Global Strength Analysis Of Ultra Deepwater Drilling Riser

Recently, the demand of energy is on the increase, which promotes the developing processof ocean petroleum; meanwhile drilling riser is important to exploitation of the oceanpetroleum. The strength of drilling riser is a complex issue, it is related to the oceanenvironment, the soil and so on. It is still on the initial stage in our nation for the ultra deepwater drilling riser. A study on the global strength of ultra deep water drilling riser is carriedout in this thesis.Firstly, the drilling riser structure and its characteristics were illustrated. And based on theparticular ocean environment, the strength analysis of the3000m ultra deepwater drilling riserwas done on the operability condition; the bearing condition of the structure was studied aswell. The strength calibration was worked out according to API RP16Q.Secondly, the analysis of the items affect the design of the ultra deepwater drilling riser wasdone, the sensitivity analysis was done quantitatively or qualitatively, which includes the risergeometrical size, the buoyancy module size, density of the mud, positioning ability of thefloater and the met ocean condition, etc. Through the parameter sensitivity analysis, the effectof the design items on the strength of the riser can be known, and so as to guarantee the safetyoperation of the riser.Thirdly, the weak point analysis was done, and the mechanics characteristic of the drillingriser was studied on the extreme sea condition. It tells us that the weak points are located atthe top of the riser, location of the tensioner ring, and also the point of the flex joint. The weakpoints should be strengthened to assure the safety during operation. According to API RP16Q,drilling riser should be disconnected from LMRP or BOP on the extreme sea condition, inorder to avoid the damage caused by the extreme sea condition.Finally, the feasibility and necessity of the riser hang-off mode was elaborated. Thedifference and feature of the two hang-off modes was introduced, and the dynamic behaviorof the ultra deepwater drilling riser during soft and hard hang-off modes were studied detailedrespectively to have verified that soft hang-off is more safety and reliable.This thesis is a reference both theoretically and practically to the ultra deepwater drillingriser design, which is complicated and time consuming.