Drill Pipe Steel Research Articles

Study on S-N Curve and Fatigue Limit of Drill Pipe in Offshore Short-Radius Sidetracking Process

To evaluate the fatigue reliability of different types of drill pipes during an offshore short-radius sidetracking process, the fatigue life and limit of G105, S135, and V150 steel and a new titanium alloy drill pipe were studied in air, high-temperature conditions, drilling fluid, and drilling fluid containing H2S. First, the chemical composition, microstructure, and tensile properties of four kinds of drill pipe materials were tested. Secondly, the fitting effects of different S-N models were evaluated and identified, a fatigue test of four kinds of drill pipe under different environments (air, high temperature, drilling fluid, and H2S drilling fluid) was carried out, and the S-N curves and fatigue limits of different drill pipes under different environments were obtained. Finally, the fatigue sensitivity of drill pipes to different factors was studied, and the potential corrosion fatigue mechanism was explained. The research results show that the fatigue life of a drill pipe in a non-corrosive environment (air and high temperature) is mainly related to steel grade, and the fatigue life of a titanium alloy drill pipe is better than that of a steel drill pipe in a corrosive environment. The dense passivation film on the surface of a titanium alloy drill pipe is an important reason for its better corrosion fatigue life than that of a steel drill pipe. This study provides important data support for selecting drill pipes in offshore short-radius sidetracking.

Corrosion Behavior and Mechanical Performance of Drill Pipe Steel in a CO2/H2S-Drilling-Fluid Environment

Objectives: This article investigates the corrosion behavior and mechanical-property changes of S135, G105, and V150 drill pipe materials in a high-temperature-resistant, potassium amino poly-sulfonate drilling fluid, which has good lubrication performance and contains CO2/H2S, by applying an 80% yield-limit-load simulation. The results show that the CO2-corrosion behavior of G105, S135, and V150 drill pipes are obvious under the simulated constant-load-stress-corrosion environments at the wellhead, well-middle, and bottomhole positions. Compared to uncorroded drill pipes, S135 and V150 drill pipes have increased strength and yield ratios, decreased fracture elongation, and increased sensitivity to hydrogen embrittlement under H2S action, and V150 has a greater risk of stress-hydrogen embrittlement. The strength and yield ratios of G105-material drill pipes decrease, while the fracture elongation increases; the intensity-change amplitude levels are ranked V150 > G105 > S135, and the fracture-elongation-change amplitude is ranked G105 > S135 > V150. The tensile-performance-change amplitude and the SSCC (Sulfide-Stress-Corrosion Cracking) sensitivity of G105 and V150 drill pipes were the highest at the bottomhole. S135 drill pipe materials were most affected by pitting and tensile action at the wellhead, and they had the with the largest SSCC sensitivity.

Optimal design and nonlinear dynamic characteristics of titanium /steel drill pipe composite drill string for ultra-deep drilling

Titanium drill pipe have promising application prospects in ultra-deep drilling, but the nonlinear dynamic characteristics of composite drill strings are very complex. It is very important to use titanium drill pipe safely, economically, and effectively in the drilling process. In this paper, different schemes of the titanium/steel drill pipe composite drill string was designed, and the statics and dynamics characteristics of these composite drill strings were analyzed. The design scheme of titanium/steel composite drill strings were optimized by using whirling characteristics, dynamic stress and vibration acceleration. The results show that the titanium drill pipe can effectively improve the tensile allowance of the wellhead and reduce the whirling velocity, dynamic stress and vibration acceleration of the drill string. By comparing and analyzing the dynamic characteristics of 3 kinds of composite drill strings, the use of titanium drill pipe for the lower 2000 m of the 4′′ drill pipe have the smaller dynamic stress and lateral vibration, and less collision with the wellbore. Based on the analysis of vibration and dynamic characteristics, an optimal scheme of drilling operation parameters for the titanium/steel composite drill string was formed finally, which can provide guidance for the use of the drill string composed of titanium/steel drill pipe in natural gas drilling of ultra-deep well.

Comparative Analysis of Friction and Wear Properties of Titanium Alloy Drill Pipe and Steel Drill Pipe

During the drilling process of complex structural wells such as horizontal wells, the wear, and tear of the drill pipe can lead to its weakened strength, which is one of the important reasons for the damage accidents of the drill pipe. Titanium alloy drill pipes are widely used in major oil fields as a new type of lightweight drill pipe with high fatigue life. To compare the wear performance of titanium alloy drill pipe with wear-resistant zones and traditional S135 steel drill pipe, this article tested and analyzed the chemical composition, hardness, and metallographic structure of these two drill rod materials and established models for these two materials. In the experiment, the wear morphology and wear rate before and after the experiment were analyzed and compared. Finally, based on the experimental results, an in-depth analysis was conducted on the wear mechanism of the drill pipe, and anti-wear measures were proposed. The results show that the hardness of the two materials decreases from the wear-resistant belt to the inner wall, and the microhardness of the S135 drill pipe is about half of that of titanium alloy drill pipe with wear-resistant belt drill pipe; the wear test shows that the wear loss of the S135 drill pipe is 0.1667 g, the wear rate is 0.042 g/h; through measurement, it was found that the wear loss of titanium alloy drill pipe reached 0.0055 g, and the wear rate is 0.0063 g/h. The wear rate of S135 steel drill pipe under the same conditions is 6.7 times that of titanium alloy drill pipe. Through analysis, it is shown that under the same conditions, titanium alloy wear-resistant belts have excellent wear resistance, which can effectively protect the inner matrix and prevent excessive wear of drill pipes. The research results of this article can provide theoretical references for the on-site use of titanium alloy drill pipe and experimental research on drilling tool wear resistance.

Research on Cuttings Carrying Principle of New Aluminum Alloy Drill Pipe and Numerical Simulation Analysis

In order to improve the cuttings transport ability and well hole purification effect of horizontal shale gas wells in the Sichuan and Chongqing area, a new type of aluminum alloy drill pipe is put forward, and the floatability is validated by theoretical analysis and actual parameter calculation. According to the cuttings migration mechanism, the cuttings cleaning simulation model of the new aluminum alloy drill pipe and the traditional steel drill pipe was established by Fluent, and the hexahedral mesh is used to divide the model. Thus, the mesh independence and convergence of the two models are verified. Then, the simulation model is verified by comparing the calculation results of the two simulation models with the experimental data of the indoor cuttings migration device. Finally, the rock-cleaning ability of the two drill pipes is analyzed under the conditions of changing the cuttings particle size, well inclination angle, displacement, and mechanical speed. Compared with the traditional steel drill pipe, the new aluminum alloy drill pipe can improve the borehole purification capacity by 13% on average. This research result is of great significance in reducing the quality of cuttings in the annulus and improving the borehole purification effect.

Study on Dynamic Behavior of a Titanium Alloy Drill Pipe in Complex Wells

Traditional steel drill pipes can no longer meet the requirements of complex wells with ultradeep, ultrahigh pressure, and long horizontal section; hence, titanium alloy drill pipes are an ideal substitute. This paper explores how titanium drill pipes behave in complex wells. The extrusion and tensile test of titanium alloy pipe was first established. Then, based on the experimental data, the downhole mechanical behavior of a titanium alloy drill pipe was studied from the buckling, contact force, and operating friction with an actual complex well. Meanwhile, the mechanism of friction reduction is analyzed and discussed. The research achievements indicate that the strength of a titanium alloy drill pipe is equal to that of a steel pipe and has good plastic deformation capacity. The titanium alloy drill pipe is more prone to buckling during operation, but it has a smaller contact force, which can effectively reduce the operation friction. It was found that the influent of buckling on slide force was much less than of the gravity and stiffness by mechanism analysis. The research achievements can provide specific theoretical and practical references for the revelation of the mechanical behavior and functional performance of titanium alloy drill pipe in the field operation.

Study on Fatigue Behavior of S135 Steel and Titanium Alloy Drillpipes: Experiment and Modeling

Summary This paper studies the fatigue failure behavior of S135 steel and titanium alloy drillpipe, tries to reveal the mechanism of fatigue fracture, and evaluates the degree of fatigue damage. First, the chemical composition, tensile test, and microstructure analysis of two types of pipes were carried out, and the difference in microstructure affects its macroscopic fatigue performance. Second, the stress vs. fatigue life (S-N) curve equation and fatigue limit of S135 steel and titanium alloy drillpipes in air and mud were obtained through the fatigue test. The equations of the S-N curves in air are NS135−air=9.45×1037(S+1776)−9.3 and NTi−air=1.41×1028(S+1124)−6.7, while in mud, they are NS135−mud=6.68×1034(S+551)−9.6and NTi−mud=5.74×1032(S+973)−8.3. Scanning electron microscope analysis results show that the S135 steel drillpipe presents brittle fracture, while titanium alloy drillpipe presents mixed fracture of quasi-cleavage and dimple. Finally, a case study of actual horizontal well was carried out to evaluate the fatigue damage of two drillpipes; compared with conventional steel drillpipe, titanium alloy drillpipe can effectively resist fatigue damage in the drilling fluid environment. The fatigue test results and corrosion fatigue mechanism analysis in this paper can provide data and theoretical guidance for the study of drillpipe fatigue life.

Fatigue and Life Prediction of S135 High-Strength Drill Pipe Steel under Tension–Torsion Multiaxial Loading

This paper investigates the fatigue behavior of S135 high-strength drill pipe steel under tension–torsion multiaxial loading. Based on the concept of critical plane during fatigue, the fatigue model under the combined loading of tension–torsion is established. The proposed model is validated, and the predicted results are in good agreement with the experimental testing results. The maximum relative errors between the estimation and the experiment are mostly within the range of factor two to three for proportional, and 90° non-proportional tension–torsion loading. Meanwhile, the failure mechanism is also discussed through fracture analysis.

Study on Simulation Law of Cuttings Migration in Shale Gas Horizontal Wells

Inland and offshore oil exploitation, large displacement, and horizontal well are more and more widely used, which can significantly improve the oilfield exploitation efficiency and economic benefits. However, in the complex drilling process, the debris particles generated in the large displacement and horizontal well section drilling are deposited in the lower low-speed area of the lower part of the ring empty shaft. It will cause underground accidents such as complex moving, drilling, increased resistance, drilling column fracture, and so on, which will seriously affect the efficiency and economic benefits of drilling. This paper addresses the problem of annular debris accumulation and the characteristics of high-density drilling fluid and uses the CFD-DEM (discrete cell method) method to simulate the debris movement process in the well eye based on the coupling of FLUENT and EDEM software. The edge calculation is used to provide strong resource allocation and calculation force support for this paper, fully consider the influence of the interaction between drilling fluid, debris particles, and drilling rod and well wall, and explore the influence law of the eccentric ring space of the conventional steel drill pipe.

Analysis of failure causes of S135 drill pipe

The drill pipes must feature sufficient strength to prevent its longitudinal bending under the action of axial loads, centrifugal forces, and torque. In the lower zone, where the stress is compressive most frequent occurrence of fatigue cracks in drill pipes. The task of the study is to investigate the reason for the premature failure of the grade S135 steel drill pipes, used for drilling oil and natural gas, which failure before reaching the permissible load cycles at a depth of about 4500 m. For this purpose, macrostructural and microstructural analysis and mechanical tests of tensile strength, impact toughness, and fatigue strength were conducted.From the performed microstructural analysis the presence of metallurgical defects (micro and mesopores) has been established, which significantly reduces the steel quality and contribute to the crack source creation leading to premature failure of drill pipes.After the mechanical tests conducted and the subsequent microstructural analysis the presence of macro defects due to pitting corrosion has been established. The active interaction of the dispersed soil primer with the macropores creates conditions for the development of a cracks on the outer surface and is also a reason for the premature failure of drill pipes.This problem can only be solved at the production stage- to be specify the casting technological parameters of billets from which the drill pipes are produced.

A modeling of the inertia properties of a drill string section as a continual bent rotating rod

The article considers the problem of determining the moment of inertia of the bent rotating section of the drill string. The tasks of such a plan are of paramount importance for the dynamic analysis of drill strings in rotary and rotaryturbine drilling methods. Presented are the exact and approximate analytical dependences for determining the moment of inertia of the bent section of the drill string, depending on the geometric parameters of its deflection. Given the scientific and practical interest in the use of pipes made of non-traditional materials, the moments of inertia for bent sections of steel, titanium, aluminum and fiberglass drill pipes are calculated. The nature of the change in the moment of inertia of sections of drill pipes of different diameters depending on the length of the half-wave and the magnitude of the maximum deflection is established. Keywords: drill string; rod; moment of inertia; deflection boom; deflection half-wave length.

Experimental and numerical simulation of fatigue corrosion behavior of V150 high-strength drill pipe in air and H2S-dilling mud environment

Experimental and numerical methods have been used to investigate the fatigue corrosion behavior of V150 drill pipes in different environments. In this study, a fatigue test machine was designed and utilized to analyze the behaviors of V150 high-strength drill pipe steels under different stress amplitudes in air, mud, and H2S mud. Subsequently, the fracture morphology and mechanism were analyzed, and the coupling behavior of stress and electrochemical corrosion was studied via numerical simulations. Finally, some suggestions were proposed for safe drilling using V150 drill pipes. The results revealed that the fatigue life of the V150 drill pipe in H2S-mud is approximately 10% of that in air and 33% of that in mud. The equations governing the fatigue life of V150 in air, mud, and H2S mud are Nair=8.59×1010(S−330)−2, Nmud=3.45×1010(S−270)−2, and NH2S−mud=2.13×1010(S−167)−2, respectively. The fracture surface exhibited ductile fracture in air, mixed ductile and brittle fracture in mud, and brittle fracture in mud containing H2S. The numerical simulation results demonstrated that the greater the longitudinal displacement, the greater the stress at the center of the corrosion pit; additionally, the more negative the electric potential, the faster the electrochemical corrosion. This study therefore explains the mechanism behind the fracture of V150 drill pipes and provides guidance for the safe use of V150 drill pipes in the drilling process.

Hydrogen effect on phase angle shift in electrochemical impedance spectroscopy during corrosion fatigue crack emanation

It is generally considered that hydrogen could accelerate the corrosion fatigue process, however, the effective monitoring approach for the corrosion fatigue development in the hydrogen related environment is still missing. In this work, the hydrogen effect on phase angle shifts in electrochemical impedance spectroscopy during corrosion fatigue crack formation in drill pipe steel was in-situ studied. The results show that phase angle shifts as a function of time could be used to monitor the corrosion fatigue development in the presence of hydrogen. The permeated hydrogen leads to a lower peak intensity and shifts the peak to a higher frequency on the phase angle vs. frequency curve. These differences are due to the formation of a corrosion fatigue crack with a shorter length than in the absence of hydrogen. The phase angle shift reveals that the presence of hydrogen results in shortening crack initiation time and corrosion fatigue life of the drill pipe steel.

Influence of Heavy Weight Drill Pipe Material and Drill Bit Manufacturing Errors on Stress State of Steel Blades

Drilling volumes should be increased in order to increase hydrocarbon production, but this is impossible without the usage of high-quality drilling tools made of modern structural materials. The study has to analyze the design, technological and operational methods to increase the performance of drilling tools made of various materials and has highlighted prospects of technological method applications. The scientific novelty of the study consists in the development of a new analytical model of PDC drill bit–well interaction. The developed model takes into account the drill bit manufacturing errors in the form of bit body–nipple axes misalignment on the drill bit strength. This result makes it possible to determine the permissible manufacturing errors to provide safe operation of the drill bit. It is established that there is an additional transverse force that presses the drill bit to the well wall in the rock due to manufacturing errors. It is determined that the magnitude of this clamping force can be significant. The material effect has been analyzed on additional clamping force. It is established that geometric imperfection of the drill bit causes the minimal effect for the elastic system of the pipe string, which includes a calibrator and is composed of drill pipes based on composite carbon fiber material, and the maximal effect—for steel drill pipes. Polycrystalline diamond compact (PDC) drill bit and well wall contact interaction during operation in non-standard mode is considered. Non-standard stresses are determined, and the strength of the blades is estimated for different values of drilling bit manufacturing error.

Effect of <i>In Situ</i> TiB<sub>2</sub> Particles on the Grain Size and Mechanical Properties of 7075 Aluminum Alloy

Light-weight and high-strength aluminum alloy drill pipes are potential and promising to replace traditional steel drill pipes. In this study, the grain size and mechanical properties of aluminum alloy drilling pipe materials reinforced by in-situ TiB2 particles were studied. The results showed when reinforced by in-situ TiB2 particles the grain size of aluminum alloy materials was refined from 155 m to 57 m and ultimate tensile strength was increased from 590 MPa to 720 MPa. Besides, the results also indicated that the friction coefficient was reduced from 0.99 to 0.50 and thus the abrasion resistance of 7075 aluminum alloy was enhanced by 34 %. This study provided theoretical basis for the application of light-weight and high-strength aluminum alloy drill pipes in directional drilling and ultra-deep wells.

Influence of internal stresses in steel as a factor of corrosion cracking and destruction of drill pipes during their operation

Drill pipes in the oil-gas industry play a major role in the extraction of petroleum products. These pipes are the main link in the drilling rig, these pipes create the necessary rotation and transfer the load to the cutting element (chisels), and they also serve to lift working tools from the bottom of the well to the surface. The main goal of the drill pipe is to supply the drilling fluid, which performs the function of cooling the bit. The destruction of such pipes leads to large economic losses, therefore, these pipes must have high quality primarily in terms of mechanical properties. Based on the foregoing, this work is aimed at studying the causes of accidental destruction of steel drill pipes during their operation in the presence of an increased level of internal stresses in them. As the main method for assessing the level of residual internal stresses, a method is proposed for measuring the groove width during the longitudinal opening of ring samples cut from the body wall of drill pipes. This method is distinguished by its clarity and high speed of obtaining the result. The increased level of internal residual stresses, combined with external working loads during operation, leads to a significant reduction in the service life of drill pipes under the influence of corrosion cracking mechanism.

Study on mechanical properties of titanium alloy drill pipe and application technology

With the increasing intensity of oil and gas field exploration and development, oil and gas wells are also drilling into deeper and more complex formations. Conventional steel drilling tools can no longer meet the requirements of ultra-deep, high-temperature and high-pressure wells. The paper first analyzes the advantages of titanium alloy drill pipe based on basic performance of titanium alloy drill pipe. The experimental results show that the basic properties of titanium alloy drill pipes meet the operating standards of the petroleum industry. Then the buckling performance of titanium alloy drill pipe and steel drill pipe is compared, the calculation results show that the buckling performance of titanium alloy drill tools is slightly lower than that of steel drill tools. Secondly, the maximum allowable buildup rate of titanium alloy drill pipe and steel drill tool is studied. The research shows that under the same condition of the drill pipe outer diameter, titanium alloy drill pipe can be used for a smaller curvature radius and greater buildup rate. This advantage of titanium alloy drill pipe makes it more suitable for short radius and ultra-short radius wells. Finally, taking a shale gas horizontal well as an example, with the goal of reducing drill string friction and ensuring drill string stability, a comparative study on the application of titanium alloy drill pipe and steel drill pipe is carried out. The results show that titanium alloy drill pipe has a wider application in the field, and is suitable for operations under various complex working conditions.

Methodology for Studying the Wear of Drill Pipe Threads during Repeated Making up and Holding under Load

Purpose of reseach is to develop a methodology for studying the wear of drill pipe threads during repeated making up and holding under load. Methods. For the research, stand “IRS-1” was used. This stand is a device for creating a torque of up to 80 kNm and transferring it to a made-up pipe. It is equipped with a make-up torque sensor and a control system that performs make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up thread pair. The test procedure for IRS-1 stand consists of the following sequence of actions: before starting the tests, the threaded protectors are removed; the threads on the nipple and sleeve are cleaned of the preservative grease and traces of corrosion by dry wiping and subsequent degreasing; the thread on the nipple is measured according to the measurement chart using a gauge. The gauge is made on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. The gap between the gauge and the thread is measured using a set of probes from 0.01 to 0.09 mm in increments of 0.01 mm, over 0.1 mm to 0.45 mm in increments of 0.05 mm, over 0.5 mm to 1 mm in increments of 0.1 mm. Results. A new tribotechnical stand of IRS-1 model was designed and created, which allows implementing various techniques for studying the wear of drill pipe threads during repeated making-up and holding under load. An important feature of the designed stand is a make-up torque sensor and a control system that perform make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up threaded pair. The maximum torque generated by the stand is 80 kNm. A particular technique was developed. The technique includes the requirements of the API 7G-2 standard and has shown its effectiveness in the study of thread wear of steel drill pipes. To implement the technique, a special gauge was developed on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. Within this technique, a measurement chart with two selected measurement areas was developed. An algorithm for making up a pipe at a uniform speed was created. The algorithm includes three stages. There was developed an algorithm of measurements using reference marks, providing measurements at four points in each selected area. Conclusion. The results obtained can be used to create resource-saving technologies for processing ingot, powder, and nanocomposite materials with different dispersion of phase and structural components that are operated under extreme conditions and states.

Analysis of API S-135 steel drill pipe cutting process by blowout preventer

In offshore oil exploration, the use of a Dynamic Positioning System (DPS) to maintain the platform at a fixed point regardless of the influence of the environment has become common practice. In the event of failure, however, the drill string inside BOP (BlowOut Preventer) must be cut and safely disconnected from the platform. Therefore, it is evident the need for an accurate and realistic virtual model of this failure process. Numerical model analysis, in addition to avoiding expensive and complex experimental tests, allows, through post-processing tools, a detailed understanding of all phases of the failure process. The present work aims to characterize the API S-135 steel, as material commonly used to manufacturing drill strings. The material parameters for the Johnson-Cook model (J-C) are obtained from experimental tensile tests on dog bone and 3-point bending beams specimens with different notch radii, covering a wide range of stress triaxialities. Experimental tests and numerical simulations were compared by means of stress-strain curves, Digital Image Correlation (DIC) and Surface Electron Microscopy (SEM) to validate the model. The material model is applied to simulate the pipe cutting process and to predict the required force for the BOP to cut drill pipes with different geometries, which in comparison to experimental tests permitted to determine BOP internal frictions. Additionally, the numerical simulation also allowed a better understanding of the cutting process here presented as well, coherent to J-C model and SEM imaging of a similar cut tube in BOP.

Characteristics and life expression of fatigue fracture of G105 and S135 drill pipe steels for API grade

Characteristics and life expression of fatigue fracture of drill pipe steels for API G105 and S135 grade were investigated experimentally. S135 steel with higher tensile strength has higher fatigue strength and fatigue limit than that of G105 steel with lower tensile strength. A modified model for the S-N data, revealing the correlation between the fatigue life and fatigue limit, equivalent stress amplitude reflecting the effect of stress ratio, is suggested for predicting the fatigue damage. The fatigue limit and the fatigue strength coefficient are correlated to the tensile properties. The mechanism of the fatigue fracture was examined by scanning electron microscopy.