Papers by Keyword: Drill Pipe

Abstract: In recent years, with the rapid development of modern petroleum industry, some conventional oil country tubular goods (OCTGs) have been unable to meet the requirements of ultra-deep oil and gas drilling and production. Titanium alloy OCTGs showed broad application prospects due to its high specific strength, Low elastic modulus and strong CO₂+H₂S+Cl^- corrosion resistance. However, large-scale applications of titanium alloy OCTGs were seldom reported, which is mainly attributed to the lack of anti-corrosive resistance and mechanical performance of titanium alloy OCTGs in the working conditions. In the present work, the research progress on properties and application of titanium alloy OCTGs were reviewed. The resistance to uniform corrosion, stress corrosion cracking, pit and crevice corrosion, mechanical properties of the titanium alloy OCTGs in air and downhole corrosion media were comprehensively discussed. Application status and prospect of titanium alloy OCTGs in oil and gas exploration were also summarized.

Abstract: Drill string failure is a prevalent and costly problem to the oil and gas industry. This paper proposes a method for remaining useful life prediction of drill string components subjected to fatigue under combined loadings, namely axial stress, bending moment, and torsion. To accomplish this, fuzzy systems are used to model the dimensionless stress intensity factor, β of different API graded drill pipes. Based on the gathered database of the dimensionless stress intensity factor for various crack types, the parameter is numerically estimated using Adaptive Neuro-Fuzzy Inference System in MATLAB. The fuzzy model is then incorporated into the available crack growth models (Paris Law & Walker’s Law) to quantitatively evaluate the number of cycles as the crack propagates from its initial size to its critical size. The nonlinear crack propagation model is solved by Euler’s Method. Finally, a parametric study is performed in order to identify the influence of load magnitudes, the variation of loadings, crack shape, and geometrical parameters on the fatigue life. The ANFIS model developed has a mean square error (MSE) of 8.3e-4, root mean square error (RMSE) of 0.0288 and R-squared error of 0.9807, thus indicating the model is highly reliable. The increase in the magnitude of stress, mean stress ratio (R) and environmental constants reduces the number of cycles to failure, thus indicating shorter RUL.

Abstract: Fatigue life of drill pipe is studied systematically based on reliability analysis. Calculation results show that bending and tensile stress in drill pipe body is significantly greater than that in the tool joint during drilling process. Drill pipe body’s fatigue strength is about 500MPa under the condition that the stress ratio is -1. The fatigue strength of tool joint is about 360MPa under the condition that the average tensile stress is 496MPa. The fatigue fracture position of drill pipe is concentrated on pipe body, and most fatigue cracks originate from pipe’s outer surface. Compared with material fatigue life, the fatigue life of whole drill pipe is significantly lower. Under the condition that the confidence level is 95% and deviation is 5%, drill pipe’s fatigue life distribution is normal distribution while the stress amplitude is 660MPa, 620MPa, 580MPa and 540MPa respectively. With the decreasing of stress amplitude, the peak of logarithmic fatigue life’ probability density distribution curve decreases gradually, and its dispersion increases gradually. Drill pipe’s fatigue life prediction equations whose reliability are 50%, 90%, 99% and 99.9% are calculated separately.

Abstract: Computer simulation of expansion of tubes by extrusion was performed. Deflected mode analysis was described. Influence of collar taper angle, radius of rounding in interface of conical and cylindrical sections of mandrel, geometry of blank on deformation behavior of tube during expansion was determined.

Abstract: In order to overcome the shortcomings of the traditional drilling rig drilling parameters cable transmission technology for high cost and high fault, a drill pipe, which functions as the transmission medium is proposed, the sound waves as carrier of drilling parameter transmission method. The intelligent drill pipe based on the acoustic transmission technology has the advantages of reasonable design, low cost, convenient installation, which can effectively overcome the shortcomings of the past similar products using electromagnetic wave pulse low rate of signal transmission, the transmission distance near, cope with the wired data transmission mode of the high cost and high failure rate, meet the needs of the large-scale development of petroleum mining industry, series standardization, specialization and high grade direction, in order to provide technical support for marine resources detection.

Abstract: This paper attempts to explain the motion behaviour of the marine riser coupled to a drill string when the vortex induced vibration (VIV) is involved. Vibrations have been reported to have a major effect on the drilling performance, affecting the rate of penetration (ROP), causing severe damages to the drilling tools and also reduces the efficiency of the drilling process. There are two major components of drilling tools that are subjected to vibration, namely the marine riser and the drilling string. Analysis of vibration in the marine riser and drill string are two topical areas that have individually received considerable attention by researchers in the past. Though these two subjects are interrelated, borne by the fact that the marine riser encapsulates and protects the drill pipe, there have been few attempts to investigate them together as a unity. Due to the complexities of the models, simplified assumptions were made in order to undertake the investigation by using staggered approach. The results were compared with the experimental and simulation data from the open literature. It was found that the maximum displacement with negative damping occurs at low frequency and rotation speed.

Abstract: The fractured drill pipe was investigated by means of non-destructive testing, chemical composition analysis, optical microscope, material property testing machine and SEM with EDS. The results showed that fracture of drill pipe body was hydrogen sulfide stress corrosion cracking. High strength, high hardness, and stress corrosion sensitivity of the drill pipe material were important reasons leading to failure.

Abstract: he macro fracture of broken drill pipe friction welded joints and characterizations of microstructure were performed by SEM and XRD, and tested its hardness. The results suggested that the large area of “gray leaf spot” (composition: Fe₃O₄) which is on friction welded joints is the main reason causing the drill pipe brittle fracture. In order to avoid excessive “gray leaf spot” defects during the friction welding, put forward practical recommendations.

Abstract: Abstract. The drill-pipe bending is a plastic with complex loads. The ratio for wall thickness to tube radius is out of the limitation of thin-walled shell. Contrary to general drill-pipe, the URRS is not elastic but plastic. Beam element cannot be used to URRS because the cross-section is changed during bending. Contrary to buckling theory, the sizes of two bending axes changed independently by using of 3D FEM simulation, and the secondary bending axis is based on loads degree whether it expands or contracts. The simulation extends the deformation theory of drill-pipe bending. The deformation of pipe cross-section is weakly dependent on the backpressure absolution, compared with the pressure difference between inner and outer. The FEM simulation well agrees with the experiments results.

Abstract: Magnetic flux leakage is one type of electromagnetic nondestructive testing (NDT) which is widely utilized in the testing the integrity of drill pipe in the field. In this paper, the 3D model of excitation unit is completely built and analyzed by ANSYS software. The magnetic field of drill pipe in the combination of full excitation device is showed by ANSYS software instead of the physic experiments which increases the efficiency tremendously and decreases the cost and achieves the anticipated desire. It is considered that this technique can provide the theoretical basis of drill pipe excitation device and the magnetic flux leakage testing of drill pipe.