Research On The Force Of Ultra-deep Casing And Casing Tools

With the development of Chinese Petroleum Industry,there are more and more difficult and deep oil in the remaining resources.Therefore,the development of deep well and ultra-deep well has been incorporated into the plan ahead of schedule.In ultra-deep drilling process,one of the most dangerous jobs is the casing.The main risks include an increase in the capacity of the drill rig caused by the length and weight of the casing string in the ultra-deep well,and the higher reliability,strength and rigidity requirements for the casing.At present the domestic ultra-deep well casing are not many success stories.Therefore,it is necessary to accurately calculate the force of the ultra-deep underground casing,check the safety of drilling rig,casing appliance,casing coupling.This article outline is the following:(1)The first section investigates the current status of the casing technology in the ultra-deep underground casing.Then,the development trends of ultra-deep well drilling rig,special deduction type of casing and casing appliance are presented.The calculation method of the maximum axial force for casing is verified by comparing with field data.The results demonstrate that the maximum axial force is equal to the sum of buoyant weight and the impact load,which is more suitable than the original one considering the floating weight of the casing.(2)In section 2,the related parameters of the ZJ70/4500 and ZJ90/6750 type ultra-deep well drilling are introduced in detail,respectively.The power of the winch,the load reserve coefficient of the hook and the casing capacity are also analyzed.Moreover,the effect of drilling fluid densities,sizes and thicknesses of the casing on the theoretic depths have been discussed.(3)In the last section,the current status of under-casing tools commonly used in ultra-deep wells in China is investigated.The types and parameters of commonly used elevators,rings,pneumatic casing chucks and casing power tongs are listed respectively.Then the finite element method is utilized to establish the simplified finite element model of the special thread,elevator,rings and pneumatic chucks respectively,and the grids are partitioned by the corresponding unit types and loaded.Finally,according to the result of the solution,the safety of using special thread,elevator,rings and pneumatic casing chucks were respectively determined,and the recommendations for field usage were given.