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Collaborating Authors
Pipelines, Flowlines and Risers
ABSTRACT This paper sums up the background and motivation for developing international pipeline codes i.e. basically the new ISO 13623 and the DNV-OS-F101 Pipeline Standards. The recent developments that have taken place are focused. Basic aspects of pipeline code development are discussed on a general basis as are the various aspects of selecting the appropriate code in a specific case. The experiences made in international use of these codes are discussed on the basis of some major pipeline projects where these codes have been applied. The discussion aims at coming up with answers to questions like: Did the codes meet the expectations as to international acceptance? To what extent have they been taken into use? Is there an optimum code to be selected for a pipeline project? The impact by the new pipeline codes on pipeline integrity management is discussed on a general basis. INTRODUCTION Pipelines are effective and highly reliable means for hydrocarbon transportation over short and medium range distances and are being built over longer distances and in deeper waters. They represent a large investment cost and will normally constitute a major part of the total cost for a hydrocarbon field development. These investment costs are influenced by the applicable codes for design and construction of the pipeline. Hence, an effective optimisation of the pipeline costs versus pipeline reliability will always be highly relevant. Fig. 1 shows a general economy comparison between different transportation means. The split between the different alternatives are naturally depending on the degree of optimisation and innovation. Even though pipelines are the biggest investment of a hydrocarbon development infrastructure, the contribution to the over all pipeline cost varies significantly depending on the pipeline. For shorter pipelines, flow-lines, the installation and fabrication cost or the operational cost may be the major cost contributor.
- North America > United States (0.94)
- Europe > Norway (0.69)
ABSTRACT A coupled analysis tool integrated with industrial experience can accurately predict global motions and mooring/riser tensions. These responses have a significant impact on hull size, structural design and overall costs. This paper discusses key technical issues for the global performance response and mooring analysis of a truss Spar in deepwater. Detailed discussions are given to 1) the influence of wave and wind spectra on slow motions of a truss Spar, 2) the distribution of extreme responses using different statistical methods, 3) Morison coefficients for motion analysis and heave plate hydrodynamics, and 4) the effects of mooring/riser added mass and damping on global responses. The discussions are based on applications of the Coupled Analysis Program (CAP), jointly developed by ABS and CSO Aker. The results include 1) the effects of API and NPD wind spectra on the Spar slow motions and tension, 2) the sensitivity of tension to wave spectrum peak enhancement parameter, 3) comparisons of Spar extreme motion responses and extreme mooring line tension based on different statistical methods, 4) the effects of heave plate drag coefficients on platform motions and 5) a comparison of responses obtained from uncoupled and coupled simulations. INTRODUCTION Since the first classic spar was deployed in the Gulf of Mexico in 1996, extensive studies have been given to the motion behavior of Spar platforms. A Joint Industry Project involving two representative Spar platforms was carried out at the Offshore Technology Research Center (OTRC) at Texas A&M University. It was observed in the experiment that the Spar responses were characterized by low frequency surge and pitch motions. The results indicate that an analysis of Spar motion responses needs to take into account second-order wave loads, which can be evaluated using second-order diffraction theory (Molin, 1979, Kim and Yue, 1990, Chau and Eatock Taylor, 1992).
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems > Mooring systems (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems > Floating production systems (1.00)
ABSTRACT This paper presents a study of a Tension Leg Platform (TLP) hull/tendon/riser coupled dynamic analysis in 1,829 m water depth. The dynamic interactions among hull, tendons and risers cannot be evaluated accurately and consistently by the traditional de-coupled method. Physical model tests also become difficult due to the limitation of the test facilities and possible scale effects with water depth increasing. Coupled dynamic analyses of TLP are becoming more and more important in deep and ultra deep water field developments since the TLP hull interacts more pronouncedly to its tendons and risers. TLP tendon is slender structure member, which connects hull and seabed, while TLP top tensioned risers (TTRs) connect production deck and seabed. TLP hull/tendon/riser coupled dynamic analysis means analyzing dynamic interactions among hull, tendons and risers including their influences of stiffness, mass and damping. With water depth increasing, both tendon and riser dry mass are comparable to or even higher than TLP hull mass. Damping of tendons and risers are becoming dominant. Thus coupled effects among hull/tendon/riser are more pronounced. Sufficient details of a TLP hull/tendon/riser coupled dynamic analyses are presented. It is the goal to identify the characteristics of coupled effects and provide guidance for TLP design and physical model tests in deep and ultra deep water. INTRODUCTION Recent drilling activities have discovered large reservoirs in the Gulf of Mexico (GOM) and West Africa in water depth of 4,000 ft and beyond. As offshore industries move into deep water, it calls for analytical tools to perform analyses and design and physical facilities to verify analyses and design. For the existing facilities, physical model tests may not be carried out at a reasonable scale, especially for fatigue sea state with small wave height and short peak period.
Time-Domain Coupled Analysis of Deepwater TLP, And Verification Against Model Tests
Ormberg, Harald (Norwegian Marine Technology Research Institute A/S (MARINTEK)) | Baarholm, Rolf (Norwegian Marine Technology Research Institute A/S (MARINTEK)) | Stansberg, Carl Trygve (Norwegian Marine Technology Research Institute A/S (MARINTEK))
ABSTRACT A time-domain global hydrodynamic analysis of a TLP in 1830 m water depth is carried out. Extreme metocean conditions in the Gulf of Mexico are simulated, including waves, current and wind in noncollinear configurations. 3-hours storms are analyzed. Wave loads on the hull are modeled by use of second-order diffraction analysis (WAMIT), including low-frequency (LF), wave-frequency (WF) as well as high-frequency (HF, springing) excitation. In addition, viscous drag forces on the hull due to relative motions in waves and current are included through a distributed slender-body load model, and wind loads are included through wind coefficients. The vessel motions are dynamically coupled in the time domain to the top-end tether and riser tensions, through detailed FEM (Finite-Element-Modeling) assuming slender-body hydrodynamics of this part of the system. The RIFLEX-C software is used. Using the SIMO software, de-coupled analyses are performed for comparison. Observed coupling effects are analyzed and discussed. The results are compared to data from 1:87 scaled model tests. Irregular wave and wind records from the actual experiments are used as input in the simulations, making direct comparison of time series and spectra possible. The capability of the numerical model to reproduce observed effects in vessel motions as well as in tether and riser tensions is evaluated, including LF-, WF- and HF contributions. Based on the comparison, hydrodynamic parameters of the numerical model are adjusted to match the measurements. Large damping contributions from the deep-water risers and tensions are identified. INTRODUCTION The need for advanced numerical computer tools for the global analysis of deepwater floating systems is growing as the oil industry is going into deeper and deeper waters. This has several reasons. First, the deep water itself represents new technical challenges and phenomena to be explored and taken into account in the system design.
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
ABSTRACT The existing optimization methods only take into account the lowest initial cost or the lightest initial weight. In fact with these methods, it may result in such design which is the lowest level design meeting the requirements of code at time the platform is put into operation. While due to the corrosion behaviour of ocean environment, the sectional dimension of structure components will decrease and the performance of steel will deteriorate gradually. So after very short time some constraints will not be satisfied and the maintenance measures should be taken immediately in order to ensure safety. In this paper, the fuzzy optimum design model of offshore jacket platform with consideration of corrosion is proposed. By means of corrosion dynamic equations, the design variables and material parameters are substituted into constraints after reduced on the base of scheduled maintenance time, while in objective function they are taken the initial values. With the illustrative example of Bo-hai BZ28–1 storage platform, the feasibility and validity of fuzzy optimum design model established in this paper is illustrated. INTRODUCTION Because of the intensely corrosive environment of ocean, the sectional dimension and material property of offshore platform will decrease or decline due to chemical action and electrochemical action of seawater. The rational optimization design technique should dynamically consider the varying procedure of design variables and allowable ranges of constraint, and take cost of structure at initial designing period as objective function, while take actual sectional dimensions and material strength at scheduled maintenance time as parameters in in constraint expressions. In the optimization design of offshore jacket platform, strength constraint, stability limitation and dimension restriction of design variable are all fuzzy subset on the real number field. So it is rational and necessary to lead in fuzzy optimization technique in design of jacket platform.
- Asia > China (0.29)
- North America > United States (0.28)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (1.00)
Experimental And Analytical Study For the Installation of Flexible Pipe In Existing Submarine Pipelines By Pipe-in-Pipe Technology
Mochizuki, Takashi (Nippon Steel Corporation) | Sakamoto, Takashi (Nippon Steel Corporation) | Yamada, Tomohiro (Nippon Steel Corporation) | Hayashi, Takayoshi (Idemitsu Kosan Co., Ltd) | Ishii, Kenichi (The Furukawa Electric Co.,Ltd) | Kagoura, Toru (The Furukawa Electric Co.,Ltd)
ABSTRACT The pipe-in-pipe technology has been developed by the authors for one of the Japanese oil refineries in order to apply the new technology in the renovation project of the existing old submarine pipeline with more than 3 km length. In the project the newly designed flexible pipe, similar to flowlines applied in the subsea projects in the world, is installed in the existing 18 inch submarine pipeline with several bends by pulling the head of the flexible pipe. The flexible pipe can be designed against the appropriate tension expected in the installation by the selection of size and number of wires called as tension members. However, the weight of the flexible pipe might be too heavy if the tension members are wrongly designed. In this report the experimental works for the pulling tension of flexible pipes with small-scale and full-scale models are shown first. Then the analytical studies based on a simple beam theory to calculate the pulling tension are presented to simulate the experimental results. Finally, the measured tension in the actual renovation project, which was successfully executed in June 2002 in Japan, and the calculated tension are compared. INTRODUCTION Under the severe economic conditions prevailing in Japan and elsewhere, Japanese oil refineries have been curbing capital investments and promoting longer service life of the existing equipment through stepped-up maintenance. For pipelines, importance is being placed on such technologies as inspection, maintenance and renewal, and the inspection technology by means of intelligent pigs and spot renovation using outer sleeves are already in practical use. As for the renewal technology of pipelines, two methods are in use, i.e., the "Insituform" by lining the pipeline from the inside with hardenable resins and the "pipe-in-pipe technology" by inserting new steel pipe into the pipeline.
ABSTRACT This paper presents the experience accumulated by Saipem in modelling the deep water sealine installation by using the J-lay method, mainly as a result of the Blue Stream Project. This Project implied the installation of two sealines in the Black Sea at a world record water depth of about 2150 meters by using the new J-lay system on SSCV Saipem7000. The paper shows the results of the studies made in order to properly model the installation of a deep water pipeline by J-lay. These studies aimed at the development of an adequate installation analysis model and tools (specially developed three-dimensional FEM analysis inhouse program), and at the definition of the installation analysis methodology. Such methodology includes the analysis of the effects of vessel displacement (forward, backward, and lateral) with respect to the target (reference) position, of seabed slope and real profile, and also the dynamics effects due to environmental loads. INTRODUCTION The offshore industry is moving into more hostile and deeper waters with exploration and oil field development and with gas trunklines crossing deep seas, as the Mediterranean Sea and recently the Black Sea. Saipem Group is in the forefront of such challenges by performing successfully the Blue Stream Project, undoubtedly the most significant deep water pipeline project ever attempted because of the difficulties in terms of design, construction, organization and logistics. Such demanding Project required important engineering efforts for both design and installation engineering, including the development of new design methodologies and tools, especially for the ultra deep section of the pipeline installed by using the new J-lay system on SSLV Saipem 7000. This paper presents the experience accumulated by Saipem, mainly as a result of the Blue Stream Project, in modelling the deep water sealines installation by using the J-lay method.
- Europe (0.94)
- North America > United States (0.46)
ABSTRACT A numerical model is proposed for the pore pressure build up in soil around a pipeline subjected to horizontal cyclic loading. The model is based on results of centrifuge tests, and the effect of various factors on the pore pressure build up is investigated through some examples using the proposed numerical model. It is found that the pore pressure build up component due to horizontal cyclic loading depends significantly on the initial settlement ratio as well as the ratio of horizontal to vertical load. It is also shown that a peak appears in the pore pressure build up response when the initial settlement ratio is larger than about 0.2. INTRODUCTION It is very important in pipeline design to evaluate the pore pressure build up in the soil around a pipeline on the seabed due to direct wave action and induced currents. The pore pressure accumulation will reduce the effective strength of the soil and degrade the bearing response of a pipeline. The reduction of bearing capacity can lead to large vertical and horizontal displacements of a pipeline. In particular, an increase of horizontal displacement of the pipeline may lead to sudden break-out, which has a serious influence on the safe operation of the pipeline. It is therefore very important for design engineers to be able to estimate the pore pressure accumulation in the soil around a pipeline under horizontal cyclic loading conditions. Although conventional small-scale model tests do not correctly model the in situ stress levels arising from gravitational body forces and also the model behavior does not accurately represent the scaled prototype response, geotechnical centrifuge testing can achieve the same state of stress in a model. Centrifuge models in offshore engineering have been used extensively to investigate the behavior of various types of offshore foundations (Murff, 1996).
- North America > United States (0.46)
- Oceania > Australia (0.30)
- Research Report > New Finding (0.50)
- Research Report > Experimental Study (0.40)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers (1.00)
ABSTRACT This paper investigates the relation between the two classic strength failure criteria, i.e. the Tresca and von Mises criteria, and their role in predicting failure pressure of line pipes with or without corrosion defects. The objective of this paper is to determine practical conditions for which each strength criteria is appropriate. Based on the instability theory of deformation and the finite strain theory, a plastic collapse model for the end-capped defect-free pipe is first developed. The constitutive behavior of materials is characterized by a power-law hardening stress-strain curve, and the plastic deformation obeys the Mises yield criterion and the associated deformation theory of plasticity. An approximate relationship between the T/Y (tensile-to-yield strength) ratio and the strain hardening exponent n is thus presented, and a closed-form solution to the limit pressure of pipes is formulated. This plastic instability solution is then extended to predict the failure pressure of corroded line pipes, and validated using the PRCI experimental database. The results show that using the nominal stresses of thin-walled pipes,the Tresca criterion reasonably predicts the failure pressure of line pipes for high strain hardening materials, the von Mises criterion reasonably predicts the failure pressure of line pipes for low strain hardening materials, an averaged result of the Tresca criterion and Mises criterion as postulated elsewhere approximates the failure pressures of line pipes for moderate strain hardening materials. INTRODUCTION The two classic strength failure criteria, i.e. the Tresca criterion and von Mises criterion, are simple and extensively used in engineering structure analysis and design. The Tresca criterion is based on the maximum shear stress, while the von Mises criterion is based on the von Mises effective stress. Therefore, it is necessary to establish which strength criterion is appropriate in predicting the failure pressure of a pipe or cylinder.
- Overview (0.48)
- Research Report > Experimental Study (0.34)
ABSTRACT This paper presents details of the methodology as well as representative results of subsea pipeline spill occurrence analyses for realistic Alaska Offshore Continental Shelf (OCS) oil and gas development scenarios ranging in life cycle duration up to the year 2038. Important general results included the distributions of spill size and occurrence frequency among pipeline locations, project life cycle spill histories, variability in spill indicators due to Arctic effect probability distributions, and comparative spill expectations for Arctic and similar non-Arctic pipeline projects. Conclusions and recommendations for future work are given. The three spill occurrence indicators - annual frequency, annual frequency per barrel produced, and spill index - exhibit a wide range of values varying with location, scenario year, facility composition, and spill size. Correlations and trends analyzed are presented in the conclusions. INTRODUCTION The U.S. Minerals Management Service (MMS) Alaska OCS Region uses oil spill occurrence predictions for National Environmental Protection Act assessments for all parts of their area of jurisdiction, ranging from onshore through shallow water, to deeper water. Although some Arctic spill statistics are available for onshore locations and a paucity of spill data for shallow offshore locations exists, there are no data to characterize spill rates in deeper waters in the Beaufort and Chukchi Seas, for forthcoming lease areas. Accordingly, the present study was implemented to develop and apply methodologies for the assessment of oil spill rates associated with exploration and production facilities and operations in the Chukchi and Beaufort seas. The prediction of the reliability (or failure) of systems without history can be approached through a variety of mathematical techniques, the most preferable and accepted being fault trees (Bercha, 2000, 1990, 1978; Bercha & Associates, 1978; US NUREG, 1975), and their possible combination with numerical methods such as Monte Carlo simulation.
- Government > Regional Government > North America Government > United States Government (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Oil & Gas > Midstream (1.00)
- Health, Safety, Environment & Sustainability > Environment > Oil and chemical spills (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)