The Design And Evalution Of New Type 374.65mm BC Casing Joint In Air Drilling

With the development of oil exploration and drilling,oil mining conditions get increasingly severe.The common API standard casing cannot completely meet the demand of Tarim Oil Field production,because most of the wells belong to high temperature,high pressure,and super deep wells,as the same time,there are complex stratigraphic sections,such as layer of gravel,creep stratum and so on.Through the research,we find that the 374.65 mm BC casing with high collapse strength is used during the air drilling.But the joint adopts the 365.13mm×13.88 mm BC casing,the meaning is that the casing thickness increases from 13.88 mm to 18.65 mm.Although this method solves the casing collapsing performance,the joint is easy to damage.This paper designs a new type of 374.65 mm BC casing,and evaluates its performance.According to the API standard,we analyze the geometry parameters of buttress thread,design the basic tooth type in accordance with 374.65 mm casing body.Afterwards,according to the theoretical calculation and analysis,we have designed the new type of 374.65mm×18.65 mm BC casing which meets the thread structure size.Theoretically calculate and analyse the physical performance which include collapse pressure,pipe body yield strength,internal pressure resistance and joint strength,as the same time,this paper uses Microsoft Visual Studio software to write the casing physical performance calculation program and to generate software interface.This paper sees the joint of the new type BC casing as research object,a two-dimensional finite element model is established,than uses ANSYS software to analyze the stress distribution of casing thread.Based on some of the assumption,four different working conditions are established,the mechanical properties of the new type of 374.65mm×18.65 mm BC casing joint are analyzed.The experimental results verify the feasibility of this model and the safety of the new type casing.According to the well structure of Tarim Oil Field,the size suitability of new type BC casing is analyzed.From the aspects of theory and experiment,the new type of 374.65 mm × 18.65 mm BC casing meets the existing well structure and working conditions.