First Deployment of the Underwater Drill Rig MeBo200 in the North Sea and its Applications for the Geotechnical Exploration

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.

Offshore Freshened Groundwater in Continental Margins

“…Unconsolidated seafloor sediment samples between 0.3 and 30 m in length can be acquired using remotely operated vehicle (ROV)‐guided push cores, video‐guided multicorer, box corer, gravity corer, and hydraulic piston corer systems operated from research vessels (Abegg et al, 2017; Lunne & Long, 2006). Offshore drilling technologies, on the other hand, allow kilometers of unconsolidated and consolidated sediments and rocks to be recovered (Spagnioli et al, 2015; Talwani, 2009). Where core recovery is good, the sediments can be assessed in terms of granulometry and hydraulic properties, whereas their pore waters are analyzed geochemically (see section 3.2).…”

Mechanisms and Nucleation Rate of Methane Hydrate by Dynamical Nonequilibrium Molecular Dynamics

“…Despite the important application- and engineering-oriented relevance of clathrates, − the fundamental mechanisms of hydrate formation, which are key in the applications mentioned above, are understood rather poorly, especially at the molecular level. For example, theoretical predictions of rates of nucleation often differ from experimentally measured rates by at least an order of magnitude, and often more .…”

“…Methane hydrates are the most widespread type of clathrate hydrates and are thought to exist in nature primarily as type I in the permafrost and deep ocean regions. With methane compositions of around 85–95% of the maximum theoretical occupation, ∼0.15 molar fraction of methane, methane clathrate hydrates constitute a possible significant energy resource. , The large quantity of available methane hydrates has driven significant interest in their use as a possible resource of methane-gas fuel, − with the relative success of several production trials (JOGMEC, Malik, SUGAR - no drilling required).…”

“…For example, theoretical predictions of rates of nucleation often differ from experimentally measured rates by at least an order of magnitude, and often more . Improving our understanding of the underlying mechanisms of hydrate kinetics is desirable in terms of enhancing the viability of large-scale technological applications of methane hydrates. − For example, an improved understanding of hydrate-nucleation mechanisms would facilitate the design process of new promoters for hydrate formation in gas-transport and storage applications or inhibitors for its formation in gas pipelines …”