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Introduction Petroleum data analytics is a solid engineering application of data science in petroleum-engineering-related problems. The engineering application of data science is defined as the use of artificial intelligence and machine learning to model physical phenomena purely based on facts (e.g., field measurements and data). The main objective of this technology is the complete avoidance of assumptions, simplifications, preconceived notions, and biases. One of the major characteristics of petroleum data analytics is its incorporation of explainable artificial intelligence (XAI). While using actual field measurements as the main building blocks of modeling physical phenomena, petroleum data analytics incorporates several types of machine-learning algorithms, including artificial neural networks, fuzzy set theory, and evolutionary computing.
Fang, Zhuo (Transport planning and Research Institute, Ministry of Transport) | Sun, Lu (Transport planning and Research Institute, Ministry of Transport) | Zang, Zhipeng (State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University) | Tian, Yinghui (State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University) | Wang, Rong (China Harbour Engineering Company Limited) | Tao, Ran (China Harbour Engineering Company Limited)
In this study, a series of numerical simulations of wave forces on a perforated comb-type breakwater at water levels below the bottom of the superstructure were conducted based on a 3D numerical wave flume. The influences of configuration parameters, such as the location of the side plate, the height of perforation below the side plate, and wave parameters, including the wave period, the wave height and water depth, on the horizontal wave force were investigated and an empirical formula for wave force coefficient was proposed. The critical conditions for the occurrence of impulsive wave forces were also discussed.
The comb-type breakwater (CTB) is a new type of coastal protection structure that has been proposed and investigated in recent years (e.g., Dong et al., 2003; Fang et al., 2011; Zang et al., 2018; Wang et al., 2019) as shown in Fig. 1(a). The CTB has evolved from the conventional caisson breakwater, with part of the main caisson being replaced by a thin side plate, and the CTB looks like a comb in plan view (see Fig. 1b). In application, the CTB is composed of a series of units (in Fig. 1a, three units are shown), and each unit consists of three portions: a main caisson, two side plates and a superstructure, as shown in Fig. 1c. Compared with the traditional caisson breakwater, its material consumption is relatively small and thus has a smaller base area, reducing the requirement of the foundation bearing capacity (Niu et al., 2001). Moreover, perforation can be designed below the side plates (see Fig. 1a), which allows passing of the current and keeping water exchange. This perforation can significantly reduce the flow velocity near the breakwater entrance, guaranteeing navigation safety, as well as keeping water clear in the harbour (Wang et al., 2019). At present, a perforated CTB has been successfully applied in the port area of Dayao Bay, Dalian, China. There are wider application prospects of this type of structure in terms of wave absorption, deep-water adaptability, water exchange and material savings.
A stiff-string torque & drag & buckling model has been coupled to a 3D meshed casing wear calculation to model the effect of drilling operations on casing wall thickness reduction. Results of the numeric simulation are compared to MFCL for field cases and provide an understanding of possible well integrity issues during the well life cycle. A Hall wear model and 3D rigid stiff string model is used to predict casing wear. Using Wear Factor Coefficients obtained for several hard-banding, casing grade and mud-types, the process was tested against numerous field cases. For each field case, a history of drill string runs were modelled and filtered into operations in which the drill string rotates such as Drilling, Reaming, Back reaming and ROB. Initially, the calliper log was not analysed to ensure the results are non-biased using experimentally found Wear Factors. In a second phase, the Wear Factors were calibrated against the measured calliper log. This paper provides a methodology that was used to successfully quantify the effect of casing wear against numerous field cases. The 3D orientation of the casing wear was found from an un-calibrated MFCL. After calibration of the new Wear Factor, the casing wear can be predicted before and after well construction. When used as a post analysis tool, the methodology helps determine if casing wear was a root cause of loss of well integrity. This process also helps reduce the uncertainty in Wear factor as a major unknow in the contact force, is now properly modelled. When used in a post analysis process, the results where quantitative (groove depth vs 3D orientation) but also qualitative, providing a post-mortem description of the state of the well to operation's personnel. The methodology presented here can be used to both predict excessive casing wear and determine if excessing casing wear was a cause of failure. It can be used to help determine the state of well for workover operations or plug and abandonment operations. Accurate casing wear prediction at planning stage allows the anticipation of costly but fit for purpose mitigation means & measures.
ABSTRACT Tidal energy is renewable and also highly predictable; however, access for maintenance operations on devices is limited and very expensive. The immense forces impacting on tidal current turbines (TCT) may cause component failures which have the potential to result in loss of power generation. Fault tolerant control offers the potential for the TCT to continue operating in the event of failures in components such as tidal velocity sensors. This paper presents a fault tolerant control methodology for maximum power point tracking in the event of a tidal velocity sensor failure with simulation results demonstrating the capability of the technique. INTRODUCTION Renewable energy is making a greater contribution than ever in supplying global energy demand. Due to the predictability and capacity of the tidal currents, the position of tidal energy in the renewable energy mix has significantly increased with tidal current energy starting to make contribution (Benbouzid et al., 2011). Tidal current turbines capture energy from tidal currents using technology which is very similar to the wind turbine capture of energy from moving air (Clarke et al., 2006). The water density is significantly higher than that of the air, so tidal current turbines operate at lower speeds but higher torques compared with wind turbines. In tidal current turbine systems, there is the potential for certain faults to cause failure of the whole system because the devices are subjected to large forces from strong tidal currents. Such failures would generally require retrieval of the device to carry out maintenance on shore but the time window to access a device is limited both by the weather and the tidal currents themselves (Sousounis et al., 2016). In order to reduce the maintenance time and increase the energy capture, fault tolerant control is essential in tidal current turbine systems. Fig. 1 shows the percentage breakdown of failures that occurred during the period 2000-2004 in Swedish wind power plants, from this figure it can be seen that the sensor faults accounted for 14.1%, faults in electric systems 17.5% and faults in control system 12.9%. These are the most common faults that might occur in the electrical side of the system (Amirat et al., 2009). The electrical control system of a tidal current turbine is sufficiently similar to that of the wind turbine for the fault data of wind turbines to be considered as a reference for tidal current turbines.
Lu, Ye (China Ship Scientific Research Center) | Ni, Xinyun (China Ship Scientific Research Center) | Zhou, Ye (China Ship Scientific Research Center) | Zhang, Hua (China Ship Scientific Research Center) | Ding, Jun (China Ship Scientific Research Center)
ABSTRACT A large amount of supplies, such as food, water, fuel, etc., were necessary in the development of oil and gas resources in the deep sea. Due to the long distances away from the land, the economic and efficiency of transportation were very low. Therefore, large-scale support platforms served for the development of oil and gas resources were designed to meet the comprehensive functions of living, medical security, supplies transferring, storage and replenishment. In this paper, the structural safety of the oil and gas resources development support platform had been successfully and efficiently evaluated by hydroelastic analysis during the design phase. INTRODUCTION Nowadays, while evaluating the motions and responses of floating bodies such as the commercial ships and ocean structures in waves, the most widely method used was the three-dimensional (3D) potential flow theory. On the one hand, it had an efficient solution speed and accuracy that can be accepted by engineering applications. On the other hand, the theory of two-dimensional (2D) and the 3D potential flow could not only be suitable for the thin-ship analysis, but also be fully available for fat-ship and marine engineering structures such as oil and gas resources development support platform. The general 3D potential flow theory assumes that the floating body was a rigid body, and the actual floating body was mostly a steel floating body, which belongs to the elastic structures. In the above assumption, Wu (1984) and Price (1985) proposed a generalised fluidstructure interface condition, and considered the floating body as an elastic body based on the 3D potential flow theory. According to the modal superposition method, the interaction with inertial force, hydrodynamic force and elastic force was studied. A 3D linear hydroelastic theory for the analysis of the dynamic response of any 3D deformable body traveling in waves or under water subjected to internal and external excitation was formed, which more accurately considers the relationship between fluid and floating structure.
ABSTRACT The dynamic response of wharf mooring ship induced by passing ship was conducted based on computational fluid dynamic method (CFD). The three-dimensional viscous flow between mooring ship and passing ship was simulated by solving the Reynolds Averaged Navier–Stokes (RANS) equations and shear stress transport (SST) k–ω turbulence model. The motions of ship were predicted by solving the equations of motion of a rigid body, and the overset grid method was used in the simulations. The mooring rope forces were obtained by solving catenary coupling equations. The method was applied to the simulations of motions for a carrier model mooring at the dock, and the simulation results were examined by the comparisons with experiment results, which demonstrate the ability of the present method to compute hydrodynamic force of mooring ship. On this basis, the hydrodynamic force and moment acting on the moored ship was investigated, the effects of passing ship speed and separation distance were illustrated. The conclusions of this paper can provide the reference for setting the restrict speed in port area, and ensure safety of wharf moored ship. INTRODUCTION Ship wave will be enhanced by the reflection of dock when ship entering or leaving port. The large amplitude ship wave may arouse wharf moored ship significant motion, which make the shipboard operation become difficult, and affect the ship collide the wharf, even cause mooring facility broken accidents in some extreme cases. Therefore, it's essential to study hydrodynamic interaction between wharf moored ship and passing ship to ensure safety. The influence of passing ship on moored ship is very complex, since it involves the problems of the evolution of ship waves and the ship's six degree of freedom motion with mooring cables. Some researches focus on the physical model test and empirical formula of the hydrodynamic force of mooring ships. Remery (1974) conducted a series model tests, and the hydrodynamic force under different speeds and transverse spacing acting on mooring ships were considered. Flory (2002) proposed an empirical formula to calculate the hydrodynamic forces between the passing ships and mooring ships. Kriebel (2007) conducted model experiments and developed empirical equations based on the measured forces and moments between the passing vessel and the moored vessel. Duffy and Renilson (2011) presented some results of hydrodynamic interaction between a berthed ship and a passing ship from model scale experiments. In recent research, some numerical studies were adopted for mooring analysis. Pinkster (2011) investigated passing vessel forces on the moored vessel using potential flow theory based on panel method using non-deforming free surface assuming the effects of surface waves on forces are negligible. Yuan Zhiming et al. (2015) proposed an uncoupled method using 3-D Rankine source potential flow theory to study the ship–ship interactions in overtaking operations in shallow water. Wang zhihong et al. (2014) made a numerical analysis on the hydrodynamic interaction between passing ships and berthing ships by using commercial software AYSYS Fluent. V. Nandhini et al. (2019) made a detailed parametric study by using commercial software Star CCM+, and provided a proper insight into the effect of full hull forms of various displacements on the passing vessel forces.
Lin, Xiang (College of Harbor, Coastal and Offshore Engineering, Hohai University / the State Key Laboratory of Satellite Ocean Environment Dynamics (Second Institute of Oceanography, SOA)) | Yang, Bo (Power China Hubei Electric Engineering Co. Ltd.) | Chen, Jun (College of Harbor, Coastal and Offshore Engineering, Hohai University)
ABSTRACT A tide-surge coupling model based on the Princeton ocean model (POM) was established to study the features of a storm surge caused by Typhoon Saomai. The calculation area of the model contains Fujian, Zhejiang, and Jiangsu provinces. Processes of the storm surge at nine stations along the coast from southern Zhejiang Province to northern Fujian Province were calculated by the model. The results showed that the storm surge variation curves at the nine stations can be classified as three types: the standard type, fluctuation type, and stochastic type. Standard curves generally occurred at stations that had the shortest distance from the typhoon landing site; fluctuation curves occurred at stations at a distance from the landing site; and stochastic curves occurred near the edge of the area affected by the typhoon. The Aojiang Station had the storm surge peak value (4.01m), which was caused by various factors, such as the location of the typhoon landing point, special topography and the interaction between the storm surge and tide. INTRODUCTION Fujian coastal areas are often subjected to typhoon storm surges in summer and autumn every year for its special geographic position and climate conditions. With the increase of global temperature, occurrence frequency of super typhoon has dramatically increased in the ten years. In 2006, "SaoMai" typhoon hit Fujian and Zhejiang province, which was the worst typhoon to impact China in 60 years. It brought catastrophic disaster to Chinese eastern coastal areas, causing a direct economic loss of 19.65 billion Yuan (Guo, 2011). Typhoon 0608("SaoMai") was formed east of Guam on August 5, 2006. It became severe tropical storm on 7th and violent typhoon on 9th, which landed in Cangnan city in Zhejiang province at 5:25 pm, August 10. The typhoon had a maximum wind speed (about 60 m/s) and a minimum pressure (about 920 hpa) in the center (Lu, et al., 2007).
Dou, Haoyu (MOE Key Laboratory of Petroleum Engineering, China University of Petroleum) | Dong, Xuelin (MOE Key Laboratory of Petroleum Engineering, China University of Petroleum) | Gao, Deli (MOE Key Laboratory of Petroleum Engineering, China University of Petroleum)
ABSTRACT Maintaining cement integrity is of great importance for ensuring zonal isolation and preventing interzonal cross-flow. In horizontal and highly-deviated wells, the cementing quality and casing centricity are barely ensured. Then casing eccentricity could cause issues in cement integrity. During the oil production and stimulation, radial cracks in the cement or interfacial cracks at the casing-cement and the cement-formation interfaces may create due to temperature and pressure perturbations. This paper presents a 2D finite element model consisted of casing-cement-stratum to analyze the stress distribution in an eccentric cement sheath. Using contour integral methods, the model estimates the stress intensity factor at a radial crack tip in cement. A parametric study investigates the influence of cement's mechanical properties, loading conditions, casing eccentricity, and the length and position of the radial crack on crack propagation. The result reveals that casing eccentricity could make a remarkable effect on the stress intensity factor of the radial crack. Heavier casing eccentricities would increase the stress intensity factor by over 0.447 N·m. It suggests that optimizing cement's mechanical properties or centralizing the casing would improve cement integrity under geological conditions. The current model provides guidelines for evaluating cement integrity with casing eccentricities. 1. INTRODUCTION Maintaining wellbore integrity is crucial to guarantee the safety and production efficiency of hydrocarbon wells over their life cycle. The main function of a cement sheath is to provide stratum zonal isolation (prevent fluid cross-flow from different zones), support the casing, and protect it from corrosion, etc. In horizontal and highly-deviated wells, the cementing quality and casing centricity are barely ensured, which makes cement integrity particularly vulnerable. Failure of wellbore integrity will reduce production efficiency and even cause serious environmental pollution problems. Hence, ensuring the mechanical integrity of the eccentric cement sheath is critical to wellbore integrity. A large number of analytical methods and numerical simulations have carried out to calculate the stress distribution in a cement sheath (Ravi et al., 2002, Gray et al., 2009, Li and Nygaard, 2017.). When the stress in the cement sheath exceeds the safety threshold, various modes of failure may occur such as radial cracking, interfacial debonding, disking and compressive shear failure (Goodwin and Crook, 1992, Boukhelifa et al., 2004; Bois et al. 2011.). The material strength criterion, used to determine the critical condition of cement failure, is suitable for characterizing material damage without any defect. However, a cement sheath inevitably contains initial small cracks during hydration or after setting. Such cracks make cement fail at far below the ultimate strength. Then the strength criterion is no longer applicable to predict these failure modes. Instead, Ulm et al. (2014) used fracture mechanics to predict radial crack propagation in a cement sheath. Dong X et al. (2019) used fracture mechanics to analyze the cement with radial cracking in HPHT wells. Choosing a reasonable failure criterion is remarkably significant for accurately predicting the failure of the cement sheath and establishing a reliable design model.
The extensive and systematic exploration and investigation of any open pit mine gives valuable data on geo-mechanical properties which can be integrated with the optimum slope design for achieving both stable and economically attractive mining. These assessments are important for all open pit mines such as those under planning and currently in operation.
In hard rock environments, rock mass classification systems are frequently used as the basis for evaluating slope stability conditions. One of the most prevalent methods is the calculation of Slope Mass Rating (SMR) based on RMR ratings. Important conditions to stability such as jointing characteristics and groundwater behaviour are underrepresented into the formulation of RMR and thereby in SMR. The aim of this manuscript is to provide a flexible and dynamic methodology to calculate SMR values based on local conditions affecting stability. A flexible modification is achieved by deriving weights, or degrees of importance, based on expert judgement and knowledge of specific conditions at the mine from back analysis and field investigations. Weights are consequently derived following the method of pairwise comparison encompassed into the analytical hierarchy process (AHP). Assessments of results based on the conditions observed in the open pit mine is provided in order to depict stability conditions and proficiency of the proposed method. Such integrated evaluation results are believed to be also helpful in assessing mining sequences and blasting for the optimum recovery without the compromise in stability and safety
Open pit mining excavates earth surface to reach deposits for extracting valuable ore. Planning of an open pit is a problem of determining the most profitable pit limit and the most economical mining sequence for a given mineralization (Steffen et al, 1970). During the extraction phase, the excavation sequence implies developing artificial slopes on which stability is a crucial factor both for safety and financial viability, which are critical components for risk management practices in slope stability, similarly as discussed by Panthi and Nilsen (2006). Therefore, the stability assessment of an open pit rock slope is a crucial requirement of the open pit mine not only during the feasibility and detail design studies but also throughout the operational life of the project. To accomplish this goal, the quality of the visible rock mass along the pit slope is evaluated using classification systems. These approaches (Q, RMR, GSI, among others) are commonly used to categorize rock mass conditions. Several rock mass classification systems have been proposed since early 60's, and of the most extensively adopted is the rock mass rating (RMR), initially developed by Bieniawski (1973, 1989). The RMR system utilizes a total of nine parameters to assess rock mass quality. The rating values of these parameters vary within a minimum and maximum. Minimum values accounts for conditions that are to be met in a weathered/deteriorated/highly fractured rock mass. The overall rating of the RMR index varies from minimum 8 to maximum 100.