bluuebunny/crossref_metadata_2025 huggingface dataset:
THE SIMULATION ANALYSIS OF A PROPOSED ‘HYDRONIC RADIATOR’ SYSTEM TOWARDS LOW COST HOUSING OPERATION IN TEMPERATE AND HOT TROPICAL CLIMATES
Authors: Noguchi Masa , Ooi Koon Beng
Published: April 2020

Fuel poverty is one of the global concerns affecting not only users' financial capacity or affordability for maintaining housing operation but also the occupants' health and wellbeing. Space heating and cooling require a relatively large amount of domestic energy use in housing. Therefore, this study was formed with the aim to propose an innovative approach to utilising free, clean renewable sources of energy applicable to the space heating and cooling of housing in both cold and hot regions. Accordingly, housing test facilities based in Melbourne, Australia, and Kuching, Malaysia, were selected and used for this study that examined the thermal performance of a proposed ‘hydronic radiator’ (HR) system through simulation and onsite measurements. The geothermal heat capacity of a ‘vertical ground heat exchanger’ (VGHE) installed in the house in Melbourne was examined previously by the authors and the VGHE measured data was also applied to this HR performance simulation. The water that circulates through the HRs is heated by sunlight and VGHE or cooled by night sky radiation. This study drew conclusions that the sole utilisation of renewable sources through these proposed HR space heating and cooling systems can provide thermally accessible or comfortable indoor living environments in both heating or cooling dominant regions. Thus, fuel poverty issues may be alleviated through HR system application. The HRs can remove a ‘sensible’ portion of metabolic heat, but they cannot effectively contribute to the ‘latent’ heat removal. Thus, the future potential use or effect of ‘flow-through’ HRs, which are integrated into a underfloor air distribution (UFAD) plenum, was also dsicussed in this study. In the test house located in Melbourne, the flow-through HR UFAD system is currently under development. Therefore, the performance will be measured once the system has come into operation for further testing.
Une évolution singulière, de la terre vers l’eau : la dendrochronologie
Authors: Guibal Frédéric
Published: April 2020

Née dans les régions semi-arides du S.O. des États-Unis des travaux d’un astronome, A. E. Douglass, qui cherchait une relation entre les cycles solaires et le climat terrestre, la dendrochronologie s’est rapidement affirmée comme une robuste méthode de datation du bois. Après un transfert de son application des zones semi-arides aux zones tempérées, elle s’est ouvert un champ d’application immense en passant de l’étude des bois secs et carbonisés des milieux terrestres aux bois gorgés d’eau des zones humides, des milieux subaquatiques et maritimes.
À propos de la voile latine : la mosaïque de Kelenderis et les Stereometrica (II, 48-49) d’Héron d’Alexandrie
Authors: Pomey Patrice
Published: April 2020

La mosaïque de Kelenderis (Turquie), datée du v
e s. ap. J.-C., constitue à ce jour le témoignage le plus précis d’un navire équipé d’une voile de la famille des voiles latines et plus précisément du type dit « voile latine orientale » (settee sail) à voile trapézoïdale. Ce document remonte de ce fait de deux siècles la certitude de l’usage de la voile latine en Méditerranée. Cependant, elle n’a fait l’objet jusqu’à présent que d’interprétations rapides (P. Pomey), voire erronées (Z. Friedmann). Aussi propose-t-on ici une nouvelle étude plus complète et plus détaillée de ce document exceptionnel d’une très grande richesse.Son analyse conduit à admettre que la voile du bateau de Kelenderis est particulièrement élaborée et serait par conséquent le fruit d’un long processus d’évolution. Selon l’hypothèse la plus vraisemblable avancée par certains auteurs (L. Basch), cette origine serait à rechercher du côté d’Alexandrie, foyer réputé d’innovations notamment dans le domaine maritime. Le graffito d’Anfouchi pourrait même faire remonter l’apparition de la pure voile latine triangulaire au i
er s. de notre ère, ce qui implique une double évolution conduisant à la voile latine triangulaire et à la voile latine trapézoïdale. Plusieurs indices suggèrent que la communauté Copte aurait joué un rôle important dans cette évolution.L’existence d’une formule de calcul de la surface d’une voile triangulaire du type voile latine chez Héron d’Alexandrie (Stereometrica, II, 48-49), viendrait ainsi confirmer le rôle d’Alexandrie dans le développement de cette voile. Même si sa date et son origine restent incertaines, ce texte s’inscrit dans la tradition alexandrine et montre l’importance pris par ce nouveau type de gréement.Le rapprochement de ces deux documents permet d’envisager sous un angle nouveau le problème de l’apparition et de l’évolution de la voile latine.
Taxpayer's Attitude Towards Tax Evasion in a Developing Country
Authors: Rashid Md. Harun Ur
Published: April 2020

As tax evasion is an acute problem in developing countries, the study aims to examine the factors that influence the taxpayers' attitudes towards tax evasion encompassing the moderating effect of demographic characteristics on tax evasion. The study uses structural equation modeling (SEM) as the tool to analyze the primary data collected from different sections of respondents. The study shows that fairness perception, tax knowledge, audit, and enforcement initiatives negatively influence taxpayers' attitudes towards tax evasion, while corruption, discrimination, and complexity in the tax system influence them positively. Further, the study found that males, younger, married, graduate, self-employed, and people with low-income become more influenced by the factors of tax evasion than female, older, unmarried, under-graduated, job holders, and people with high income. The findings of this study provide the governments of the developing countries and their tax authorities a valuable understanding, which in turn helps them reform the taxpayers' compliance framework.
Reference-Dependent Preferences and Overbidding in Private and Common Value Auctions
Authors: Runco Mariano Gabriel
Published: April 2020

This paper proposes a model of reference dependent preferences to explain overbidding in private and common value auctions. It is assumed that the reference point is proportional to the value of the object and that losses are weighed more heavily than gains in the utility function. Equilibrium bidding strategies are derived for first- and second-price private and common value auctions. I find that this model fits the data of all experiments analyzed, both private and common value, better in terms of the Bayesian Information Criterion than a standard risk neutral model; moreover, it explains overbidding in all private value and some common value auctions better than other alternative models. These results suggest that reference dependence, among other factors, might play a role in the widespread tendency of subjects to overbid in most experimental auctions.
Values Activation and Present Bias
Authors: Brewer Onna , Erdem Orhan
Published: April 2020

Present bias—difficulty resisting instant gratification over a future and larger reward (also called delay discounting)—has been associated with various suboptimal behaviors and health outcomes. Several methods have been proposed to produce reductions in this bias and promote self-control. In this randomized experimental study of 137 undergraduate college students, the authors examined the effect of a 10-minute values clarification writing exercise on present bias in a monetary decision-making task compared with a neutral writing activity. While participants in the values clarification condition showed less present-biased behavior, this finding was not statistically significant at the .05 level. Thus, they place emphasis on implications for future research and practice with the aims of reducing present bias and building better communities.
Installation Qualification for Reeled Electrically Trace Heated Pipe-in-Pipe
Authors: Chalmers Martin , Pratt Ed , Pepin Aurelien , Tkaczyk Tomasz
Published: April 2020

Standard pipe-in-pipe (PiP) technology consists of an inner flowline insulated with high performance dry insulation and an outer carrier pipe that protects the insulation. Electrically Trace Heated Pipe-in-Pipe (ETH-PiP) technology is an adaptation of the standard PiP where electrical trace heating (ETH) and fiber optic (FO) cables are wound around the flowline, under the insulation, to provide active heating and temperature monitoring of the conveyed fluid. ETH-PiP allows operators to optimise field layout and production and minimise the risk of pipeline blockages.

Reel-lay is an efficient installation method for subsea pipelines. Reel-lay is well suited to ETH-PiP as critical fabrication activities can take place onshore and before pipeline installation. Reeled PiP flowlines are subjected to plastic bending. During offshore installation, the flowline may see a combination of this plastic bending and high axial tension due to the catenary. The combined loading leads to permanent elongation of the inner pipe which has the potential to transfer tensile loads into the electrical and optical cables. Moreover, the annulus space between the inner flowline and outer carrier pipe is reduced during reeling which may put electrical components at risk of mechanical damage.

This paper discusses an extensive qualification programme which was performed to quantify the cable loading during installation, and to demonstrate the subsequent cable and splice integrity and fitness for service. A physical bending trial was performed where several ETH-PiP specimens were subjected to plastic bending on a cantilever bending rig while axial tension was applied to the flowline. This represents an industry first for a practical test which realistically replicates the loading conditions experienced by a PiP system during reeled installation.

Throughout the bending trial, the cables were strain-gauged to record axial tension, and the anulus space around the cables/splices was measured to record radial compression. Following bending, the cables and splices were removed from the test specimens and subjected to third party electrical and optical testing to verify integrity. The qualification scope not only verified that cable integrity is maintained throughout reeling, but also quantified the loads involved. Data gathered from the testing was subsequently used to benchmark finite-element (FE) reeling models. These models allow more accurate prediction of cable loading on future reeled ETH-PiP systems, including deep water pipelines.
Balanced Characterisation of Fine-Grained Soils: Application to Carbonate Sediments
Authors: Zhou Hongjie , Sharma Shambhu , Amodio Alessandro , Boylan Noel , Gaunt Peter
Published: April 2020

For subsea structures placed on soft seabed comprising fine-grained sediments, geotechnical design may be equally governed by the foundation settlement and stability requirements. For this reason, the soil stress history parameter, i.e. yield stress (σy), becomes as important as the strength parameter, i.e. undrained shear strength (su). Common practice in characterisation of fine-grained sediments focuses more on deriving the su profile than on evaluating the σy profile. More often, the underlying connections between these two important parameters are overlooked in the interpretation process. As a result, the selected design line of σy may be incompatible to that of su. This paper presents a balanced characterisation of fine-grained soils, focusing on interpretation of in-situ su and σy using a coherent and simple framework underpinned by the Stress History and Normalised Soil Engineering Properties (SHANSEP) relationship. Interpretation procedure, performance and advantages of the proposed framework are demonstrated by a real application to an offshore site dominated by fine-grained carbonate sediments.

In this framework, the two SHANSEP parameters, including normally consolidated normalised strength ratio (S) and empirical constant (m), need to be quantified for the site of interest. This is achieved by performing a series of laboratory strength and consolidation tests on undisturbed samples, with the strength tests being performed respectively under in-situ and elevated stress conditions for determining in-situ su and the values of S and m. Once the SHANSEP parameters and the su profile are derived, the σy profile can be calculated. These two profiles can then be refined further by comparing against the measured su and σy at discrete depths respectively from the strength and consolidation tests.

Since this proposed framework allows the user to consider the results from the in-situ and laboratory tests (including both strength and consolidation tests) holistically, more reliable and coherent interpretation of the su and σy profiles can be achieved. In addition, the framework allows for an easy estimation of consolidation-induced strength gain due to the permanent load applied by the subsea structures by simply using the derived σy profile and updating the vertical stress in the parameterised SHANSEP relationship. This may reduce the conservatism in the foundation design and provide optimisation opportunities.
Combined and Re-Deployable Platform and Storage Solutions for Stranded Reserves
Authors: Mikalsen Kristian , Wassink Alain
Published: April 2020

Unlock marginal and stranded reserves in shallow waters that are far away from existing infrastructure. The solution is a system that employs a jack-up based mobile offshore production unit (MOPU) in combination with a modular subsea storage system. The storage system is an unmanned solution that is designed with an integrated offloading system.

Integrated into a single, integrated system, this robust solution encompasses all necessary components thus reducing both CAPEX and OPEX.

The case is based on standard MOPU designs with compact process modules to reduce weight and cost. Additional cost savings come from standardization and placing fully integrated components subsea. An integrated process train ensures the right quality of oil or condensate is sent to the subsea storage tanks, ready for tanker pick-up. This paper also describes how the associated gas will be handled. The field-proven offloading system is linked to storage, ensuring correct metering and safe mooring for any vessel.

Combining modular subsea solutions with field-proven components gives operators access to technologies that provide an increased return on invested capital.

The storage system is developed based on existing storage solutions. It is an energy-efficient system with a low environmental footprint. Recent engineering studies and testing have proven the feasibility of operating a subsea storage unit with a flexible membrane defining the horizontal interface between oil and seawater.

This paper presents new results from a downscaled subsea storage system model testing conducted by an original equipment manufacturer (OEM) together with a major operator. The innovative cluster design will enable re-deployment of the storage units, which opens new combination possibilities with MOPU's. Interfaces between the various system components have been streamlined to create an integrated system and when deploying these different building blocks in that way, a custom field solution can be provided for marginal field developments – including an option to modify and re-deploy.

Research has shown that replacing the floating storage and offloading vessel (FSU/FSO) with subsea storage reduces offshore manning and the environmental footprint. This technical paper explains the modularity and the economics of an installation-friendly design.

Lower complexity, in combination with cost-effective installation, introduces new opportunities for field developments. The integrated solution is also designed with the option to operate below wax appearance temperature and can make even smaller field developments profitable at a lower cost, in an energy-effective manner, and with a low environmental footprint. With this new solution available, the market can take a whole new view on small pool developments.
Improved Operational Efficiency in Deepwater GOM with Innovative Liquid Cement Additive
Authors: Pearl, Jr William , Bowman Joseph , Agapiou Kyriacos
Published: April 2020

Offshore cementing operations may require the use of liquid additives for logistical and blending requirements. Some additives should be suspended in hydrocarbon fluid because the active material cannot be readily liquefied in water. These suspensions often exhibit rheological instability and high viscosity, posing issues with shelf life and dosing through delivery lines. This paper describes the use of an innovative liquid cement additive designed to overcome limitations of conventional oil-based suspensions and improve cementing operations.

The new microemulsion fluid loss additive overcomes shelf-life stability and fluid transfer issues inherent to conventional oil-based suspension additives, while providing excellent fluid loss control in cement. Shelf-life stability and fluid transfer rates affect the quality of mixing cement slurry, reduce delivery/pump rates, and extend overall job times. The microemulsion fluid loss additive chemistry was verified to provide improved shelf-life stability and reduced viscosity. Fluid loss, mixability/rheology, and stability tests in cement slurry evaluated the additive performance. Flow tests and calibrations using conventional liquid additive injection pumps were performed before deployment. Benefits of the microemulsion fluid loss additive were validated in a cement design for deepwater offshore work.
Offshore Urban Extension of the Anse Du Portier in Monaco
Authors: Aristaghes Pierre , Compte David
Published: April 2020

As part of the Monaco offshore extension project, Bouygues Travaux Publics is in charge of design & build a maritime infrastructure as the first step of the six-hectare expansion of the city into the sea. This maritime infrastructure consists of a fill enclosed by a band of 18 trapezoid reinforced concrete caissons and will serve as base for construction of the new eco-neighborhood in Monaco. The caisson precasting area is located in the port of Marseilles, using a dedicated floating dock.

The paper focuses on some of the problems which had to be solved, among which : The optimization of promenade level, searching for : ○a compromise between architectural point of view and safety related to storm wave overtopping, taking into account sea level rise and correlations between extreme waves and water levels;○minimal reflection coefficient for vertical concrete caissons, so as to minimize impact on existing Port Hercules wave disturbance.Caissons and rubble mound foundation stability related to waves and seism, including extra seismic forces due to buildings considering the high reclamation height (up to 40 m) and the immediate proximity of building foundations.The presence of a small craft harbor, whose location was fixed for urbanistic reasons, which requested optimizations in detail of anti-overtopping devices as much as possible integrated in the urban context, including a low crested "swimming pool caisson breakwater"Design and build of a dedicated floating yard

Design has required a multidisciplinary approach (urbanists, landscapers, architects, marine infrastructure engineering, biologists), with unconventional infrastructure solutions due to the very specific context (direct exposure to offshore waves, proximity of sensitive port and natural areas, seismic hazard associated with buildings very close to 25 m high concrete caissons …).
Innovative Integrated and Compact Gas Oil Separation Plant for Upstream Surface Facilities
Authors: Soliman Mohamed Ahmed , Salu Samusideen , Al-Zahrani Talal , Ansari Nisar
Published: April 2020

The objective of this paper is to evaluate and analyze energy savings and process optimization opportunities in the gas-oil separation plants (GOSPs) in upstream surface facilities. This approach resulted in the development of a new design for a compact gas-oil separation plant (C-GOSP) to meet the crude oil export specifications with less process equipment and operating costs, and higher oil product yield compared to conventional GOSPs. The new design was materialized as patents granted by the U.S. Patent and Trademark Office (USPTO). The innovative C-GOSP is based on the integration of the gas compression system with production traps to conserve energy consumption and minimize capital cost and increase crude production. Atmospheric and hot discharge gas from low pressure compressors will be rerouted and directly mixed with the incoming wild crude before entering the production traps. This process will result in simultaneously cooling the compressors' discharge gas and heating the incoming crude while increasing crude production. Hysys simulation was used to model and verify the feasibility of the C-GOSP. A 300 MBD production facility was used to benchmark the Hysys simulation model and to verify the feasibility of these promising energy saving opportunities.

The extensive process simulation modelling using Aspen Hysys and benchmarked with the actual plant energy consumption revealed the feasibility of this innovative C-GOSP, which will result in the following benefits:

Lowering the capital cost by eliminating the compressors discharge after coolers, liquid pumps, discharge KO drums and minimize the surface area of the crude heat exchangers. Lowering operating cost by eliminating the after coolers and heating medium required to heat the crude. Increase crude production yield by condensing the heavy hydrocarbon from the gas stream. Minimize the spacing requirements, which make ideal for offshore applications.

The innovative approach of direct heating and cooling by mixing of hot and cold streams is superior to any other optimization approach. Consequently, a patent was granted from the USPTO on July 17, 2018, for the innovative C-GOSP. The patent number is 10023811.
Hydrocyclone Micrometer Sized Separation Technology for Exploitation of Natural Gas Hydrate
Authors: Wu Jiwei , Lin Haitao , Huang Yuan , Wang Hualin , Zhou Shouwei , Fu Qiang
Published: April 2020

Natural gas hydrate is a key future clean energy resource, and sand control is crucial in natural gas hydrate production. However, the sand control is still inefficient, which impedes industrialized development of natural gas hydrate. From production test carried out in the South China Sea, we found the separation of micrometer-sized sand from the fluid is the main challenge in sand control. Based on high-speed motion in our 3D rotating turbulent flow field of hydrocyclone, our study presents a new technology to realize efficient separation of micrometer-sized sand and breaking consolidation between hydrate and sand. As results of hydrocyclone separation experiments, we have the high separation efficiency that is up to 92.23% for silica sand and 98.87% for PP; also only 0.46%~1.05% of PP powder remains in recovered materials. In conclusion, the technology proves the ability of breaking-consolidation and realizes the goal of separation of micrometer-sized particles, and thus improve the sand control in exploitation of marine natural gas hydrate.
Innovative as-Built 3D Model and BIM of Subsea Objects Using Basic Sensors – Application to Seawall Concrete Armour Units
Authors: Bugnet Yoann , Le Bars Steven , Macaigne Vincent , Launay Timothée , Vessiot Thomas , Cartier Rémi
Published: April 2020

Objectives/scope

The control of monolayer concrete armour units on coastal protection breakwaters can be time and cost consuming, especially underwater. It is even more the case when - for maintenance and control purpose - they are conducted long after the completion of the construction (positioning issues, number of units to control, etc).

However, this occurs frequently on construction projects which last for several years, or during the operation and maintenance of such structures. On top of that, the complexity of this type of projects - usually coastal constructions such a dike easily exceeds 6000 units/km - requires precision and productivity for the control inspections.

As a result, specific control solutions have been developed on the NRL project to inspect and monitor the breakwater after its construction.
Study and Optimization of the First Horizontal Well Steamflooding Pilot for Offshore Oilfield
Authors: Han Xiaodong , Zhong Liguo , Liu Yigang , Wang Qiuxia , Chen Cunliang , Wu Xuanren
Published: April 2020

The steam and flue gas co-injection technology is proposed and applied to NN Oilfield whose oil viscosity ranges from 413 to 741mPa.s for field pilot since 2008. With increase of the stimulation cycles, the gas channeling problem had bad influence on the production performance, and the production rate declined rapidly.

To further improve the oil recovery, research is carried out for optimization of the replacement production method. First, the reasons for gas breakthrough are analyzed. Potential methods are all analyzed and compared by reservoir simulation and physical experiments. By considering the equipment capacity, platform limitations and economics, the optimized production method is determined. For the NN Oilfield developed with horizontal wells, the steamflooding is a good way of further exploitation after steam and flue gas co-injection. The key injection and production parameters are all optimized with the results of steam injection rate 300 m3/d, production-injection ratio 1.4, and downhole steam quality 0.4-0.6. To further improve the field performance, the nitrogen foam could be injected to mitigate the steam breakthrough. Simulation study shows that it is significantly effective for the improvement of oil production rate. Detailed project design has been completed and illustrated in detail. Steam flooding would be an effective replacement technology after huff and puff for further enhancing oil recovery of offshore heavy oilfields.
Integrated Technologies in the Floating Hydraulic Fracturing for Unconventional Offshore Reservoir
Authors: Li Shuai , Yi Xinbin , Kuang Ming , Xie Ying , Zhang Ziming , Wang Xiaochao , Gao Yuebin
Published: April 2020

The ultra-high pressure and high temperature (HP/HT) unconventional offshore reservoir in Liaohe Oil Field in Bohai Bay Basin has characteristics of deep depth (4500m), high temperature (145°C), low permeability (1.2mD) and low porosity (9.4%), until now, a floating hydraulic fracturing has been successfully performed in this area and an integrated technology has been formed.

In this paper, we firstly delivered a case history of the hydraulic fracturing treatment, in particularly describing the main problems we met and the main method we take to solve these problems. Then the case study was given in consideration of a geo-engineering integrated fracturing design workflow. (1) Fracturing vessel arrangement to full fill the fracturing demand. (2) Sweet spot prediction and well trajectory optimization were performed based on a fine geological model. (3) Perforation optimization were made in consideration of the ground stress, natural fracture development, well logging and hydrocarbon display. (4) A hybrid fracturing mode (linear gel and crosslinked gel) was applied to connect more natural fractures and build a more complex fracture network. (5) Multi-size sand combination to match different artificial cracks. (6) Mini-frac test to analysis the stress situation and optimize the stimulation schedule. (7) Acid pre-treatment to reduce fracture initiation pressure, proppant multi-stage slug to reduce pumping pressure.

Integrated technologies in the floating hydraulic fracturing for unconventional offshore reservoir in Bohai Bay Basin can be good reference to the hydraulic fracturing treatment of similar reservoirs.
Innovative Use of a Rov to Control Underwater Coastal Protections
Authors: Nicolas Thebaud , Vincent Macaigne , Steven Le Bars
Published: April 2020

The control of monolayer concrete armour units on coastal protection breakwaters can be time and cost consuming, especially underwater. It is even more the case when - for maintenance and control purpose - they are conducted long after the completion of the construction (positioning issues, number of units to control, etc). However, this occurs frequently on construction projects which last for several years, or during the operation and maintenance of such structures. On top of that, the complexity of this type of projects - usually coastal constructions such a dike easily exceeds 6000 units/km - requires precision and productivity for the control inspections.

As a result, specific control solutions have been developped on the NRL project to inspect and monitor the breakwater after its construction.

The NRL project lies in La Reunion (Indian Ocean). It is due to replace the current coastal road, which was built at the foot of a 100m height cliff. Indeed, after heavy rainfalls, rocks are falling from the cliff. The road is also usually closed during storms as the road is submerged by the sea on one side, and by rainfalls on the cliff side.

The objective of the project is to build a new road at sea to secure this vital economical axis between the cities of Saint-Denis - the island capital - and La Possession.
Hydrate Equilibrium Model for Gas Mixtures Containing Methane, Nitrogen and Carbon Dioxide
Authors: Sadeq Dhifaf , Al-Fatlawi Omar , Iglauer Stefan , Lebedev Maxim , Smith Callum , Barifcani Ahmed
Published: April 2020

Gas hydrate formation is considered one of the major problems facing the oil and gas industry as it poses a significant threat to the production, transportation and processing of natural gas. These solid structures can nucleate and agglomerate gradually so that a large cluster of hydrate is formed, which can clog flow lines, chokes, valves, and other production facilities. Thus, an accurate predictive model is necessary for designing natural gas production systems at safe operating conditions and mitigating the issues induced by the formation of hydrates. In this context, a thermodynamic model for gas hydrate equilibrium conditions and cage occupancies of N2 + CH4 and N2 + CO4 gas mixtures at different compositions is proposed. The van der Waals-Platteeuw thermodynamic theory coupled with the Peng-Robinson equation of state and Langmuir adsorption model are employed in the proposed model. The experimental measurements generated using a cryogenic sapphire cell for the pressure and temperature ranges of (5-25) MPa and (275.5-292.95) K, respectively, were used to evaluate the accuracy of this model. The resulting data show that increasing nitrogen mole percentage in the gas mixtures results in decreasing of equilibrium hydrate temperatures. The deviations between the experimental and predictions are discussed. Furthermore, the cage occupancies for the gas mixtures in hydrate have been evaluated. The results demonstrate an increase in the cage occupancy for both the small and large cavities with pressure.
Key Technology and Industrial Application of HPHT Drilling and Completion in South China Sea
Authors: Shujie Liu , Zhong Li , Jin Yang , Renjun Xie , Yanjun Li , Gang Tong , Ming Luo , Yi Wu , Guoxian Xu , Qishuai Yin , Nanding Hu
Published: April 2020

South China Sea is one of the offshore HPHT region, with the maximum 2.38 pressure coefficient, 480 degF bottom temperature and 50% CO2. The drilling and completion are challenging problems.

This paper reviews the past 20 years' researches and practices in South China Sea HPHT area. Based on theoretical study, laboratory tests and site experiments, the project team has been working on solving problems of formation pressure prediction, wellbore integrity, testing and operation technology.

The understanding and achievements are abundant. First, an accurate prediction method of multi-source abnormal pressure was built and a quantitative control drilling technique was developed, which helps relize continuous circulation in 0.01∼0.02 g/cm3 density window. Second, the "self-repair" HPHT cement slurry systems have been created and the multi-barrier wellbore integrity protection technology has been constructed to implement normal pressure in casing annulus. Third, an intrinsically safe testing system, which includes 7 major factors, was created. The safety of offshore HPHT testing can be guaranteed. Fourth, a water-based high temperature resistant drilling fluid and series acceleration tools were created, realizing the high-quality and efficient HPHT field operation.

This series of technology has helped build China's first HPHT gas field and can be a reference for similar area.
Potential Oil Recovery Enhancement by a Polymeric Nanogel Combined with Surfactant for Sandstone Reservoirs
Authors: Almahfood Mustafa Mohammed , Bai Baojun
Published: April 2020

The aim of this study is to examine the effect of a novel combination that consists of polymeric nanogel and surfactant on oil recovery. The paper will report the extent to what the nanogel, alone and combined with surfactant, can improve oil recovery for sandstone reservoirs and reveal the mechanisms behind it. A negatively charged nanogel was synthesized using a typical free radical suspension polymerization process by employing 2-acrylamido-2-methyl propane sulfonic acid monomer. In addition, a fixed concentration of negatively charged surfactant (sodium dodecyl sulfate or SDS) was combined with different concentrations of the nanogel using seawater. The combination effect on sandstone core plugs was examined by running a series of core flooding experiments using multiple flow schemes. The synthesized nanogels showed a narrow size distribution with one peak pointing to a predominant homogeneous droplet size. They were also able to adsorb at the oil-water interfaces to reduce interfacial tension and stabilize oil-in-water emulsions, which ultimately improved the recovered oil from hydrocarbon reservoirs. The results suggest the ability of the nanogel, both alone and combined with SDS, to improve the oil recovery by a factor of 15% after initial seawater flooding. Although nanoparticles have received a great attention in the research aspect of the oil industry, however, the characterization of polymeric nanogels, alone and combined with other additives, is still to be investigated. Due to their unique properties and mechanisms, nanogels have a great potential for application in the oil industry. This study is aimed to examine and evaluate the combination of charged polymeric nanogel and surfactant dispersed in seawater through core flooding experiments using multiple injection schemes.
Potential Cost Savings from Converting California Outer Continental Shelf Oil and Gas Platform Jackets to Artificial Reefs
Authors: Smith John Bridge , Byrd Robert Clark
Published: April 2020

This paper reviews cost estimates for decommissioning and fully removing the 23 oil and gas platforms located on the federal Outer Continental Shelf offshore California and estimates the costs that could be avoided (saved) if the platform jackets are partially removed and reefed in-situ rather than fully removed. The cost savings are calculated by estimating the weight of the jacket structure that would remain in-situ and multiplying that weight by a demolition cost ranging from $3,000 to $7,000/ton (short tons) for structure removal. This cost range was derived from a review of published information on estimated and actual jacket removal costs. The calculations show that if all 23 platform jackets are reefed in-situ the estimated total cost savings achieved would range from $856 million to $2.0 billion. On a per platform basis, the cost savings range from a low of $0.3 million for Platform Gina (84 tons remaining in-situ) to a high of $494 million for Platform Harmony (70,540 tons remaining in-situ). Under the California Marine Resources Legacy Act (AB 2503) the owners of oil and gas platforms who obtain approval to reef a platform jacket are required to share 65% to 80% of the cost savings with the State of California. Based on the cost savings estimates presented in this paper, the State of California would receive an allotment ranging from a low of $685 million to as much as $1.6 billion if all 23 OCS platforms were approved to be reefed in-situ.
An Innovative Approach for Free Span Analysis of Subsea Pipelines to Optimize Free Span Corrections
Authors: Saleem Qasim , Al-Shiban Riyadh Saad
Published: April 2020

The integrity of subsea pipelines is required to be verified through external surveys and inline inspection to ensure safe operation. If free spans based on external subsea inspection exceed the design calculated allowable free span length, free span corrections are performed by placing grout bags or mechanical supports along the span. However, as free span corrections are very costly, therefore, further free span assessment should be performed prior to any subsea intervention.

An alternative approach of "local free span analysis" is proposed to optimize the free span corrections. Local free span assessment can be performed for each survey span exceeding allowable span length taking into consideration the relevant input data applicable for the specific free span location rather than for a section of the subsea pipeline. It shall be noted that during design phase, allowable free span lengths are calculated by dividing the total pipeline length into segments, and for each segment the worst case input data is conservatively taken. On the contrary, local free span analysis approach considers key input factors such as effective axial force, wave and current (environmental) data, water depth and pipe-soil interaction parameters pertinent to explicit span location.

Local free span analysis has been successfully applied for free span assessment of a number of operating and new subsea pipelines. This paper will present case studies where revised allowable free span lengths have been calculated prior to previous approach of direct subsea intervention and highlight the associated benefits.

Local free span assessment approach will significantly reduce the number of required free span corrections especially for long length subsea pipelines. The optimization of free span corrections will result in significant cost savingsas well as schedule improvement.
Systems Thinking to Value Protection
Authors: McLachlan Duncan
Published: April 2020

This paper demonstrates how the adoption of systems engineering practices, where functional requirements are established and interdependencies are dynamically modelled, allows optimisation of the project holistically to create value at the earliest stage, and for this value to be protected throughout the lifecycle.

We will explain how functional requirements and project value drivers are identified; causal loop diagrams are utilised to ensure causal precision; the conversion of causal loop diagrams to stock flow diagrams to allow the incorporation of algorithms, which dynamically model the interdependencies. We will demonstrate how this model is utilised to optimise and protect value.

This has been implemented successfully on several projects. Two case studies will be presented: one where systems engineering was used where field production from a complex group of 350 offshore wells producing from different reservoirs was anticipated to decline in the medium term and a best technical solution to maximise Net Present Value (NPV) for the asset was required. The second application of this approach was the development of a Normally Unmanned Installation (NUI) concept that removes 250t of topsides equipment, a 90% reduction based on previous wellhead towers in the same basin, achieves a 98% reduction in power consumption, and only requires planned offshore working once per year. The systems model was established in concept and is continuing to be used through the Front End Engineering and Design (FEED) phase of the project to protect this value created and prevent "death by a thousand cuts", or the slow process of erosion of value brought about by individual, seemingly inconsequential, decisions that aggregate over time to cause project failure.
Design Considerations for the Configuration of a Production Riser for Deepsea Mining of Polymetallic Nodules
Authors: Wu Shukai
Published: April 2020

The technical feasibility of deepsea mining operations of polymetallic nodules in 5,000m+ water depth has been demonstrated through a number of pilot tests done in the later 1970s and early 1980s. Since then, there have been significant technological advances, especially those in the offshore deepwater oil and gas exploration and production. Market demands for rare-earth minerals and specialty metals, such as cobalt which is essential for a wide variety of high-tech and industrial applications have seen a rapid growth, and the trend is projected to accelerate. The existence of these mineral resources in large abundance in many parts of the world's deep oceans are well known, such as the Clarion-Clipperton Zone (CCZ) and southeastern regions of the Pacific Ocean. All those factors have contributed to the renewed interest in commercial-scale deepsea mining development projects.

A key component in a deepsea mining system is the production riser used to transport the production stream, usually in the form of multi-phase slurry, from the seabed level to a production vessel at the surface. For this reason, the riser is also known as VTS (Vertical Transport System). Unlike a normal production riser for oil and gas field development where the riser is "anchored" to the seabed, a production riser for deepsea polymetallic nodule mining operations is suspended and free-hanging off, and is under tow by, a production vessel floating on the surface during normal mining operations. To fulfil other functional requirements, the riser also needs to carry other pipes bundled to it as well as the umbilicals for system monitoring and seabed mining operations.

This paper presents an outline description of the mining operations and a production riser design using airlift proposed for a prospective deepsea mining project. The principal design drivers and major considerations in the production riser configuration development for commercial deepsea mining of polymetallic nodules are the primary focus of the discussion presented in this paper. Critical load cases to be considered for the preliminary engineering design assessment are summarized.
Challenges for Design, Manufacture and Installation of HP/HT Risers for Deep Water
Authors: Jones Richard Lloyd , Karunakaran Daniel , Toguyeni Gregory
Published: April 2020

With the increasing development of high temperature/high pressure wells, particularly in deep water, riser designs using conventional strength material are utilising increasingly heavier wall thickness pipe, up to 50mm wall thickness in 8" and 10" OD X65 linepipe. Such riser designs are challenging existing seamless linepipe manufacturing and girth welding capabilities. Consequently, Subsea 7 undertook a linepipe material and welding qualification programme in order to provide confidence in the use of heavy wall pipeline and riser designs and installed by R-lay.

Riser designs with heavy wall thickness may impose excessive top tension requirements making them difficult to install cost effectively using R-lay technology. Additionally, such risers may pose excessive payloads on the floating production vessel. Fatigue requirements at the hang off and touch down zones pose further limitations on the use of heavy wall risers. These limitations may impede cost effective development of HP/HT fields.

The application of high strength steel for HT/HP applications as riser material is an attractive alternative. High strength steel reduces the wall thickness and thereby reduces payloads on floating hostfacility and top tension requirements for R-lay installation. Application of high strength steel improves the top end interface design also, due to reduced tension. The qualification status of reelable X80, including CRA lined pipe will be presented.

Another challenge for HP/HT riser application is the top end connection to the floater. Traditional flex-joint solutions may not be feasible, requiring a Stress Joint at the top. For ultra-deep water conditions, special stress joints with titanium may be necessary. The limitation and application of such top end solutions for HP/HT application will be presented in this paper.
Applications of Metal Additive Manufacturing in the Oil and Gas Industry
Authors: Wooldridge Madison , Wangenheim Christoph , Herberg Wolfgang , Wettmarshausen Thomas
Published: April 2020

Additive Manufacturing (AM) is a set of technologies that has historically found fertile applications in the aerospace and healthcare industries, while adoption in the Oil and Gas (O&G) sector has progressed slower. Nonetheless, AM is reaching maturity in this industry as well, allowing for significant innovation. The scope of this paper is to describe how AM is integrated within the value chain of a major O&G service company, highlighting specific peculiarities for each of its business segments. "Fullstream" activities cover the whole O&G value chain, from the exploration of reservoirs and production (upstream) to the transportation and storage of hydrocarbons (midstream), as well as refining and industrial power processing (downstream). AM technologies within the O&G service provider have originally been deployed for rapid prototyping and have matured as strategic manufacturing pillars. Several manufacturing methods within the AM landscape can be deployed, depending on the technical requirements of the components and the environment in which they are operating. Here, powder bed processes are in focus, with an emphasis on the Selective Laser Melting (SLM) process. O&G equipment end users face several challenges when dealing with spare parts management, such as performance, total cost of ownership, procurement time, inventory levels, and obsolescence. From an OEM standpoint, serving a wide fleet with a variety of products and their different versions (with an unpredictable and unstable demand) is challenging. AM is the tool that enables a new way to serve such an installed fleet. The O&G service provider has already experimented several applications regarding obsolete spare parts reintroduction through AM, gaining strong benefits (50%+) in terms of cost and procurement time reduction. Thus, it is important to continue adopting AM to deliver faster outcomes for the customer. This, in turn, fosters the development of sound know-how and references, which can then be used to develop further solutions and value propositions for the customers.