Case Study: Munin Unmanned Platform Walk-to-Work Landing Elevation Design Considerations

Epibenthic assemblages on vertical artificial substrates: recruitment and succession patterns in offshore Qatari waters

Offshore oil and platforms are found on continental shelves throughout the world’s oceans. Over the course of their decades-long life-spans, these platforms become ecologically important artificial reefs, supporting a variety of marine life. When offshore platforms are no longer active they are decommissioned, which usually requires the removal of the entire platform from the marine environment, destroying the artificial reef that has been created and potentially resulting in the loss of important ecosystem services. While some countries allow for these platforms to be converted into artificial reefs under Rigs-to-Reefs programs, they face significant resistance from various stakeholders. The presence of offshore platforms and the associated marine life alters the ecosystem from that which existed prior to the installation of the platform, and there may be factors which make restoration of the ecosystem unfeasible or even detrimental to the environment. In these cases, a novel ecosystem has emerged with potentially significant ecological value. In restoration ecology, ecosystems altered in this way can be classified and managed using the novel ecosystems concept, which recognises the value of the new ecosystem functions and services and allows for the ecosystem to be managed in its novel state, instead of being restored. Offshore platforms can be assessed under the novel ecosystems concept using existing decommissioning decision analysis models as a base. With thousands of platforms to be decommissioned around the world in coming decades, the novel ecosystems concept provides a mechanism for recognising the ecological role played by offshore platforms.

Ambient and forced vibration tests were recently conducted on an offshore steel template platform in the Ekofisk complex of the North Sea. Valuable information about the dynamic characteristics of the structure was obtained. This paper focuses on the measurement and analysis of damping data for the platform. Modal damping values are very important in the dynamic analysis of offshore structures. Correct values of modal damping need to be utilized for the dynamic analysis to accurately predict the response of the structure. Little experimentally verified information of the modal damping characteristics of the fundamental and higher order modes of offshore structures is currently available. Damping values were calculated for the fundamental and higher order jacket modes which included natural frequencies up to approximately 5 Hz. Damping values are compared for forced and ambient vibration data, for bandwidth and response techniques, and for different excitation levels. The general results indicated that the fundamental modes important in fatigue had damping values of 1 to 3 percent of critical and the higher order modes had damping values of 2 to 3 percent of critical. Emphasis is placed on the apparent merits and limitations of the data presented. Response comparisons are also presented using an analytic model of the platform with various values of critical damping. INTRODUCTION Accurately predicting the dynamic behavior of offshore oil and gas production platforms to withstand the effects of earthquakes and environmental fatigue due to wind and wave loading is an essential part of the design of such structures. Research and development work currently being undertaken to apply integrity monitoring techniques to these platforms also requires an accurate interpretation of the structural dynamic behavior. These applications of vibration technology translate directly into cost effective design and increased reliability and safety of offshore structures. The complexity of these structures requires a high level of theoretical analysis in developing models which duplicate the dynamic behavior under design loading conditions. Current state-of-the-art modeling methods usually apply finite element techniques which discretize the structure into an assemblage of mass and stiffness matrices which mathematically define the structure. The complexity of these structures also implies the need for confirmation and improvement of the structural models by experimental techniques. Using system identification methods, both analytic and experimental results can be used to accurately define the dynamic behavior of structures. Structural damping is one of the least understood yet most vital design characteristics of dynamically loaded structures. An analytical model of a structure in which low critical damping values are used will respond much differently to environmental loads than one in which higher damping values are used. This paper presents values of critical damping obtained experimentally on an offshore platform and comparisons are made to an analytic model of the structure. The vibration tests were conducted on an offshore steel template platform in the Ekofisk complex of the North Sea. Both ambient and forced vibration test procedures were utilized.

In this research, the environmental feasibility of a hybrid renewable source of wind‐solar energy has been assessed and the amount of this energy on offshore oil and gas platforms has been estimated in three basins of the Caspian Sea. Extractable wind‐solar energy around the Caspian oil and gas platforms was investigated using the Medium‐range Weather Forecast database by applying a resolution of 0.125° and a time step of 6 h for 10 years (2005–2014). The findings showed that the average wind energy in the northern, middle, and southern basins at the height of 10 m are 1.10, 0.89, and 0.43, respectively. Centralnoy field with an average energy of 2.398 MWh/m 2 .year is the most suitable oil and gas offshore platform for a hybrid application of wind‐solar energy. Inkie Moor field has the lowest amount of hybrid energy (1.432 MWh/m 2 .year) in the Caspian Sea.

Oil and gas platforms as artificial substrates for epibenthic North Sea fauna: Effects of location and depth

Since the exploitation of offshore oil and gas, after decades of development, it has gradually played an important role in world economic development. The central control system of offshore platforms is the core equipment of offshore oil and gas fields. Offshore platform industrial process control requires PID control most of the time. However, in practical applications, the tuning of PID parameters has not been well resolved. This paper combines neural network and PID control to build a neural network PID controller. At the same time, using OPC communication technology, the intelligent control PID algorithm is perfectly combined with the central control system, and the optimized model and parameters are applied to the actual control object of the oil level control of the offshore oil production platform, and the control effect is obtained satisfactorily.

In the offshore oil and gas fields, facilities decommissioning research has become a very important topic. The offshore oil and gas facilities should be deposit and abandon after stop production. This paper proposes decommissioning method of the offshore platform by studying this problem.

Many challenges arise when designing offshore structures for iceberg loads in arctic and subarctic regions. To help the designer, the ISO 19906:2010 standard provides guidance for the calculation of design ice loads using both deterministic and probabilistic approaches. In determining design loads for different environmental factors, both principal and companion actions must be taken into account; an example is iceberg actions and companion wave actions. ISO 19906 allows the designer to calculate the companion wave action as a specified fraction (combination factor) of the extreme level (EL) design wave load. Alternatively, the designer can calculate appropriate companion wave loads explicitly. A methodology has been developed at C-CORE in which representative iceberg actions are determined using a software package, the Iceberg Load Software (ILS). This is a probabilistic tool which uses Monte Carlo simulation to obtain a distribution of global impact forces based on the expected range of iceberg and environmental conditions that a structure would likely encounter. The software provides a reasonably accurate representation of the iceberg loading situation, following the provisions of ISO 19906:2010, without introducing unnecessary conservatism in the design load. In the software, the influence of waves on the iceberg actions are considered, but companion wave loads must be calculated and added externally to the software, The software accounts for the probability of different sea state conditions and the influence of the sea state on the probability and severity of iceberg impact, given the correlations between the sea state, iceberg management effectiveness and iceberg drift and wave-induced velocity. The additional hydrodynamic pressure due to the wave during the period of the impact; is not considered. This wave loading will be complicated by the influence that the presence the iceberg and structure have on the local sea state. In this paper, brief descriptions are provided of background studies on companion wave loading and the application of companion load factors in ISO 19906. The companion load factors allow the designer to apply the design wave load, which is calculated for situations with no iceberg present, to the case of iceberg impacts. In this study, a methodology is presented for determining companion wave loads based on the distribution of sea states expected during an iceberg impact. These sea states are significantly less severe than that associated with the design wave load as iceberg impacts are rare events. The companion wave loads are determined without accounting for the influence of the iceberg; this is thought to be quite conservative. An example application of the methodology is presented for a hypothetical platform located on the Grand Banks, off the east coast of Newfoundland. Iceberg actions, wave actions and combined iceberg-wave actions are estimated using the described methodology. Comparisons are provided for the resulting companion loads and those based on ISO 19906:2010 companion load factors applied to the extreme level wave load.

Some offshore Oil and Gas platforms act as mini de facto Marine Protected Areas, supporting diverse marine ecological reef communities. Many policies mandate the removal of most O&G infrastructure at the end of its operational life, potentially harming marine species and removing critical habitat. One unexplored notion is that repurposed offshore platforms could be considered (and/or augmented) as ‘nature-in-design reefs’ in a variation of the ‘rewilding’ context, which involves restoring the complexity of food webs, natural disturbances, and the spread of ecosystems so that they need minimal human intervention in the long term. In 2017, as part of a Net Environmental Benefit Analysis Comparative-Assessment procedure, the subsea ecological importance and optimal jacket cut-off depth of a 34-year-old North Sea platform scheduled for decommissioning were assessed using incidentally collected Remotely Operated Vehicle imagery data. Species presence, richness, diversity, and vertical distribution were analysed, and 33 taxa across ten phyla were identified, with 23 taxa at species level. Species assemblages varied significantly with depth; algae, mussels, and serpulid polychaetes were abundant in shallow waters, while anemones and soft corals, were prevalent at depths of 15–100 m. Commercially important fish species were found predominantly below 70 m. Optimal jacket cut-off depth was recommended to be 15 m below Lowest Astronomical Tide. This research demonstrated the extensive diversity of native and protected species on an ageing North Sea oil platform and takes the first step in considering the potential environmental, societal, and economic net benefits of decommissioned platforms in the context of a rewilding paradigm.

Offshore oil and gas production platforms are complex and hazardous process facilities which are usually attended by a permanent human crew to run the daily operations. In recent years, the oil and gas industry has demonstrated strong commitment to change this traditional operations approach and move towards inherently safer philosophy in offshore facilities design and operations, i.e. removing human crew from the facility and operating it remotely from a safe location over extended periods. This paper aims to demonstrate the readiness of robotics technologies coupled with digitalization technologies in process control and facility automation in transforming offshore oil and gas production platforms into smart unmanned installations. This paper is focused on the application of smart robotics, with highly dexterous capabilities and equipped with multiple sensing instruments, in maintaining an offshore oil and gas production facility in full operation without a permanent human crew, and with planned visits to the platform at 12-week intervals, in a case study. The robots are developed to be remotely operated from an onshore control center and/or may be programmed to function autonomously for routine missions on the offshore facility.

Black‐legged kittiwake (Rissa tridactyla) populations are in decline globally, including in Britain and Ireland, which support internationally important numbers. Although kittiwakes typically nest on coastal cliffs, they are known to colonise anthropogenic structures, including offshore oil and gas platforms. Lack of monitoring of offshore platform colonies represents a potentially important gap in our understanding of kittiwake population size and dynamics. The presence of nesting kittiwakes on oil and gas platforms presents a practical challenge for operators in relation to decommissioning and re‐purposing works. We use preliminary data from surveys of colonies on offshore oil and gas platforms to speculate on the scale of platform colonisation by kittiwakes and the potentially significant contribution this may make to the wider population. Practical Implication: We identify several research priorities to help address important evidence gaps and inform management strategies: (1) regular monitoring of offshore populations to inform national population censuses, (2) improved understanding of the ecological drivers of offshore breeding including selection of nesting sites and foraging habitats, fitness benefits and connectivity with onshore colonies and (3) collaboration with platform operators to develop practical approaches to minimise impacts of essential operational work on nesting kittiwakes.

Offshore Oil and Gas platforms mostly utilize gas or diesel generators to produce reliable energy. As a step towards low carbon economy, Offshore Wind Energy is studied to reduce dependency on this fired turbomachinery. Since Malaysian Offshore Oil and Gas platforms are mostly situated in water depths deeper than 50 m, floating offshore wind turbine is considered. Floating offshore wind technology has roots on well-known platform designs from the Oil and Gas industry. However, specific solutions adaptations are required since floating platforms are expensive whilst floating offshore wind solution is cost driven. Furthermore, there is a need for high dynamic stability. Therefore, the fully coupled analysis (aero-hydro-servo-elastic simulations) will be briefly presented. This study will focus on GICON’s tension leg platform and ELEON’s single-sided supported direct drive wind turbine. The concept of hybrid microgrid is introduced as part of the bigger picture of energy transition towards low carbon technologies.

Offshore oil and gas platforms are a notable source of methane (CH4) in the marine environment, yet there remains a lack of comprehensive understanding regarding their impact along the coastal areas of China. Besides, relevant emissions are generally derived from systematic inventory and rarely quantified by top-down methods. To this end, a ship-based measurement of CH4 emissions from three offshore oil and gas platforms with different oil and gas production levels was conducted over the Liaodong Bay of China in August 2023. The results demonstrated that there were differences in CH4 background concentrations around the three platforms (2291 ± 15 ppb, 2468 ± 32 ppb and 2100 ± 12 ppb). At moderate wind speeds, CH4 levels showed a gradual increase as the ship approached the target upwind, with peak concentrations typically observed within a range of 2-3 km from the platform. Along with meteorological data and the Gaussian plume model, CH4 emission rates were determined corresponding to the average values of 229 ± 48 kg h-1, 59 ± 16 kg h-1 and 13 ± 8 kg h-1 for the three platforms. By analyzing the concurrent changes in carbon dioxide concentration, it was hypothesized that gas flaring was the primary source of CH4 emissions from one of the platforms. Additionally, when considering the revised emission factors for the oil and gas industry from the IPCC and combining them with the production data from the three platforms, the results clearly demonstrated a substantial contrast between top-down emissions and inventory emissions. Diverse platforms and continuous monitoring are necessary to validate the aforementioned perspective and ultimately enhance the precision of CH4 emission data provided to regulators and the general public.

In Malaysia, numerous offshore oil and gas platforms are approaching the end of their operational lifespans and will soon be scheduled for decommissioning. Traditional decommissioning typically involves the complete removal of the platform from the seabed, consequently resulting in the destruction of the established marine life communities present on the structure. A Rigs-to-Reefs strategy provides an alternative to the complete removal of obsolete, non-productive offshore oil and gas platforms, by converting the platform into a permanent artificial reef by utilizing one of the following three methods: partial removal or topple-in-place (in-situ), or tow and place (ex-situ). In-situ reefing provides a means of conserving the marine communities found on the platform by decommissioning the platform jacket in place as an artificial reef. However, not all platforms are good candidates for a Rigs-to-Reef conversion. Thus, pre-decommissioning biological assessments should be undertaken to determine the most appropriate decommissioning strategy on a case-by-case basis. In this study, a biological assessment was developed to catalog the marine life assemblages present on two offshore oil and gas platforms in Malaysia using remotely operated vehicles. Given the limited amount of biological data available on the marine ecosystems found on Malaysia’s platforms, this data may be useful for minimizing adverse impacts of platform removal, while enhancing benefits to the marine environment.

This article presents results from the first detailed study on the feeding habits of fish assemblages associated with offshore oil and gas platforms in the North Sea. Multi-seasonal sam- pling was conducted at one of the oil platforms located in the central North Sea between Septem- ber 2010 and January 2014 to characterise temporal variation in the stomach contents of different fish species. A total of 6 fish species were recorded, including commercially important gadoids such as saithe Pollachius virens, haddock Melanogrammus aeglefinus and cod Gadus morhua. Saithe fed predominantly on euphausiids and haddock consumed a large proportion of ophi- uroids, whereas cod were mainly piscivorous. The prey compositions were significantly different between species, indicating the presence of interspecific prey resource partitioning among those species. To further investigate possible links between the feeding habits of the most dominant fish species, saithe, and the physical presence of offshore platforms across the North Sea, a separate set of stomach data was collected during the 2012 Quarter 3 International Bottom Trawl Survey aboard the FRV 'Scotia'. The multivariate analysis of both data sets showed that the observed spatio-temporal variability in the saithe diet was significantly explained by proximity to the near- est offshore platforms and changes in water temperatures, which appear to reflect patterns of euphausiid availability over space and time. The physical presence of the offshore structures may potentially affect the distribution/availability of zooplankton (i.e. euphausiids) and thereby influ- ence the feeding behaviour of saithe and any other marine populations that are interconnected to the dynamics of such trophic interactions.