Study On The Mechanism And Inspection Technics To The Transition Region Of Drilling Tool

Oil drill pipe is an important part of the drill string, during its using process, it often causes fatigue and corrosion cracks and other defects, if could not be detected in time, it will lead puncture or rupture accident and causes great economic losses. According to the International Association of Drilling Contractors Rod Failure statistical analysis, drill thickened area is prone to failure portion(70% to 80% occurred in thick band), it usually presents three forms: crack, puncture and breaking. There has been no detected agencies at home and abroad to detect HWDP transition zone, there is a great need to establish a complete and accurate inspection system to detect the transition zone of HWDP.In this paper,the analysis and research on ultrasonic phased array imaging techniques of the drill pipetransition zone and drill pipe transition zone ultrasonic phased array inspection,etc.Through theoretical calculatethe stress concentration factor of the drilling tool, estibalish the finite element model, process experiments and analysis of drill pipe corrosion defects,drill pipe transition zone corrosion ultrasonic phased array imaging technology and HWDP transition zone detection technology.In this paper, it begins with failure of drilling tools, the failure process and types,through theoretical calculatethe stress concentration factor of the drilling tool, estibalish the finite element model, and to analyze the boundary conditions, then calculate the tensile strength and torsional strength of the pipe, analyze the regularity between residual strength of corrosion pits and geometric dimensions changes. It can be known that in the corrosion pit,when the depth are same, the stress concentration factor of the bottom decreases with increasing of the width of the pits; when the width are same, the stress concentration factor of the bottomincreases with increasing of the width of the pits. Stress coefficient of pits is between 1.5 to 2.5. In order to study drill pipe transition zone corrosion ultrasonic phased array imaging technology,this paper introduces a calibration test block, to help analyze corrosion mapping, through experiments on the transition zone defects of the drill pipes,since the inner surface is not smooth and there is a relatively large curvature, there is a certain bias between mechanical processing with digital caliper measurements and ultrasonic measurements. If it neededthe actual detection in the calibration step, the dimensions,materials of the calibration workpiece must be the same as the atual workpeice, and it required a relatively smooth surface. During the research on HWDP transition zone detection,This paper through make the development of the general idea, research HWDP transitionzone laterally, circumferentially detection technology, and analyze the applicability of magnetic particle testing. During the research on detection of drill pipe transition zone, select the appropriate probe, such as in transverse flaw detection, select 2.5P9 × 9 K2 probe and5P9 × 9 K1 probe; such as in circumferential flaw detection, select 2.5P9 × 9K1 probe, the gain is 61.9 dB, through comparative experiment shows that during the circumferential cylindrical surface probe, the arc length L> horizontal distance l, the depth H <d, the result increases with the increasing of d. During the analysis of field flaw detection, select coil longitudinal magnetization method as both ends of drill transition zone magnetic detection mode.