bluuebunny/crossref_metadata_2025 huggingface dataset:
A Force-resultant Model for Spudcans in Soft Clay and Application to Jack-up Push-over Analysis
Authors: Zhang Youhu , Bienen Britta , Cassidy Mark Jason
Published: April 2012

With the development of the offshore oil and gas industry, mobile jack-updrilling platforms are increasingly required to operate in deeper waters andharsher environments. The improvement of the jack-up site-specific assessmentpractice is vital for safely meeting this demand. In soft clayey seabeds, thespudcan foundations of the jack-up platform penetrate deeply into the soil, andcomplete or partial backflow occurs. In recent years, a number of studies haveinvestigated the performance of spudcan foundations in soft clay to improve therelevant recommendations in the industry guideline published by SNAME. In thispaper, a brief review of recent research in this area is first provided. Then,a force-resultant model that is suitable for performing integratedsoil-structure analysis is proposed. An example of the application of thismodel is finally provided, and important comparisons with the SNAME model aredrawn.

Introduction

Although they were originally designed and built for shallow waters, mobilejack-up platforms are now more broadly used for offshore drilling activities. Due to the development of the offshore oil and gas industry, the demand forjack-ups to operate in deeper waters and harsher environments has increased, requiring improved site-specific assessment practices for both economical andsafety considerations. In many offshore areas, such as the Gulf of Mexico, theseabed consists of soft clayey soil, which often features an increasingundrained shear strength profile with a small intercept at the seabed surface. Jack-up installation in such soil conditions often results in significantfoundation embedment; embedments up to several spudcan diameters are common. The SNAME T&PB 5-5A guidelines are often used by the industry to performsite-specific assessments for the suitability of jack-up platform (SNAME,2008). The recommendations in the SNAME guidelines, however, do not reflect themechanisms of a deeply embedded spudcan in soft clay, but they are derived fromthe observed behavior of shallowly embedded foundations. Conservatism in theSNAME guidelines exists and in practice this can result in an unfavorablesite-specific assessment for a jack-up platform. This paper will brieflyhighlight some recent studies on the behavior of spudcans in soft clay andcompare these to the SNAME guidelines. Then, a plasticity force-resultantfooting model appropriate for spudcans in soft clay is proposed. Examplejack-up analyses with the proposed new model are provided, highlighting thedifferences in prediction with this new model.
Results of Frequency Based Interpretations of Deep Water Passive EM Survey Data
Authors: Mes Marius J. , Bruns David Robert , Johnson Ed A.
Published: April 2012

Airborne 3D high resolution EM survey data were collected by eField in thenorthern Norwegian Sea. Survey areas included a producing field, a drystructure and other deep water areas. We confirmed with newly developedfrequency-based algorithms that:The 3D passive airborne system recognized areas with and without largehydrocarbon deposits,Relative depth information was obtained from a parallel interpretation withgeophysical data,Multiple hydrocarbon bearing strata were identified,Consistent survey results were found in 1200 meters of water.

Data interpretations supporting these claims are included.

We used the results for basin evaluations in support of a license applicationbecause the survey method allows us to optimize existing data (such asgeological and seismic data) interpretations with independent EM datainterpretations. Such combined interpretations can reduce the explorationrisk.

Introduction

The purpose of a high resolution electric and magnetic (EM) airborne surveyoffshore is to provide an economic basin evaluation for the presence of largedeposits of hydrocarbons. The resolution of this evaluation can go down to thedevelopment field level. We developed a novel survey system and a datainterpretation procedure to conduct such surveys and obtain interpretationsthat can be mapped. This paper describes the survey system and the validationresults.

Commercial capabilities exist to conduct aerial EM surveys. However, thecommercially available data interpretation capabilities are very limited. Wecompleted a three-year R&D project to develop a new frequency-basedinterpretation for the non-stationary 3D EM signals. We also defined the tunedE and M sensor, receiver and compatible interpretation systems speciallyadapted to the software development.

The EM interpretations can be used for independentbasin evaluations,prospect evaluations anddrilling site selections.

In the ideal case independent EM survey results should be integrated with otherinterpretations based on geological, geophysical and other data sources, suchas Fig. 1 depicts.
Subsea Technology: A Reflection on Global Challenges and Solutions
Authors: Liddle David
Published: April 2012

The research and development (R&D) of new technology is an essentialactivity for the oil and gas industry and is undertaken by a range oforganisations for a variety of reasons. These organisations may carry outR&D in order to reduce costs and increase profits, maximise recovery, findnew hydrocarbon resources, improve QHSE performance (Quality, Health, Safetyand Environment), or gain competitive advantage.

New technologies will be required to meet operational demands. Subject matterexperts from ITF members, major operating and service companies in the oil andgas sector, have met at two international ITF Technology Challenge Workshops inPerth (WA) and London (UK). They explicitly identified the current sharedchallenges they are facing in both the domestic and the internationalmarket.

ITF has sought solutions to the challenges in the areas of: Subsea Power; FlowAssurance; Subsea Separation; Temperature Management; Pipeline IntegrityManagement; Cost Reduction; Low Cost Intervention.

This paper reflects on the industry's solutions and achievements in the area ofsubsea technology, it identifies the technological challenges as currentlydefined by major industry players and that continue to elude and lie ahead ofus.
Field Deployment of the World's First Electrically Trace Heated Pipe in Pipe
Authors: Fisher Robert , Hall Scott James , Cam Jean-Francois , De La Porte Dominique
Published: April 2012

Description

This paper details the result of onshore industrialisation and offshore fieldtrials undertaken for Electrical Trace Heating solution for reeled Pipe-in-Pipe(ETH-PiP) as part of the overall delivery of the Islay Project, located in theNorthern North Sea. Specific attention is drawn to the onshorepre-commissioning executed through 2010 and 2011, the equipment developed toallow remote intervention and the performance of the system for a range offield conditions

Application

Long subsea tie-backs are increasingly considered for offshore " step-out" fielddevelopments, which often have intermediate or smaller reserves and complexflow assurance issues. In such cases, the flowline architecture can either meanprohibitive insulation costs or curtailment of prospect development due to thephysical limits of insulation systems being exceeded. Hence, in addition to thepassive thermal insulation, the heat losses must be compensated by ActiveHeating. The Total Group has identified, beside other available technologies, the Electrical Trace Heating of subsea pipelines as a promising solution, withhigher energy efficiency and the ability to be installed on a host platformwith a limited impact, thus leading to economic optimization.

During the last decade, anticipating the interest of the iIndustry, Techniphave has run a comprehensive R&D programme for the developed on an (ETH-PiPtechnology). Following a successful qualification programme of more than twoyears, Total and its partners now consider the technology mature enough to forthe next stages of development: industrialisation and field deployment.

The Islay Project, recently awarded by Total as a full EPCI contract toTechnip, has been selected to pilot the ETH-PIP technology.

Results, Observations and Conclusions

Field performance data from initial start-up trials and subsequent operationswill be presented. Information will include power input data, thermalperformance and correlation with bespoke design models developed for this newtechnology.

Significance of the Subject Matter

Whilst ETH-PiP is not the primary hydrate mitigation strategy for Islay Project- this being achieved by an innovative seabed conditioning scheme thatminimizes the methanol injection requirements - it presents an opportunity toperform " full scale" offshore field testing and can be considered as the finalqualification process for future large scale projects in the North Sea andworldwide.

Background and History of ETH-PiP

Technip began development of electrical trace heating (ETH) technology in thelate 1990's having identified a future need for efficient active heating ofsubsea pipelines in order to unlock reservoirs with complicated flow assuranceissues.
An Engineering Approach to Upstream Insurance: Risk Management or Poacher Turned Gamekeeper?
Authors: Gnanendran Athith , Hayes Martin James Stanfield , Watson David
Published: April 2012

Recent accidents in the Gulf of Mexico, East Timor Sea and North Sea are, amongst others, regarded as catastrophic events by the insurance industry dueto loss of life and financial loss. Traditionally, upstream insurance reliesheavily on underwriting judgement for decision making. It is evident that theupstream offshore energy insurance industry lags behind other specialistinsurance areas in assessing pure engineering aspects of a risk. This presentsa problem in an area that requires wide engineering expertise to perform a riskassessment. Such expertise covers construction, well control, property damage, pollution, business interruption and any combination of these.

Further, the impact on insurance companies has been almost overlooked by theExploration and Production (E&P) industry as they concentrate on fulfillingtheir owners and regulatory requirements. Catastrophic events are considered, even within the E&P industry, as being " unfortunate". However, for theinsurance companies and E&P companies they can be disastrous.

These events have highlighted the importance of detailed engineering riskassessment on each area of engineering including: structures, process, controlof well and construction. Within these areas, risk factors including;management and process systems, competency of personnel, technical and designdetails will be reviewed in detail together with pricing implications to theinsurance industry.

Insurance costs for E&P companies can form a substantial part of theirannual expenditure, especially for new projects and new companies. Effectiverisk assessment, together with correct pricing, could be of benefit to allstakeholders.

This paper discusses the factors relating to the risk assessment of upstreaminsurance projects and suggests ways of improving risk to both insurancecompanies and E&P operators by identifying best practice in each area ofengineering. This will assist E&P companies adapting or modifying theirexisting operational systems and enable them to enhance their own riskmanagement process by benchmarking against similar operators.
Adapting the OPTI-EX Topsides to Suit the Who Dat Reservoir
Authors: Tucker Bob , Meyers Patrick , Sakers Michael , Mullett Craig , Krekel Marcus Hendrik , Mahase Deodath
Published: April 2012

The OPTI-EX Floating Production System (FPS) was commissioned on speculation. Its foreseen areas of deployment were the Gulf of Mexico, Brazil or WestAfrica. Before the project was sanctioned, a marketing study was undertaken onpotential prospects to support the formulation of a basis of design (Phase I). The marketing study summarized all known marginal fields and early-developmentfields for which an FPS could be suitable. The study helped to confirmviability of a speculative FPS and helped the design team to focus on the rightsize of production facility.

A production system (Phase II) was designed that was highly modular, whichallowed for a maximum of flexibility in production. The capacity of thetopsides comprised 40 Mbop/d plus 50 MMscf/d. For equipment that was toofield-specific, only space, payload and utilities were provided. The FPS wasbuilt and subsequently laid-up, awaiting a deployment contract.

When the current owner procured the FPS, they completed the facility by addingthe field-specific equipment and modules to it (Phase III). Also, the capacitywas increased to 60 Mbop/d plus 150 MMscf/d. The paper describes how theseupgrades were achieved, where the original design philosophy worked well, andwhere it was deficient.

The paper addresses the possibilities and limitations of generic productionfacilities design, using the " Who Dat" deployment of the OPTI-EX FPS as a casestudy.

Most of the modifications of the facilities in effect, comprised the additionof the field-specific equipment and modules originally anticipated. Only alimited number of existing systems were converted. By adopting a modular designwith sufficient flexibility and capacity, a wide range of field conditions canbe accommodated.

There is an industry tendency to " prototype" a standard facility time and timeagain. In a field development, significant schedule and cost gains can be madeby using an existing FPS, provided its facilities have sufficient capacity /flexibility and the FPS has adequate spare payload, space and utilities.

The Project

The Exmar OPTI-EX™/ LLOG Who Dat project was unique from start to finish. Theunique deep-draft semisubmersible OPTI-EX floating production system (FPS), conceived by Exmar Offshore Company (EOC), was designed and constructed to bere-deployable for use in early production and marginal field developmentopportunities, for medium to large reservoirs, and in waters ranging up to10,000 feet. It was the first independently-owned facility with this capabilityand the first speculative FPS constructed in the industry. One of the mostunique features of the structure was its generic single-level topsides, whichmade it capable of being modularized for customization to be used multipletimes in global fields. Fully outfitted, the OPTI-EX is capable of producing60,000 barrels of oil per day (bop/d) plus 150 million standard cubic feet ofgas per day (MMscf/d).
Pazflor - The Challenges of the Offshore Phase
Authors: Rouyer Sebastien
Published: April 2012

HSE

The Pazflor SURF installation campaigns kicked-off on 05th September 2010 withthe mobilisation of the first construction vessel and ended in September 2011. With over 800 people present offshore at peak of activity and 1.5 millionmanhours upon completion, it has unfolded without any major incident.

During the preparation phase, particular attention was paid to the bridging ofthe HSE management system of the 3 main contractors with the system of Total, and especially the emergency response procedures.

During the execution phase, the project installation team focused on theanticipation of co-activities between construction vessels, other vessels suchas drilling rigs and surface or subsea assets and was successful in eliminatingmost of these situations, or properly preparing the one that couldn't beavoided.

Campaign size and integrated schedule

Pazflor subsea installation campaigns involved the installation of 180 km ofpipelines, 84 km of umbilicals, 17 risers (including 2 IPBs) and 7 dynamicumbilicals as well as over 120 subsea structures totalling about 10,000 tonnes. Over 350 ROV tools and accessories were necessary to perform more than 200subsea tie-ins.

The campaign has involved up to 6 main construction vessels at peak of activity(the complete construction spread reaching nearly 40 vessels and barges)working in conjunction with 3 drilling rigs and seismic acquisitionspreads.

Potential interferences between the construction spread and other vessels wereanticipated using an integrated location-based planning and were all butcompletely avoided in spite of a very intense period of activity in the firstsemester of 2011.

Campaign complexity

Both Pazflor Oligocene and Miocene production systems consist in complexassemblies of components with very different design principles and installationconstraints (flexible risers, rigid lines, flextails, subsea connectors, rigidspools, subsea structures…), which require specific installation means anddictate the installation and test sequence. As a consequence, the plannings ofall the main construction vessels are heavily inter-dependant.

Such interdependence raised the stakes of respecting vessels' respectiveschedules a step higher than is usual in offshore operations. Preparation andprior full scale testing allowed to ensure no unexpected event affected thegood development of the more complex installation phases.
Pazflor: Performing Fabrication and Construction in Angola
Authors: Croguennec Steven
Published: April 2012

Between 2001 and 2008, the production of the Angolan oil industry trebled from700,000 to more than 1.8 million barrels of oil per day. For Angola, it is acrucial challenge to spread the benefits of this windfall throughout theAngolan economy as a whole and to stimulate the creation of value on a localscale. In collaboration with all the contractors, Pazflor encouraged localmanufacture of project facilities and equipment whenever possible. Identifyingthe production capacity available at existing yards, scoping out local skillsand reviewing the workload of local companies were all preliminaries to thecontract awards.

During the Project execution phase, Angolan yards made a significantcontribution to the construction of project equipments. Around 3.8 millionsmanhours, 10% of the overall project workload, were spread over 4 fabricationyards, with a strict respect of HSE project requirements. In line with projectschedule, local companies achieved the fabrication of various equipements:suction piles, FPSO structures, offloading buoy, subsea manifold modules, XTfunctional testing and almost all umbilicals of the project lay-out.

These 3.8 millions manhours performed for Pazflor represent in average around500 persons working on a full time basis during the 3 years of the fabricationphase on the Angolan ground
Pazflor SSPS Project; Testing and Qualification of Novel Technology: A Key to Success
Authors: Eriksen Steinar , McLernon Hildegunn , Mohr Camilla
Published: April 2012

The paper will address the development, qualification, engineering and testingphases for the Total's Pazflor Subsea Separation and Production System (SSPS). Items to be discussed will be qualification challenges associated with thespecific component test, factory acceptance test, extended factory acceptancetest, system integration test, shallow water test and cool down test. Pazfloris the first full-scale green field development with subsea separation andboosting as a prerequisite to producing two different grades of hydrocarbonsfrom four independent reservoirs. Other challenges which are discussed are thedynamic simulation and full-scale function.

Total is the operator of the Pazflor development, located in Block 17 Angola, wich consists of 2 different fields: the Oligocene field has light oil atmedium pressure and medium temperature while the Miocene field has heavy(viscous) oil with low pressure and temperature. One of the challenges for thisdevelopment was to produce common equipment and systems capable of meeting thetechnical requirements for both fields, e.g. hydrate formation challenge vs.high temperatures. For the Miocene field the low reservoir pressure and deepwater in combination with high viscosity and stable emulsion creates the largepressure drop in the flowline and risers which therefore requires boosting ofthe production fluid from start-up of the field.

This paper provides details of the extensive test program required tosuccessfully deliver a major Subsea Separation and Production System. It showsthe systematic and integrated process required from qualifying products atcomponent level to further verification in an overall system testprogram.

New technology such as integrated insulation on pipe termination heads andsubsea separation systems together with a new system philosophy regardinginstallation of equipment and thermal performance has been verified.

A successful offshore installation campaign took place during 2010 and 2011, confirming that potential issues were identified and rectified through the testprogram.

The Pazflor subsea field development consists of two parts; the subseaproduction system (SPS) and the subsea separation system (SSS). The latter isexpected to be applied on several more subsea developments for both brown fieldand green field applications in the future.

This Paper provides details on how these two parts were integrated into onesuccessful overall project with a focused engineering, execution and testprogram.
Applying a Real-Time Engineering Methodology To Drill Ahead of Potential Undesirable Events
Authors: Perez Tellez Carlos , Rodriguez Rosas Reginaldo , Ramirez Ignacio , Bermudez Martinez Rafael Angel , Palavicini Cham Carlos Alberto
Published: April 2012

Current methodologies for drill planning, widely implemented by Oil Companiesto optimize the definition of technical and economic options for the drillingprocess, are based on a scrupulous analysis of the production requirements, thetechnical risks, and the geological uncertainties. Planning and designingdrilling projects begin by considering the problems observed in correlationwells drilled in the same field, in order to obtain a successful mechanicalmodel.

Once the drilling process begins, an evaluation of the continuing operationsallows drilling engineers to control and adjust the differences that may arisebetween the drilling plan and the actual conditions observed while drilling. These identified variations are related to uncertainties in the criticaloperational parameters, such as pore pressure and fracture pressure gradients, salt intrusions, and changes in the planned lithology column, such as, shaledomes, and gas shows. Dealing with these variations is imperative, as they candetermine either the success or the failure of the well.

This Paper proposes a Real-Time Drilling Engineering Methodology that allowsoperations staff to drill ahead in depth and time by anticipating geological, mechanical and operational conditions, thus allowing preemptive actions. ThisMethodology allows forecasting the adequate drilling parameters by visualizingthe current conditions of the well. These include the analysis of theinteraction between the drill string and the fluid with the formation, thenormalization of mud densities in the areas of interest, and the analysis ofgeopressures from logging-while-drilling data. Other parameters that need to beconsidered might include the variation of casing and hydraulics designs, andthe optimization of the well path from Real-Time Trajectory and Log Data.

This Real-Time analysis leads to immediate engineering recommendations that caneliminate and avoid ongoing and potentially undesirable situations whiledrilling, such as stuck pipes, gasifications, and runoffs, thereby allowing apreemptive response to the variations that may occur between the proposeddrilling plan and the actual drilling conditions. By applying this Methodologyin several oilfields in Southern Mexico, an observed 20% increase of thetechnical efficiency of the drilling process has been reported, resulting inover 80% of the wells operating under normal conditions, with a reduction inthe average cost of the well for the operator.
Improvements to Deepwater Subsea Measurements RPSEA Program: Meter Alteration Effects From Fouling and Erosion
Authors: Zanker Klaus , Stobie G. J.
Published: April 2012

Multiphase/wet gas flow meters used in deepwater subsea conditions are known tohave problems with scale from produced water and erosion from sand production. The objective of this RPSEA project is to evaluate the flow meter performancechanges produced by these meter altering mechanisms

Multiphase/wet gas meter elements: Venturi, cone and wedge meters, werephysically tested and subjected to Computational Fluid Dynamics (CFD)simulations.

The erosion testing was done with water-sand and air-sand on one size and onebeta ratio of each meter type. CFD simulations were used to extend the sizerange, the beta range and the fluid densities to cover the multiphase densityrange between air and water.

Erosion results are presented that allows the user to estimate the possibilityor likelihood of wall penetration, the measurement error on a flow meter andthe effect of a flow meter on the erosion of a downstream bend.

The scale deposition testing was done with brine of mostly sodium and calciumon one size and one beta ratio of each meter type. No attempt was made to useeither multiphase flow or realistic subsea conditions.

Scale deposition is a highly complex and variable process that is difficult tomodel. For CFD to be able to estimate meter error it would have to predict thedistribution and thickness of scale in the meter. At present this is beyond thecapability of CFD. However, CFD simulations were run to assess how meters areaffected by scales that are sensitive to fluid scouring, pressure distribution, particle accretion and thermal effects.

These CFD-based methods are sufficiently realistic to provide an insight intothe effects of scale. They are used to compare different meter designs andhence identify design features that may be desirable if scale formation is aconcern.

1. Introduction

This RPSEA 07121–1301 [Ref. 1] project addresses gaps in the deployment and useof multiphase and wet gas meter technology in deepwater production systems. Inparticular the objective of this task is to understand the ways in whichproduction fluids affect subsea meters and thereby affect their meterresponses.

It is known from field operations that meters can become fouled internally bydeposits of scale, or altered by erosion. At present these effects are not wellunderstood and the objective is to estimate their magnitude.

Flow tests and computational fluid dynamic (CFD) analyses have been performedto evaluate the effects of alteration on Venturi, cone and wedge meters, byscale deposition and by sand erosion. The results are interpreted to give aclearer understanding of these meter alternation effects on subsea multi-phasemeter response.
Qualification of a DP-Based FPSO Offloading Vessel
Authors: Diederichsen Kim , Olsen Frode
Published: April 2012

As the oil and gas industry moves into deeper and deeper waters, the need foran efficient system to offload crude oil from FPSOs to tankers is steadilyincreasing. Furthermore, oil transportation and trading has becoming moreinternational, where oil companies tend to seek solutions that allow forconventional oil tankers to offload directly from FPSOs and transport the crudeoil directly to the market.

Traditionally, offloading of crude oil from FPSOs to the tankers is carried outeither in tandem configuration or via a remote Single Point Mooring (SPM) buoysolution. Tandem operations are normally carried out by use of specially builtDynamically Positioned (DP) tankers or with conventional tankers along with theuse of several tugs in order to keep the tanker at a safe distance from theFPSO. The new DP based offloading vessel is designed to dock onto and keep anyof the existing 2000 conventional tankers, from Aframax to VLCC size, safe onposition during the typical 24 hours of offloading operations.

First applications of new innovative technologies are often perceived asinvolving potentially increased risks, with possible significant adverseconsequences and high levels of uncertainties. Hence, the development anddeployment of an innovative technology is often hindered by the view of suchrisks and uncertainties.

This paper is prepared and presented by Remora and it addresses the steps andresults of a 10-year development and qualification process for new DP basedFPSO offloading vessel particularly suited for the new deepwater fields in WestAfrica, Brazil, GOM, etc.

The paper explains the methodology applied for the qualification and describesthe entire qualification process. It outlines the main challenges anduncertainties identified during the process and the mitigations implemented anddescribe the results obtained. As part of the qualification process for the DPbased offloading vessel, extensive Sea Trial's with simulator validations andfollowing real life operations have been executed off of the west coast ofNorway throughout Q1 and Q2 2011.
Improved Pile Driving Predictions in Carbonate Soils and Rock
Authors: Brunning Paul , Ishak Baidrul
Published: April 2012

Driving piles into carbonate strata, particularly weak rock (calcarenite) andcemented sands is traditionally thought to carry high risk in terms ofpremature refusal, exceedance of fatigue criteria or pile tip buckling. Although soil resistance to driving (SRD) algorithms have been developed forcarbonate deposits they are based on limited experience (primarily ArabianGulf) and there is a need to expand this database to include installationexperience elsewhere in carbonate conditions such as the Australian north westshelf where significant oil and gas developments are planned.

Much of the uncertainty surrounding the prediction of pile driving in carbonatestrata can be attributed to the difficulty in establishing a reliable andcontinuous soil resistance profile which is primarily due to i) the difficultyobtaining suitable samples of rocks such as calcarenite for compressivestrength testing, and ii) the equipment limitations for pushing conepenetrometers into weak rock.

It is standard industry practice to base hammer selection, fatigue damageanalyses and driveability assessments on upper bound plugged conditions which, for weak rocks such as calcarenite, gives significantly higher resistances thanfor the unplugged case and this can lead to the conclusion that driving iseither completely unfeasible or not possible beyond a certain depth.

This study presents data from a pile installation in the Timor Sea to supportmodifications that may be made to existing SRD algorithms to improvereliability of the predictions, at least for this particular site. Back-analyses of the installation data show that unplugged conditions are farmore likely to prevail when driving a large diameter pile which suggests thatautomatically assuming plugged conditions is over-conservative. Possiblecorrelations between cone tip resistance and unconfined compressive strength(UCS) of calcarenite are made by fitting SRD algorithms that require UCS as aninput to those that are based on cone tip data.

Introduction

Offshore pile fabrication and installation is expensive and anyover-conservatism in the design or in driveability predictions can result inproject costs being significantly higher than they might otherwise be. On theother hand, unplanned problems such as premature refusal or pile tip bucklingduring installation are potentially even more costly which is why a cautiousapproach is normally adopted. Where an over-conservative approach leads to piledriving appearing to be marginal, or indeed unfeasible, an alternative andpotentially very expensive solution such as grouted piles or contingencydrilling equipment may have to be adopted. A more balanced approach based onthe most likely driving behaviour would result in optimised project costs.
Pore Pressure Monitoring of Active Fault-Fluid-Hydrate System in Deep Water, Nigeria
Authors: Sultan Nabil , Riboulot Vincent , Ker Stephan , Marsset Bruno , géli Louis , Tary Jean-Baptiste , Klingelhoefer Frauke , Voisset Michel , Lanfumey Valentine , Colliat Jean-Louis , Adamy Jerome , Grimaud Sylvie
Published: April 2012

To characterize the link between faults and fluid release and to identify therole of fluid flow in gas hydrate occurrences, four piezometers were deployedat the border of a shale-cored anticline in the eastern Niger delta. Two ofthose piezometers were deployed along a major fault linked to a shallowhydrocarbon reservoir while the two others were deployed within two pockmarkfields. Pore pressures were measured for periods ranging from 370 and 435 days. The two piezometers deployed along the fault simultaneously registered aprolonged fluid flow event lasting 90 days.

By combining and analyzing acquired data, we show that the fluid-fault systemoperates according to the following three stages:upward pore fluid migration through existing conduits and free gascirculation within several shallow sandy layers intersecting the majorfault,gas accumulation and pore pressure increase within sandy-silty layersandhydro-fracturing and fluid pressure dissipation through sporadic degassingevents, causing pore fluid circulation through shallow sandy layers andattracting seawater into the sediment.

The present work clearly demonstrates how an integrated approach based onseafloor observations, in situ measurements, and monitoring is essential forunderstanding fault-fluid-hydrate systems.

Introduction

Published research papers concerning gas hydrates have exponentially increasedthose last three decades and mainly since natural gas hydrates have beenrecovered worldwide from polar regions to deep-water shelves (Kvenvolden,1994). Generally, most of those research papers focus on one of the followingthree main topics: role of gas hydrates in global climate change (see forinstance Kvenvolden, 1994);gas hydrates as a potential cause of sedimentdeformations and submarine slope instabilities (see for instance Kayen and Lee,1991);gas hydrates as a an unconventional energy resource (see forinstance Collett, 2002).

Detecting gas hydrates and understanding the dynamic of any gas hydrates systemassociated to climate changes, geohazards, and/or energy resources leads toinvolve integrated approaches combining geophysical data, geochemical analysis, geotechnical testing and in situ monitoring. The present work aims to highlightthe importance of pore pressure monitoring in such integrated studies and todemonstrate the importance of such measurements in the comprehension of acomplex active fault-fluid hydrate system in deepwater Nigeria.
Advancements in Structural Well Integrity Design and Operation
Authors: Buchmiller David , Rengard Ole , Haug Lars Tore , Horte Torfinn , Grytoyr Guttorm , Katla Erling
Published: April 2012

With the heightened focus on safety in drilling operations, Det Norske Veritas(DNV) AS together with the drilling industry has started development of aseries of Recommended Practices (RP) for structural design and operation ofdrilling and well systems. The motivation for developing the industryguidelines stems from the fact that existing international standards providelimited or no guidance on overall system design and structural integrity. Theaim in creating the new RP series is to provide a sound framework for theentire drilling and well system in a systematic manner. The new RP seriestackles issues such as system engineering and interface design as well asproviding detail guidance on strength and fatigue calculation and informationand integrity management.

It is seen as crucial that the drilling industry incorporates and adheres to asystematic and consistent method for safe design and operation of itsequipment.

The RP development is part of an ongoing joint industry project (JIP)facilitated by DNV with participation from BG Group, BP, Chevron, Det Norske, Eni, ExxonMobil, GDF Suez, Lundin, Marathon, Nexen, Shell, Statoil, Talisman, Total and Woodside. The core of the RP series provides an overall design andoperational philosophy of drilling and well systems, and as there typically aremany individual components in a drilling and well system, the RP seriesprovides guidelines with regard to interface interactions and control ofresponsibility throughout a well's entire lifetime. The RP series combines thestrengths of the already existing design methodologies available in theindustry today, and provides specific guidance on structural strength andfatigue design. As such it represents a significant improvement derived fromkey elements of the best practices from around the world.

The RP series consists of 4 separate volumes. Volume 1 provides an overalldesign philosophy for drilling and well equipment; Volume 2 covers strengthcapacity design, i.e. ULS/ALS. Volume 3 covers fatigue design, i.e. FLS andVolume 4 addresses integrity and information management.

Introduction

Ensuring structural integrity of drilling and well systems has been importantin the offshore industry ever since the first offshore wells were drilled inthe Gulf of Mexico. With current technology and its challenges where manyconductor and wellhead systems are located on the seabed and connected to anoffshore drilling unit, structural integrity has become a focus area for thedrilling industry. Even with current international codes and standardsavailable, a systematic method for ensuring structural integrity of the wellsystem has yet to be fully implemented. Ensuring structural well integrity isdefined in the JIP project as taking into account all of the loads acting onthe well system during its lifetime, i.e. drilling, completion, production, workover/intervention and plug and abandonment.
Qualification of Unbonded Dynamic Flexible Riser With Carbon Fibre Composite Armors
Authors: Do Anh Tuan , Lambert Anais
Published: April 2012

With the increasing water depth of offshore field developments, the suspendedweight and the fatigue performance of dynamic risers become more and more oftena driving design factor. The use of light weight composite materials is ideallysuited to this challenge as the strength/weight ratio of a typical carbon fibrecomposite material can be an order of magnitude greater than the equivalentsteel solution. The introduction of this technology to a new domain such asflexible risers requires careful consideration of material selection andqualification criteria.

When developing a composite material the key point is to perform the rightselection of carbon fibre and matrix, that is able to sustain continuouslyduring twenty or thirty years both the mechanical loading and theenvironment.

The exceptional fatigue performance of the Carbon fibre composite under axialloads makes it a material perfectly suited for tensile armour reinforcement indynamic deepwater risers. In case of sour service conditions generated by thepresence of H2S, the structural layers of a classical flexible pipe require theuse of steel with reduced mechanical properties (i.e sour grade). The typicalcombination of sour service conditions and Ultra-Deep Water (UDW) riserapplications generates a design of considerable weight and top tension. Forsuch applications, the advantages of Carbon Fibre Armours (CFA) are twofold dueto the fact that CFA has a higher strength/weight ratio and is also notsensitive to H2S.

Technip has been engaged for a number of years in the development andqualification program of CFA. The high level performance of the qualifiedflexible pipe integrating CFA allows now to propose light weight flexible risersolution and also allows to reduce or to remove the requirement for buoyancyelements for UDW configurations.

The first part of this paper is dedicated to the comparison of flexible risersystems designed with CFA versus steel armour flexible pipe.

The second part of this paper will focus on the material tests and full-scaleflexible pipe prototype qualification. In particular, results generated duringthe last full scale test will be presented with the associated qualifiedapplication domain.
Wireless Reservoir Surveillance Using Intelligent Tracers
Authors: Williams Brock , Nyhavn Fridtjof
Published: April 2012

Offshore developments in deepwater are very high cost ventures in complexreservoir environments. Seismic imaging challenges induce significantuncertainty in reservoir descriptions. Reservoir surveillance, especiallyinflow distribution across the reservoir interval, is a valuable contributor tounderstanding reservoir performance however acquiring this information usingconventional technology, such as production logging tools, is very problematicin the deepwater environment where wireline intervention into live wells is amajor risk and cost.

Intelligent chemical tracers are a new technology that provides insight intothe inflow distribution without intervention operations or major alterations tothe completion design. The tracers consist of smart plastic and unique chemicalcompounds that are combined into a matrix that resembles strips of plastic. Thematrix is designed to be sensitive to either oil or water. For example, whenwater sensitive matrix is contacted by water, the matrix releases its uniquechemical fingerprint (tracer) at a prescribed rate. The water sensitive matrixis dormant when contacted by oil, gas or air. Oil sensitive matrix behavesexactly the same way but with oil being the target fluid.

Unique chemical tracers are deployed at strategic locations in the completionso that fluids entering the completion contact the tracers. At the surface, samples are taken and analyzed for the presence and concentration of eachunique tracer that has been deployed in the completion. The concentration datais plotted vs time and produced fluid. Analysis of these plots can yieldanswers to very valuable reservoir management questions like:Are all the intervals producing?What is the relative contribution of each interval?Where is water break-thru occurring?

This paper reviews:How the technology works.Interpretation techniques.Case histories of intelligent tracer responses.The value this knowledge can bring to deepwater reservoir management.
Subsea Intervention Tool for Deep Waters and Harsh Environments
Authors: Kleinen Torsten , Knodt Steffen , von Wirth Hermann-Josef
Published: April 2012

When offshore oil and gas production goes deeper (more than 2,000 mWD) or intopartly ice covered regions you have to think about different methods /scenarios of preparatory work, installations, maintenance anddecommissioning.

Based on this the technical challenges have to be identified and you have tofind proper strategies and solutions - different to actual ones.

By changing the available tools a step far beyond actual limitations ispossible.
Asphaltene Deposition Tool: Field Case Application Protocol
Authors: Kurup Anjushri Sreedh , Buckley Jill S. , Wang Jianxin , Subramani Hariprasad J. , Creek Jefferson Louis , Chapman Walter G.
Published: April 2012

In the petroleum industry, arterial deposition of asphaltenes is one of theissues requiring flow assurance consideration during asset development. As thephysical or chemical conditions inside the reservoir, and hence the wellbore, changes, the originally stable asphaltenes in the oil, can precipitate, potentially leading to deposition in the wellbore. The arterial deposition ofasphalenes then would reduce the production rate of oil. Remediation bysolvent-soaks and squeezes is expensive, on the order of several milliondollars. The economic impact of such deposition must be anticipated and asuitable philosophy for management of these deposits should be developed. A keyitem in the successful management of asphaltene deposition requires reasonableestimation tools regarding the growth rate and location of deposits since thiseffects the gross up time of the production facility being designed.

In this work, a simulation tool that can be used to predict the amount ofgrowth rate and location of asphaltene deposits in wellbores / pipelines ispresented. In this asphaltenes deposition simulator, the transport equationsare coupled with kinetic models to describe the precipitation, aggregation, anddeposition of asphaltenes. The phase behavior of asphaltenes in oil isdescribed by using the Perturbed Chain version of Statistical Associating FluidTheory Equation of State (PC-SAFT EOS). In this paper, the protocol that needsto be followed for the application of this deposition simulator to ascertaingrowth rate and location of asphaltenes in field scenarios is presented. Theexperimental methods required to obtain the kinetic model parameters are alsodiscussed. Application of the simulator to study asphaltene deposition in oneof the pipelines in the Gulf of Mexico that has reported asphaltene depositionproblems is also presented.
Online Structural Integrity Monitoring of Fixed Offshore Structures
Authors: Manzocchi Mark , Wang Liangsheng , Wilson Mark
Published: April 2012

Natural frequency monitoring of offshore platforms is a valuable tool forstructural integrity management. Online structural integrity monitoring assumeseven greater significance when platforms are highly susceptible to damage dueto environmental wave loading and fatigue processes. The implementation of anonline monitoring system allows rapid detection of member failures therebyminimizing the possibility of exposure to a high risk of platform collapsebetween inspection intervals and improving the structural reliability. Thispaper illustrates an application of online structural natural frequencymonitoring applied to a fixed North Sea jacket structure and describes how itis used within the context of structural integrity management.

Introduction

Structural failure of offshore platforms can lead to loss of life, loss ofasset and environmental pollution, and this risk needs to be reduced to anacceptable level. Monitoring of structural integrity of offshore fixedplatforms is essential for ensuring their safety in service. Structuralmonitoring measures the structural response with damage being identified by achange in the measured response such as natural frequency (Roitman et al. 1992, Sanderson et al. 2002), flexibility (Sunder and Ting 1985), accelerations(Hillis and Courtney 2011) and vibration modes (Li et al. 2008, Mangal et al.2001). The UK Health and Safety Executive (HSE) published a state of the artreview on the offshore structural monitoring techniques (OTO 97 040 and OTO 98046).

Many offshore fixed platforms are approaching or have exceeded their originaldesign life, with a good proportion seeking life extensions. Maintainingstructural integrity of aging offshore structures is an ever increasingchallenge. Consequently, there is a growing interest in techniques that onlinemonitor the state of a structure. The assessment of remaining life can beenhanced with knowledge of the structural performance during a period of time, resulting from the use of online monitoring. These can provide both acost-effective solution to integrity management, as well as providing acontinuous output on the state of the structure. The implementation of anonline monitoring system allows for instantly detecting member failures therebyminimizing the possibility of exposure to an elevated risk of platform collapsebetween inspection intervals and improving the structural reliability. Onlinestructural integrity monitoring assumes even greater significance whenplatforms are highly susceptible to damage due to environmental wave loadingand fatigue processes. This paper illustrates an application of naturalfrequency based online structural integrity monitoring applied to the CNRInternational-operated Ninian Southern Platform, which is sensitive to fatiguedamage, and describes how online structural monitoring is used within thecontext of structural integrity management.