Influence of irregular waves on the dynamic response of a vertical transport system for deep sea mining

2021 ◽  
Vol 229 ◽  
pp. 108443
Author(s):  
Qi Wu ◽  
Jianmin Yang ◽  
Xiaoxian Guo ◽  
Lei Liu
Author(s):  
Stanislav Verichev ◽  
Valery Drobadenko ◽  
Nikolay Malukhin ◽  
Alexandr Vilmis ◽  
Pieter Lucieer ◽  
...  

Successful mining of deep sea deposits strongly depends on the proper choice of the right equipment. The most probable concept for a deep sea mining system would consist of the three major sub-components: Seafloor Mining Tool, Vertical Transport System and Mining Support Vessel. In this paper, emphasis is placed on the Vertical Transport System. We analyse the pros and cons of the different concepts such as hydraulic transport using centrifugal or positive-displacement slurry pumps, conventional and unconventional airlift systems, vertical offshore mining systems and vortex slurry transportation systems. All these systems are considered for their applicability at different water depths (from the relatively shallow to the relatively deep) for the different types of materials (from the relatively fine to the relatively coarse) and various production rates in terms of the efficiency, reliability and state of the art of technology.


2020 ◽  
Vol 101 ◽  
pp. 102188 ◽  
Author(s):  
Qi Wu ◽  
Jianmin Yang ◽  
Haining Lu ◽  
Wenyue Lu ◽  
Lei Liu

Author(s):  
Stephan D. A. Hannot ◽  
Jort M. van Wijk

Deep ocean mining systems will have to operate often in harsh weather conditions with heavy sea states. A typical mining system consists of a Mining Support Vessel (MSV) with a Vertical Transport System (VTS) attached to it. The transport system is a pump pipeline system using centrifugal pumps. The heave motions of the ship are transferred to the pump system due to the riser-ship coupling. Ship motions thus will have a significant influence on the internal flow in the VTS. In this paper, the influence of heave motions on the internal flow in the VTS for a typical mining system for Seafloor Massive Sulfide (SMS) deposits in Papua New Guinea is analyzed. Data on the wave climate in the PNG region is used to compute the ship motions of a coupled MSV-VTS. The ship motions then are translated into forces acting on the internal flow in order to compute fluctuations in the internal flow. In this way, the workability of the mining system with respect to the system’s production can be assessed. Based on a detailed analysis of the internal flow in relation to ship motions, the relevance of a coupled analysis for the design of VTS is made clear. This paper provides a method for performing such analyses.


Author(s):  
P. M. Vercruijsse ◽  
R. Lotman

Experience in the area of wet mining and the dredging industry learns that the excavation system cannot be seen separate from the slurry transportation system. These two key systems in a deep sea mining operation interrelate to such extend that they must be developed towards an integral solution. The nominal production, peak production and variability of these figures must match for all sub-systems in the overall mining system to optimize for mining efficiency; we call this the ‘game of capacities’. Also the configuration of the excavation and transport system has great consequences. For instance an important question is whether to place the first pump and its drive of the slurry transport system on the seafloor mining tool or in the riser system. The choices made impact amongst others on; the mining tool’s reach (and thus efficiency), the seafloor mining tool’s propulsion system and its geo-mechanical interaction, the slurry transport flow and pumping power requirements. This paper will discuss the several dependencies of the (producing) subsystems and important choices for configuration and their consequences regarding technology, capex, opex, reliability and maintainability.


1996 ◽  
Vol 41 (8) ◽  
pp. 1651-1668 ◽  
Author(s):  
Karline Soetaer ◽  
Peter M. J. Herman ◽  
Jack J. Middelburg

Author(s):  
Marcio Yamamoto ◽  
Shotaro Uto ◽  
Tomo Fujiwara ◽  
Motohiko Murai

In the past of the offshore petroleum production, each riser had conveyed the hydrocarbon production from a single vertical well; the riser’s internal flow rate was relatively low and only the internal fluid pressure was taking into account for the riser analysis. Other internal flow effects, such as internal fluid’s linear moment, and Coriollis effects, were neglected. However, the paradigm for petroleum production in ultra-deepwater is shifting nowadays. New technologies, such as horizontal wells, have increased the production rate from a single well. In addition, a subsea booster system can increase both pressure and flow rate of the riser’s conveyed fluid. Further, the Offshore Mining is rising as a new industry and will demand riser systems to convey, at high flow rates, the mineral ore’s slurry from the seafloor up to the production support vessel. In a previous experiment, the effects of the internal flow on a vertical riser were investigated. In the current experiment, the main objective is to investigate the effect of the internal flow on the dynamic response of a pipe in “jumper configuration”. The experiment was carried out at the Deep Sea Basin of the National Maritime Research Institute using a 10 m long flexible pipe. The actual “jumper” is a piece of flexible riser, in U-shaped configuration, that connects the main structure of “Self-Standing Hybrid Riser” to the production vessel. During the experiment, fresh water was pumped into the model by positive displacement pump; and an oscillator applies a harmonic vibration on one pipe’s end. Then the pipe’s dynamic response is measured by the Deep Sea Basin’s 3D Visual Measurement System. Results for different internal flows and oscillations are compared.


Author(s):  
Shaosong Zhang ◽  
Yongming Cheng ◽  
Yuanlang Cai ◽  
Ning He ◽  
Xiaolong Yang ◽  
...  

Abstract Steel Catenary Risers (SCRs) are widely used in deepwater and ultra-deepwater field developments. The dynamic strength of SCRs is a concern in terms of the global performance. The analysis results are quite scattered in many cases due to the nature of the irregular wave stochastic properties. The widely accepted approach to predict the riser dynamic response in the irregular seas is to run the multiple time domain simulations based on different random seeds. This paper will address the impacts on the predicted riser dynamic response due to the random seeds selection. The discussion is based on the independent engineering verification work for a production Semi project in South China Sea. The site specific irregular waves are usually defined by not only the wave spectrum, but also the properties of individual waves, such as maximum wave height and minimum wave trough, which have big impacts on the riser extreme response. The code recommended approach for irregular wave simulation is based on the linear wave theory, which can ensure the match of the target wave spectrum, for example, Hs, Tp (or Tz), wave peakness for JONSWAP spectrum. But the variation of simulated individual wave properties to the specified value can be significant or there is no specified value to match. The simulated irregular waves based on linear theory is also a distortion to the real wave elevation time trace, such as the asymmetry of the wave crest and trough, especially for the tropical cyclone sea states. Some riser response, such as the compression load at riser touch down zone, can be significantly impacted by the nonlinear nature of the waves and the variation to the target individual wave properties. This paper will discuss the random wave simulation and its impacts on riser dynamic response. A SCR strength design case is presented for illustration in this paper. Key parameters are identified to show the correlation with the SCR dynamic response. The conclusion is finally drawn from the work presented in this paper.


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