Design And Performance Study Of A New Type Of Internal Blowout Preventer

With the rapid development of the economy,human demand for oil and gas resources is growing.With the further exploitation of oil and gas resources,some oil and gas wells gradually entered the late stage of mining.The difficulty of exploration and mining is gradually increasing,and the requirements for the safety of well control equipment are gradually increasing.This paper investigates several inner blowout prevention tools commonly used in today's drilling engineering,analyzes and summarizes their working principles and failure modes.On this basis,this paper proposes a new type of spin-in type inner blowout preventer,which has the characteristics of sensitive reaction,smooth and unobstructed flow passage,simple and reliable structure.This paper has carried out research work from the following aspects based on this structural scheme.(1)The upper and lower joints and the wall thickness of the spin-in type inner blowout preventer are designed and checked;The cone angle is designed from two aspects of statics and finite element simulation;The specific structural dimensions of the upper and lower seat are designed;The structural sealability was designed with verified according to the theory of sealing specific pressure;The dimensions of the steel ball and the spiral raceway are designed;From the theoretical check and finite element simulation,the strength of the valve body under different working conditions is checked,and the maximum equivalent stress at the positioning ring of the upper valve seat is obtained.It is found that the tensile load has the greatest effect on the strength of the valve body,the internal ballast load is the second,and the torsional load has the smallest effect.It provides a powerful theoretical reference for the strength design and production and manufacture of valve body.(2)Based on the erosion theory,the internal flow field of the spin-in type inner blowout preventer were simulated and analyzed.The analysis shows that the easy-erosion wear parts of the inner blowout preventer are at the edge of the valve flap and the inner wall of the lower joint,and the number of valve seat runners is optimized according to the erosion effect.Secondly,according to the rheological properties of the drilling fluid used in the field,the pseudoplastic fluid in the power law fluid is selected as the research object.The relationship between fluid rheology and erosion characteristics was studied by using the consistency coefficient and the fluidity index as a single variable.It is found that with the increase of the consistency coefficient or the increase of the fluidity index,the erosion effect of the fluid on the inner blowout preventer is decreasing.This conclusion provides a theoretical basis for guiding the practical application of the project.And through the literature research,the intensive solution to the easy-erosion parts is proposed.(3)Using Ls-dyna and other software,the impact of the lower seat on the upper seat is simulated and analyzed when the new internal blowout prevention tool bears the highest pressure 70MPa under the condition of blowout.The results show that the impact force of the inner blowout preventer does not yield deformation to the structural strength under the highest pressure,which meets the requirements of use.Also found some problems:? Because the spiral raceway on the valve body plays a guiding role in the rising process of the lower valve seat,the one side of the valve has always suffered a large pressing stress,and the wear on the side will be faster in the long run.?The steel ball is less stressed during the ascending process of the lower seat,and mainly plays a guiding role.However,due to the rebound of the lower ball seat after the first impact,the steel ball and the spiral raceway generate instantaneous large shear stress.A large impact on the steel ball will reduce its service life.