bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic Modeling Analysis and Characterization of a Gas Hydrate and Free Gas Mixed System in Green Canyon, Gulf of Mexico
Authors: Zhang Zijian , McConnell Daniel Russell 
Published: July 2010

Abstract
The Bottom Simulating Reflector (BSR) has been used extensively to interpret possible gas hydrate from seismic data. However, a BSR is not found in the Green Canyon (GC) 955 of Gulf of Mexico, where gas hydrate deposits were predicted and confirmed through drilling. The stratigraphic facies where gas hydrates are indicated by Logging Wile Drilling (LWD) drilling in GC955 have a complex amplitude response of high negative and high positive amplitudes showing both continous and discontinous character with different modes of stacking and complexity, e. g. low positive over high negative, high positive over high negative, etc. Rock physics-based modeling, with basic parameters guided by the existing well data, are used to decipher the complex amplitude signatures to discriminate gas hydrate sands from gas prone sands.
Field data are reprocessed conventional 3-D seismic data. Three scientific wells provide the basic constraints for the rock physics-based seismic modeling. The rock-physics modeling suggest that high positive amplitude and moderate to high peak/trough ratio are associated with high concentrations of gas hydrate; high negative amplitude and low peak/trough ratio will be associated with a gassy zone or a gas zone with low concentrations of gas hydrate above. The output of this modeling to the 3-D seismic data that traverse the scientific and industry well control points (wells) is consistent with drilled results and reveals variations in the depth of gas hydrate sands and gassy sands suggesting that there are localized non-equilibrium environments within the gas hydrate stability zone. The agreement with the drilled data suggests that a new and useful seismic attribute can delineate gas hydrate filled sands.

Introduction
A major challenge in gas hydrate exploration is the mapping of the distribution and concentration of gas hydrate deposits. As a gas hydrate indicator, the BSR has been used extensively in seismic interpretation of gas hydrate (Shipley et al., 1979; Hyndman and Spence, 1992). A BSR is parallel to the seafloor reflector and has the opposite polarity. Recent studies suggest that BSR is caused by a sharp drop in compressional velocity in the underlying gas zone (Singh et al., 1993; Mackay et al., 1994; Zhang and McMechan, 2006). Numerous expeditions have shown that the presence of a BSR does not correlate to high concentrations of gas hydrate above the BSR (Lu and McMechan, 2002; Tréhu et al., 2003). Thus, it is necessary to investigate better methods to image high concentrations of gas hydrate with seismic data. This paper reports a successful example of the application of rock physics based modeling to derive a seismic attribute, that when applied to conventional 3-D seismic data, identifies high concentrations of gas hydrate in Pliestocene clastic deposits in the Gulf of Mexico.
Converting Existing LNG Carriers for Floating LNG Applications (FLNG, FSRU, FSO)
Authors: Franklin David , Reeve Henry , Hubbard Brad 
Published: July 2010

Abstract
Despite the recent economic downturn and reduced need for LNG, long-term demand will be strong and opportunities to convert existing LNG carriers (LNGC) into floating LNG plants are growing. Costs, schedules, and permitting challenges for onshore LNG production facilities have trended upward making it difficult for project developers to get financing. Cost reduction strategies across the LNG value chain have resulted in significant changes in LNG shipping. To increase fuel efficiency, LNGC capacity has doubled in the past 30 years, and propulsion technology has migrated from steam to high efficiency diesel and dual fuel engines. Smaller, less efficient LNGCs are being displaced by new ships and the owners of the older LNGCs are seeking new roles for their vessels. This paper explores the opportunities and challenges of converting existing LNGCs for Floating LNG Liquefaction FPSOs (FLNG), Floating Storage and Regasification Units (FSRU) and Floating Storage and Offloading Vessels (FSO) service.
The costs of onshore LNG terminals with storage facilities, protected jetty, and cargo transfer equipment have increased sharply whereas converting an LNGC for liquefaction, regasification or storage creates a self-contained LNG terminal that can reduce overall LNG terminal cost by 30% to 50% compared to onshore alternatives.
Converting LNGCs into floating LNG plants raises myriad design challenges when developing a project. Specific project requirements will lead LNG project developers to choose the appropriate LNGC for conversion. Below is a partial list of topics, taken from experience, that require engineering study. These will be discussed further in this paper.Delivery flow rate and composition requirementsProducts to be marketedProject location specificsGas pre-treatment or LNG processing requirementsAppropriate ship type and size from available vesselsLiquefaction or regasification technologiesEquipment space requirementsVessel motion impact on process and storageMooring and berthing systemsOffloading configuration and methodsFitness for service and life extension, Class requirementsRequired utilities and integration with ship systems
DeepStar Jules Verne Subsea Processing Road Map
Authors: Lowry Timothy , Ray Tony 
Published: July 2010

Abstract
This paper presents the technology development road map prepared for the DeepStar Jules Verne Subsea Processing Study. DeepStar, the study sponsor, is a joint industry technology development project focused on advancing technologies to deliver increased production and reserves for its member's deepwater assets.
The purpose of the Jules Verne Study was to:Evaluate the technical maturity of an all subsea processing development of a subsalt, high pressure, high temperature, black oil field in the Gulf of MexicoIdentify the gaps related to the all subsea processing developmentPrepare a program of projects (Road map) to close these gaps
Gaps for the following subsea systems were identified during the Jules Verne Study:Boosting (single phase liquid, gas compression, multiphase)Controls / Instrumentation (to identify technologies required for an all subsea processing development)Power Transmission / Distribution (high voltage umbilicals, connectors, penetrators, transformers, variable speed drives, circuit breakers, switchgear, etc…)Subsea Separation (gas-oil-water separation—including sand management and produced water treatment)
Other supporting systems were also evaluated, including, raw seawater injection systems and subsea chemical storage / injection systems.
Qualification of Dynamic Deep Water Power Cable
Authors: Slora Bjorn Roger , Karlsen Stian , Lund Sjur , Osborg Per-Arne , Heide Kristian 
Published: July 2010

Abstract
The exploration of new oil- and gas fields tends to go to deeper waters. Electrical power is mainly required for subsea processing equipment. In addition there is a growing demand for Direct Electrical Heating of pipelines, also in deeper waters. Consequently, there is a growing demand for dynamic deep water power cables in the offshore industry.
Hence, Nexans initiated a development programme to qualify a dynamic deep water power cable for 3000 m water depth in accordance to DNV-RP-A203.
Power cable conductors are made of pure Electrolytic Tough Pitch (ETP) copper due to its excellent conductivity. Due to its mechanical properties it is found imperative that the cable design relieves the copper stress in deep waters.
A double armoured three-phase power cable concept was selected for the qualification programme. An ingenious design, with special emphasis on controlling the lay-angles and radial displacement, has shown to be crucial in order to achieve the desired stress distribution in the cable and preventing mechanical over-loading of the copper conductors.
The electrical integrity of the manufactured prototype cable was intact after tensioning to 2040 kN, which corresponds to 13 000 m static water depth.
Careful examination and comparison of results from testing and cross sectional analysis has verified that the stress distribution in a dynamic deep water copper cable can be properly determined.
The study has documented, by cross section analysis and dynamic analysis, that the prototype cable will withstand the extreme loads and more than 300 years in operation at 3000 m water depth with good margins.
As the final step in the qualification programme a full scale flex test will be performed to verify that the cable is capable of withstanding the extreme and fatigue loads during a service life of 30 years.
SS - Gas Hydrate : Study for the Estimation of Seabed Stratum Deformation in Methane Hydrate Production
Authors: Ogisako Eiji , Nishio Shinya , Denda Atsushi , Oka Fusao , Kimoto Sayuri 
Published: July 2010

Abstract
The simulations and numerical analyses of triaxial compression tests on soil samples recovered from the East Nankai trough have been performed by the elasto-viscoplastic constitutive equation. And the numerical analyses of the laboratory model tests on ground deformation in methane hydrate production were carried out by finite element method. From the comparison with the experimental results it is proved that the simulations can express well the behavior of experiments and the numerical analysis results can well reproduce the deformation behavior of ground in the model tests.

Introduction
Methane hydrate is currently being eagerly examined as a next-generation energy resource in Japan to replace oil and natural gas. The Research Consortium for Methane Hydrate Resources in Japan was established to undertake research in accordance with Japan's Methane Hydrate Exploitation Program prepared by the Ministry of Economy, Trade and Industry. To produce methane gas from methane hydrate safely and without damaging the environment, it is necessary to address many wideranging environmental issues. One of them is to assess seabed deformation during methane gas production. In the above Consortium we are investigating the deformation of seabed ground which may occur due to the production of methane gas from methane hydrate.
Geotechnical properties of seabed ground have a significant effect on the deformation behavior. Soil samples were recovered from the East Nankai trough which is expected as one of the fields of natural resources of methane hydrate. We performed the soil index tests, consolidation tests and triaxial compression tests on these soil samples and estimated the geotechnical properties of soil samples based on the results of these laboratory tests. Then we identified the material parameters for the elasto-viscoplastic constitutive equation which can express the mechanical properties of the seabed ground and we performed simulations of triaxial compression tests on soil samples by this constitutive equation. Further we developed a simulator for the estimation of seabed ground deformation using the above constitutive equation. We carried out the laboratory model tests on ground deformation in methane hydrate production and we performed the numerical analyses of these model tests by this simulator.

Outline of Triaxial Compression Tests
The digging of wells was carried out in deep sea at the East Nankai Trough. We performed triaxial compression tests on core samples recovered from the Nankai Trough Well (Nishio et al., 2006). The triaxial compression tests were carried out in K0 consolidation undrained condition. The depth of core samples used in tests is 8.5-225.0m below the seabed surface. The samples used in the tests are mainly cohesive soil.
Large scale condition monitoring for a subsea gas compression system pilot
Authors: Eriksson Klas Goran , Staver Knut Ola 
Published: July 2010

Abstract
A pilot for a subsea 12,5 MW Gas compressor system is built, and will be operated in an onshore test pit environment for 2 years before being evaluated and deployed subsea. Several new components have been qualified during the pilot project, e.g. subsea UPS, subsea High Voltage Circuit Breakers, subsea Variable Speed Drives, Active Magnetic Bearing system and electric valve actuators. During these 2 years of pilot testing, a large number of parameters will be monitored and logged (in the order of 1 million data stored per second). After 2 years, there will be logged appr. 250 TByte of data. The intended use of this data is to obtain detailed knowledge on the behavior of the various components, to observe gradual degradation in performance over time, and for trouble-shooting and diagnostics in case of upsets. For the final subsea plant, the goal is to have a system for Condition Based Maintenance, based on the knowledge gained during the pilot testing. This paper describes the plant, the various data sources, the data network collecting the data, the storage system and the retrieval / visualization / analysis system.
Lessons Learned From Observing Walking of Pipelines with Lateral Buckles, Including New Driving Mechanisms and Updated Analysis Models
Authors: Bruton David A.S. , Carr Malcolm , Sinclair Forbes , MacRae Ian 
Published: July 2010

Abstract
Pipeline walking is a phenomenon that causes global axial movement of a whole pipeline. Pipeline walking has been observed on a number of pipelines to date and if left uncontrolled can lead to potential failures at connections or risers.
Designing to control or mitigate pipeline walking can result in significant changes to field layouts and high installation costs associated with pipeline anchors, which have been installed on a number of recent developments. It is therefore essential to be able to assess whether walking is a potential issue early in the design process.
Walking is a stepwise ratcheting mechanism that occurs during changes in operating conditions, particularly during shutdown and restart operations. A number of contributory mechanisms are known to cause pipeline walking:Sustained tension, applied to the end of a pipeline by a steel catenary riser (SCR);Seabed slopes, along the pipe length, defined by route bathymetry;Thermal transients, defined by changes in fluid temperature and thermal loading during shutdown and restart operations;Multiphase flow behavior during shutdown and restart operations.
This last multiphase flow mechanism has only recently been identified from observation and measurement of operating systems and is not addressed by previously published analytic pipeline walking models developed by the SAFEBUCK JIP, published at OTC in 2006[1]. This fourth mechanism is described along with a discussion on the impact of multiphase flow on pipeline walking, axial friction response, anchor loading and route curve stability. A new analytic modeli is presented to assess pipeline-walking rates due to this behavior.
This paper also illustrates pipeline-anchoring solutions that have been employed to control pipeline walking on a number of deepwater developments and discusses the issues with these control methods, including the increased potential for route-curve pullout. The paper also investigates the complex interaction between pipeline walking and lateral buckling. It is known that lateral buckles along a pipeline can significantly influence both pipeline walking and end expansion predictions. The complex cyclic interaction is explained and methods for predicting the cyclic response either analytically, or using FEA techniques, are described. i Errata - This revision includes updates to equation 11.
Bottom Current Measurements at GoM Furrows for the Cascade and Chinook Fields Development
Authors: Lima Jose Antonio , Ribeiro Eric Oliveira , Daniel Jeremiah , Ivanov Leonid I. 
Published: July 2010

Abstract
This paper presents near-bottom current profile measurements in furrows located east of the Sigsbee Escarpment in the Cascade-Chinook field development flowline route from the facilites to the Chinook manifold in the Walker Ridge region of the Gulf of Mexico in water depths greater than 2500 meters. These furrows are deep channels aligned with the southwestward direction and in a variety of configurations with typical dimensions of 5 to 10 meters depth and 15 to 50 meters width. The measurement systems were custom designed bottom frames with acoustic current profilers and turbidity sensors deployed by Remotely Operated Vehicle (ROV) to accurately position the frames in predetermined positions inside the furrows. An innovative approach was developed to address cost effectively the technical challenge of the scheduled regular 4-month data recovery. To reduce costs, it was elected to deploy an acoustic modem from a vessel to download data from the subsea frames in lieu of recovering and redeploying the frames with the use of an ROV.
In general the Sigsbee Escarpment region experiences a complex deep water flow regime not completely evaluated or understood as yet. The steep gradients of the continental slope act as a wave guide for many flows associated with conservation of potential vorticity such as the Topographic Rossby Waves (TRW). The propogation of these waves and their flow affects the bottom currents in the furrows and on the sea floor. Spectral analysis of the bottom current measurements indicated a 12-day coherence peak that may be associated with TRWs. Speed values above 0.30 m/s were measured at the first bottom bin and the direction of the flow was most frequently aligned with the furrow's main axis.

Introduction
The production facilites of Petrobras America Inc. (PAI) Cascade and Chinook fields in Walker Ridge Block 249 and adjacent blocks are close to the base of the Sigsbee Escarpment. There is limited knowledge of the currents at the site in this complex bed form. PAI launched a rigourous current measurement program at the site which included measurement of current in the furrows, to develop an appropriate current profile design criteria for the project. This paper provides the preliminary data analysis of measurements taken over a 12 month period by PAI Contracor, the Woods Hole Group (WHG).
Figure 1 provides a general view of the eastern Sigsbee Escarpment and furrows fields on the vicinity of Cascade and Chinook fields, located on Walker Ridge area.
Demonstrating the Feasibility of Steel Catenary Risers from a Cylindrical FPSO in Harsh Deepwater Locations
Authors: Aarsnas Jan V. , Major Fredrik , Rooney Phelim , Muren Jan 
Published: July 2010

Abstract
The cylindrical FPSO is now in operation at three offshore oilfields, on in Brazil and two in the UK Central North Sea. It is furthermore selected for a field development in the harsh and sub-arctic Norwegian Barents Sea. Full scale monitoring of motions on units in operation has verified predictions, confirming very favorable motions when compared to shipshape FPSOs and even semi submersibles.
In 2009, a study was awarded by a major oil company to investigate the feasibility of applying Steel Catenary Risers (SCR) with a cylindrical FPSO at a location with deep water and very harsh environment. Results from the initial analysis proved feasibility and associated model testing has allowed calibration of first order and second order analysis methods and particularily have lead to a better understanding of second order and heave coupled pitch motion effects.
Adaptation of the cyclindrical hull to improve its characteristics as a host platform for steel catenary risers has been the incentive for the case study outlined in this paper. Platform and riser optimisation should be field specific, but the results presented for a very harsh environment, demonstrate the feasibility of steel catenary risers with a cylindrical FPSO at any location, worldwide.
In this paper, the focus is on demonstrating how a cylindrical FPSO/SCR design spiral can progress towards meeting the challenges of a harsh environment with competitive hull/riser combinations.

Introduction
The cyclindrical FPSO/SCR challenge is to provide an SCR hang-off location with motions, as follows, even in very harsh environments.The maximum downwards vertical velocity in 100-year design conditions should be less than 2,4 m/s (1,9m/s in 100 year conditions is achieved)The long term distribution of all motions at the riser hang-off shall provide a robust SCR fatigue life (achieved with low amplitude heave RAO within Tp range with high % occurrence)Angular motion should stay within a range of +/- 25 degrees at hang-off (achieved 18,1 degres)Horizontal offsets envelope within 2,5% of waterdepth in 100 year conditions with intact mooring (achieved 2,3%)
A cylindrical FPSO with SCR hang-off in a moonpool is demonstrated to meet the above criteria with margins, even for very harsh environments. The Cylindrical FPSO is arranged so that the SCR hang-off is located very close to the centre of the FPSO, within a moonpool, and thus the predominantly heave induced vertical motion at the riser hang-off meets SCR hang-off motion targets. Mooring systems are developed to meet the offset criteria.
The case study responses are reported for a 16" gas export riser, based on API standard seamless pipe dimensions with 5 mm corrosion protection coating, resulting in an "OD/weight submerged" ratio with 148 kg/m3 contents of 3,0 m2/tonne. Equivalent 123/4" and 103/4" production SCRs with contents 800 kg/m3 and high insulation are outlined for benchmarking.
The Medgaz Ultra Deep Water Pipeline Project
Authors: Chaudhuri Jay , Pigliapoco Mauro , Pulici Massimo 
Published: July 2010

Abstract
Recent completion of the marine pipeline linking Algeria and Spain across the Mediterranean Sea, with a 24-inch pipeline, as part of the Medgaz Gas Transmission project, successfully overcame the challenges of 2,155 metres water depths, deep water cable crossings and sea bed post trenching activities. This paper summarizes the various key design considerations addressed to meet the demanding requirements of the ultra deep Medgaz pipeline together with the engineering challenges met by Saipem in planning and executing the laying of the 24-in. gas pipeline in the Mediterranean Sea ultra deep water.
Design issues discussed include route optimization, efforts in relation to mitigating geohazards and challenging seabed topography characterising both Algerian and Spanish continental slopes. The intrinsic difficulties in performing intervention works in ultra deepwater, stimulated the application of advanced analysis methodologies for the assessment of in-service buckling and long term freespan fatigue. The installation of the Medgaz marine pipeline presented numerous difficulties which were of more complex nature than for the normal laying of a trunk line. Crossing of the Alboran Sea (the particular area of the Mediterranean Sea), (see Fig. 1) with a 24-inch pipeline that reached a depth of 2,155 metres was, without doubt, the most complex part of the entire works, involving two large semi submersible pipelay vessels: Castoro Sei and the Saipem 7000. The paper presents an overview of the main aspects of pipelay technology facing long trunk lines in ever great water depths and outlines the many engineering challenges faced as well as the solutions adopted that contributed to an effective development in pipelay technology. The presentation reviews also the post-lay intervention work using the Beluga deepwater trencher, the Innovator Remotely Operated Vehicle guiding ultra deep water laying and crossing of five existing seabed cable. Resolution of the many technical problems faced during the execution of the Medgaz Marine Pipeline project has proven the soundness of the engineering solutions adopted for the implementation of this ultra deep water pipelay project.

Introduction
The pre-commissioning of the Medgaz pipeline, one of the most important projects in the subsea deepwater pipeline gas transport sector ever implemented in the world for its complexity and technological content, was successfully completed in March 2009, in compliance with the target schedule (Ref. 1).