bluuebunny/crossref_metadata_2025_split huggingface dataset:
Consolidation Around Seabed Pipelines
Authors: Gourvenec Susan , White David 
Published: July 2010

Abstract
The build-up of pipe-soil resistance that can be mobilized on a seabed pipeline, particularly in the axial direction, is affected by consolidation of the seabed beneath the pipeline after it is laid. On fine-grained soils the consolidation period may extend well beyond the laying period, and involve a significant gain in pipe-soil resistance: a process analogous to the set-up of piles driven in clay. The available level of pipe-soil resistance affects many aspects of pipeline design, such as stability on route curves and down slopes, geohazard vulnerability, lateral buckling and axial walking behaviour. This paper considers consolidation around on-bottom pipelines through a numerical study, supported by field data. The soil is modeled as an elastic material with coupled Biot consolidation. Pipe embedments of up to 0.5 diameters have been considered and the effect of soil berms adjacent to the pipe, formed of the displaced soil, has been explored. The solutions and guidance provided in this paper allow pipeline designers to estimate the ‘set-up’ periods over which the effective stress at the pipe-soil interface will rise in the period after laying, indicating the build-up of available axial pipe-soil resistance. The results account for the enhancement of this resistance through a ‘wedging’ action. The dissipation process is retarded by a factor of up to 2 if the displaced soil forms a berm that is collapsed against the pipe wall. Similar solutions for the analogous situation of consolidation (‘set-up’) around driven piles have existed for many years. This paper provides the equivalent design tool for on-bottom pipelines.

Background
Subsea pipelines are commonly laid directly on the seabed. The axial resistance that can be mobilized between the pipe and the seabed is an important consideration for both the installation and the in-service behaviour. It is an input into the following design aspects, and others:Resistance during shore pulls and bottom-tow installation.Stability of route curves during laying.Stability on a sloping seabed.End expansions and buckle feed-in in response to internal temperature and pressure.Restraint to support the pipe adjacent to externally-loaded sections - such as when impacted by submarine slides.
When a pipe is laid on the seabed it penetrates into the surficial soils, which are typically very soft in deep water. In finegrained clayey soils the usual rate of laying is such that the embedment response is undrained. Excess pore pressure is generated in response to the imposed weight of the pipeline, and due to shearing of the soil. The effective stress in the soil remains low, as it was in situ, until drainage occurs. After full dissipation of the lay-induced pore pressure, the sum of the vertical effective stress around the pipe-soil contact equals the pipe weight.
Prediction of Wave Impact in Extreme Weather
Authors: Stansberg Carl Trygve , Baarholm Rolf , Berget Kjetil , Phadke Amal C. 
Published: July 2010

Abstract
There is a need for improved analysis and verification tools against wave impact, partly due to updated metocean criteria in various geographical areas, but also due to the complex nature of the problem. Model tests are usually recommended in the final design verification. In this paper, improved engineering methods and procedures in predicting wave impact loads on FPSO's and offshore platforms in severe weather are described. Applications include wave-in-deck on jacket platforms, wave amplification with wave impact on large-volume platforms, green water /bow flare slamming on FPSO, and impact on columns. The resulting theoretical procedures and tools are in particular intended for early stages in the design.
State-of-the-art knowledge is combined with systematic analyses of experimental data. New recommended tools and practical procedures for the fast, accurate and robust prediction of wave impact loads due to random waves are established and validated against model tests. Robust and practical methods are emphasized. Basic physical mechanisms and parameters critical to wave impact are pointed out. Experimental data includes existing data sets as well as new experiments. New engineering software tools are developed. Recommendations on model testing procedures are also given.

Introduction
Hydrodynamic impact loads resulting from random, extreme ocean waves are important factors in the design of ships and offshore structures. This includes extreme global loads such as ringing and whipping, global impact loads on fixed and floating platform type structures, and local impact loads due to green water, bow slamming and wave-in-deck impact forces. An example of the type of practical problems that may occur is the bow flare slamming event that was experienced on the Schiehallion FPSO North of Scotland /1/. The relevance of the wave impact problem is recently also increased due to new metocean criteria being established /2,3/. Because of the strongly nonlinear effects, and limited accuracy or robustness of available theoretical models for such applications, the loads are often estimated by use of model tests in offshore basins. Examples from experiments with structures in extreme waves are shown in Fig. 1.
Special Session : Advances in Flexible Riser Technology: Challenges of Flexible Riser Systems in Shallow Waters
Authors: Hanonge Didier , Luppi Ange 
Published: July 2010

Abstract
While much focus is given to the challenges of designing and manufacturing riser systems for extreme deep waters, the challenges are certainly not less when one tries to push the limit at the other end of the spectrum: in very shallow water. Due to their advantages FPSO's are being used in increasingly shallow waters (less than 50m water depth is current practice in Vietnam now days). This puts real challenges on the mooring and riser designers together with FPSO contractors and forces them to come up with novel configuration designs in particular when the very shallow water is combined with harsh environmental conditions and significant vessel motions. An active collaboration between the mooring and the riser designers is then of upmost importance, and requires validation of the concept at the earliest stage of the project: during FEED studies.
The main challenges reside in the need to accommodate the two extreme positions of the surface floater (Far/Ballasted and Near/loaded) which often result in contradicting requirements. Interference is also a main concern, be it with the hull of the FPSO, the seabed, the free water surface or other risers. Marine growth is also a critical issue as it impacts the riser configuration on the full length. To adequately address all those requirements, novel, generally complex, configurations are needed using combinations of clump weights, tethers, buoyancy elements and rigid or flexible structural members.
This paper will present and discuss the different issues faced when designing flexible riser systems in these very shallow waters and present a number of novel solutions to address those. It will also present some actual field experience on two very shallow water riser systems installed over the last two years and will explain how the designer reached the specific chosen solution.

Introduction
This paper will concentrate on challenges of flexible riser systems design (this is mainly focusing on unbonded flexible pipes but may be fully applied to umbilical) in very shallow waters, typically around 50m water depth.
Unbonded Flexible pipes are key elements for offshore oil & gas production, enabling connection of subsea wellhead to floating platforms in shallow to ultra deep water fields. Design of these risers is a complex and long iterative process; design criteria are well defined in relevant codes and standards (See Ref. [1], [2]).
Offshore Liquefaction of Natural Gas
Authors: Unum Arnfinn Ingar 
Published: July 2010

Summary
BW Offshore (BWO) has operated 3 gas liquefaction FPSO's in the period 1983-2005, two units in Angola (same field) and one unit in Nigeria.
The units liquefy LPG and partly fractionize the components into a controlled single phase or mixture, and it normally involves pre-treatment in the form of separation, dehydration and dew point control.
Capacities vary between 5,000 bpd and 12,000 bpd of gas mixture.
The vessels used are converted gas carriers, where existing storage systems are utilized.
The vessel sizes are typically 35 meter wide and 220 - 230 meter long with cargo capacity approximately 70 - 75,000 cubic meters.
Usually, some of the boil off is used for fuel, while regasification units are used to keep cargo volumes cold and stable.
Offloading is by flexible hoses held by cranes.
The Angola operations are in relatively benign conditions with normal wind speeds of less than 20 knots, but local thunderstorms and wind gusts up to 75 knots can be experienced. Swell of 15 feet is normal.
The Nigeria operation was in the Niger Delta with benign conditions but significant currents from time to time.
During more than 20 years of operation, no problems of significance have been experienced, but precautions have been implemented for offloading by installing Azimuth thrusters and special procedures. Only one offloading has been missed due to environmental conditions.
Based on the LPG FPSO's operational experience, BWO has developed a more generic design through concept developments and studies. Two of these are described in more detail.
Basically, this design includes higher capacities (250 MMscfd of natural gas), more extensive pretreatment and a design to internationally recognized standards. Otherwise the operational mode and offloading is based on the principles from the operating units. DNV has approved the concept.
Furthermore, BWO has developed a liquefaction FPSO handling LNG. This unit handles between 250 and 300 MMscfd of gas and produces 1.7-2 Mtpa of LNG. Storage capacity of LNG is 180,000 cubic meters and there is room for another 100,000 cubic meter of storage for other hydrocarbons (condensate, potential LPG).
The vessel is 60 meters wide and 350-390 meter long depending on deck space and storage needs, with a Moss type LNG storage system.
Parque das Conchas (BC10): Subsurface Challenges in Developing a Deepwater Shallow Structurally Complex Field.
Authors: Stockwell Leon L. , vanKonijnenburg Jan-Henke , Stewart Greg , Holmes Gunnar , Zambrano Santiago 
Published: July 2010

Abstract
As part of the Parque das Conchas project, located in the BC-10 block offshore Brazil, the structurally complex Cretaceous moderately heavy oil " Ostra?? reservoir is developed in a deepwater, shallow overburden setting. Based on data from a vertical exploration and an appraisal well, the development plan called for completion of six producers with 600-1100m long horizontal sections. The integration of subsurface and drilling data and technology was critical in overcoming numerous challenges encountered during drilling.
Challenges encountered included:The shallow nature of the field (~900 mTVD below mudline) necessitated starting the build-up section near the mud line. Building the 16?? hole to 40º in 550 m TVD proved to be very challenging in the soft Pliocene and Miocene sediments using the original drilling assembly.The 12 1/4?? build-up section was drilled with synthetic-based mud (SBM). Build rates were problematic; Induced fracturing, opening of minimum-stress faults and the presence of high permeability sands resulted in substantial SBM losses.The high net-to-gross (NTG) reservoir model predicted from the vertical well control, and the need for gravel pack sand control, lead to a completion interval design with a straight line well path inclined near 88º for the 9.5?? reservoir section. This philosophy based on the appraisal and exploration data proved too simplistic and changes to the well trajectories were made to account for the formation encountered.
Many aspects of the drilling planning and while-drilling procedures were updated to improve performance and well placement. Mud weights were reduced, drilling fluids modified, and BHA configurations changed to meet the challenges faced while drilling the wells. The basic well design and drilling philosophy was updated to include geo-steering in the reservoir and additional pilot wells were drilled in the field. Advanced technology logging while drilling (LWD) tools (such as the Deep azimuthal resistivity, Imaging, and NMR) were incorporated to optimize the available data and to increase reservoir penetration. The correlation of 2D and 3D seismic data to steering ratios, build angles, rate of penetration, and weight on bit were novel approaches to improve wellpath planning and optimize geosteering. Collaboration of the subsurface and drilling teams lead to significantly improved drilling performance and well placement over the course of the 6 wells drilled to date.
SS: Mooring System Integrity: Phase 2 Mooring Integrity JIP - Summary of Findings
Authors: Brown Martin , Comley Andrew , Eriksen Morten , Williams Ian , Smedley Philip , Bhattacharjee Subir 
Published: July 2010

Abstract
Phase 1 of the Mooring Integrity JIP, as reported at OTC 2005 [2], highlighted a number of important mooring integrity challenges for the offshore industry. To address these challenges phase 2 was launched, which has attracted the support of 38 international participating organisations including Oil Companies, Operators, Design Contractors, Equipment Suppliers, Consultancies and Regulatory Authorities.
This paper presents a summary of some of the finding from the Phase 2 JIP, which has focused on testing, data gathering and improving design guidance. This paper covers the following areas:Formulation of a practical method to estimate wear/corrosion based on calibration with field measurementsFeedback on the break testing of worn mooring componentsThe influence of proof load on fatigue enduranceMaterial compatibility guidanceReview of the effects of Microbiologically Influenced Corrosion (MIC)Guidance on how to monitor station keeping performance and what to do with the data receivedSummary of mooring line failure detection optionsInspection guidance for ROV operators
Phase 2 has continued to bring to the fore the importance of mooring integrity which has led to improved offshore inspection and condition monitoring. This paper presents the steps which have been put in place to improve mooring durability both in terms of design and integrity management, based on the operational experience. This information is thus fed back to designers to improve future systems.

Introduction
Phase 1 of the Noble Denton managed Mooring Integrity JIP highlighted the susceptibility of the moorings on even custom designed Floating Production Systems (FPS's) to a number of degradation mechanisms [1] and [2]. This led to the launching of our phase 2 JIP to try to tackle some of the most pressing issues. Phase 2 has been well received by the industry and the number of participating organisations has increased from 23 in phase 1 to 38 in phase 2.
During the course of the phase 2 JIP a number of high profile mooring failures have continued to take place, see for example [3] and [4]. These problems have illustrated the continuing difficulties of achieving mooring integrity while also, in certain cases, providing vital forensic evidence as to the possible cause of some of the failures. The main subjects that have been studied in phase 2 are outlined in the bullet points in the abstract. It is appreciated that these represent a fairly varied collection of topics, but this was judged to be necessary to tackle the key priority areas of mooring integrity as quickly as possible. It should be noted that at the time of writing the JIP programme is still underway, so this paper represents work in progress to date.
Experience to date and future opportunities for subsea processing in StatoilHydro
Authors: Davies Simon R.H. , Bakke William , Ramberg Rune Mode , Jensen Roger Oen 
Published: July 2010

Abstract
Subsea processing involves one or more combinations of fluid conditioning and pressure boosting of wellstream fluids and water at the seabed. The main benefits of applying subsea processing include increased hydrocarbon recovery and accelerated production, together with reduced CAPEX and OPEX, and HSE benefits.
This paper provides an overview of field operating experience for subsea boosting in the LuFeng field and the separation, produced water reinjection and fluid boosting applications at Troll Pilot and the Tordis fields, including the Tordis restart plans. The paper also describes design and installation of the Tyrihans raw seawater injection and summarises the gas compression technology qualification activities underway for the Gullfaks 2030, Åsgard Minimum Flow and Ormen Lange Pilot projects.
An overview of Statoil's future subsea processing opportunities is then presented and discussed, including new opportunities being assessed at the Norne and Astero and fields.
All aspects of subsea processing are reviewed, including boosting, raw seawater injection, separation, sand handling and produced water reinjection, and subsea gas compression technology. The important role of large scale testing and technology qualification, and close collaboration with key technology suppliers is described, together with a step-wise approach to deploying increasingly complex subsea processing systems in ever more challenging environments. Step out distance, water depth and harshness of the local environment for new fields are all increasing and new, more cost-effective technologies will be need to profitably develop future fields.
It is concluded that subsea processing has already provided positive business upsides, despite certain technical challenges, and Statoil expects to continue a stepwise development and deployment of subsea processing technology in the near and longer term future.

Introduction
Subsea processing involves one or more combinations of fluid conditioning and pressure boosting of wellstream fluids and water (from a reservoir or from the water column) at the seabed. Conditioning can include water removal from hydrocarbons, separation of liquids from gas, separation of sand and other solids from fluids, fluid cooling (or heating) and chemical injection.
There are currently four main types of subsea processing application:Single and multiphase hydrocarbon boostingGas compressionSeparation systems (gas / liquid and liquid / liquid with produced water reinjection)Raw seawater injection
Fit-for-Service Assessment of Deepwater In-Service Low Toughness Mooring Shackles
Authors: Mcmaster Fraser J. , Abadin Jose , Waldhart Chris , Lee Yi-Der , Das Samrat , Greiner Bill 
Published: July 2010

Abstract
Due to a recent mooring shackle failure within the offshore industry, focus has been directed toward existing in-service facilities that have similar manufactured shackles installed in the mooring systems. An in-service deep water facility was identified as having similar mooring components by the same manufacturer that failed in-service. A subsequent assessment of the material properties was undertaken on readily available spare shackles that identified Charpy impact toughness values below the original material specification. Consequently, a fitness-for-service assessment was carried out that included the assessment of the shackle fracture toughness, a finite element analysis of the shackle and associated mooring components, and a deterministic analysis procedure that assessed the structural capacity of the shackle by considering the response of the shackle to the presence of a crack or flaw located at a shackle stress hot spot coupled with a significant return period event. Finally, full-scale structural testing of spare shackles was performed to enable verification of actual shackle load capacity with a flaw located at the shackle stress hot spot.
The focus of this paper is on presenting an overview of the fit-for-service methodology and the results of the structural integrity assessment. While a full quantitative risk assessment of the effect of a low fracture toughness shackle in the mooring system would have been ideal, due to the level of data available and the timeframe required for a probabilistic assessment, it was deemed appropriate to undertake a deterministic assessment of the mooring shackles under realistic scenarios representative of service and severe loads that may accompany the service. The results of the deterministic assessment on an actual in-service deepwater floating facility will be presented. The fit-for-service methodology presented in this paper provides a robust method to assess in-service floating facilities that have been identified or suspected of having below-specification mooring components. It has successfully been applied to a number of Chevron in-service floating facilities in different geographical locations.

Introduction
Following the early failure of a mooring shackle on a new deepwater floating facility, attention has been directed to other new and existing assets that have similar manufactured mooring shackles installed in the mooring system. Additionally, the release of Safety Alert No. 256 from the U.S. Department of the Interior (Minerals Management Service), provided recommendations to operators to review their current specification and testing requirements for mooring systems to ensure that the mooring components are adequate for the proposed or current usage.
Smarter Pipe-Soil Interaction in FE Pipeline Analysis
Authors: Deis R. , De Brier C. 
Published: July 2010

Abstract
Due to unknowns in soil behaviour, a new deep water in-situ system has been designed to measure the interaction forces between the seabed and pipelines in the vertical, axial, and lateral directions. The system was used for the first time in deepwater in 2008. Several lessons were learnt during this deployment and significant modifications of the system were carried-out before mobilisation of the equipment on a second deepwater project in 2009. The paper summarizes the recent developments of the system and presents typical testing procedure and test results with an emphasis on how a better knowledge of the pipe-soil interaction can improve reliability of pipeline design.

Introduction
The understanding of pipe-soil interaction for High Pressure High Temperature (HPHT) pipelines installed in deepwater weak soils is of paramount importance for reliable pipeline design. Considerable advancements have been made recently in the study of pipe-soil interaction at low effective stresses. However, there are still some knowledge gaps and assumptions to be validated (Hill and Jacob, 2008) motivating the need for in-situ measurements. The FUGRO SMARTPIPE® was developed to fulfil this need. The in-situ soil-pipe interaction results allow to investigate the fundamental properties of the deepwater near surface soils such as consolidation rates or pore pressure response during pipe movement. With this knowledge, it is possible to test and calibrate theoretical and empirical models against real pipe behaviour and in-situ (undisturbed) soil conditions.
This paper presents recent developments of the SMARTPIPE® tool following lessons learnt from the first deepwater deployment in 2008. The paper focuses on the main operational and Data Acquisition (DAQ) issues encountered during field work operations and on how these issues where addressed in order to ensure reliable measurements. A description of the system is provided. Main findings following the first deep water deployment (offshore West Africa, 2008) are described including recent system developments. Typical results of the last site investigation (Offshore West Africa, 2009) are presented to illustrate the capabilities of the equipment. Interpretation of test results collected during this project will be presented in a follow-up paper.

System Description
This section provides a brief overview of the system. More detailed information on the system can be found in Jacob and Looijen (2008) and in Hill and Wintgens (2009).