bluuebunny/crossref_metadata_2025 huggingface dataset:
Further Weight and Cost Saving of Fire and Blast Resistant Walls on Offshore Installations, Through the New, 4th Type and a Comprehensive Decision Making Model
Authors: Groeneveld A. B.
Published: April 2016

This paper presents an overview of 50 years of development of fire and blast resistant walls for offshore installations and introduces the fourth generation or "Type" of wall. This thoroughly tested and certified 4th Type was developed as a response to the continuous quest to further optimise the cost and weight of offshore topsides, thus allowing operators and designers to accommodate more equipment and higher field yield.

Inductive research indicates that the selection of a fire and blast resistant wall design amongst the available Types is very often biased and predominantly based on past experience. As such, the traditionally selected option has been a monocoque structural design incorporating load bearing walls instead of framed construction designs with non-load bearing infill walls. This bias can lead to sub-optimal design and execution of offshore installations.

This paper reflects on 4 Types of offshore fire and blast walls. From the 1st Type, derived from the shipbuilding industry up to the 4th Type, initially used on recent offshore wind HVDC transformer platforms and more recently also on the oil and gas platforms as a response to the continuous need to reduce weight and improve on safety. This 4th Type, with a weight of just 25 kg/m2, is certified as capable of withstanding up to 2 hour hydrocarbon fires and has been tested with a considerable free span.

In this paper, all 4 Types of walls are assessed against a limited series of hard and soft performance criteria, according to a decision making model which can be used to select the fittest-for-purpose Type of wall system. This model includes the distinction between internal fire walls, external fire walls and external fire and blast walls.Table 1Offshore fire wall comparison table – core criteriaOffshore fire wall comparison tableCriteria:Wall Type:Type IStressed skinType IICorrugated skinType IIIBuilt-up wallType IVPrefabricated sandwich constructionWeight100%60%45%35%Installation time100%70%60%15%Overall cost100%80%60%40%Installation time for wall penetrations100%100%40%30%
Metal Seal Technologies in Subsea Applications
Authors: Krishna Cindy , Lefrancois Michel
Published: April 2016

As the environment for the oil and gas industry has become increasingly demanding, so has the need for reliable sealing solutions and related standards.

Traditionally, metal seals and gaskets had been considered of interest because of their high temperature resistance and mechanical properties. However, their obvious downside of limited ductility and elasticity, compared to non-metallic materials, remained difficult to overcome. Soft, compressible elastomers provide good sealing performance, but are porous and cannot reliably withstand temperatures in excess of 482°F (250°C). They also become hard and brittle in cryogenic service. Metal seals have much greater temperature capabilities, high mechanical properties, lack of porosity and long shelf life, but as mentioned, ductility and elasticity have always been the limiting factor. Understanding application requirements and design criteria is critical to selecting the proper sealing solution in challenging applications such as subsea oil & gas production.
Wax Deposition Modeling with Considerations of Non-Newtonian Fluid Characteristics
Authors: Zheng Sheng , Saidoun Mohamed , Mateen Khalid , Palermo Thierry , Ren Yiyu , Fogler H. Scott
Published: April 2016

Wax deposition poses severe risks to crude oil production systems. In order to remediate wax deposition, pigging operation is performed routinely to scrape wax deposits from the pipe wall. Proper determination of the pigging frequency is crucial to estimating the operating costs associated with the pigging operations as well as the risks of pipeline blockage by wax deposit. In order to predict the wax deposition rate and the deposit thickness to be pigged, existing wax deposition models simulate the hydrodynamics, heat and mass transfer of oil pipe flows based on Newtonian fluid mechanics. However, when temperature of the oil drops below the wax appearance temperature (WAT), wax molecules precipitate to form a suspension of wax crystals in oil, resulting in non-Newtonian fluid characteristics. In order to generate more reliable wax deposition predictions, the methodology to model the hydrodynamics, heat and mass transfer as well as deposit growth considering the non-Newtonian fluid characteristics needs to be developed.

In this study, we present an improvement of the existing university-developed wax prediction model1 by incorporating the non-Newtonian fluid characteristics of waxy crude oil described by the suspension of fractal aggregates (SoFA) model. This enhancement is first presented for laminar flow regime. This improved model is then applied to provide insights on 1) the impacts of non-Newtonian characteristics on the heat and mass transfer aspects of wax deposition, 2) the effect of shear on wax deposition and 3) the role of wax inhibitors on wax deposition.
Designing for Turbidity Currents in the Congo Canyon
Authors: Cooper C. , Wood J. , Imran J. , Islam A. , Wright P. , Faria R. , Tati A. , Casey Z. , Casey R. T.
Published: April 2016

This paper describes the measurement and modeling of turbidity currents (TC) in the Congo Canyon and the application of that data to design of a telecommunications cable. There are few direct measurements of TCs largely because the measurement instruments are often damaged. Indeed, this is only the second set of measurements ever recorded in the Congo Canyon, and the only set that shows the propagation of TCs through multiple sites. Four moorings were deployed in 2013 along a 500 km stretch of the Canyon and measured roughly a dozen TCs during a 5-month period. The largest event reached 150 cm/s. Two-D and 3-D numerical models were set up and calibrated using the measurements. The 3-D model shows significant along- and cross-channel variations and these results were used to select optimal crossing locations. The models were then integrated with cable data to permit stress and fatigue analysis at selected cable installation locations, permitting both cable route and cable type to be evaluated.
Smart Novel Semi-Active Tuned Mass Damper for Fixed-Bottom and Floating Offshore Wind
Authors: Tsouroukdissian A. Rodriguez , Park S. , Pourazarm P. , Cava W. La , Lackner M. , Lee S. , Cross-Whiter J.
Published: April 2016

The intention of this paper is to present the results of a novel smart semi-active tuned mass damper (SA-TMD), which mitigates unwanted loads for both fixed-bottom and floating offshore wind systems. The paper will focus on the most challenging water depths for both fixed-bottom and floating systems. A close to 38m Monopile and 55m Tension Leg Platform (TLP) will be considered. A technical development and trade-off analysis will be presented comparing the new system with existing passive non-linear TMD (N-TMD) technology and semi-active. The SA-TMD works passively and activates itself with low power source under unwanted dynamic loading in less than 60msec. It is composed of both variable stiffness and damping elements coupled to a central pendulum mass. The analysis has been done numerically in both FAST (NREL) and Orcaflex (Orcina), and integrated in the Wind Turbine system employing CAD/CAE. The results of this work will pave the way for experimental testing to complete the technology qualification process. The load reductions under extreme and fatigue cases reach up significant levels at tower base, consequently reducing LCOE for fixed-bottom to floating wind solutions. The nacelle acceleration is reduced substantially under severe random wind and sea states, reducing the risks of failure of electromechanical components and blades at the rotor nacelle assembly. The SA-TMD system is a new technology that has not been applied previously in wind solutions. Structural damping devices aim to increase offshore wind turbine system robustness and reliability, which eases multiple substructures installations and global stability. The paper is part of the US Department of Energy grant # DE-EE0005494.
Analysis of Physico-Chemical Constraints on Surfactant Blends for Offshore Reservoirs
Authors: Garcia-Olvera Griselda , Reilly Teresa M. , Lehmann Teresa E. , Alvarado Vladimir
Published: April 2016

Chemical enhanced-oil recovery has been applied successfully in reservoirs with mild salinity and temperature conditions. Offshore reservoirs challenge chemical flooding, e.g. low-tension and foam flooding, because of the combined hardness and salinity of seawater along with characteristics of the reservoir connate brine. These physico-chemical conditions impose severe limitations to adequate phase behavior for most commercial surfactants. The purpose of the research described herein is to analyze surfactant phase behavior for scenarios with seawater as the main carrying fluid for surfactant systems.

Thermal stability and solubility were analyzed for a number of surfactants provided by two companies. Tests were conducted using a range of simulated connate brines and seawater compositions. Critical Micelle Concentration (CMC) values were estimated using a Nuclear Magnetic Resonance (NMR) protocol developed in our laboratory, recently published (Garcia-Olvera et al., 2016). NMR data were taken from solvents and co-solvents to analyze individual components in chemical blends. Phase behavior experiments were run to determine which blend composition and brine salinity would enable the desired phase behavior. A medium-gravity oil thoroughly studied in our lab was selected for phase behavior studies. Finally, a coreflood was conducted on a subset of surfactants to evaluate the additional oil recovery for one of the evaluated scenarios.

Some surfactants were disregarded for further analysis, due to their lack of thermal stability (dropout from solution was observed). In some cases, co-solvents were added to increase solubility in surfactant blends with a high divalent ion content, which in some cases was insufficient to stabilize the blends. Phase behavior experiments show that some surfactants did not yield Type III microemulsions, and therefore were disregarded for low-tension flooding applications. NMR data for surfactants and co-surfactants yielded good results even when the NMR spectra for different blend components overlaid significantly. Softening of high-salinity brines indeed improved micro-emulsion volume in the phase behavior tests, as demonstrated in the coreflood. However, this strategy is shown through geochemical analysis to be risky for more reactive lithologies, where dissolution and precipitation events are prompted by reduction in hardness in the injection brine.

Our use of an advanced spectroscopic technique (NMR) provides a more quantitative way of determining constraints associated with solubility limits and poor phase behavior under physico-chemical conditions of harsher environments. Geochemical considerations are important for mitigation strategies in reactive lithologies.
Well Control in Carbonate Zone – Total Loss and Kick in Gas Reservoir
Authors: Mahry Arvandi , Suryadi Dedi , Sufiadi Eri , Hadinata Dwie , Wahyudi Yudantoro
Published: April 2016

North Senoro Gas Field is located onshore at Sulawesi Island, operated by JOB PERTAMINA – Medco E&P Tomori Sulawesi. The aim of North Senoro Project Development is to produce gas from limestone reservoir (Mentawa reef) which has unique characteristic formation that total loss hazard wasn't found at the adjacent well. One of effort to solve the problems is bullheading. In this paper, it will explain how bullheading might become a sufficient method for controling pressure during stripping operation while curing loss circulation problem. Well control situation in sandstone and carbonate formation has different characteristic. In carbonate, well control issue is mostly come by total loss which caused the mud hydrostatic pressure was less in the wellbore. Curing loss circulation was the first major to control pressure on the well. Also on sandstone formation, has more compact if hasn't fault or fracture on there.

The well control issue happened in 8-1/2? hole section; the situation occurred when suddenly got total loss in the bore hole. It was followed by the increasing number of background gas from the cutting. Shut in well, got record of SICP is 1700 psi and SIDP is 0 psi. The operations continued with circulate gas out through choke simultaneously with original mud and LCM to try plugged the loss zone and filled up the hole. The result was same with no indication of curing the loss problem. Decided to circulate on the two side, through annulus and inside drill string, while circulate mud and LCM through drill pipe got plugged. The engineer team made some analysis then created few scenarios, such as severing BHA, perforate drill pipe to make communication with annulus, continued pumping mud and LCM via annulus (bullheading), or stripping operation. With all assumptions and condition, the stripping operation while bullheading became the best choice to POOH BHA and running OE to cure loss circulation with BDOP/BDOC, then continue with circulate out gas/kick. Finally, with 2 spot BDOC and the last BDOC was modified using LCM to mitigate micro fracture in cement, loss circulation solved then following circulate out gas by driller method.

For total loss and kick issue, the important thing that we have to assure is pressure gradient and availability of water and LCM material. Setting casing shoe at the high rating pressure will give us much possibility to select the way of curing loss circulation and kick. RIH OE pipe and spot BDOP & BDOC through OE pipe became success story to curing the loss for next well. Finally, the safety for crew, environment and production target is achieved with this option at North Senoro Gas Field.
3000 m Water Depth Flexible Pipe Configuration Portfolio
Authors: Vidigal da Silva J. , Damiens A.
Published: April 2016

Since several years, Technip flexible pipe technology has been successfully used in water depths down to 2500 m and a test campaign was completed in 2010, proving its suitability down to 3000 m Water Depth (WD). However, hitherto no complete engineering studies had been conducted in realistic project environment for such WD. The aim of this paper is to deliver optimized flexible pipe configurations using conventional or alternative optimized technologies to reach 3000 m WD.

This engineering study has been conducted on realistic project specifications, representative of the Brazilian Offshore Region, adjusted to 3000 m WD with the objective to cover conventional applications such as Oil Production, Gas Injection, and Gas Export. The process was o challenge and push further the engineering and technology to a very detailed level, using these case studies to highlight the benefits of the most cutting-edge technologies. In particular the development of Carbon Fiber Armours (CFA) with high strength/weight ratio, high fatigue performance and corrosion free has opened new frontiers for Ultra Deep Water (UDW) with optimized riser configurations.

The result is a portfolio of advanced flexible pipe configurations for a set of applications in a water depth of 3000 m, derived either from conventional configurations, such as Lazy Wave and Free-Hanging, or alternative concepts such as Free Standing Flexible Riser. One of the main conclusions of this engineering study is that the use of Carbon Fiber Armours permits more simple configurations when compared to conventional ones, which has a positive impact on interference issues, simplifies the installation process, by removing the need for buoyancy modules, and finally leads to a global CAPEX reduction. Additionally, the use of the high inertia pressure armour wires, called "PSI", enables considering higher diameters in this water depth by optimizing the weight of the flexible pipe structures.

This portfolio aims at anticipating the petroleum industry needs with diversified flexible pipe configurations as well as identifying and adressing the design challenges to address Ultra Deep Water developments.
Direct Electrical Heating of a Flexible Pipe
Authors: Holst T. , Larsen T. , Straarup A. , Glejbol K. , Olsen K. S.
Published: April 2016

This paper describes a new direct electrical heating method which offers unique flow assurance opportunities in flexible pipe systems. The method effectively expands the operational envelope of flexible unbonded pipes by offering prevention/removal of hydrate plugs, mitigation of vax precipitation and allowing for the transportation of viscous fluids over longer distances by distributed heating along the entire pipe length. Furthermore, the direct heating system can be applied continuously or intermittent as required by operation, e.g. after prolonged shut down periods.

The direct electrical heating solution for flexible pipe takes advantage of the electrical insulation properties of the polymeric pressure sheath in a flexible pipe. The system is effectively operated as a coaxial cable, where electrical current is passed through the carcass and returned via the tensile armor layers. Normally, the electrical resistance of the carcass is significantly above that of the tensile armor resulting in heat being primarily generated in the innermost carcass layer and in direct contact with the bore fluid. Thus, the presented system is a highly effective heating solution of the transported fluid which minimizes heat loss to the ambient structure. Furthermore, it is also highly beneficial that the existing type-approved pipe structure can be used without any modifications.

A full-scale demonstration of the new heating concept is presented here, where a 125 m long flexible pipe with a 12 in. bore diameter was placed in a water tank and subsequently heated electrically. Optical fibers for distributed temperature measurements were integrated in the pipe structure to monitor and regulate the bore temperature in a feedback loop with the power system.
In-Situ Production Profiling for Recovery Optimization via Fiber-Optic Monitoring
Authors: Chen Kyle , Lee Erik , Duncan Roger , Howard Jesse , Denney Tommy
Published: April 2016

Lower Tertiary reservoirs are characterized by high temperature and pressure, but low drive energy due to compaction and cementation. Primary recovery factors are expected to be low and enhanced recovery through waterflood is an anticipated recovery strategy.

Design and implementation are constantly changing throughout the life of a field with the desire to converge to an optimal solution as data is gathered and models are refined. Accurate input of production and injection allocation history reduces the need to rely on assumptions and generates more productive designs, faster. Lower Tertiary fields can see particular benefit due to the fact that there are a relatively large number of geologic unknowns, uncertain injector/producer connectivity, and relatively high vertical heterogeneity.

Highly heterogeneous vertical geology and poor communication suggest the need for high spatial resolution measurements. Wireline spinner surveys require mobilization and intervention costs that limit their utility in deep water applications. However, fiber-optic surveillance has the potential to provide the necessary information. Permanently installed fiber-optic systems can enable equivalent surveys to be conducted with in-situ equipment, on-demand, for the life of the asset. This will have a substantial impact on the cost to obtain data, significantly improve measurement frequency, and reduce the time required to implement changes that improve recovery rates. Even small relative changes in the recovery rate can translate into substantially improved project economics. Optimizing the enhanced recovery process with fiber-optic surveillance provides this opportunity. A wide range of fiber optic sensing applications have been evaluated and employed throughout the oil and gas industry. In this paper, an overview of fiber optic sensing applications will be discussed and their use in Lower Tertiary reservoirs will be evaluated.
Monotonic and Cyclic p-y Curves for Clay Based on Soil Performance Observed in Laboratory Element Tests
Authors: Zhang Youhu , Andersen Knut H , Klinkvort Rasmus T. , Jostad Hans Petter , Sivasithamparam Nallathamby , Boylan Noel P. , Langford Thomas
Published: April 2016

This paper presents a numerical framework for monotonic and cyclic p-y curves for piles in clay, based on soil performance observed in laboratory element tests. A framework of constructing monotonic p-y curves from the stress-strain response measured in direct simple shear (DSS) tests is firstly introduced. The framework is developed from a parametric finite element study. An extension of the framework for analysing cyclic loading is then described, with the use of the cyclic accumulation procedure established at NGI in the last few decades. Finite element analyses are performed for a pile element subjected to various cyclic load parcels in order to validate the extension, using a soil model that follows the cyclic contour diagrams. The procedure to apply the proposed framework for calculating the overall pile response under monotonic and cyclic loading within a conventional beam-column type analysis is then described.

The proposed framework offers a rational approach for the p-y response of a pile element under monotonic and cyclic loading, with the possibility to consider the site specific pile-soil interface roughness, soil properties as well as the cyclic loading conditions. Finally, an example case using a program (NGI-PILE) that implements the proposed procedure is presented and validated against finite element analysis.

The currently proposed framework has potential applications for design of a range of offshore structures, including offshore well conductors, anchor piles and pile foundations supporting jacket structures.
Liner Hanger Rating Methodologies Validated with Physical Testing
Authors: Payne Curtis W. , Warneke Jacob S. , Kaculi Jim T.
Published: April 2016

Currently there are no industry standards specific to the design of liner hangers that provide guidance for determining equipment capacity. The demand for increased pressures, temperatures, and load capacities within stringent space constraints has added complexity to liner hanger design. As wall thickness decreases, capacities are more sensitive to geometrical features and imperfections such as slots, grooves, ovality, and end effects. Classical engineering calculations become increasingly inaccurate as liner hanger geometries become more complex, driving a demand for more precise methods of design verification and validation. Advanced 3-D finite element analysis (FEA) with elastic and elastic-plastic analysis and non-linear geometrical behavior is being used to more accurately quantify stress levels and identify sources of instability in complex liner hanger geometries. The addition of axial slots to a cylindrical pressure vessel result in localized bending stresses which are often overlooked when using only classical engineering calculations for cylindrical members. FEA captures these bending effects, resulting in more accurate ratings. Additionally, external pressure failures due to instability are difficult to capture with classical engineering calculations. Unlike hand calculations, 3-D FEA allows the user to accurately detect instability in liner hanger bodies with complex geometries and end effects. Although 3-D FEA is more accurate than classical engineering calculations, it is imperative that the inputs and assumptions that go into the model accurately represent the physical conditions of the validation test and end use. Internal and external pressure tests have been conducted and the information obtained was used to validate the FEA verification methods. By using a combination of verification analysis with advanced FEA and test validation, an accurate and proven rating methodology for liner hanger systems has been developed. Details about the calculations, FEA, testing, safety margins, and a proposed methodology for rating liner hangers are presented.
Permanent Chemical Tracers Piloted for Inflow Monitoring in Cemented Production Liner
Authors: Oftedal Gaute , Recordon Marion , Loddervik Christer , Nyhavn Fridtjof
Published: April 2016

This is the world's first field trial where inflow tracers have been permanently integrated into a cased, cemented and then perforated production liner; previous inflow tracer deployments have been into non-cemented lower completions. This field trial took place for an oil production-well in the Vigdis field located in the North Sea. The objectives for the tracer deployment for the field trial were: To demonstrate a tracer deployment method not causing complications during Run-in-hole or cementing, while allowing tracer marking of produced oil and water.To demonstrate inflow tracer monitoring specifically for cemented linersTo improve the understanding of inflow and reservoir dynamics specifically for this well and the Vigdis field

Inflow tracers are unique tracer chemicals suspended in a plastic material, designed to release by liquid contact. These were deployed in a metal chamber at the outside of the production liner, to protect from the cementing operations. The liner joints containing the tracers were then spaced out at strategic locations across different reservoir intervals, and the production liner was cemented in place. After perforating, the tracers were exposed to flow, allowing surface sampling and later analysis of each unique tracer. Inflow along the wellbore was then determined through the use of sophisticated tracer transport models.

To ensure the success of this first field trial, the following items were specifically explored: Care was taken to build the customized metal chamber with a smaller outer diameter than the couplings used for the 7inch liner, and to fill this with low solid oil-based mud. The integrity of the tracer systems and the deployment method were proven by:?No complications were observed during Run-in-Hole (RIH) or cementing?All tracers were detected with strong signals in liquid samples,Tracer transport models were applied to the tracer signals and related production data, enabling:?Identification of the location of early water inflow?Defining which of two reservoir layers held the highest pressure?Verifying contribution from the toe during cleanup
Applied Geostatistical Reservoir Characterization in R: Review and Implementation of Rock Facies Classification and Prediction Algorithms-Part I
Authors: Al-Mudhafar Watheq J.
Published: April 2016

Many multivariate statistical learning algorithms are used for rock facies classification. These algorithms are done through several commercial software packages with limitations in terms of availability and computation time consuming. In this paper, we introduce a simplified reservoir characterization workflow through seven multivariate statistical analysis algorithms of rock facies classification modelling, prediction, and validation with high-quality results visualization. That workflow was done through R, the most powerful open-source statistical computing language.

R codes were prepared for seven Facies classification algorithms, which are either supervised learning or regression based. The algorithm are Nave Bayes Classifier (NBC), Logistic Boosting Regression (LogitBoost), Linear Discriminant Analysis (LDA), Multinomial Logistic Regression (MLR), Tree-Based Classification Models (RPART), and Kernel Support Vector Machine (KSVM). These algorithms were modeled rock facies given core and well log attributes for a well in sandstone reservoir in West Africa. The predicted discrete and posterior facies distributions could be used to build the spatial facies distribution and trend modelling, respectively.

To predict the discrete and posterior probability for the clustered Facies, seven algorithms were modeled in R given core and well log attributes. Naive Bayes Classifier and Linear Discriminant Analysis adopted Bayes rule to compute the facies discrete and conditional posterior probabilities. The LogitBoost classification is based on weighted vote of weak classifiers that are sequentially added to the model to minimize the residual loss. The MLR is used to predict the facies probabilities given each independent variable by constructing a weighted linear predictor function. TBM are a recursive partitioning methods that build Classification and Regression s for predicting continuous facies probabilities. Two nonlinear classification algorithms that are efficiently achieved accurate facies modelling and prediction: Kernel Support Vector Machine and Probabilistic Neural Networks. KSVM recognizes the discrete facies based on maximizing the margin around the separating hyperplane and the decision function is fully specified by a subset of the supporting vectors. The accurate models could be adopted to predict facies distribution at other wells in the reservoir for geospatial modelling.

The comparison between these seven-classification algorithms was done through confusion table, transition probability matrix and total percent correct (TPC) of the predicted facies that reflect the classification accuracy. It was noticeable that LogitBoost, KSVM is the most accurate models by achieving the highest TPC as they incorporate nonlinear modelling. Conversely, the lowest TPC was by LDA as linear classifier and NBC as Bayesian one. However, the in-between approaches are MLR and TBM.
High Strength Tapes Layer Design and Qualification, Reinforcement Solution Against Armor Buckling of Flexible Pipe
Authors: Gasc S. , Lambert A. , Do A. T. , Félix-Henry A.
Published: April 2016

Unbonded flexible pipelines for deep water field applications are subject to elevated hydrostatic constraints; bore pressure being dropped brings high compressive stresses due to reverse end cap effect. If the external sheath is unsealed, the axial compression loads transmitted to the tensile armors induce their radial expansion, which can lead to their buckling. Specific layers shall be added in order to maintain armors in place: anti-buckling tapes. These layers, designed with high performance fibers, have been introduced in the early 1990's when the use of flexible pipe has grown in deep water.

Various failure modes are expected and observed depending on the fiber characteristics, tape construction, tensile armors properties and annulus environment. For each pipe design, an optimum has to be found between the anti-buckling tapes loads and the compressive stress in the armor layers in order to ensure sufficient safety margins against both tapes breakage and different buckling modes of the armors.

Anti-buckling tape interaction with the tensile armors and annulus environment main influencing parameters will be explained in the light of full scale tests performed on flexible pipes in hyperbaric tank. Specific laboratory devices have also been developed to be representative of the operating behavior of both armors and high strength tapes.

In parallel, this paper will present qualification tests performed in compliance with the requirements of 2014 editions of API standards 17J and 17B.

The tests showing tape resistance and flexible pipe behavior have enabled to establish a robust design rule. This process is being scrutinized by an Independent Verification Agent and aims at leading to Type Approval Certification according to the latest edition of API 17J.
Application of CFD for Computing VIM of Floating Structures
Authors: Kara M. C. , Kaufmann J. , Gordon R. , Sharma P. P. , Lu J. Y.
Published: April 2016

Under certain current conditions (e.g., the Loop Current in the Gulf of Mexico), floating structures such as semi-submersibles, spars, and TLPs may experience significant vortex-induced motion (VIM). VIM is one of the key drivers of fatigue damage for risers and moorings. It is essential that fatigue from VIM is properly accounted for in design and operation of the structure.

A CFD study was performed using OpenFOAM™ on a model scale, deep draft, "Paired-Column" semi-submersible to estimate the VIM response. The CFD results are compared to model test data. The study concluded that the calculated VIM responses obtained using OpenFOAM™ is comparable to those from model tests. Therefore, if used properly, the CFD approach can be a cost effective and reliable alternative to model testing, which is costly and schedule constrained making it impractical in the early phase of a project.

The paper also describes a set of sensitivity studies based on a fixed, single square column of the semi-submersible which was undertaken to: (i.) better understand the differences in the flow characteristics at model and full scale and (ii.) identify meshing requirements for future calculations.
Integrated Project Management Applied to Ocean Bottom Seismic
Authors: Hartland Martin John , Platz Michael Scott
Published: April 2016

Objectives

This paper lays out key elements of an Integrated Project Management Approach for Ocean Bottom Seismic Projects involving multiple vessels and combined data acquisition services.

Methods

The methodology is based around a generic data acquisition project life cycle and a group of main activities. The guidelines for several of the activity groups will be explained using diagrams and narrative. The context in which this methodology is applied is set around seafloor seismic acquisition which typically will involve a fleet of three to six offshore service vessels (OSVs) working together on a survey, very often significant SIMPOS activity will be experienced. The vessels utilized will often be considered as critical path resources and therefore system redundancy is important to maintain. Services of multiple data providers need to be integrated and combined to support operational efficiency and acquisition deliverables.

Conclusions

The methodology employed has proven to be successful on several complex OBS projects, and where the project objectives have been achieved to the satisfaction of the client and the contracted company. Being able to successfully execute complex data acquisition projects requiring the integration of multiple data acquisition service providers has become extremely important as oil reserves are increasingly scarce and oil companies seek to maximize the recovery from these fields, Seafloor seismic is considered the highest quality of Marine Seismic data available and keeping the cost to controlled and predicted levels is essential for both contractor and client. It is through an Integrated Project Management approach that this can successfully be achieved. The methodology can be applied in other areas of offshore project management with some adaption for the specific business sector requirements.

Additive Information

Existing methodologies and techniques are considered to be highly generic and therefore fail to approach the real challenges faced by organizations who attempt to deploy these methods. This paper is intended to provide insight into integrated project management specifically intended for ocean bottom seismic data acquisition projects. The Case study based around a real project executed from June 2014 – to November 2015 in the Bay of Campeche Mexico will demonstrate the effectiveness of the Integrated Project Management approach.
An Improved Method for Model Test Based Identification of Drift Coefficients and Damping for Floating Platforms
Authors: Rogne Øyvind Ygre , Haug Nora , Løken Rolf
Published: April 2016

A new method for identification of wave drift coefficients and low-frequency damping from model tests is presented. The method is motivated by the lack of robust numerical methods for the calculation of the viscous contribution to the mean and slowly varying wave drift forces – often the largest contribution for semisubmersibles in storm sea states. The drift coefficients represent the diagonal of the difference frequency quadratic transfer function, and because Newman’s approximation is implied by the method, these drift coefficients will give rise to both mean and slowly varying forces.

The new method is based on a weighted least squares solution of the equation of motion, and uses a combination of linear and non-linear least squares methods. The parameters are identified such as to minimize the error in the slowly varying horizontal motion over the entire measurement record.

The method will be demonstrated using data from physical model tests of three different semisubmersibles in a large number of different sea states, including wave only, wave+current and wave+current+wind tests. The accuracy of the obtained results is investigated by the ability of the identified model to back-calculate the measured motions. In addition, a "standard error" on the drift coefficient curves is provided that shows the frequency interval where the identified drift coefficients can be trusted.

The case studies show that the identified models are able to back-calculate the measured motions with good accuracy. Both viscous effects and wave-current interaction is seen to have an impact on the drift coefficients and damping. The quadratic damping is seen to be of much less importance than the linear damping in most cases. Still, it is argued that a significant portion of the linear damping comes from viscous effects, and that the linear viscous damping represents a low-frequency best-fit to the actual all-frequency quadratic damping.
Auto-ID Tracking System Monitors the Location and Compliance Status of Offshore Assets
Authors: Coaton N.
Published: April 2016

The objective of this paper is to demonstrate the value of utilising automatic identification (auto-ID) technology to monitor the location and compliance status of offshore transportable Cargo Carrying Units (CCUs) and other oilfield equipment in the oil and gas sector.

It is very common to see logistical inefficiencies in the oil and gas supply chain. As a result, there is an increasing demand for solutions that will minimise those inefficiencies, improve productivity and reduce operational costs. The most requested solutions are those focused on achieving improved and automated capture of data related to asset and material movements using globally accessible web-based applications and auto-ID hardware components, such as GPS and RFID, which are certified to critical hazardous area standards such as ATEX and IEC-Ex. Any solution deployed must also be internationally applicable and based on open standards to ensure global use and cost-effective interoperability.

A key concern for Operators' Logistics functions and Service Companies is ensuring that asset turnaround time and on site asset handling costs are kept to a minimum. Therefore, removing manual processes and improving data fidelity and accuracy is key.

By applying auto-ID technology to assets and deploying RFID reader infrastructure, many manual processes related to asset tracking, logistics coordination, reporting and administration are greatly reduced or removed (Gaukler, Hemmige and Merchan 2009). Bottlenecks and inefficiencies are also highlighted when the data set is accurate and current.

An Operator was internally reporting 88 days and 58 days respective turnaround times for Offshore Chemical Tanks and CCUs which far exceeded their global KPI targets (56 days and 28 days respectively). However, by applying GPS the reported turnaround for the tagged units was actually averaging 33 days for tanks and 18 days for CCUs – a variance of 78%. The increased visibility and accurate data that auto-ID technology produced, identified where the inefficiencies in the supply chain were and focused efforts on specific bottlenecks.

A major Service Company also achieved a combined 40% reduction in their rental asset sourcing and handling costs within one of their major facilities by introducing active RFID tags and associated reader infrastructure on site.

Additional benefits that can be realised from auto-ID tracking of offshore assets include: Up to 20% reduction in transport costsReduction in operational costs and duplicate ordersUp to 25% increase of asset utilisationReduction in billing disputes and back office administrationReduced headcount to manually track asset location
An Integrated Geomechanical Modeling and Completion Selection for Production Enhancement from Lower Tertiary Wells in GOM
Authors: Bagci S. , Tjengdrawira M. , Park N. , Hustedt J.
Published: April 2016

An integrated study involving geological, geomechanical, reservoir and completion analyses were conducted to design a new completion system for optimizing production in Lower Tertiary play in deep-water Gulf of Mexico (GOM). Lower Tertiary reservoirs are generally characterized by lower productivity potential due to low permeability and poor reservoir energy in some areas due to low GOR, little/no gas cap and very limited water drive. Multiple reservoir sand layers need to be hydraulically fractured for production under a potentially high geo-pressure and stress environment. The design of a lower completion system focused on stimulation, sand control systems and their impact on production. The proposed lower completion system has a large ID to maximize production rates and supports stimulating reservoirs with high proppant volumes and pump rates to increase the number of treatment zones.

Petrophysical and geological analyses were conducted to determine the distribution of sand bodies in thirty study wells drilled across from Alaminos Canyon through Keathley Canyon to Walker Ridge (W-E). A geomechanical analysis was conducted to determine the variation of rock mechanical properties and stresses across these regions. Sanding analysis was conducted to assess the risk of rock failure and the effect of production in open-hole completion under the high draw-down scenarios.

Frac-Pack fracture modeling was conducted with an optimized stress profile for a candidate well for three lower completion systems to select the optimal fracturing intervals and treatment schedules that will maximize well performance. Possible oil production rates were estimated for various scenarios involving natural flow, ESP and subsea boosting.

This study focusing on understanding the reservoir characteristics for lower completion systems design ensures optimal technology selection to ultimately enhance well productivity and ROI with better production rates and ultimate recovery.
Cessão Onerosa FPSOs - Challenges and Achievements Conducting Four Simultaneous Hull Conversion Designs
Authors: Portella R. B. , de Souza Lima H. A.
Published: April 2016

Under the development of the Brazilian pre-salt onerous concession areas Petrobras contracted Enseada Industria Naval for the conversion of 4 (four) VLCC ships into the hulls of FPSOs P74, P75. P76 and P77, for which PROJEMAR have awarded a contract for the complete hull conversion engineering design.

Even with the accumulated experience on the design of 12 (twelve) FPSOs conversions, nothing could be compared with 4 (four) ships being simultaneously converted in two shipyards, being one in Brazil and one in China, to receive 4 (four) Process Plants weighting about 35.000 t designed by 3 (three) different Topsides engineering designers.

This paper intends to describe the main challenges and achievements of the engineering design work for the conversion design of the 4 (four) FPSOs, where the need to maximize standardization conflicted with the different hull configuration of the VLCCs that were being converted, with the different production characteristics of the two shipyards involved on the conversion work and with the different design philosophies of the Topsides engineering designers. These can be exemplified by: The need to face single hull and double side VLCCs that were built in different shipyards in Korea and Japan, what led to different main deck reinforcement and different strategies for steel renew;The different Topsides engineering led to different main deck reinforcements for the Topsides equipment and structures;The main equipment was standardized, but the different ship´s hull structure led to different structural solutions, and smaller equipment were acquired from local suppliers close to shipyards;Different arrangements and tanks configuration led to different piping designs;A new standard accommodation block needed to be fitted in different main deck structure configurations;Individual motions analyses were carried out for each FPSO, but needed to be validated by a unique model tests program;etc

In summary, maximize the design standardization is a key path to improve construction productivity, but as an FPSO conversion design is essentially a tailor made activity, this duality was highly pronounced when dealing with the multiple simultaneous activities of the Cessão Onerosa FPSOs design.
Deepwater Hydraulic Well Intervention at Tahiti: A Creative Hybrid Solution
Authors: Beard J. , Boiteau J. , Chauvin R. , Conner B. , Courtois C. , Theall T.
Published: April 2016

Acid stimulation and scale squeezing are generally well-established hydraulic well intervention practices, although methods for delivering such treatments specifically to deepwater, subsea wells are a less mature area of application. A rig-less intervention alternative provides a more economic option for intervening on subsea wells, in comparison to traditional rig-based methods. This technical paper describes the planning and execution of a multi-service vessel (MSV)-based hydraulic intervention campaign at Chevron's Tahiti field in the U.S. Gulf of Mexico.

Challenged with early-life well productivity decline and imminent injected seawater breakthrough, the Tahiti asset formed a multi-disciplinary team to develop a fit-for-purpose solution to remediate and mitigate these concerns. Acid stimulation was selected to arrest and recover well productivity, while scale squeezing was required for protection against barium sulfate scaling from the mixing of formation water and injected seawater. These treatments were to be delivered to subsea production wells in water depths of ~4,200 ft.

The design basis of this hydraulic intervention system involved dual, open-water coiled tubing strings deployed from the MSV to a subsea stimulation module. This module is landed and secured subsea on a modified suction pile, allowing structural isolation from the horizontal subsea production trees. In turn, a flexible jumper from this module to a valve package and modified choke insert on the tree enabled access to the wellbore for delivery of the treatments. De-coupling the stimulation module from the tree interface alleviated the risk and complexity of removing crown plugs and imparting load forces on the tree, and denotes the ‘hybrid’ nature of the system.

Design and operational phases required overcoming challenges such as coiled tubing fatigue management, unexpected loop current conditions, and deployment sequence optimization. Given the first-time deployment of this hybrid system, detailed front-end engineering and design was required for validation of an enhanced well control and emergency disconnect system, to accommodate safe execution. The 5-well campaign was executed incident-free during 2015, delivering a total treatment volume of almost 30,000 bbls, resulting in 8,500 BOPD gross initial production uplift, and cost savings of 85% in comparison to traditional rig-based methods.