The Analysis Of Strength And Safety Reliability For Complex Deep Well Casing String

In recent years,global demand for oil that is growing faster than the supply,which led to oil production turn into complicated.High temperature,high pressure,high formation and so on,which happen in complex deep well formation,have become the main influence factors of casing strength.The oil production environment have become more and more complex,which made down hole casing damage easily.With increasing of the number of deep well,casing damage has become a problem,which can not be allowed to ignore.In this paper,I have referred to the related literature about casing damage,analyzed the failure modes and force distribution of casing in,and have summarized the failure mode of casing and calculation formula of casing by load,which is under different conditions.In addition,based on the theory of elastic mechanics knowledge,by using the ANSYS finite element software,firstly,I have studied the influence factors of casing strength,which is under complex deep well,got nephograms of well bore temperature field distribution under high temperature and the relationship between casing bend curvature and casing collapsing strength;Secondly,based on the well bore integrity,I have analyzed the influence relation between wear depth of casing wear,horizontal ground stress and stress intensity of casing,and carried on the finite element simulation,which is based on how the degree and position of missing of cement ring affect on complete casing stress intensity;Finally,based on the theory of reliability method,combined the Monte-Carlo random simulation of ANSYS finite element software,I have analyzed the casing reliability.By judging the sensitivity of how the random input variables for casing pipe affect on casing reliability,you can know the influence of the random input variables on the casing reliability,which has certain reference significance for the deep well casing string strength reliability analysis in the future.