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Oelker, Stephan (BIBA – Bremer Institut für Produktion und Logistik GmbH at the University of Bremen) | Alla, Abderrahim Ait (BIBA – Bremer Institut für Produktion und Logistik GmbH at the University of Bremen) | Büsing, Silas (BIBA – Bremer Institut für Produktion und Logistik GmbH at the University of Bremen) | Lütjen, Michael (BIBA – Bremer Institut für Produktion und Logistik GmbH at the University of Bremen) | Freitag, Michael (BIBA – Bremer Institut für Produktion und Logistik GmbH at the University of Bremen / University of Bremen, Faculty of Production Engineering)
ABSTRACT Offshore wind energy has become a key technology for the generation of electricity. In conventional installation concept, the base port is considered as a hub for the handling and storage of different components of offshore wind turbines. Trends of the wind energy industry influence offshore base ports. Therefore, a simulation study is carried out, which considers the influence of the increasing installation trends in different scenarios, resulting from different settings of parameters. Recommended measures that can optimize the capacity utilization of base ports and the influence of the trends on the base port will be derived from the simulation study. INTRODUCTION As a hub between the sender and recipient of goods, the port is generally an integral part of the supply chain and plays an important role in the management and coordination of material and information flows (Hoa and Haasis, 2017). The base port as a hub for the installation of offshore wind turbines (OWTs) in particular acts as a funnel for a large number of water and land-based material flows from the suppliers' production facilities. Due to the dimensions and weights of the large components of WTGs, this results in extremely high logistical and technical costs, which have to be met by the port operator (Schütt and Lange, 2014). In addition, offshore logistics is subject to trends such as the constantly evolving large components and the rapid growth in the size of construction and supply ships (Färber and Kohn, 2014). Wind energy has established itself as an alternative to traditional power generation. Due to the restriction of suitable land areas, offshore will in future play an increasingly important role in the energy turnaround compared to onshore (Oelker et al., 2017). Another reason is the significantly higher wind energy potential (Lau, 2013). Figure 1 shows the development of installations in the German North Sea and Baltic Sea in terms of cumulative number and annual growth over time.
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 29069, “How AI and Robotics Can Support Marine Mining,” by Peter Kampman, Leif Christensen, Martin Fritsche, Christopher Gaudig, Hendrik Hanff, and Marc Hildrebrandt, German Research Center for Artificial Intelligence (DFKI), and Frank Kirchner, DFKI and University of Bremen, prepared for the 2018 Offshore Technology Conference, Houston, 30 April–4 May. The paper has not been peer reviewed. Copyright 2018 Offshore Technology Conference. Reproduced by permission. Marine mining initiatives open a new field of subsea operations. Offshore oil and gas sites are still located primarily in areas where divers can support maintenance and repair requirements, but future marine mining will take place in greater depths and with a complexity of machines that requires support from robotic systems equipped with a substantial amount of artificial intelligence (AI). Technologies are being developed that have the potential to support marine mining in all stages from prospection to decommissioning. These developments will likely have substantial influence in the oil and gas industry, itself searching for ways to maximize exploitation of assets. Robotic Systems Under Current Development Increasing Autonomous Underwater Vehicle (AUV) Intelligence. Commercial off-the-shelf AUVs rely mostly on acoustic and inertial sensors for their navigation. Speed measurements from a Doppler velocity log are combined with orientation values from gyroscopes and accelerometers to estimate current position. These updates are sometimes augmented by absolute-position fixes from an ultrashort baseline system. However, during such a mission, the inspection assets might not be located exactly at their expected positions. This might be because of incorrect positioning during installation, objects being dragged off location by fishermen, or sediments hiding a pipeline gradually from the view of standard sensors. Therefore, equipping modern AUVs with sensors and software that can search for, detect, track, and re acquire inspection targets is essential. In addition, classical sensor suites consisting of cameras and sonars can be augmented with higher-resolution 3D sensing such as laser-line projectors (structured light). This enables an AUV’s onboard software to create a millimeter-precision 3D model of the asset, which can be compared with computer-aided-design models or previous-inspection-run data. By using a fully automated 3D-model cross-check, the AUV could detect asset deformations, defects, or marine growth, even while still submerged during the inspection run. Seafloor AUV Support Infrastructure. Current AUVs have limited endurance, mostly because of limited battery capacity. Depending on the sensor suite, on-board data-storage space also can be a limiting factor. This causes AUV missions to run no longer than a few days at most, depending on AUV size and shape, propulsion, sensor efficiency, and environmental conditions in the deployment area.
ABSTRACT In this real case study two data sets of small strain shear modulus Gmax from laboratory and in-situ measurements are compared. The two data sets are used as inputs to a linear elastic 3D finite element numerical model to estimate the initial lateral pile-soil stiffness. The question of how much the pile deflection curve depends on the different Gmax derivation methods is discussed throughout the paper. The study reveals a high importance of stratigraphy for this task, and shows that average input stiffness differences up to 20% throughout the profile do not lead to pile deflection changes at the mudline for the discussed regime. INTRODUCTION Recent monitoring of wind turbines supported by monopile foundations shows that the measured fundamental frequencies are higher than the design predictions (Kallehave et al., 2015 and Versteijlen et al., 2014). This may be caused by an underestimation of the soil stiffness at small strain regimes. The total foundation stiffness has to provide structural frequencies in a specified range in order to avoid resonance with the rotor and blade passing frequencies and with the wind and wave loading. Underprediction as well as an overprediction of stiffness can therefore lead to unacceptable structural responses. The current state of the art for designing monopiles is the p-y curve method described in the offshore standard DNV (2014). However, this approach was developed based on full-scale load tests on slender piles with diameters under 1.0 m. Indeed, the standard DNV (2014) recommends validation of p-y-curves for monopile design, for instance by means of finite element modelling (FEM). Several modifications of the p-y-curve methods have been proposed to account for overprediction of soil-pile stiffness under extreme loads and its underestimation under fatigue loads in monopile design (Wiemann et al., 2004; Soerensen et al., 2012; Kallehave et al., 2012; Kirsch et al., 2014;Thieken, 2015). Regardless of the design method, soil-structure responses calculated at different stress regimes are combined into foundation stiffness and damping matrixes, which serve as boundary conditions for the offshore wind turbine structural design and in turn, among others, for the prediction of the natural frequency.
Spagnoli, G.. (BAUER Maschinen GmbH) | Finkenzeller, S.. (BAUER Maschinen GmbH) | Freudenthal, T.. (University of Bremen) | Hoekstra, T.. (A.P. van den Berg Ingenieursburo bv) | Woollard, M.. (A.P. van den Berg Ingenieursburo bv) | Storteboom, O.. (A.P. van den Berg Ingenieursburo bv) | Weixler, L.. (BAUER Maschinen GmbH)
Abstract As the drilling technology has advanced, recent deepwater developments and explorations are currently taking place in Gulf of Mexico, Brazil and West Africa where deeper reserves of oil have become more accessible. The study of the subsea soil (e.g. soil investigation, positioning foundation design) is one of the activities required for the subsea field development. Electromagnetic tests, CPT tests, gravity, piston core or vibrocore samples are obtained by deploying down-hole systems from drilling vessels. However, because of the high costs and low availability of drill ships, and because ship and drill-string motion due to wind, currents and waves affect the quality of the drilling process, robotic drill rigs are currently more widely used. The following paper describes the MeBo200 as a novel underwater drill rig for geotechnical/geological explorations. The MeBo200 drilling rig is lowered to the sea floor and operated remotely from the ship to drill up to 200m into the sea floor at an ambient pressure of up to 400bar. It was developed in cooperation by MARUM Center for Marine Environmental Sciences (University of Bremen) and BAUER Maschinen GmbH. The complete system is transported within seven 20 ft containers. MeBo200 is a second generation of the MeBo, which was the first remote-controlled deep sea drill rig that uses a wireline coring technique. The weight of the MeBo200 is about 10 tons in air and 8 tons in water and therefore it does not need special drill ships to be managed reducing therefore the mobilization costs for worldwide deployment. The MeBo200 was deployed in the German sector of the North Sea in October 2014 to test the functionality of the seabed-based drill rig. Currently MeBo200 is being upgraded with CPT technology from A.P. van den Berg Ingenieursburo bv.
Abstract Deepsea mining sites are usually large areas of polymetallic nodules or seafloor massive sulfide (SMS) deposits. Prior to underwater mining campaigns, successful exploration programs have to be taken into account in order to include selection of target areas by means of seafloor and sub-seafloor surveys of the rocks and sediments. Coring of the submarine sediments plays a major role for evaluating of the marine sediments and they are useful for future mining operations. The main geology which hosts the polymetallic nodules is pelagic clay. On the seafloor and specifically at the mudline, this kind of soils has very low undrained shear strength up to 20 kPa. In order to properly design the nodule harvester, which will be in contact with the sea floor, physical properties of the seabed and shallow subsurface (i.e. the upper 100–200m)are needed to compute bearing capacity. Underwater soil cores can be used to evaluate soil type, cohesion, unit weight of soil, modulus of elasticity. Seafloor massive sulfide (SMS) deposits are very different from the polymetallic nodules. In this case, cores are needed in order to assess possible anomalies. Measured uniaxial compressive strength (UCS) values strengths in the SMS zone can be very high. Drill cores are required for assessing the mineral content at these deposits. The MeBo200 is a sea bed drill rig presently developed by the MARUM Center for Marine Environmental Sciences at the University of Bremen and the department of Maritime Technologies of BAUER Maschinen GmbH. It is well suited for core drilling in formations of comparable strength and therefore it is suitable preparatory geotechnical exploration. MeBo200 is the second generation of MeBo. From 2008 to 2012 MeBo was employed in 9 expeditions. 66 deployments took place in up to 2,050 m water depth. 1,445 m were cored in different type of geologies, concentrating more on the quality of the cores. These include crystalline rocks from the Porcupine Bank west of Ireland, as well as very soft homogenous silty clays in the Gela Basin with very low undrained shear strength values. The recovery rate was good for hard rocks and cohesive soft sediments. Taking into account the case histories of MeBo it is possible to state that for underwater mining applications the new MeBo200 can be utilized for geological and geotechnical drilling campaigns.
Waldmann, Christoph (University of Bremen, MARUM Center for Marine Environmental Sciences) | Freudenthal, Tim (University of Bremen, MARUM Center for Marine Environmental Sciences) | Kopf, Achim (University of Bremen, MARUM Center for Marine Environmental Sciences)
Abstract Any intervention into the seafloor will have an impact on the structural integrity of the material in the affected region and will hence result in variation in stress, pore water pressure, and temperature. As a consequence fluids maybe mobilized and may in turn affect the intervention process. To closely track such processes or monitor safe operations in areas of e.g. hydrocarbon exploitation, seafloor mining or marine renewables, new measuring strategies have to be developed to allow a spatio-temporal coverage via a sensor network. With the deep-sea drill MARUM-MeBo that has been developed at the University of Bremen/MARUM new opportunities are opened up to deploy sensors in shallow boreholes (<80 m sub-seafloor depth). MeBo is characterized by its versatility and high mobility with deployments down to water depths of 2000 m. Materials recovered via wire-line coring technique included both soft sediments and hard rocks. After drilling a 2.35 m section the core is recovered using a wire that is latched to the inner core barrel with an overshot. The outer drill string stays in the drilled hole during the entire drilling process. Recently, simple self-contained borehole instruments were developed that are placed in the hole, in which the outer drill string serves as casing. We propose to employ MeBo to deploy a network of instrumented boreholes in the region of deep-sea interventions to monitor the environmental conditions continuously over long time intervals. Data can be exchanged via acoustic modems and may serve to archive time series and use in hazard assessment and early warning.
ABSTRACT Visual detection of whales during seismic surveys for mitigation purposes is a labor intensive and exhaustive task, feasible only during daylight hours. These constraints are overcome by the MAPS (Marine Mammal Perimeter Surveillance) system, which employs a ship-borne, 360°, cooled thermal imager in conjunction with a newly developed automated whale detector, which processes this video stream in real time to alert observers to the possible presence of whales and to provide night time vision. MAPS was developed and extensively tested during three recent expeditions into the polar oceans, providing IR footage of far over 1000 whale spouts at up to 5 km distance.
Abstract Under-ice exploration in the Arctic Ocean requires robust and reliable robotic tools. Autonomous underwater vehicles (AUVs) used in this environment have to be able to navigate reliably and with precision without the help of a dedicated infrastructure. They also have to be able to adapt and to react to changes in their environment. In this paper, new methods for AUV infrastructure-independent navigation and self-localization, as well as for an adaptive AUV control architecture are presented. These methods were developed at the DFKI within the framework of several nationally funded research projects. They were implemented on experimental AUVs and showed promising results in preliminary lab and field tests. Introduction Robots are needed to operate in areas that are too difficult or to too dangerous to access for humans. In remote areas like the deep sea and the Arctic Ocean, robots are invaluable helpers for scientific exploration, environmental monitoring, economic exploitation and other endeavours. As of today, robots have been used successfully by oceanographic research institutes, oil companies, and other stakeholders to access and explore the depths of the Arctic Ocean. However, the application of these robots - like the application of most professional service robots in harsh environments - is still hampered by a lack of autonomy, robustness and dependability. So far, robots can only be used in well-supervised short-term missions that require intensive support by an associated research vessel. A robust long-term deployment of autonomous robots in harsh environments, with a minimum of human supervision and support, is well beyond the current-state-of-the-art. In this paper, we will present new methods that lead towards solutions for two key obstacles in the way of robust operation of robots in arctic exploration, namely the problem of reliable under water and under-ice self-localization and navigation, and the problem of adaptive mission control for AUVs. Both methods are the results of ongoing projects at the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI-RIC) in Bremen, Germany. AUV Navigation and Self-Localization Introduction The ability to follow a given course without deviation and to determine it's own position without error is a challenge for any underwater vehicle, and in particular for AUVs that operate under ice. Nevertheless, depending on the mission profile as well as on the precision and type of self-localization required, there are numerous methods to determine the current position of an AUV.
ABSTRACT: The acquisition of a 3D VSP in a densely populated environment onshore Germany, in a complex geological setting under sub-salt conditions, entails high costs while running a significant risk of obtaining disappointing results. RWE Dea was involved in such an operation for the last 2–3 years with local and international service companies (main contractor Schlumberger). This talk is to report about the acquisition procedure and the lessons learnt, and to discuss involved efforts and survey results. We belief we have gone the right way and we are happy to present the results today, indeed, other solutions may be possible under different conditions. RWE Dea's most important domestic asset is a 1994 discovered, deep (4,500 m bsl) Rotliegend Gas field near Bremen/Germany. The field has produced some 10 BCM gas from 15 wells during the last 15 years. The geological structure of the field is complex containing many tectonically separated compartments along a regional shear zone, in where the best producers of the field are located, but also tied wells. In addition the surface seismic image is disturbed by overburden Zechstein salt forming irregular salt bodies. After one of the old wells in the shear zone took water it was decided to produce the remaining potential by a new well drilled in an up-dip position. The production of this well was, however, much lower than anticipated, so that the idea of side tracking this well was raised during the first year of production. Since the surface seismic image in this area is poor, it was essential for locating the landing point of the new well to improve the existing seismic image in such a way that it allowed a reasonable prediction of less-faulted acreage and suitable facies conditions. With that the idea to acquire a 3D VSP was born, which was in fact the first 3D VSP in Germany. Our approach consisted of a 4 step procedure during the years 2006/07: a pre-survey reprocessing and modeling phase followed by the acquisition of a test Walk Away VSP in an analogue position, the preparation of the survey well (i.e. pulling out the production string and cementation of the reservoir section), the acquisition, processing and the interpretation of the 3D VSP, and finally the drilling of the side track, which will commence in summer 2009. If succeeding, the same approach could be used for other sub-salt situations in the North German basin
Mosher, D.C. (Natural Resources Canada, Bedford Institute of Oceanography) | Christian, H. (Seabed Geotechnics Ltd) | Cunningham, D. (ODIM Brooke Ocean Technology) | MacKillop, K. (Natural Resources Canada, Bedford Institute of Oceanography) | Furlong, A. (ODIM Brooke Ocean Technology) | Jarrett, K. (Natural Resources Canada, Bedford Institute of Oceanography)
ABSTRACT A free fall cone penetrometer (FFCPT) probe was developed by ODIM Brooke Ocean Technology Ltd for use in offshore geotechnical foundation condition assessment and seabed characterisation. The probe measures acceleration and pore pressure as a function of depth of penetration into the seafloor. This combination of sensors provides two independent means of calculating undrained shear strength, as well as engineering variables that are used to identify sediment grain size characteristics. The Harpoon FFCPT couples to a large piston coring system, penetrating normally consolidated sediments 10 to 15m below the seafloor. Results show strong correlation of undrained strength profiles derived from the dynamic penetration response of the tool with predicted (normal consolidation) and measured (mini-vane and triaxial vane) strength profiles from companion cores, spanning a variety of sediment types and water depths. The FFCPT tool provides the potential for acquiring in situ engineering data rapidly and without the need for extensive sample collection and laboratory analysis. INTRODUCTION Marine sediment physical property data are required for a number of applied purposes in addition to scientific understanding. Engineering applications include offshore dredging, aggregate mining, hydrocarbon exploratory drilling and production development, and pipeline trenching (as a few examples). Naval defence require seafloor property information for mine burial assessment and understanding seafloor acoustic propagation characteristics. Geoscientists require equivalent information for assessing conditions of slope stability, sediment transport and linking geological to geophysical data. Biologists require seafloor classification information for habitat assessment. The principal means for acquiring such data of near-surface seafloor sediment engineering data has been either acquisition of sediment cores combined with laboratory measurement of recovered sediment, or in situ testing with conventional cone penetrometer testing (CPT) using drill rigs or similar technologies. Equipment for such in situ data in deep water are largely restricted to the Penfeld CPT and a recent development of a free fall cone penetration tool by a group at the University of Bremen. ODIM Brooke Ocean Technology (ODIM BOT), with funding support from Natural Resources Canada and Petroleum Research-Atlantic Canada, developed two models of a free fall cone penetrometer in response to this recognised need for in situ offshore engineering data that could be provided rapidly and yet ensuring safe and economical development of offshore resources. Shear strength of sediments is the internal resistance per unit area that the sediment possesses to resist failure. It is an important parameter for foundation of seafloor structures and for understanding the stability of the slope. Shear strength is determined in several ways. In situ methods, such as the field vane shear test and CPT, determine the shear strength indirectly but avoid some of the problems of disturbance associated with the extraction of soil samples from the ground. Coring and laboratory methods, on the other hand, yield the shear strength directly and give valuable information about the stress-strain behaviour and the deployed from either a moving vessel profiler (MVP) winch or standard winch. From the latter, the vessel must be stationary and cable is flaked on the deck providing slack for the free fall operations.