Working window analysis method of deepwater drilling riser based on system weakness and platform drift analysis:A case study on LS17-2 gas field
The deepwater drilling riser is a key equipment used to connect floating drilling platform with blowout preventer in deepwater drilling engineering.During service process,risers face complex and diverse marine environments,and undergo harsh operating loads,exhibiting complex mechanical behaviors.Therefore,their safe and reliable operation is a prerequisite for efficient development of deepwater oil and gas resources.In this paper,the independently developed deepwater LS17-2 gas field in the South China Sea is taken as a research object to understand the operation windows of deepwater drilling riser under different working conditions.Based on marine environment,floating platform and riser system,the riser system weakness analysis and the platform drift analysis are conducted,and the operation windows of riser under different working conditions are evaluated.On this basis,the riser configuration scheme is formulated,and the method for analyzing operation windows of deepwater drilling riser is developed,and has been successfully applied in Well LS17-2-A7.The following results are obtained.First,the conductor joint is the weakest point of the riser system.The upper and lower ball joint angles,the conductor stress,and the tensioner stroke are the main factors influencing the riser operation window.Second,under the working condition of normal drilling,the operation window is mainly limited by upper and lower ball joint angles,while under the connecting without drilling and the survivor conditions,it is mainly under the limitation of tensioner stroke and conductor joint capacity.Third,under the once-a-year current condition,the maximum offset of the platform is 1.6%and 3.2%of water depth when the wind speed is 33.4 m/s and 17.5 m/s,respectively.When the platform drifts by 24.0 m and 46.0 m,the platform emergency release(EDS)must be activated to ensure the platform drift distance not to exceed the maximum allowable drift distance.In conclusion,the proposed analysis method of operation window for deepwater drilling riser provides a technical support for the safe and efficient drilling in LS17-2 gas field,and is of great guidance significance for the design and application of deepwater drilling risers in the complex marine environment of the South China Sea.
LS17-2 gas fieldDeepwater drillingRiserOperation windowDrilling platform
万方数据
