Onshore Processes Research Articles

Unravelling mechanisms behind population dynamics, biological traits and latitudinal distribution in two benthic ecosystem engineers: A modelling approach

The mechanistic approach consisting of coupling Dynamic Energy Budget (DEB) models to Individual-Based Models (IBMs) allows simulating individual and population biological traits and their dynamics. This approach was developed here to study population dynamics of two sympatric intertidal ecosystem engineers, Arenicola marina and Arenicola defodiens (Annelida Polychaeta) occurring in the North-East Atlantic from Portugal to Sweden. Latitudinal heterogeneity of the two species’ performances were investigated in terms of population dynamics and biological traits using latitudinal differences in environmental forcing variables. The impact of the forcing variables on population dynamics processes (shore colonisation and migration, spawning and recruitment, etc.) within a specific foreshore (mean values and seasonal patterns) was also assessed. Published DEB parameters were used for A. marina and a specific calibration was undertaken for A. defodiens, combining literature data and new laboratory experiments and field data. Our DEB-IBM simulated super-individuals’ growth and reproduction while lugworms were colonising, migrating and dying over a simulated foreshore. Density rules affected population dynamics. Environmental forcings consisted in monthly values of chlorophyll-a (chl-a) concentrations and daily values of SST. Scenarios focusing on the two most contrasted of these forcing variables time series were used to explore their relative effects over populations’ dynamics and on-shore processes were investigated at two sites displaying highly different simulated population abundances. Overall, northern sites with higher chl-a levels performed better displaying higher biomass, maximum length and reproductive outputs for both species. As expected, Sea Surface Temperature (SST) changes between sites did not impact greatly populations dynamics. Under favourable environmental conditions, intra- and inter-specific competitions emerged from the model. Under non-favourable environmental conditions, A. defodiens’ populations crashed and A. marina displayed atypical population processes, with rare spawning events barely allowing the population’s renewal, and lower size at maturity. Further use and development of this model will lead to better insights on the lugworm populations’ evolution over the next decades.

A Case Study of Asset Integrity and Process Safety Management of Major Oil and Gas Companies in Malaysia

Asset integrity is closely intertwined with process safety where the latter is often perceived to be equivalent or a subset of the former. In Malaysia, the requirements for offshore process safety are set by Petronas assuming exclusive rights to petroleum in the nation. It imposes and enforces these requirements on oil and gas companies entering into its production sharing contracts via the common law. Process safety management in Malaysia is strongly influenced by the US OSHA 3132 with elements comprising process safety information, process hazard analysis, operating procedures, employee participation, training, contractors, pre-startup safety review, mechanical integrity, hot work permit, management of change, incident investigation, emergency planning and response as well as compliance audits. These elements are largely included in the Mandatory Control Framework of Petronas and the trio of design, technical and operating integrity adopted in the process safety management of other oil and gas companies. These management practices align with the reiterative plan-do-check-act model. Process safety performance is also gauged with indicators suggested by international institutions such as the American Petroleum Institute. On top of the Control of Industrial Major Accident Hazards Regulations 1996 for onshore processes, this study deems that establishing statutory law for offshore installations will be beneficial to propel offshore safety in Malaysia to a greater height.

Techno-Economic Comparison of Onshore and Offshore Underground Coal Gasification End-Product Competitiveness

Underground coal gasification (UCG) enables utilization of coal reserves, currently not economically exploitable due to complex geological boundary conditions. Hereby, UCG produces a high-calorific synthesis gas that can be used for generation of electricity, fuels, and chemical feedstock. The present study aims to identify economically-competitive, site-specific end-use options for onshore- and offshore-produced UCG synthesis gas, taking into account the capture and storage (CCS) and/or utilization (CCU) of produced CO 2 . Modeling results show that boundary conditions favoring electricity, methanol, and ammonia production expose low costs for air separation, low compression power requirements, and appropriate shares of H 2 /N 2 . Hereby, a gasification agent ratio of more than 30% oxygen by volume is not favorable from the economic and CO 2 mitigation viewpoints. Compared to the costs of an offshore platform with its technical equipment, offshore drilling costs are marginal. Thus, uncertainties related to parameters influenced by drilling costs are negligible. In summary, techno-economic process modeling results reveal that air-blown gasification scenarios are the most cost-effective ones, while offshore UCG-CCS/CCU scenarios are up to 1.7 times more expensive than the related onshore processes. Hereby, all investigated onshore scenarios except from ammonia production under the assumed worst-case conditions are competitive on the European market.

Proactive Maintenance in the Context of Integrated Operations Generation 2

Summary With increased requirements to improve production availability and to have a continuous updated overview of the condition status of subsea production systems (SPSs), oil and gas operators have increased focus to reach beyond the current practice of integrating onshore and offshore centers and processes for continuous onshore support. Integrated operations (IO) Generation 2 is a further extension to integrate operation centers of the operator and their vendors with heavily automated processes and digital services in a round-the-clock operation. To reach IO Generation 2, proactive management as a foundation for operations with a pre-emptive maintenance program giving an early insight on coming abnormal issues is essential. Focusing on knowledge and understanding of how the equipment and installed base perform is essential and will be empowered by a management system that takes a holistic approach while an automatic integrity diagnoses functionality. To achieve IO Generation 2, work processes that promote collaboration and continuous improvements and visualization of the equipment will be necessary to facilitate a common awareness and maintain an optimum field operation. By continuous monitoring of the integrity of the SPSs in an IO Generation 2 context, the condition and performance management (CPM) system enables pre-emptive maintenance leading to maximum production at minimum maintenance cost. Increasingly important, and supported by the CPM system, is the enforcing of health, safety, and environment (HSE) standards as stipulated in company goals and in national and international regulations. The CPM system facilitates enhanced collaboration, and it is configured to support the identified IO Generation 2 work processes regarding work interfaces and roles. The agreed work processes for an IO Generation 2 setup make up the base foundation of the CPM system, from day-to-day monitoring and collaboration to in-depth analysis and improvement of the installed base performance.

Physical modelling of tsunami using a new pneumatic wave generator

The physical simulation of tsunami in the laboratory has taken a major leap forward with the construction and testing of a new wave generator, capable of recreating scaled tsunami waves. Numerical tools fail to reproduce tsunami nearshore and onshore processes well, and physical experiments in large scale hydraulic facilities worldwide have been limited to the generation of solitary waves as an (controversial) approximation for evolved forms of tsunami. The new concept in wave generation presented herein is born of collaboration between UCL's Earthquake and People Interaction Centre (EPICentre) and HR Wallingford. It allows for the first time the stable simulation of extremely long waves led either by a crest or a trough (depressed wave). This paper presents the working concepts behind the new wave generator and the first stages of testing for verifying its capacities and limitations. It is shown that the new wave generator can not only reproduce solitary waves and N-waves with large wavelengths, but also the 2004 Indian Ocean Tsunami as recorded off the coast of Thailand (“Mercator” trace).

Integrating distributed work: comparing task design, communication, and tacit coordination mechanisms

AbstractWe investigate coordination strategies in integrating distributed work. In the context of Business Process Offshoring (BPO), we analyze survey data from 126 offshored processes to understand both the sources of difficulty in integrating distributed work as well as how organizations overcome these difficulties. We find that interdependence between offshored and onshore processes can lower offshored process performance, and investing in coordination mechanisms can ameliorate the performance impact of interdependence. In particular, we outline a distinctive set of coordination mechanisms that rely on tacit coordination—and theoretically articulate and empirically show that tacit coordination mechanisms are distinct from the well‐known duo of coordination strategies: building communication channels or modularizing processes to minimize the need for communication. We discuss implications for the study of coordination in organizations. Copyright © 2010 John Wiley & Sons, Ltd.

A liquefied energy chain for transport and utilization of natural gas for power production with CO 2 capture and storage – Part 2: The offshore and the onshore processes

A novel energy and cost effective transport chain for stranded natural gas utilized for power production with CO 2 capture and storage is developed. It includes an offshore section, a combined gas carrier, and an integrated receiving terminal. In the offshore process, natural gas (NG) is liquefied to LNG by liquid carbon dioxide (LCO 2) and liquid inert nitrogen (LIN), which are used as cold carriers. The offshore process is self-supported with power, hot and cold utilities and can operate with little rotating equipment and without flammable refrigerants. In the onshore process, the cryogenic exergy in LNG is used to cool and liquefy the cold carriers, which reduces the power requirement to 319 kWh/tonne LNG. Pinch and exergy analyses are used to determine thermodynamically optimized offshore and onshore processes with exergy efficiencies of 87% and 71%, respectively. There are very low emissions from the processes. The estimated specific costs for the offshore and onshore process are 8.0 and 14.6 EUR per tonne LNG, respectively, excluding energy costs. With an electricity price of 100 EUR per MWh, the specific cost of energy in the onshore process is 31.9 EUR per tonne LNG.

A liquefied energy chain for transport and utilization of natural gas for power production with CO 2 capture and storage – Part 1

A novel transport chain for stranded natural gas utilized for power production with CO 2 capture and storage is developed. It includes an offshore section, a combined gas carrier, and an onshore integrated receiving terminal. Due to utilization of the cold exergy both in the offshore and onshore processes, and combined use of the gas carrier, the transport chain is both energy and cost effective. In this paper, the liquefied energy chain (LEC) is explained, including novel processes for both the offshore field site and onshore market site. In the offshore section, natural gas (NG) is liquefied to LNG by liquid carbon dioxide (LCO 2) and liquid inert nitrogen (LIN), which are used as cold carriers. The LNG is transported in a combined gas carrier to the receiving terminal where it is used as a cooling agent to liquefy CO 2 and nitrogen. The LCO 2 and LIN are transported offshore using the same combined carrier. Pinch and Exergy Analyses are used to determine the optimal offshore and onshore processes and the best transport conditions. The exergy efficiency for a thermodynamically optimized process is 87% and 71% for the offshore and onshore processes, respectively, yielding a total efficiency of 52%. The offshore process is self-supported with power and can operate with few units of rotating equipment and without flammable refrigerants. The loss of natural gas due to power generation for the energy requirements in the LEC processes is roughly one third of the loss in a conventional transport chain for stranded natural gas with CO 2 sequestration. The LEC has several configurations and can be used for small scale (<0.25 MTPA LNG) to large-scale (>5 MTPA LNG) transport. In the example in this paper, the total costs for the simple LEC including transport of natural gas to a 400 MW net power plant and return of 85% of the corresponding carbon as CO 2 for a total sailing distance of 24 h are 58.1 EUR/tonne LNG excluding or including the cost of power. The total power requirements are 319 kWh/tonne, hence the energy costs are 31.9 EUR/tonne LNG adding up to 90.0 EUR/tonne LNG. The exergy efficiency for this energy chain including power production and CO 2 capture is 46.4% with a total cost of 20.4 EUR/MWh for the produced electricity. The total emissions (in CO 2 equivalents) in the chain are 1–1.5% of the transported CO 2.

Integrating Distributed Work: Comparing Task Design, Communication and Tacit Coordination Mechanisms

We investigate coordination strategies in the remote delivery of business services (i.e. Business Process Offshoring). We analyze 126 surveys of offshored processes to understand both the sources of difficulty in the remote delivery of services as well as how organizations overcome these difficulties. We find that interdependence between offshored and onshore processes can lower offshore process performance. Investment in coordination mechanisms such as modularity, ongoing communication and generating common ground across locations ameliorate the performance impact of interdependence. In particular, we are able to show that building common ground - knowledge that is shared and known to be shared - across locations is a coordination mechanism that is distinct from building communication channels or modularising processes. Our results also suggest the firms may be investing less in common ground than they should.