Zeng Ji

Study on Weight Control Methods of Single Point Mooring System of FPSO in Deepwater

This paper applies 3D potential theory and non-linear time domain coupled analysis method to analyze motion response of FPSO and dynamic response of mooring line of single mooring system. In addition, respectively to calculate mooring line tension of tension type and composite mooring line type and added buoy in mooring line. There the paper analyze different mooring lines to affect on the weight of single point mooring system of deepwater FPSO. Which expects to provide a theoretical basis for single point mooring system design and weight control.Copyright

The Study on Hull Structure Strength Analysis and Opening Calculation of CJ46 Jack-Up Drilling Unit

The structural strength of jack-up units is the key issues in the design of ship and ocean engineering structures. Based on ABS MODU, the yield strength of CJ46 self-elevating drilling platform main hull structure is checked. Firstly, the environmental loads (wind, wave and flow) in three loading conditions which are required by specification are calculated by using GeniE (DNV). Then the 3D finite element model of main hull structure is established. The yield strength is checked and the results shown the large stress areas are leg well, jackcase which is connected with the leg and bulkhead which is main support structure under the cantilever sliding device, while the results meet the requirements of ABS MODU. Finally, the influence of the openings located in main longitudinal bulkheads are evaluated, meanwhile the main longitudinal bulkheads under skidding box need particular concern.Copyright

The Research on the Fatigue Analysis of the Jack-Up’s Leg Based on SESAM Software

In this paper, a fatigue assessment based on spectrum analysis for Jack-up’s legs is performed by adopting stochastic method for three water depths using DNV/SESAM. Firstly, force transfer function is determined by the DNV/WAJAC for each wave direction considered. Secondly, members end stresses are computed by the DNV/SESTRA. Then SCF (stress concentration factors), DAF (dynamic amplification factor) and P-delat effects are applied in the stress range calculations. Finally, the cumulative fatigue damage of unidirectional waves to the critical connections is determined by the DNV/FRAMEWORK. The critical connections at the chords and the braces are selected and reviewed for fatigue life calculation. The results show that the legs have fatigue lives exceeding the expected design life of Jack-Up Drilling Unit of twenty-five (25) years and meet ABS requirement.© 2015 ASME

The Effect on Hydrodynamic Performance of Multi-Point Moored FPSO in Swell Condition of West Africa

The paper respectively study the effect on hydrodynamic performances of FPSO under only swell and only wind-sea based on 3D potential theory and non-linear time domain coupled analysis method. The analysis results indicated that swell and wind-sea act as the same role in low frequency response. Swell is key factor in wave frequency response. Incident angle of swell evidently effects on mooring line tension. So it is necessary that we should consider swell and wind-sea at the same time in studying the hydrodynamic performances of FPSO in West Africa. The study offered an important reference on FPSO hydrodynamic performances analysis in West Africa.Copyright

Derrick Structure Design and Finite Element Analysis of CPOE-16 Jack-Up

Drilling derrick, acting as one of the most important structures in Jack-up Rig, is designed to accommodate drilling machines like top drive, utility winches and so on. According to the requirement of API Spec. 4F, the accuracy of the standard design ratings of each structure shall be tested by proof loading or a computer model such as Finite Element Analysis. Therefore, this thesis utilizes Finite Element Analysis software, ANSYS, to verify the design of derrick structure for CPOE-16 (No. 16 jack-up rig for China National Petroleum Offshore Engineering) jack-up based on API 4F [1], AISC Allowable Stress Design [2] and ABS MODU rules [3]. The permanent loads, live loads (variable functional loads), environmental loads (mainly wind loads) and dynamic loads will be included in the total derrick structure strength calculation with the purpose of verifying the security and reliability in all required conditions by rules and regulations. Furthermore, on the basis of analytical result, the authors focused on the adverse beams provide an optimization solution by improving the section of beams for reducing the distortion, and ultimately deal with the distorted problem.© 2014 ASME