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Chenhao, Mao (School of Port and Transportation Engineering, Zhejiang Ocean University) | Binyu, Wang (Guangxi Vocational and Technical College of Communication) | Yunlin, Ni (School of Port and Transportation Engineering, Zhejiang Ocean University) | Yifan, Gu (School of Port and Transportation Engineering, Zhejiang Ocean University) | Hao, Zeng (School of Port and Transportation Engineering, Zhejiang Ocean University) | Wei, Chen (School of Port and Transportation Engineering, Zhejiang Ocean University)
The construction of wave dissipating platform would cause the sediment transport in the surrounding waters, changing the erosion and silting situation in the seabed, which may even lead to the abandonment of the original dock. In this paper, a 2D hydrodynamic and sediment transport model is established for Shengsi islands, Zhoushan and the surrounding area by using MIKE21. The model has well been validated through observation data of tidal level, flow velocity and direction. The influence of dissipating platform construction on the erosion and deposition of surrounding water is analyzed. The results show that the maximum diffusion envelope of suspended sediment (concentration higher than 0.02 kg/m3) in Huangsha village, Bianjiaoao and Huicheng village are 20,947.02, 19,799.04 and 5,311.35 m2 respectively. The project has little impact on the surrounding water quality environment.
The coastal construction has created enormous social and economic benefits, but the construction project has caused sediment transport in the surrounding waters, causing erosion and siltation changes which may even cause the original dock abandoned (Tsoukala et al., 2015; Plomaritis and Collins., 2013; Song et al., 2017; Zhang et al., 2005). Meanwhile, it exerts negative effects on marine ecological environment, arousing wide public concern of scholars (Sravanthi N, 2015; Yao et al., 2018; Gu et al., 2012; Tian and Xu, 2015).The suspended sediment produced during the construction process will form water masses with high suspended matter content within a certain range, weakening or even blocking the light transmission capacity of the water body, affecting the photosynthesis of phytoplankton. The reduction in the number of phytoplankton will cause a corresponding reduction of zooplankton. In addition, suspended sediment will attach to the surface of aquatic animals, interfere with their normal physiological functions, and more seriously enter the digestive system, causing death (Huang et al., 2019). Zhang (2015) used the ECOMSED model to simulate the terminal project of Shandong LNG project. The research obtained the maximum spreading range of suspended sediment produced by excavation of base trenches, stone dumping and dredging works during the spring and neap tides, and analyzed the impact of the project on marine life. Yan (2019) established a two-dimensional model by using MIKE21 FM, simulating the envelope area of the suspended sediment caused by the 10 kv submarine cable laying at Lvhua Island-Huaniao Island. The results show that the construction period has a greater impact on the marine ecological environment, and the service period has basically no impact on the marine ecology. In order to serve human life and protect the environment, numerical simulation has been widely used in engineering construction (Vu, Nguyen and Nguyen.,2020; Agrawal et al.,2019).
Shen, Wenjun (Tianjin Research Institute for Water Transport engineering, M.O.T) | Chen, Hanbao (Tianjin Research Institute for Water Transport engineering, M.O.T) | Jiang, Yunpeng (Tianjin Research Institute for Water Transport engineering, M.O.T) | Gao, Feng (Tianjin Research Institute for Water Transport engineering, M.O.T)
The ship to ship operation system of FSRU and LNG is taken as the research object in this paper. Based on the three-dimensional frequency-domain potential flow theory, numerical analysis of the resonance characteristics of wave surface elevation in the gap between FSRU and LNG. The effect of potential flow was modified by adding artificial damping, and the influence of wave period (wave frequency), incident direction and other parameters on the wave surface elevation was discussed. Furthermore, the problem of the resonance of the intermediate water body was further explored and analyzed based on the different distances between the two ships and different draughts.
Floating LNG storage and regasification unit (FSRU), which integrates LNG receiving, storage, transfer, regasification and export and other functions, it can used as LNG receiving terminal while it is moored at the dock and can also be used for the transportation of LNG. As the emergence of FSRU, it has become an important option for the receiving of LNG, and adopted by more and more countries and regions. According to statistics, up to now, there are 30 projects in operation and another 8 projects area being under construction.
In the loading and unloading operation period, ship to ship operation mode between FSRU and LNG is usually used, as shown in Figure 1. While this mode is used, the hydrodynamic interference and coupled motion between them are more complex. Especially when the two ships are very close to each other, the disturbance between the two ships is aggravated, which brings great safety risks to the loading and unloading operation. Therefore, it is necessary to consider the interaction of the hydrodynamic forces between the two ships, and know well about the hydrodynamic characteristics of the two ships in different conditions and the wave surface rise between the two ships.
Wei, Z. J. (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology) | Shen, L. M. (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology) | Du, X. P. (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology) | Wang, Z. M. (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology) | Zhai, G. J. (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology)
In order to investigate the effect of the entrapped air on liquid impact, a series of experiments are designed and performed in an elastic rectangular tank under nearly 2D shallow-water condition. The evolution of free surface and the development of entrapped air near the vertical wall are recorded by the high-speed camera. Furthermore, the impact pressure and the wall deformation during slamming are measured. The results show that the presence of entrapped air can change the impact mode. Furthermore, the impact pressure and wall deformation induced by liquid slamming decreases due to the entrapped air, which shows the air cavity plays a cushion effect during liquid slamming. It is suggested to consider air compressibility during liquid slamming with entrapped air.
The challenges to design Floating Liquefied Natural Gas facilities have attracted enough attention from industry and academia. The FLNG is used for production, liquidation, storage and unloading offshore gas. Therefore, the FLNG system needs lager volume tanks and has no restrictions of filling condition. Liquid tends to slosh in a partially tank during shipping. Sloshing-induced slamming in a tank at low filling depth resulting in the structural local damage during FLNG shipping is one of the main loads in the design of super-large storage tanks (Gavory and De Seze, 2009). Thus, it is important to determine the slamming load and investigate the physical evolution of a wave impact during the sloshing process in a partially field tank. But during liquid impact, the physical phenomena with gas-liquid, gas-solid and gas-liquid-solid are complicated for researchers to predict the evolution of free surface and slamming load with theoretical and numerical methods (Abramson et al., 1974; Lee and Choi, 1999; Faltinsen and Timokha, 2009). For example, Delorme et al. (2008) numerically found that the maximum pressure calculated by their numerical method is greater than the experimentally measured values due to the presence of air. Therefore, from physical mechanics point of view, it is necessary to use experimental methods to study the liquid impact with entrapped air in the tank.
Liang, Hui (Technology Centre for Offshore and Marine, Singapore (TCOMS)) | Chua, Kie Hian (Technology Centre for Offshore and Marine, Singapore (TCOMS)) | Wang, Hongchao (Technology Centre for Offshore and Marine, Singapore (TCOMS))
The fluid response at resonance in a narrow gap between two identical fixed barges is investigated for three typical wave headings including: beam sea, quartering sea and head sea conditions. A potential-flow model with energy dissipation effects is developed based on the boundary element method. The dissipation surface is devised at the bottom opening as well as two end openings of the gap, and both linear and quadratic damping terms are accounted for. Satisfactory agreement with experiments demonstrates that the response in the gap at resonance exhibits nonlinear correlation with the wave amplitude indicating the importance of the quadratic damping.
Liquefied Natural Gas (LNG) is an attractive source of clean energy, and it features easy transportation and relatively low carbon dioxide emission. The offloading of LNG from a floating LNG (FLNG) facility to a LNG carrier in a side-by-side configuration in the open sea is widely applied in offshore industry (Zhao et al., 2018a). Due to the presence of a narrow gap between the FLNG and LNG carrier, resonance of the partially-entrapped water column may occur under certain wave frequencies leading to large fluid motions in the gap. The consequence of large fluid motion may influence the relative motions of vessels, and induce large drift forces which in turn may pose various hazards that affect the cargo transfer operations (Kristiansen, 2009). The gap response is of particular interest because of strong resonant phenomenon where viscous dissipation effects may exert a significant influence.
The study of natural frequencies of standing wave patterns in the gap spurs the interests of researchers. Due to the narrow nature of the gap in between two vessels, the energy is trapped resulting in large response at resonance. Compared to the width of gap, the beam of the LNG carrier and FLNG can be assumed to be infinite. Under this assumption, Molin (2001) analytically studied resonant frequencies and natural modes for a side-by-side configuration in two dimensions and a rectangular moonpool in three dimensions, and explicit expressions were presented. To incorporate the end effect of two vessels, Newman and Sclavounos (1988) suggested that homogeneous Dirichlet conditions can be simply imposed at the ends (velocity potential equals to zero). Based on such assumption, Molin et al. (2002) derived an analytical formula to estimate the natural frequencies of gap resonance. Sun et al. (2010) verified Molin's formula numerically, and reported the sensitive hydrodynamic effects due to gap resonance. Zhao et al. (2017) experimentally studied the resonant fluid response in the gap driven by a transient focussed wave group, and observed that the duration of the liquid motion in the gap is much longer indicating the energy is partially trapped in the gap.
Sempra Energy’s Energía Costa Azul LNG (ECA LNG) subsidiary reached a final investment decision (FID) to build its $2-billion Phase 1 natural gas liquefaction export project in Baja California, Mexico. ECA LNG, a joint venture between Sempra LNG and its Mexico subsidiary IEnova, is the only LNG export project to reach FID in 2020, and is slated to be the first on the Pacific Coast of North America. The facility will connect natural gas supply from Texas and the western US to Mexico and other countries across the Pacific Basin. First production from Phase 1 is expected in late 2024. The company secured a 20-year supply agreement with Mitsui and an affiliate of Total for the purchase of 2.5 mtpa and is working with Total for a potential equity investment in the facility.
The sustained increase in global demand for cleaner fuels continues to drive the gas industry growth. Liquefied natural gas (LNG) has been a key enabler for this growth by making sizeable remote gas re-serves, which are unreachable by pipeline, accessible to the major and emerging gas markets. Every segment of the LNG supply chain has its own set of technical challenges. On the upstream side, many gas resources require significant pre-treatment before liquefaction, and the feed gas to the LNG facility is typically a mixture of various compositions from multiple sources; this composition mix evolves over the life of the project. The main challenge is development planning for the contributing reservoirs under the constraints imposed by the processing facility– managing reservoir deliverability, scheduling & sequencing of wells, and downtime management while maintaining the inlet stream specification. To aid with long-term planning for such assets, a virtual field management system is needed that can emulate a real-world hydrocarbon producing asset by capturing all operational constraints, resource lim-its, and complex operating logic.
This paper describes a comprehensive field management framework that can create an integrated vir-tual asset by coupling reservoir, wells, network, and facilities models and provides an advisory system for efficient asset management. The field management component can replicate any operational logic, exercises holistic control over the sub-surface model, integrates with the surface network model, and provides optimization capabilities. This paper demonstrates this for a complex LNG asset that is fed by sour gas of different compositions from multiple reservoirs.
We describe the different levels of constraints the asset needs to operate under, including treatment plant capacity, the LNG production capacity, the contractual LNG specifications, the disposal of gas impurities and imposes them on the model by utilizing a flexible and extensible logic framework. Con-straints applied at different levels can be mutually competing and their combination with recovery opti-mization goals increases complexity. The unified field management system uses a robust scheme to bal-ance the coupled system under these constraints while optimizing overall recovery. The optimization is enabled through the ability provided by the field management system to query and retroactively control flow entities during the simulation at the desired frequency.
Customization through scripting was necessary to implement this advanced logic and was enabled by the extensible nature of the field management framework. This extensibility, along with native capabili-ties, ensures that any level of complexity can be captured, and the workflow described in this paper can be applied to any hydrocarbon producing asset for short-term and long-term development planning.
ADNOC LNG signed a supply agreement for up to 6 years with Vitol for the sale of 1.8 mtpa of post-2022 LNG volumes, and a 2-year supply agreement with Total for 0.75 mtpa of 2021 and 2022 LNG volumes. The agreements continue ADNOC’s transition to a multi-customer strategy that began in 2019, and follow its investment partnership with Vitol in global storage terminal owner and operator VTTI. Since then, the company shifted from supplying 90% of its LNG to Japan to supplying 90% of LNG to clients in more than eight countries from across southern and southeast Asia. The agreement is also in line with its 2030 gas strategy to deliver value for UAE and meet global demand, which is expected to grow by up to 5% annually over the next 20 years. ADNOC LNG, owned by ADNOC (70%), Mitsui & Co (15%), BP (10%), and Total (5%), produces about 6 mtpa of LNG from its Das Island facilities off the coast of Abu Dhabi.
The Gorgon gas plant produces 15.6 Million Tonnes per Annum (MTPA) Liquified Natural Gas (LNG) from the Gorgon and Jansz-Io subsea gas fields. First LNG production commenced on the Barrow Island, Australia facility in 2016. One of the first systems commissioned was the wastewater treatment, collection and disposal system, a critical support utility for production operations. The Produced Water Disposal (PWD) facility is unique on Barrow Island due the location's national nature reserve status, and all treated waste must be disposed downhole. The objective of this paper is to review key lessons from design, startup and steady state operations. Perspectives will be given on facility/well management and production operations of PWD at the Gorgon plant.
Wastewater on Barrow Island is generated from several sources: Condensed water originating from hydrocarbon gas (separated at gas dehydration and Mono-Ethylene Glycol (MEG) regeneration facilities), drainage and runoff water from the plant, treated sewage effluent and other ad hoc liquid waste. These sources are collected and treated before the final product is pumped into two available onshore disposal wells. One of the challenges initially faced was that the disposal water quality did not meet the design specification required to maintain well performance. This problem reduced as the plant reached steady state operations and the team gained a better understanding of well performance over time. Other current challenges include hydrocarbon carryover and water polishing, so Engineering and Operations work together closely to ensure reliable water disposal and hence LNG production.
This case study will explore the success and lessons learnt in Gorgon PWD through a summary of field data, facility descriptions and experiences. An overview of the design will be given along with photographs of key components. The required design performance will be compared against actual operating data. In the new energy landscape, the Upstream Operators' social license to operate centers around our environmental performance. In our work we demonstrate that it is possible to treat and dispose of waste liquids responsibly while generating cashflow through LNG production.
This paper presents details of a comprehensive array of technical and commercial challenges associated with the feasibility of a long distance deepwater Middle East to India Deepwater Pipeline (MEIDP) providing information on the technical and commercial feasibility of the deepwater gas transportation system, which will reach a record water depth of 3450m, cross two continental slopes, an earthquake subduction zone (the Owen Fracture Zone) and outfall debris of the river Indus fan in 2500m water depth. It examines the techniques, analysis and technology development now available to make such challenging routes increasingly feasible.
The economic and political drivers for such a project are presented together with details of the overall project cost and tariff calculation to allow successful gas utilization by India's gas starved and stranded power stations. The challenges faced by the project from both a design and installation perspective are discussed together with some of the detailed geohazard assessments performed for the pipeline crossing and active fault zone (OFZ) and the Indus Fan.
High pressure trunk lines have proved to be the safest, cheapest way of transporting gas to market for short to medium distances up to 2,500 kilometers, making the proposed SAGE - Middle East to India Deepwater Pipeline the optimal solution for gas delivery to the Indian Subcontinent. Linking Middle East gas fields of Saudi Arabia, UAE and Oman to India across the Arabian Sea for an offshore distance of 1200 kilometers. The MEIDP gas transmission pipeline is designed to transport up to 1.1BCFD gas into the Indian energy markets.
The qualification plan developed with DNVGL is described together with details of the future construction schedule for first Gas. The Middle East to India Deepwater Pipeline
The Middle East to India Deepwater Pipeline
Kannan, Srinivasan (National Petroleum Construction Company) | Joshi, Chahit (National Petroleum Construction Company) | Subramanian, Senthilkumar (National Petroleum Construction Company) | Mudu, Balu (National Petroleum Construction Company) | Selvaraj Edwin, Jose (National Petroleum Construction Company) | Paul, Raju (National Petroleum Construction Company) | Kamal, Faris Ragheb (National Petroleum Construction Company) | Takieddine, Oussama (National Petroleum Construction Company)
Pigging Operation is high risk activity in-terms of process safety. Pigging can be safely initiated only when safe operating conditions are maintained at both ends of pipeline. Pigging involves human intervention and thus increasing personnel risk. Deploying smart, keyless system solutions on this fully manual operation for control and safety will definitely enhance safety level. NPCC presents their design and implementation experiences of smart keyless system for pigging on a recent offshore project.
Pigging involves sequential steps and imposes safety risks due to possibility of manual errors; since, significant number of steps and checks involved. High pressure, flammable/toxic gas release may leads to Catastrophic Personal, Asset and Environmental damages. Traditionally, mechanical key interlocking mechanism or similar mechanical safety interlocks deployed, which has inherent deficiencies like mechanical failures, key loss, minimum intelligence/ operator guidance. Ultimate aim is to ensure no pressure/ toxic gas inside pig-trap when opened for inserting/removal of pig-tool. Implementing smart keyless system with safety interlocks overcomes the shortfall of existing system with reliability. Safe methodology ensured through Risk based Assessment.
Pipeline pigging is required mainly to maintain pipeline efficiency, avoids potential flow-assurance issues and helps in corrosion control/integrity. The key design parameters are: MOV configuration: As the operation involves a number of MOVs (around 13 MOVs per Scrapper), a 2-wire digital loop was considered with hardwired permissive signal at suitable steps. Control System configuration: Entire operation is guided by Graphics in local field-mounted HMI involving sequential logic check as well as operator acknowledgement before proceeding to next predefined step. The position status of MOVs and Pressure conditions are used in the system logic for authorization to proceed to next step. Safety Interlock configuration: Safety critical checks implemented as hardwired permissive signals for MOV operation. Interlock prevents operation of MOVs, both from Local and Remote unless the safety conditions are met.
As the operation involves a number of MOVs (around 13 MOVs per Scrapper), a 2-wire digital loop was considered with hardwired permissive signal at suitable steps.
Control System configuration:
Entire operation is guided by Graphics in local field-mounted HMI involving sequential logic check as well as operator acknowledgement before proceeding to next predefined step. The position status of MOVs and Pressure conditions are used in the system logic for authorization to proceed to next step.
Safety Interlock configuration:
Safety critical checks implemented as hardwired permissive signals for MOV operation. Interlock prevents operation of MOVs, both from Local and Remote unless the safety conditions are met.
Although Pigging is a safety critical sequential process, this smart, keyless, system based sequential Pigging not only resulted in significantly safer operation, provides operator guidance and eliminates error/ negligence. This smart keyless system successfully designed, implemented and tested (FAT, IFAT & SAT) and currently in operation with Client's satisfaction. Automatic logging of pigging operation and reporting are available.
Smart keyless system based interlocks is the integral part of this novel solution and allows the high-risk pigging process to be performed safely with added convenience and security of an electronically integrated system. This paper intends to present a case study based on actual project, highlighting design challenges and experience gained during execution as well as providing HSE benefits to all stakeholders in the upstream hydrocarbon industry.