naoki (3)
- Niedzwecki, J.M. (3)
- Ochi, H. (2)
- Ochi, Hiroshi (2)
- Ogawa, K. (2)
- Ogawa, Koichi (3)
- Pákozdi, Csaba (2)
- Qu, Yuexia (2)
- Ragupathy, P. (2)
- Randolph, M.F. (2)
- Ronalds, B.F. (2)
- Saeki, Hiroshi (3)
- Saijo, Osamu (2)
- Sakai, Masafumi (3)
- Sasa, Kenji (2)
- Sasaki, Toshihiko (3)
- Sawai, T. (2)
- Seliverstov, Vladimir L. (2)
- Serizawa, Hisashi (2)
- Setoguchi, T. (3)
- Shigeiri, Yoshiharu (2)
- Shiraishi, Satoru (4)
- Soukissian, Takvor H. (2)
- Sriskandarajah, T. (2)
- Stansberg, C.T. (3)
- Steinhagen, Ulrich (2)
- Suga, Y. (2)
- Surkov, G.A. (2)
- Takao, M. (2)
- Takayama, Tomotsuka (2)
- Takeuchi, Takahiro (3)
- Tamura, Kenkichi (2)
- Tanaka, M. (2)
- Teigen, P. (4)
- Terashima, Takashi (3)
- Thakker, A. (6)
- Tsukioka, Satoshi (2)
- Tsvetsinsky, Alexander S. (2)
- Ueda, Shigeru (3)
- Ueda, Yukio (2)
- Ushikoshi, Juntaro (2)
- Wang, J. (3)
- Wang, Yongxue (2)
- Ward, E.G. (3)
- Wilkins, R. (2)
- Wilmshurst, S.R. (2)
- Winterstein, Steven R. (3)
- Woolsey, J. Robert (2)
- Yamaguchi, Hiroshi (2)
- Yamamoto, Y. (2)
- Yamane, K. (2)
- Yamase, Seigi (2)
- Yen, Ben T. (2)
- Zaman, Md. Hasanat (2)

to

Go **Concept Tag**

- amplitude (29)
- analysis (81)
- angle (18)
- Artificial Intelligence (136)
- boundary (25)
- breakwater (14)
- calculation (16)
- capacity (20)
- case (35)
- change (13)
- coefficient (53)
- Comparison (25)
- component (16)
- condition (75)
- control (15)
- cylinder (17)
- deformation (13)
- design (61)
- development (16)
- direction (22)
- displacement (34)
- distribution (43)
- effect (63)
- elevation (14)
- energy (15)
- equation (73)
- excitation (14)
- experiment (31)
- factor (20)
- failure (26)
- fatigue (21)
- field (14)
- floating production system (30)
- free surface (15)
- frequency (48)
- function (41)
- health safety security environment and social responsibility (29)
- Horizontal (23)
- ice (24)
- incident wave (15)
- increase (26)
- installation (30)
- line (22)
- Load (37)
- loading (19)
- machine learning (32)
- management and information (125)
- material (21)
- method (69)
- Midstream Oil & Gas (15)
- model (105)
- mooring system (24)
- nonlinear (26)
- ocean energy (20)
- Offshore (32)
- offshore pipeline (28)
- operation (19)
- penetration (14)
- performance (15)
- pile (14)
- plate (18)
- platform (26)
- power (14)
- probability (16)
- problem (18)
- process (19)
- production control (15)
- production monitoring (15)
- relationship (14)
- renewable energy (24)
- Reservoir Characterization (57)
- reservoir description and dynamics (147)
- reservoir simulation (24)
- Reservoir Surveillance (15)
- Response (47)
- riser (26)
- sample (17)
- ship (23)
- Simulation (27)
- SOIL (27)
- solution (17)
- specimen (28)
- spectrum (18)
- stability (15)
- strain (16)
- strength (32)
- stress (44)
- structure (91)
- study (16)
- subsea system (109)
- surface (29)
- system (54)
- test (78)
- Thickness (20)
- Upstream Oil & Gas (239)
- US government (13)
- vessel (18)
- water (62)
- Wave (143)
- wind (15)

to

GoWalz, Christian (BIAS -Bremen Institute of Applied Beam Technology) | Stiebe-Springer, Ingo (H. Butting Edelstahirohre) | El Rayes, Magdy (Alexandria University) | Seefeld, Thomas (BIAS - Bremen Institute of Applied Beam Technology) | Sepold, Gerd (BIAS - Bremen Institute of Applied Beam Technology)

Economical aspects in the offshore industries lead to new materials and due to these materials to new production technologies. One of these technologies is the hybrid welding process. Compared to laser welding, the combination of the laser and one conventional welding process (e.g. MIG) offers many advantages like wider gap bridgeability, enhanced process stability and higher welding speed. Hybrid welding allows the geometrical design of weld seams on demand. The paper shows the results of hybrid welding experiments with austenitic stainless steel and supermartensitic 13%Cr steel. Tensile tests and hardness measurements were carried out. All tests have been performed in the as-welded and in the post weld heat treated conditions. The results show a very good behaviour of the hybrid welded samples with seam properties close to the properties of the base material. It is concluded that the hybrid welding process has the potential to be implemented in industrial production in the near future. Introduction The Hybrid welding process is defined as the coupling of the laser beam welding with a conventional welding process, such as the MIGwelding process. This process has, as arc augmented laser beam welding, been investigated since the first experiments of Steen in the seventies [1]. Research work has been done concerning the potential and advantages of the process combination [2,3,4]. The potential is to increase the weld bead penetration, the width and the weld speed. The laser beam process with its characteristic high and focused power density leads to deep and narrow welds. The comparably wide process zone of the arc process enables the better gap bridgeability and reduces the joint preparation effort in this way. Higher welding speeds lead to less heat input (at constant power), less thermal distortion and thereby less reworking of the components.

ISOPE-I-01-380

The Eleventh International Offshore and Polar Engineering Conference

A selected range of problems and solutions in hydrodynamic model testing is discussed. The work is limited mainly to the interpretation of data from experiments in irregular waves. Procedures within nonlinear data processing and the probabilistic interpretation of test data are briefly reviewed, including cross-bi-spectral analysis and the statistical analysis of extreme values in a record. Examples from application in various practical cases are shown. This includes the slow-drift analysis o1 moored floating platforms, statistical analysis of long-duration laboratory records, as well as wave run-up on a vertical column in irregular sea.

The rapid development within computer technology results in considerable advances in the hydrodynamic analysis of offshore structures. Thus the need for model testing has also changed. With more advanced numerical tools, the requirements to experiments and the analysis of data become stronger. Through proper planning and interpretation, the knowledge and information gained from tests can be significantly improved. In particular, this is the case for the study of nonlinear and complex processes, and for extremes in severe weather conditions. A description of data analysis in hydrodynamic model testing is given in Chakrabarti (1994). The role of model testing in the field of offshore industry has been addressed in Dyer & Ahilan (2000). A special challenge is identified within the verification of ultra-deep water systems, for which methods of integration of model testing and numerical models are developed (Stansberg et. al., 2001). There is a range of topics within the field of model test data interpretation. In the present overview study, it is not the intention to cover all the range. Here we will focus mainly on the treatment and interpretation of data from tests in irregular waves, with emphasis on quadratic signal analysis and extreme values including a brief review of the work in Stansberg (1997a).

ISOPE-I-01-236

The Eleventh International Offshore and Polar Engineering Conference

analysis, Artificial Intelligence, estimate, experiment, floating production system, identification, interpretation, irregular wave, machine learning, management and information, model, model test, nonlinear, Proc, procedure, Response, Stansberg, State, statistics, structure, subsea system, test, testing, Upstream Oil & Gas, Wave

SPE Disciplines:

The power output from wave energy converters (WECs) may be increased by controlling the oscillation in order to approach an optimum interaction between the WEC and the incident wave. Optimally controlled WECs, designed to operate at full capacity a rather large fraction of their lifetime, may improve the economic prospects for wave power significantly. An upper bound is given to the ratio between the converted power from a given wave, and the geometrical volume of the converter. One control strategy for maximising the converted power is based on measuring the incident wave, whereas another strategy utilises measurement of the WEC''s own oscillation as input to the controller. In either case the measured quantity has to be predicted some seconds into the future because of non-causal control functions.

Most of the proposed devices for conversion of wave energy are oscillating systems with a frequency-dependent response showing the phenomenon of resonance. At resonance, that is when the wave period agrees with the natural (eigen) period, the fraction of converted energy attains maximum. With wave periods off resonance the conversion is less powerful, in particular so if the resonance bandwidth is narrow. Wave-energy converters (WECs) of large horizontal extension, socalled "terminators" and "attenuators", have rather broad bandwidths, whereas "point absorbers", for which the extension is very small compared to the predominant wavelength, have rather narrow bandwidth. On the other hand, an advantage with point absorbers is that the smaller the structural volume of the converter is, the larger is the ratio between the potentially converted power and the mentioned volume (Budal& Falnes, 1980). Hence, for a point absorber it is imperative that means are provided for optimum control of the oscillatory motion in order to achieve a maximum of power conversion.

ISOPE-I-01-085

The Eleventh International Offshore and Polar Engineering Conference

Kim, Youseok (Daewoo Institute of Construction Technology) | Kim, Seongwoon (Daewoo Institute of Construction Technology) | Park, Joongbai (Daewoo Corporation) | Kim, Sungjoon (Daewoo Institute of Construction Technology) | Kim, Heungseok (Daewoo Institute of Construction Technology) | Kim, Kyoungo (Daewoo Institute of Construction Technology)

This paper describes a centrifuge model test program of suction pile installation in sand. The purpose of the centrifuge tests was to establish relationships between the applied suction pressure inside the pile and the resulting pile penetration to validate an analytical solution for large-sized suction piles. This paper describes the details of the centrifuge model tests, including the experimental setup, instrumentation, and test results. Eight model suction pile installation tests were conducted under conditions that directly simulate the non-linear behavior of the sandy seafloor soil. Test parameters included the amount of applied surcharge, pile diameter, and initial pile penetration. However, the applied suction is limited due to the possible soil instability within the pile.

The South Dakota School of Mines and Technology (SDSM&T), Rapid City, South Dakota, USA, is currently conducting a technical feasibility study of utilizing suction piles for mooring Mobile Offshore Bases for the US Navy (Bang, 1997). In concept, a Mobile Offshore Base (MOB) is a modular floating base up to 2 kilometers long that can be deployed to any area of the globe to provide flight, maintenance, suppl); and other forward logistics support operations. SDSM&T developed an analytical solution to help install suction piles successfully in the field (Bang and Cho, 2000). The analytical solution is capable of estimating the correct suction pressure that can safely penetrate the pile into the seafloor soil without creating any instability at a given pile penetration depth. The lower bound value corresponds to the suction pressure inside the pile that can barely overcome the pile bearing capacity so that the pile can penetrate into the soil, whereas the upper bound suction pressure is the value that initiates the instability of the soil inside the pile, i.e., boiling of the sand.

ISOPE-I-01-218

The Eleventh International Offshore and Polar Engineering Conference

An analytical solution procedure that can estimate the resistance of suction piles against horizontal loads were developed by considering the truly three-dimensional behaviors. It considers the development of three-dimensional normal and shear stresses along the circumference of the pile surface as well as a threedimensional soil failure wedge. The geo-centrifuge test results were analyzed and compared to validate the analytical solution of the Ultimate horizontal loading capacity of suction piles.

The US Navy is currently conducting a technical feasibility study pertaining to the construction of Mobile Offshore Bases (MOBs). This is expected to be a self-propelled, floating military base with a runway on top and other supporting facilities below such as living quarters, material storage areas, docking facilities for transport ships, etc. The proposed dimension of the MOB is approximately 1,500 meters by 150 meters. The South Dakota School of Mines and Technology is participating in this MOB feasibility study to provide an adequate mooring technique for this very large floating structure. Suction piles are currently being investigated analytically and experimentally to provide the necessary mooring capacity. Suction piles typically have a large diameter (up to 30 meters to date) with a relatively small length-to-diameter ratio. They are installed by applying a suction pressure inside the pile, which acts as an external surcharge to push the pile into the seafloor. They may be retrieved later by applying a positive pressure inside the pile. This paper describes an analytical solution procedure that can estimate the resistance of suction piles against horizontal loads. Numerous experimental and analytical studies on the pile lateral resistance have been conducted in the past (Bierschwale et al., 1981; Ivey et al., 1968; Kasch et al., 1977; Matlock, 1970; Senepere and Auvergne, 1982).

ISOPE-I-01-209

The Eleventh International Offshore and Polar Engineering Conference

Industry:

- Government > Military (0.68)
- Energy > Oil & Gas > Upstream (0.67)
- Government > Regional Government > North America Government > US Government (0.34)

SPE Disciplines: Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (0.68)

In recent years the possibility of constructing onshore pipelines with high design pressure has been focused. The major reason for this has been to effectively use the higher grade steel now available. (Dr.lng. Lund, 1983) Åsgard Transport System (AT) has, due to the high content of heavy gas components, to be operated at minimum pressure in excess of 112 barg. This has, together with the wall thickness requirements to avoid hydrostatic collapse in the deep water section, led to the adoption of a system design pressure of 212 barg. The downstream part of the system operates at significantly lower pressures. Hence a reduced design pressure of 172 barg for the onshore section could be used by the installation of an appropriate pressure protection system. Parallel to the onshore section of the pipeline system are the already constructed Statpipe and the Sleipner condensate pipelines. For the same reason as for Asgard, Statpipe has a design pressure of 172 barg. The onshore section of the AT posed significant challenges both in design and construction. This paper discusses the challenges faced with design and construction of a high pressure pipeline close to other high pressure pipelines and electrical power transmission lines. The paper further discusses the construction of three major fjord crossings. Finally the paper discusses the challenges in construction of large diameter high pressure pipelines.

The ÅT pipeline system is a 707 km long gas gathering pipeline connecting the Åsgard field to the gas treatment plant at K~trsto. The pipeline is designed for capacity exceeding the expected Asgard field production rates, allowing other gas producing fields to be linked to the system. Six T-connections have been installed along the offshore section of the system for this purpose. An overview of the ÅT system is given in figure 1.

ISOPE-I-01-129

The Eleventh International Offshore and Polar Engineering Conference

SPE Disciplines: Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)

A major design feature of the Mobile Offshore Base (MOB) is its ability to transit anywhere in the world in the required time frame. This means that the MOB must be able to transit in severe environmental conditions. In these extreme sea conditions, a primary cause for concern is the large accelerations that the vessel motions might experience due to the high static stability of the MOB at Transit Draft. Furthermore, since the vessel has minimum freeboard in this condition, it is exposed to green water over the pontoon tops. The submergence of the pontoon deck causes a considerable loss in the vessel''s restoring moment. These concerns have warranted a study by the Office of Naval Research into the Transit Draft Dynamics of the MOB. A part of the research in progress involves the development of a non-linear system modeling and optimization tool utilizing Reverse MUSO techniques. Reverse MI/SO is based on the statistical signal processing of the recorded time histories of the excitation and response of the non-linear multi-degree-of-freedom system. This method of analysis is functional and reliable in identifying an ideal representation of the linear and non-linear terms of the system under consideration. Reverse MI/SO is a frequency domain analysis technique that also provides coherence functions for each of the terms in the model enabling an evaluation of the correctness of the proposed integro-diffrential equation of motion representing the system.

This paper is part of two years of research and analysis as a part of a multi-faceted study on the Mobile Offshore Base (MOB) Transit Draft Dynamics and Stability. The preliminary results of this project have been presented at various technical conferences (see e.g., Falzarano, et al, 1999)(Falzarano, et al, 2000a &b).

ISOPE-I-01-041

The Eleventh International Offshore and Polar Engineering Conference

Industry:

- Government > Military > Navy (0.66)
- Government > Regional Government > North America Government > US Government (0.46)

SPE Disciplines:

The paper deals with floating systems (VLCC''s converted to FPSO''s) moored in deep water in the presence of currents. The offioading operation is carried out in a tandem arrangement from the FPSO to a shuttle ship of lesser capacity. According to the classical theory of dynamic systems, a study of the behavior of floating units is developed by determining the equilibrium position and then performing a local stability analysis about this position. This analysis is complemented by time domain simulations. This procedure is extended to the case of systems in spread mooring configuration. The other systems can be seen as particular cases.

These last years the conversion of VLCC''s (Very Large Crude Carrie0 into FPSO (Floating, Production, Storage and Offioading) units has been used by Petrobras in Brazil offshore to exploit oil in deep water, a consequence of the necessity of large storage unit with the capability to transfer the oil to shuttle ships. A group of VLCC hulls was converted to FPSO, with the installation of process plants, turrets and so on. The use of these units grew up the last years. Mostly common ships have been moored in single point (SPM), at the sea-floor through an installed turret (TMS), in spread mooring configuration (SMS) and also with the use of dynamic positioning system (DPS). This has motivated the development of many different works about their dynamics. The stability analysis of this kind of system is based on the theory of dynamic systems expressing the hydrodynamic forces acting on the bodies as function of their velocity components. First the equilibrium positions of the system are determined and around these positions the stability of the system is studied. This is not a very difficult job when the number of variables is small.

ISOPE-I-01-169

The Eleventh International Offshore and Polar Engineering Conference

Industry:

- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > South America Government > Brazil Government (0.35)

SPE Disciplines:

The author proposes a theoretical granular model to elucidate the hydraulic mechanism of a rubble mound breakwater, which has been solely studied through hydraulic model experiment. Wave transmission is caused by the reproduction of wave energy. Wave reflection depends on returning momentum. Stability is prescribed by the impulse on unstable rubble and expressed by more comprehensive formula than Hudson''s.

A rubble mound breakwater consists of rubbles with uneven weight and shape. Therefore its functions are solely evaluated through experiment that cannot give us insight or foresight to other cases than model tests experimented. Here the author proposes a theoretical granular model with uniform spheres that explains the effects of each element on the phenomenon synthetically, regarding wave transmission, reflection and stability. All experimentally measured values ought to be compared with their corresponding theoretical values. WAVE TRANSMISSION Transmitted wave is generated by reproduction of overtopping and infiltrating wave energy. I) Overtopping Suffixes I, R and T are attached to incident, reflected and transmitted waves, respectively. Overtopping occurs during the period (equations and figures shown in paper) EXEMPLAR In order to grasp overall effect of hydraulic quantities, some calculations are exemplified under the basic conditions that h=5m, H

ISOPE-I-01-330

The Eleventh International Offshore and Polar Engineering Conference

Offshore pipelines are to be stabilized against external loading mainly caused by wave and currents. As pipelines are placed in a trench, the forces acting on them are reduced considerably. The forces can be divided into three components, drag, inertia and lift. To investigate the stability in various trench sections, the flow over the pipeline is numerically simulated and compared with experimental results obtained from PIV measurement. In the computation, Smagainskys eddy viscosity model combined with a truncated deductive model is applied to represent the SGS stress field in quadrilateral structured grid system. The present results are produced at a Reynolds number ranging from 6x10

The offshore industry has long recognized the importance of subsea pipelines as a virtual link for the transmission of materials between onshore and offshore facilities. To insure their continuous operation, adequate criteria for design must be provided. A lack of necessary information for their design has introduced high safety factors which in turn have increased the construction cost. Information concerning hydrodynamic loads can help to reduce the uncertainty and therefore the overall cost (Knoll and Herbich, 1980) The instantaneous flow variables satisfy the Navier-Stokes equations. The strategies for dealing with turbulence are many: turbulence models (educated guesses about the needed Reynolds stresses), statistical theory of turbulence (to gain fundamental understanding), and direct numerical simulation.

ISOPE-I-01-135

The Eleventh International Offshore and Polar Engineering Conference

SPE Disciplines:

Thank you!