Safety Analysis Of Mechanical Behavior Of Coiled Tubing

Coiled tubing has the characteristics of continuous tripping and low cost,which can replace conventional tubing for a variety of operations.In recent years,with the rapid development of coiled tubing technology,it has been widely used.However,due to the complexity of downhole operation conditions and the limitations of downhole operation analysis,coiled tubing lock,burst and collapse accidents occur frequently,resulting in low efficiency and serious economic losses of coiled tubing operation.Therefore,the research on the mechanical characteristics of coiled tubing operation and the safety analysis of coiled tubing operation have important guiding significance and great engineering value for the safe operation of coiled tubing on wellsite.This paper focuses on the mechanical safety characteristics and software architecture design criteria of coiled tubing operation,develops coiled tubing operation mechanical analysis module and coiled tubing operation mechanical safety analysis module,analyzes the influencing factors of coiled tubing operation running and safety,so as to improve the safety of coiled tubing operation.The main research contents of this paper are as follows:(1)Based on the study of fluid circulation characteristics and string buckling behavior in different well sections,the mechanical analysis of coiled tubing micro element section and bottom hole assembly is carried out.The actual situation such as whether to use fluid circulation and buckling is fully considered,and combined with the force of coiled tubing in the wellsite,the mechanical analysis module of coiled tubing operation is developed.And the mechanical analysis module of coiled tubing data in this paper is compared with the surface weight collection data of five operation wells.The results show that the trend of the calculated data of the mechanical analysis module of coiled tubing operation developed in this paper is consistent with the collected data of the surface weight of the field operation well,and the error is within the allowable range,which meets the needs of the field use.(2)In order to improve the accuracy of coiled tubing running operation,the operation data of 202H2-3 well is selected to analyze the running performance of coiled tubing from four aspects: end axial force,friction coefficient,type of circulating fluid and flow rate of circulating fluid.The relationship between bottom hole tension,weight on bit,friction coefficient,fluid flow rate,circulating fluid type and coiled tubing operation depth in coiled tubing running operation is obtained.The analysis results are in line with the actual operation situation of the wellsite.(3)In order to improve the safety of coiled tubing operation,this paper is based on the research of coiled tubing operation accident,the stress of coiled tubing is analyzed,the operation safety criteria are obtained,and the mechanical safety analysis module of coiled tubing operation is developed,the safety of coiled tubing operation is analyzed from the aspects of outer diameter and wall thickness of coiled tubing,yield strength of tubing and length of unsupported section,the case analysis shows that the yield strength of tubing is positively related to the safety performance of coiled tubing operation;the outer diameter of tubing is positively related to the tensile fracture resistance and collapse resistance of coiled tubing operation,but negatively related to the blast resistance and collapse resistance;the length of unsupported section is negatively related to the compressive yield caacity of coiled tubing at wellhead.