Study On Test And Assessment Specification Of Wellhead Drilling String Stress Concentration Based On Magnetic Memory Method

With the development of tarim oilfield exploration to complicated geological conditions,exploitation accidents caused by the early failure of drilling tools are becoming more and more serious.The early detection and diagnosis of the drilling string stress concentration in the tripping process can avoid injuries drilling tools into a well.The fatigue damage condition of existing drilling tools is acquired.The combined use of drilling tools is optimized.It is a great significance to prevent the occurrence of fatigue fracture.According to the need of drilling site,this thesis mainly analyzes the following contents:(1)The failure risk assessment method of drilling tools used in tarim oilfield is proposed,the risk of failure of drilling string in different blocks is got.It is difficult to monitor drilling string thread and tube body online,In order to solve this problem,the test plans using magnetic memory method is proposed for well drilling string in the tripping process.(2)According to the testing plan and scheme,the magnetic memory test of drilling string,which can be two types: tracing and working condition,are carried out.The effect of magnetic memory testing using in the drilling string stress concentration is verified.The change and distribution of magnetic memory characteristic parameters regulation about drill string with using times in different blocks are got.(3)According to the testing results,an evaluation method of parameter and waveform analysis about drilling string thread and tube body stress concentration state is proposed.Based on magnetic memory characteristic parameters of different levels drilling tools,A criterion of evaluating the stress concentration for the drilling string is set.The ZG301 H well drilling tools are emblematically evaluated.(4)Based on the testing and assessment for stress concentration of the drilling string by magnetic memory method,the research on drilling tool applies and management specification is carried out.A using rules of wellhead drilling tool is suggested.The management method of drilling tools between drilling site and base is perfected.