Numerical Analysis On Bearing Capacity Of JJ225/41-K Type Derrick Under Wind Load

Derricks are the main bearing structures in the process of petroleum exploration and extraction. These structures suffer the severe environment and working conditions. Along with the development of offshore oil industry, close attention is paid to the safety of derrick under wind load. The present thesis focuses on the analysis of mechanical properties of wind load on JJ225/41-K type derrick. Based on this analysis, evaluation on the safety of derrick is realized. It represents the important significance for the wind-resistant and safely production in oil field.In the thesis, state and arts of wind loads on structure were reviewed. By the reasonable assumption, the mechanical model for numerical computation of derrick structure is established. The commercial software FLUENT is adopted to analyze the effects of wind load on JJ225/41-K type derrick in flow field. This software is well adapted to the analysis of air flow. First, the members of square cross section in equal edges are used to replace the members of H section. Meanwhile, the shape coefficients of square and H section in load standard were verified. The effect of diagonal bracing remove on computation results has been considered.. The simulation results have been compared with the United States and Chinese specifications on wind pressure. Analysis is made to justify the results. The flow field around derrick under different wind speed and direction. The wind pressure and pressure variation on derrick is investigated, too..Finite element model for JJ225/41-K type derrick structure has been established, FEM software ANASYS is used to analyze the stress and deformation of derrick under several typical kinds of the wind load conditions. The maximum stress and deformation under each kind of working condition are determined. Then the weak positions in structure are found by the static analysis. Meanwhile, the effects of drilling pipe stacking on stress and deformation of the derrick structure are examined. The safety assessment was carried out based on the theory of strength and stability. The results show that the strength at lower segments of the derrick legs in opening direction of the derrick may be insufficient under hurricane. Low safety factor appears. The maximum displacement is close to the acceptable limit. Damage of the structure may be induced by instability. The results of computation and corresponded analysis represent important significance for installation of drilling equipment working in the area of corresponded wind condition.