bluuebunny/crossref_metadata_2025_split 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

Abstract
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.
Reducing the Environmental Footprint: Innovations on the CLOV Project
Authors: Vallot Patrick , Kang B.K. 
Published: April 2015

Abstract
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

AbstractChemical 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.
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

Abstract
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

Abstract
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

AbstractLine 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.
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

Abstract
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

Abstract
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

Abstract
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.