bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the Focus of the ACG Geohazards Image–20 Years of Data Acquisition
Authors: Dingler Jeffrey A. , Dingler Allison , Hill Andrew W. , Wood Gareth A. , Ford Alan
Published: April 2015

The super-giant ACG field lies in the Azerbaijani sector of the south Caspian Sea. Since the signing of the "Contract of the Century" in September 1994, the significant complexity of the geohazards setting over this field has required near continual acquisition of geophysical imagery to better understand the various geohazard issues faced.

Upon signing of the PSA it was known that there was very little geophysical imagery of the shallow section in existence. As such, the first geophysical operation over the PSA contract area in 1995 was a blanket regional 2D survey of the entire 450km2 PSA contract area to allow regional geohazards mapping to be undertaken. This entailed acquiring a regional grid of HR2D seismic data and a seabed survey that included collection of swath bathymetry. The challenges of importing acquisition systems into Azerbaijan, and mobilizing the equipment onto vessels of opportunity, limited the systems that could be used at the time. Therefore, the bathymetric model that was produced, for example, was useful, but limited by a swath bathymetry system that could only image to ~210m of water depth while PSA contract area water depths vary between 96 and 425m.

Over the following decade, geophysical site investigations of appraisal wells, platform sites and pipeline routes followed industry norms of site specific 2D surveys.

However, in 2004, one pass HR3D and seafloor surveys were acquired making use of a 3D seismic vessel. The use of the larger vessel had various advantages. Firstly, the capability to safely tow four streamers and two sources allowed acquisition of eight lines of subsurface coverage per sail-line. Secondly, the more stable vessel platform, allied with a more robust design of over-side mountings, provided a far superior platform for acquisition of swath bathymetry data. The resulting seabed and sub-seabed imagery were far superior to preceding imagery.

In 2007, another step change in data quality was achieved with the acquisition of the first ever deep-water AUV survey acquired in the Caspian Sea. Using a Hugin 3000 vehicle, the resulting swath bathymetry, sonar and sub-bottom profiler imagery saw another step change in quality.

HR3D and AUV data of the entire PSA have now been acquired in a phased approach. Included in the HR3D acquisition were undershoots of the six producing platform complexes to verify the integrity of overburden conditions below the platforms.

This paper will show the improvements in data quality that have been achieved over life of the PSA, and demonstrate the impact these improvements have had on better understanding of geohazards for future development and ongoing operations across the field.
Advancing Cold Water Intake Riser Design through Model Test
Authors: Cao Peimin , Xiang Sherry , He Jingxi , Kibbee Steve , Bian Sean
Published: April 2015

Water Intake Riser (WIR) offers the potential to convey a large amount of cold water from deep ocean to improve the topside process efficiency and reduce overall cost of a FPU, FPSO or FLNG vessel. Its large diameter (>1m) and high flow rate presents unique design challenges and performance uncertainties. A model test campaign of a large diameter WIR concept has been planned, designed, and executed in an offshore model basin on a fast track basis. The pipe was carefully scaled and fabricated to meet the test objectives. The model test setup included a riser model instrumented with optical strain sensors, a planar motion mechanism which simulates the vessel motions, and an internal water flow system. More than 200 cases were performed in the model basin including sinusoidal and random motion tests in combination with various flow rates. This paper discusses the challenges, observations and lesson learned during the model test, and some of the key results in comparison with analysis models. The successful execution of this project demonstrates that model testing is an important tool in advancing complex deepwater riser concept.
Reducing the Environmental Footprint: Innovations on the CLOV Project
Authors: Vallot Patrick , Kang B.K.
Published: April 2015

This paper describes how the CLOV project team reduced the environmental impact of operations on its Floating Production Storage and Offloading (FPSO) vessel through the use of a number of different innovative systems.

The approach focussed on three different aspects of topside operations: power consumption, gas handling and produced water disposal.

Power usage is based on the ‘all-electric’ concept making use of variable speed drives to manage consumption with the aim of reducing generation requirements and improving efficiency.

On gas handling, under normal operating conditions, the FPSO flare system will be flameless, including the pilot. The philosophy behind the design and advantages of reducing gas emissions will be explained.

Finally, the reduction of discharges to sea will be discussed. This involves the use of both produced water in the water injection system to provide pressure support for the reservoir and the application of wash tanks for the retrieval of produced sand for transport to shore.
A New Approach for Offshore Chemical Enhanced Oil Recovery
Authors: Delamaide Eric , Moreau Patrick , Tabary Rene
Published: April 2015

Chemical Enhanced Oil Recovery (EOR) has seen numerous applications worldwide onshore but very few offshore. The reasons for that are mostly related to the technical and logistical challenges that need to be overcome for the successful implementation of chemical EOR: transporting various chemicals to the platforms, the need for space for the mixing skids and storing chemicals on the platforms, the need to use sea water as the injection fluid among others. As primary and secondary recovery reach their technical and economical limits in offshore fields, the operators are faced with the dilemma of abandoning the field and the platforms or resorting to EOR to increase recovery and extend the life of the field. Non chemical EOR techniques face their own challenges such as the need for large gas supply for gas injection so chemical methods cannot be ruled out so easily. However new approaches need to be defined to make chemical EOR a realistic method for offshore reservoirs. A large part of these issues arise from the mindset which associates chemical EOR with Alkali-Surfactant-Polymer injection. The approach proposed is to use only surfactant in cases where polymer is not absolutely required and to eliminate alkali altogether. This will eliminate various obstacles such as deck space limitations and the need to soften the injection water. This approach opens new doors for chemical Enhanced Recovery offshore. Such an approach is possible thanks to the progress in surfactant formulation and the development of adsorption inhibitors which allow dealing with seawater as an injection fluid. The novelty is not the technology but the way the standard approach is discarded to the benefit of a simpler solution.
Tank Test Results and Numerical Prediction of Structural Response of an innovative TLP for Offshore Wind Turbines
Authors: Dahlhaus F. , Großmann J.
Published: April 2015

The Offshore Wind Resources in deep water, but also the currently experienced issues with conventional foundations, are driving the solution requirements for new offshore wind power platforms. The latest monitoring results of German offshore wind farms show the challenges the industry is facing. Ecological impacts as well as foundation technology issues are forcing the sector to look for alternatives. The presentation will introduce a technology of a floating TLP-structure with a specific mooring line configuration as an innovative foundation concept for offshore wind turbines suited for water depths greater than 30 meters. The unique aspect of the GICON TLP is its modular, frame-work structure which allows buoyancy and load transfer functions to be decoupled from each other and instead be applied to the specific structural elements. In contrast to classic TLP designs and semi-submersible floaters, additional stabilizing effect achieved by this additional bracing minimizes the movement of the entire system. Due to this stable behavior of the TLP standard offshore turbines as currently available in the market should be usable for this platform. Furthermore results from model basin tests will be described. Also the comparison of calculated and experimental data obtained by extensive tank experiments with a scale model of an offshore turbine at Maritime Research Institute Netherlands (MARIN) in summer 2013 will be presented. These experiments include wind and wave loads that represent different sea states of the proposed location for the full scale prototype. In numerical simulations the dynamic behavior of the TLP under linked hydrodynamic and aerodynamic loading is taken into account also regarding different geometric configurations of the mooring line system and various types of anchorage systems at the sea floor. Using characteristic Campbell-diagrams structural stiffness of each component is optimized aiming at a soft-stiff design of the TLP-structure. The results of the scaled tests at MARIN have confirmed that a superposition of internal forces of the moored structure in operation for wind and wave loads can be assumed. Numerical modeling validation is confirmed by tank tests. Data and video from the tank tests will be shared as part of the presentation. GICON researchers plan to install a full- scale pilot plant in the German Baltic Sea in 2015.
State of the Art of 1D Steady State Flow Assurance Models for Deepsea Mining Production System Using Air-Lift Pumping
Authors: Beauchesne Claire , Tzotzi Christina , Parenteau Thomas
Published: April 2015

The flow assurance aspects of all subsea projects have a major contribution to the pipe design, field layout, choice of lifting equipment (subsea-pump or air lift), power requirement and system operability. In the context of deep-water mining, the most important is the pressure drop estimation in the flowline and riser as well as the flow regime. These are needed to guarantee the production target at steady state.

Among the pumping options, Air Lift stands out as valuable option for bringing ore minerals from seabed up to the surface. The principle is to reduce the mixture density by introducing air at a given water depth. That way, the slurry (consisting of ore minerals and seawater) in the pipe lower section is forced into the upper pipe section and brought up to the surface. For drawing up preliminary field architecture, a simplified one dimensional model is required. It brings into play a straight vertical pipe with single solids size and density flowing into a carrier liquid at steady state. This is the first step for assessing the field operability as well as the preliminary field architecture and flexible riser design. However, deep-sea mining conditions push the existing flow models beyond their validation limits.

This paper starts with a state-of-the-art of the one dimensional modelling of air-lit pumping. It points out their differences and limitations regarding subsea mining applications. In particular, the large riser internal diameter and the very large operating depths put into question the applicability of those models. Finally, further improvements will be proposed for extending the applicability to deep-sea mining conditions.

It is of great importance to assess the feasibility of air-lift pumping for deep-sea mining, which stands as a simple way to lift ore up to the surface. However, the lack of direct control upon the mixture velocity at top and upon the flow regimes all along the riser renders this option tricky. That is why a reliable modelling of the air-liquid-solid three-phase flow in large diameter pipes and under high pressure is absolutely necessary.
CFD tools and adapted methodologies for Marine and Offshore Engineering projects
Authors: Thilleul O. , Drouet A. , Andrillon Y. , Guilcher P-M. , Jacquin E. , Barcarolo D. , Berry L. , Ledoux A. , Guillerm P-E. , Le Touzé D. , Derbanne Q. , Legregeois N.
Published: April 2015

Computational Fluid Dynamics (CFD) tools have progressed greatly in the past decades in such a manner that they have become a recurring tool during the workflow of an engineering project. In the specific case of Marine and Offshore Engineering, these tools are more and more used to predict forces on structures with a very detailed level of precision, to optimize hull forms to conceive more efficient and environmentally friendly designs and also to reassure structural engineers with respect to the assumptions made during complex engineering problems.

In this article several examples of how these tools and methodologies have been employed in the design process of Marine and Offshore structures will be presented. Validations compared to tank tests and wind tunnels will be presented for damping coefficients, green water impact, aerodynamic coefficients and non-linear wave loading studies. Throughout these examples it will be shown how the need of dedicated tools/methodologies is necessary in order to efficiently use the CFD tools during the Naval and Offshore design process.

Very often, distinct phenomena need to be modeled in order to correctly apprehend the complexity of the flows. To do so, coupling distinct approaches is sometimes necessary: CFD solver to a potential one for instance. In the paragraphs below four examples are illustrated: nonlinear wave loading computations, damping coefficients computation, aerodynamics winf loads estimation on complex topside structures, and prediction of green water impact on a FPSO.
Challenges in Wave Force Modelling for Mooring Design in High Seas
Authors: Stansberg Carl Trygve , Kaasen Karl Erik , Abrahamsen Bjørn Christian , Nestegård Arne , Shao Yanlin , Larsen Kjell
Published: April 2015

Line breakage events have been experienced on moored structures during recent years. These are often occurring in heavy weather and overload is one of the reasons pointed out. The present paper identifies posible physical phenomena that may lead to wave forces higher than predicted by state-of-the-art hydrodynamic tools and procedures, and thereby higher mooring line loads, in high and steep waves. In particular, a need to re-explore wave-group induced slowly varying, low-frequency (LF) drift forces has been identified. Both mobile offshore units (MODU's) and permanently moored floaters are considered, semisubmersibles and FPSOs. Empirical corrections are sometimes being applied in design of mooring lines, while not in general, and there is no established common industry practice on such corrections. More advanced tools and knowledge do exist in research communities, while they still need further development for robust engineering use.

A brief overview is given of state-of-the-art methods and tools in modelling of the hydrodynamic forces on large-volume floaters, with particular focus on slowly varying wave forces. Full scale experiences from real sea events and from a variety of earlier case studies including model tests are reviewed. It is found that several items may be critical in the proper prediction of LF wave forces in high seas and combined current and should be investigated further, in particular: –Wave-current interaction–Viscous wave drift forces–Large and nonlinear wave-frequency vessel motions.

Based upon these preliminary investigations, the paper gives recommendations for actions and further developments for improved predictions in industry practice.
Application of Real Time Calibration as a Tool for Resolving Geomechanical Model Uncertainties in Bonga North West Well Delivery
Authors: Ijeoma Anselem , Adeleye Olayinka
Published: April 2015

The Bonga North West (BNW) field is located in Shell operated Oil Mining Lease (OML) 118, approximately 110 km southwest of Forcados Terminal, offshore Nigeria and 5 to 10 km west of the Bonga Main field, in water depths ranging from 990 m – 1170 m. The license is operated under a production sharing agreement with the Nigerian National Petroleum Corporation (NNPC) by Shell Nigeria Exploration and Production Company Limited (SNEPCo) in partnership with Esso E&P Nigeria Ltd, Nigeria Agip Oil Company (NAOC) and Total E&P Nigeria.

The first phase of the Bonga Main development comprised of 16 wells which were mainly short to medium reach wells. Development drilling of Bonga Main Phase 2 is currently ongoing while BNW Phase1 has been completed. The Bonga Main Phase II & BNW Phase I wells consist of high angle medium to very extended reach wells. Drilling the early extended reach wells on Bonga Main phase II presented borehole stability challenges that led to significant budget over-runs. To mitigate against this a process was put in place where well-specific borehole stability study was carried out to determine the optimum mud weight to use for drilling each hole section. This process resulted in reduction in borehole stability related nonproductive time (NPT) on the phase II wells. However there are challenges associated with this approach:

Limited rock property data availability to facilitate delivery of accurate model outputs.

Bonga field consists of stacked sand - shale sequence. The fracture gradients of the sands are typically less than that of the shales and the well designer is presented with a challenge selecting the optimal mud weight to keep the shales from collapsing while ensuring that the sands are not fractured.

A wellbore stability study was performed for the first BNW well (W-1). The mud weight output from the study presented a challenge that will have required additional casing strings to deliver the well. This paper describes the technique utilized to manage the challenges on BNW (W-1) and deliver the well without any borehole stability related downtime.
Delivery of Nigeria's First Brownfield Deepwater Triple Daisy Chained Subsea System
Authors: Brewer Richard , Ajayi Olusayo , Ilesanmi Olaniyi , Jukes Steve , Mohammed Musa , Ikhenebome Thomas
Published: April 2015

SNEPCo's Bonga North West (BNW) Project has successfully installed and commissioned the Gulf of Guinea's first brownfield deepwater triple manifold daisy chain system, integrating two different subsea Vendor's production and water injection systems in a unique achievement. Two new-build 90Te 4-slot subsea manifolds were connected to an existing end-of-line Bonga Main 4-slot production manifold via a retrofit Cross Over Module (COM), using a series of pipe-in-pipe flowlines and sleds. This paper will describe the technical and organizational enablers that were identified, developed and implemented to successfully achieve this complex task in over 1000 m water depth offshore Nigeria.

Integration of the two new subsea production manifolds to the existing subsea system was achieved via the COM. In principle, the design of the COM is a dual header fixed hub system that bridges the new subsea infrastructure to the existing manifold, originally proposed to enable concurrent operations and new field tie-in. The COM is equipped with an isolation arrangement giving double isolation to each of the dual headers, to enable continued Bonga Main production after COM installation and prior to completion of other BNW facilities. This decoupled and de-risked the short COM installation operation from the lengthy BNW facilities installation phase, giving schedule flexibility, and minimum production deferment.

Removal of the selected Bonga Main Pigging Loop Module (PLM), located at all end manifolds, was required without hydrocarbon leakage to the environment. Various options for displacing stabilized flowline hydrocarbons present within existing flowlines, necessary for replacement of the PLM by the COM, were considered. Treated produced water available on the Bonga Main FPSO to flush the flow loop was selected for the displacement process, and was readily achieved by re-directing produced water into a dedicated clean slop tank on the FPSO. Displacement (de-oiling) of the production flowlines using this method enabled the regulatory water quality requirement of 30ppm required for discharge into the environment to be met. Good collaboration between various specialized teams in the replacement of the PLM with the COM, covering Operations, Intervention, Subsea Surveillance, Flow Assurance and Subsurface, was critical to the overall delivery success of the project.

Integration of BNW subsea hardware and flowlines with existing Bonga Main subsea infrastructure was completed safely and seamlessly to give first oil on time and with minimal disruption to existing production. New flow assurance challenges associated with the triple manifold daisy chain system were observed during early operation and will be discussed further herein.

Significant insights and learnings were gained regarding in-country fabrication, specifically concerning onsite dimensional control and achievement of fabrication tolerances.
Effects Of Platform Pitching Motion On Floating Offshore Wind Turbine (FOWT) Rotor
Authors: Sivalingam Krishnamoorthi , Bahuguni Anand , Gullman-Strand Johan , Davies Peter , Tan NGUYEN Vinh
Published: April 2015

The increasing demand for offshore wind energy is leading the industry to look for expansions into deep oceans. This development has compelled the industry to venture in to floating offshore installations for wind turbines. The floating installations lead to complex rotor motions in 6 degrees of freedom. The current work focusses on various aerodynamic effects on the turbine rotor due to coupled wind and wave forces. In this research work, the dynamic effects of the platform pitching motion on the rotor for OC3 phase IV case 5.1 are studied with rigid body assumption using high fidelity CFD (Computational Fluid Dynamics) commercial tool and semi empirical tool called FAST which is developed by NREL, USA. The hydrodynamic effects leading to the pitching motion of the turbine platform are extracted from the NREL FAST software. These pitching motions are coupled with the rotating blades to study transient flow behaviors using CFD tools. The results are compared with the standard BEM based methods to identify the discrepancies if any. Moreover, fine variation of rotor power/load due to dynamic pitching of the floating platform is also compared. The induction factors are extracted from the CFD results for every time step and are compared with those obtained with BEM based methods. Moreover, the application of CFD induction factor methods are introduced for cyclic load variations due to the rotor plane motions to check the validity of the BEM for FOWT application.
A Design Framework for Sliding Foundations: Centrifuge Testing and Numerical Modelling
Authors: Wallerand Regis , Stuyts Bruno , Blanc Matthieu , Thorel Luc , Brown Neil
Published: April 2015

Pipeline end termination (PLET) structures used in subsea deepwater developments are subjected to significant axial expansion forces arising from heating up and cooling down of the incoming HP/HT pipelines. Resisting these forces with a fixed foundation solution such as a skirted mudmat or hybrid foundation with pin piles would lead to excessive foundation sizes when axial expansions are large. Allowing the foundation to slide over the seabed as a whole could lead to a more economical solution (Bretelle & Wallerand, 2013).

A study has been initiated to develop a design framework for sliding PLET foundations, allowing a controlled movement of the foundation during its design life. Such a performance-based design needs to characterize displacements and rotations of the foundation during several cycles of large-amplitude foundation movement in order to provide a robust design.

Series of scale model tests in the centrifuge of IFSTTAR in Nantes have been performed to validate the performance based design approach outlined by this study. These tests have focused on the influence of the interface roughness and degree of soil consolidation to characterize the soil response under in-plane loading.
Wave Energy Conversion: Opportunity, Challenges, and Design Considerations
Authors: McCall Alan , Clabby Darragh
Published: April 2015

Objective/Scope This paper reviews the state of Wave Energy Conversion (WEC) technology as it relates to the ASCE COPRI Marine Renewable Energy (MRE) Committee's efforts to study and disseminate information on marine renewable energy facilities. Of particular interest are topics within the field related to risk and reliability aspects of WECs, the opportunity of devices within the field of Wave Energy, and how moorings requirements differ from device to device. Methods, Procedures, Process A set of WEC device types, including the predominant technologies such as: point absorber, attenuator, and surge converter type devices, as well as emerging device types will be reviewed at a high level. Each device type will then be investigated to understand which aspects are most critical to performance, risk and reliability. These devices will also be examined for the links between performance and the role of moorings, drawing out the relationship between each device and its mooring requirements. Results, Observations, and Conclusions This paper will result in a clear understanding of the current WEC landscape with respect to how each device type potentially fits into the industry. Specific outcomes will include: An overview of some of the most significant device types, new and alternative device types, important design considerations for both performance and reliability, and the relationship between each device and its mooring. Novel/Additive Information Readers of this paper will gain an understanding of the strengths, weaknesses and risks of each of the WEC device types covered. This paper will also provide the reader with knowledge of which design parameters are most relevant to each specific device type covered.
First Usage of an Effective Device for Landing the Production Tubing in Subsea/Deep Water Wells in Malaysia
Authors: Taylor Dan , Thomson Dave , Ong Benjamin , Roane Tom
Published: April 2015

Spacing out production tubing and landing the tubing hanger in subsea completions is particularly challenging in wells with extreme well depths or in highly deviated well bores, as rig heave can significantly challenge space-out operations. Another problem also can occur when attempting to enter the casing at the subsea blowout preventer (BOP) in deep water, since the subsea currents can initiate a bending motion to the riser, causing the bottom of the completion to enter the subsea blowout preventer (BOP) at an angle. If the angle is too high, set-down weight or compression must be applied to push the completion through, placing shearable travel joints at risk of prematurely shearing. Even after pushing the travel joint through the subsea BOP, the completion design must manage friction induced by well deviations or ‘S’ curve well bores. Also, the travel joint must remain rigid enough to land seals into production packers at the formation. Often, these challenging scenarios with high angles can be further complicated by limited available slack-off weight. This paper will discuss how the development of new travel-joint designs were capable of resolving challenges such as those mentioned above that were encountered on the the first deepwater subsea development for an operator in Malaysia. This was also the first entirely deepwater subsea development in Malaysia, and at the time of the commencement of its development, an average production of 135,000 barrels per day of hydrocarbon was expected from the project.

To address the completion obstacles discussed above, a service/engineering company developed a long, space-out travel joint (LSOTJ) designed to telescope downward in response to a timed application of a compressive load rather than a shearing event as in standard designs. The LSOTJ slowly scopes downward during lowering of the production tubing until the hanger is landed. Equipment development was comprised of two versions of the long space-out travel joint; one version is a non-continuous sealing (NCS-LSOTJ) version, and the other is a continuous sealing (CS-LSOTJ) version

This paper will discuss the design and development of the two LSOTJ versions, and the first usage of the continuous sealing version in Malaysia, which was also its first usage world-wide.
Temperature Distribution of Shallow Medium during Deepwater Drilling
Authors: Li Chaowei , Fan Honghai , Wang Zhiming , Deng Song , Ren Weiyan , Yan Bo , Liu Weichao , Kang Bo , Zhang Ming , Peng Qi
Published: April 2015

Since depth of shallow layers in the deep water is general 1500 ft or more, the temperature is approaching the freezing point of water at this depth. Moreover, Drilling Fluid always has a high temperature which can lead the originally stable gas hydrate, shallow flow and shallow gas to disorders, for example, corrosion and deformation of drilling strings, blowout and pipeline jam can be induced by shallow flow, shallow gas and natural gas hydrate respectively. This paper conclude a new method to describe the complex temperature gradient in the shallow layers.

A new model of heat transmission about shallow layers including shallow flow, shallow gas and wellbore is established. Thermodynamics and heat transfer are used in this paper either. Meanwhile, assuming the heat transfer among surface casing, formation and shallow flow is stable, whereas the transfer among drilling fluid, drilling strings and casing is unstable, a temperature simulation in the shallow could be done. Furthermore, this paper adopts an infinitesimal control body as a research object and establishes nonlinear partial differential systems. A fully implicit finite volume method is adopted to discrete the control equations. Then through the equation integral in the control domain, the discrete equations of conservation are obtained. Meanwhile, the alternating direction method is used in order to improve the solution efficiency, stability, and convergence.

This paper also cities a well data in South China Sea as an example. Through the analysis of different displacement, wellbore and shallow water distance, the new model calculation results are accurate compared with the classical model validation. It can be concluded that the drilling fluid temperature has a great influence on the shallow. The greater heat transfer coefficient of shallow flow, the faster the temperature rises. Some new solutions to solve geological hazards are obtained in the shallow in which the special temperature profile can trigger natural hazards.

Safety becomes the biggest concern during drilling in the shallow of deep water. This paper mainly focus on the temperature prediction in the shallow. On one hand, the complex temperature changes can cause numerous geological hazards during drilling or cementing process. On the other hand, the narrow density window of safe drilling fluid demands high standard of techniques. So the accurate temperature distribution of shallow layers in deep water has great significance in drilling works.
Pore Pressure Calculation Method for Deepwater Shallow Layers with Log Data
Authors: Deng Song , Fan Honghai , Zhou Yuyang , Zhang Ming , Liu Jinge , Niu Jun
Published: April 2015

Deepwater drilling practice faces numbers of geological hazards which happen in shallow area due to abnormal pore pressure, and these phenomenon go worse, even affect the drilling process, combining with shallow flow, shallow gas, and gas hydrate conditions. However, applicable pore pressure calculation methods were not established in last decades.

Formation pore pressure change closely with SDT, especially the reaction more obvious mudstone formation. In this paper, based on shallow soil attributes, two kinds of logging-based calculation methods are put forward. One is a comprehensive interpretation method, in which porosity, shaliness and effective stress are taken into account. The other is a multi-regression method with the consideration of P-wave velocity, affected by shallow gas velocity and shallow flow velocity, and mathematical model is established by multi-regression.

Two wells in Yingqiong basin are exampled to verify above two methods. Meanwhile, calculation results are consistent with testing data, and geological hazards can be detected. Results shows that the multi-regression method is more suitable for fast prediction, and the comprehensive interpretation method is more accurate.

Pore pressure calculation in deepwater is different from the shallow case due to soil attributes. How to accurately analyze it still has a long way to go. The methods proposed in this paper have been applied in many wells in the South China Sea, and provide reasonable references to drilling practice.
Novel Anchoring Solutions for FLNG - Opportunities Driven by Scale
Authors: O'Loughlin C.D. , White D.J. , Stanier S.A.
Published: April 2015

FLNG facilities present a more onerous anchoring requirement than existing floating structures. Optimisation of the anchoring technology through improved design or through novel anchor types offers potential cost and risk benefits. These benefits may also be applicable to smaller moorings for MODUs and FPSOs. This paper uses concept–level design calculations of anchor capacity to compare different anchor technologies in the context of FLNG and MODU/FPSO applications. Also, new observations from physical modelling of chain–soil interaction are presented. Opportunities are identified for significant cost and schedule savings by adopting the alternative plate anchor technologies that are either suction or dynamically installed. Considering fabrication alone, the estimated costs are reduced by 70% for FLNG and 80% for MODUs relative to the conventional suction caisson option. When installation vessel costs are considered, the absolute cost saving could be far higher than from fabrication alone because installation could be from an anchor–handling vessel rather than a construction barge with a heavy lift crane. Torpedo anchors have also been considered, but are less attractive. Centrifuge model data and calculations of the shape and capacity of the embedded anchor chain suggest that there may be over–looked capacity from the mooring chain both on and within the seabed. At the same time, upscaling of embedded plates to the scale required for FLNG applications increases the amount of chain slack that would be released into the mooring during in service loading, and this effect requires consideration in the overall mooring system design. Research and development activities aligned with the opportunities for reduced cost and risk in anchoring design are set out.
Environmental Consequences of Engineered Nanomaterials: An Awareness Campaign to Promote Safe Nanotechnology and Dispel Related Misconceptions
Authors: Pavan M. V. Raja , Khabashesku Valery N.
Published: April 2015

Nanomaterials comprise a wide range of material compositions, existing in the form of particles or aggregates that have at least one dimension in the nanoscale regime. They have several unique characteristics such as high surface area, customizable chemical functionalities, and unique electrical, magnetic, and mechanical properties. Examples of synthetic nanomaterials and nanostructured materials include carbon nanotubes, silver nanoparticles, nanoporous silica, and polymeric nanocomposites. Nanomaterials have been extensively studied in relation to applications such as sensors, coatings, and composites, in a wide range of industrial sectors.

Thus, it is safe to assume that the application potential for nanomaterials is expanding. This is particularly true in the case of the oil and gas industry wherein several new technological developments are anticipated in relation to nanomaterials and nanotechnology – it is in a relation to a growing need for high-performance materials capable of functioning under adverse field conditions. High-strength polymer nanocomposites come to one's mind as a prominent example of a nano-related application in the oilfield sector.

This paper presents an overview of the existing literature on the general impact of engineered nanomaterials from the perspectives of first, human health and the environment, keeping in mind the need to foster safe and responsible use of these materials, and considering the numerous benefits they offer in relation to various applications. In-vitro studies have shown that nanoparticles could potentially inhibit the growth of mammalian cells while in-vivo studies have shown adverse effects of nanomaterial exposure on various organs such as skin, lungs and corneas. In-vitro (on mammalian cells) and in-vivo (on laboratory animals) studies are meant to safely simulate the biological impact of the nanomaterials. However, these studies may not reveal the complete picture, and it cannot be stated that nanomaterials are generally harmful to all life forms. Microbial interaction studies have demonstrated mixed results in that carbon nanotubes were not found to inhibit the growth of E. coli in certain instances where a biofilm was formed. These trends highlight the need for each category of nanomaterial to be understood in the context of its properties, and its application or exposure route.

Similar to the case of conventional / commonly used industrial chemical substances, the reviewed results serve to create an awareness of "nano-safety". They point to the need to develop appropriate measures to mitigate any potentially adverse effects of nanomaterials on human health and the environment. This is accomplished through measures such as secure containment of related wastes, choice of appropriate environmentally benign nanomaterials, and a well-planned procedure to handle unintended release of nanomaterials, etc.
Extending Anchor Handling Vessel Capabilities and the Technical Innovations that Make it Possible
Authors: Miller Jonathon D. , O'Driscoll Michael A. , Farrow Mark
Published: April 2015

As more structures are installed in offshore deepwater locations, the demands on the fleet of vessels that support the work increase. Deeper installation depths require the employment of emerging technologies and novel installation practices to safely accomplish installation and commissioning of the station keeping system. Deepwater operations can be costly and operators often enter extended contracts with vessel owners to support a variety of offshore operations as a cost reduction measure. In the autumn of 2014, the Delta House floating production system (FPS) was connected to its pre-set taut-leg mooring system in approximately 4,500 feet of water. Mooring installation costs were reduced by utilizing an anchor-handling vessel (AHV) already on long-term contract with the Operator's drilling department.

The Delta House hull and mooring designs were created by EXMAR Offshore, and the mooring components were specified and ordered knowing that the components exceeded the handling capacity of the selected installation vessel. This created unique challenges as the normal handling practices and equipment could not be employed. This paper summarizes the challenges and solutions found during the installation of the Delta House FPS for LLOG Exploration. It highlights innovations that extended the installation vessel's capacity and compares the size of the Delta House mooring components with those installed for LLOG's previous OTPI-Ex hull (Who Dat) in 2011. It describes enabling technologies that made installation possible with the specified asset.
An Experimental Study of Paraffin Deposition under Two-Phase Gas-Oil Slug Flow in Horizontal Pipes
Authors: Rittirong Ake , Panacharoensawad Ekarit , Sarica Cem
Published: April 2015

Paraffin or wax deposition under two-phase gas-oil slug flow in horizontal pipes was studied experimentally. The experiments were conducted using a 2.067-in large-scale multiphase flow loop under an operating pressure of 350 psig. Testing fluids were Garden Banks condensate and natural gas. Hydrodynamic experiments were performed prior to the wax deposition experiments to verify the flow patterns and examine the flow behavior. The hydrodynamic and heat-transfer variables were estimated using the unified mechanistic model (Zhang et al., 2003). Wax deposition experiments were conducted under single-phase and slug flows with parametric variation of oil and gas superficial velocities and testing durations of 4, 12, and 24 hrs. The bulk fluid and initial pipe wall temperatures at a removable spool piece were kept below WAT and relatively constant to control the initial concentration driving force. In this study, unprecedented detailed measurement and analysis of the circumferential local samples were conducted. A new pigging tool was designed and constructed for selective wax sampling at top, side, and bottom quarters of the circumference of the removable spool piece. Local deposit thicknesses were calculated from the direct measurements of deposit mass and density. Wax samples were analyzed by using DSC and HTGC for wax content and composition. The impact of the physics of the slug flow on wax deposition was investigated.

The results indicated that deposit thickness, wax content, and wax mass were affected by the change in superficial velocities or the flow rates of the phases. It was found that the deposit thickness increased with time. The thickness decreased with increasing superficial liquid velocity; whereas, it increased with increasing superficial gas velocity. The trends of the thickness were found to crossover each other at a certain time for different superficial gas velocities. In slug flow, circumferential variations of the deposit characteristics were analyzed. The deposit at the top wall was thicker, softer, and contained more oil than the bottom. Wax fraction increased with time reflecting the aging. Moreover, wax fraction increased with higher superficial liquid and gas velocities at a given time. The crossover of the wax fraction trends with different superficial gas velocities occurred. In slug flow, deposit at the top wall always had lower wax fraction than the bottom. Average carbon number and WAT of the deposit relatively increased with wax fraction. Wax deposits under slug flow had longer chain paraffins compared to the single-phase flow with the same wax fraction. Wax mass at the top wall was higher than the bottom. This new set of experimental data can be used as a verification tool for further development of wax deposition mechanistic model under such conditions.
Stationkeeping Technology for Frontier Deepwater Floating Systems
Authors: Duggal Arun S. , Izadparast Amir H. , Pothuganti Vijay K.
Published: April 2015

This paper provides an overview of the challenges associated with the stationkeeping of floating systems in frontier deepwater, and the range of solutions to address them. The paper presents the use of existing technologies, materials and components, and compare and evaluates them to the use of novel materials, new and possibly not field proven technologies, and design approaches.

The paper provides a high-level design basis and strategies for the stationkeeping system design, identifying key drivers in the selection of the stationkeeping system. The paper then utilizes an example of an FPSO system moored in a range of water depths to illustrate the current capabilities of conventional technologies and strategies to improve performance.
CFD-Based Numerical Wave Basin for Offshore Floater Design
Authors: Kim Jang Whan , Jang Hyunchul , Kyoung Johyun , Baquet Aldric , O'Sullivan Jim
Published: April 2015

Technip recently has developed new cost-effective and riser-friendly Semi-submersible hull forms adapted to various operation sites, with considerable saves in design cost and time. This achievement is greatly in debt to Technip's numerical wave basin, which has been developed and validated through previous projects and collaborative R&D efforts with clients. Validation of the numerical wave basin against the model test and full-scale measurement data has proven that the numerical wave basin can provide more realistic and reliable prediction of the wave- and vortex-induced motion than the physical model test. The validated numerical wave basin has been applied to develop a new semi-submersible hull design for a given design environment, partially replacing the role of the physical model test in the traditional design spiral. The new design spiral based on numerical wave basin provides optimized hull design more expeditiously and efficiently than the traditional design spiral based on physical model test. Review of the development, current status and future prospects of numerical wave basin for offshore platform design is presented in this paper.
Single-walled carbon nanotubes toxicity to the freshwater amphipod Hyalella azteca: influence of sediment and exposure duration
Authors: Revel Messika , Fournier Michel , Robidoux Pierre Yves
Published: April 2015

Carbon nanomaterials are present in various industrial applications and therefore their release into the environment including freshwater ecosystem is expected to increase. The aim of the present study was to investigate the influence of several parameters on the toxicity of single-walled carbon nanotubes (SWCNT) to the freshwater amphipod, Hyalella azteca. The effect of period of exposure, sediment presence and possible impurities released during SWCNT preparation on survival and/or growth of such organism was evaluated. We measured a reduction of survival at concentrations ranging from 10 to 40 mg/L after 96-h exposure, while no mortality was observed with the same concentrations and in the presence of artificial sediment after 14 days of exposure. It is possible that SWCNT are adsorbed on the organic matter from the artificial sediment leading to a decrease of SWCNT bioavailability. The survival and growth toxicity tests revealed a stronger effect at 28 days compared to the 14 days of exposure, and full mortality of organisms at 1000 mg/L for both exposure times. The presence of SWCNT in the gut of survived organisms was observed. The present study demonstrates that the interaction with sediment should be considered when carbon nanotubes toxicity through water exposure is investigated.