Hollow Rod Hot Wash Process And Risk Analysis

The proportion of wax content of crude oil in our country is higher,which the wax content of crude oil are more than 20%,some even as high 40%?50%,which belongs to the heavy oil production countries.In order to solve the problem of oil wells in production due to the temperature and pressure lead to wax the tubing wall,which the hollow sucker rod hot wax cleared this technology came into being.In thermal well washing process,which the well depth of oil well is different.According to different well depth,which the hollow sucker rod is connected with a plurality of sucker rod string.In the hollow sucker rod string if there is a hollow sucker rod string failure,such as fault,then it will make the whole pumping rod can not work normally.In the field operation,the need for timely replacement of hollow sucker rod when the hollow sucker rod is broken.In the hot washing wax removing process,the hollow sucker rod will be subject to thermal influence of load coupling stress.Failure of hollow sucker rod will be under the action of stress should be in heat.Therefore the normal work of the hollow sucker rod is in favor of improving the yield of crude oil,which will reduce the rate of accidents,not only has more economic benefits but social benefits.According to the requirement of safety production of hollow sucker rod in the use of process safety and made corresponding research,including the main research Cdirection:(1)In order to guarantee the service life and according to the selection criteria of hollow sucker rod,sucker rod tensile stress,deformation,thread connection and other aspects of its strength check from the hollow and we determine the choice of hollow sucker rod model is in conformity with the requirements of production.(2)This paper deals with the calculation of suspension point load for hollow sucker rod pumping unit and the calculation of hollow sucker rod body and a joint stress and its strength.Simulations were carried out and the simulation by ANSYS software,get the hollow sucker rod to simulate tensile strength of cloud;the maximum stress value of the position is located in the hollow sucker rod top position,the stress from the top to the bottom of the numerical gradually become smaller;get equivalent thread analysis stress nephogram,the thread can be obtained by the stress at the two ends of the thread are obviously greater than the ends of stress;analysis of hollow sucker rod anti collapse strength,obtains the eccentric tubing wear distance affects the tubing wear strength relationship.(3)This paper analyzes the hollow sucker rod hot washing wax in the process of removing heat effect.Including the effects of hollow sucker rod heat washing of heat expansion and cold contraction effect and the thermal efficiency of the analysis and calculation,calculation of thermal deformation on the production condition and the solution can be taken.The establishment of the hollow rod hot washing wax removal model of temperature field,hollow pumping deformation under thermal stress calculation of the rod;ANSYS has been the use of hollow sucker rod internal diameter temperature curve along the path change;the hollow sucker rod internal radial,circumferential distribution curve of stress along the path,from the picture can be seen in the stress distribution along the circumferential and radial inner and outer diameter of hollow sucker rod heat.(4)Risk analysis of the sucker rod system is carried out by using the fault tree analysis..According to the common failure mode of the sucker rod system,the fault tree model of the hollow sucker rod system is established..Analysis of the established fault tree,qualitative analysis is mainly to identify the lead to the top event of the minimum cut sets,quantitative analysis combined with hollow sucker rod system each part failure probability statistics and calculate the probability importance degree.Through the analysis,it can be concluded that the minimum cut set is the minimum of each bottom event in the fault tree model,but the probability of each bottom event is different.The stress concentration failure,the stress concentration of the coupling,the failure of the eccentric wear,the thermal stress coupling failure have a great influence on the hollow sucker rod system.