Drill Pipe Joints Research Articles

Effect of graphene content on the tribological and corrosion behavior of high-speed-laser-clad high-entropy-alloy composite coatings

To repair oil drill pipe joints that have failed owing to dry wear and tribocorrosion, graphene-reinforced CoCrFeMo0.5NiTi0.5 high-entropy alloy composite coatings (HEACCs) were developed through high-speed laser cladding. The HEACC containing 1.5 wt% graphene exhibited dry wear and tribocorrosion rates that were 59.18 % and 32.20 % of those observed in the high-entropy alloy coating, respectively. The HEACC exhibited a corrosion current density of 2.475 × 10−7 A/cm2. The HEACC containing 1.5 wt% graphene underwent progressive damage during dry wear owing to the combined effects of abrasive wear, which created furrows; adhesive wear, which led to flaking; and oxidative wear, which formed oxide layers. During tribocorrosion, chloride ions exacerbated surface damage caused by hard abrasives and asperities, intensifying corrosive–abrasive wear interactions.

Dynamic calculation of stress influence law of rubber core sealing surface of the rotating blowout preventer with defects

The bubble and crack defects in the production and operation of the rubber core of the rotating blowout preventer (RBOP) easily cause fatigue failure, leading to well-controlled severe accidents. Based on Yeoh’s principal structure equation, the dynamic sealing model of rubber core was established in this paper. The sealing process of the rubber core in lifting and drilling was calculated and analyzed. The stress influence law of typical cracks and bubble defects that affect the fatigue failure of rubber core sealing surface was analyzed. The results are as follows: (1) When the drill pipe joint passes through the RBOP, the structure of the rubber core is significantly deformed. This stage may cause damage and failure of the rubber core. (2) The cracks and bubble defects lead to a decrease in the stability of the sealing surface. With the increase of stress at the defect, the crack of the rubber core is easy to expand. (3) In the same location of the rubber core defects, cracks compared to bubble defects have a more significant impact. For the same type of crack, the bottom left side (A1) and the outer surface underside (D1) crack reduce the stress at the position of the rubber core sealing surface to the maximum. The research results provide a reference basis for defect detection, sealing performance, and service life of rubber cores, in order to improve the reliability evaluation standards of blowout preventer rubber cores, improve well control safety, reduce the occurrence of safety accidents, and improve operational efficiency.

Three-dimensional mechanical characteristics analysis of double-shoulder tool joint under complex loads

Taking a new type of special threaded drill pipe joint as the research object, a 3D nonlinear finite element model of the double-shoulder tool joint (DSJ) including the engage and retract groove structure is established by considering the factors of structural asymmetry and contact of each engaging surface. ABAQUS/Explicit finite element method (FEM) is used to study the stress and contact pressure distribution characteristics of the critical structure of DSJ under make-up torque and axial tension. The accuracy of the finite element model was verified by combining with a full-scale physical test, and the connection strength and sealing performance of DSJ are evaluated. The results show that the stress concentration occurs at the key structure of DSJ under the make-up torque. The geometry size and structural discontinuity at the transition fillet of the double-shoulder structure have a significant effect on the stress and contact pressure distribution on the shoulder. Under axial tension, the stress level and stress concentration area of the whole joint and the key structure change, especially in the thread section. The sealing performance on the shoulder decreases significant, while that of the thread section increases slightly. The test results are consistent with the finite element analysis findings, and this joint shows good mechanical properties, which can meet the design requirements of drilling tool manufacturers and provide data support for its optimal design and application.

Analysis of the Influence of Thread Parameter Deviation on The Sealing Performance of Drill Pipe Joint Under Axial Load

To explore the influence of the limit deviation of the thread parameters of the drill pipe joint on its sealing performance, based on the API NC38 drill pipe joint, the existence of the limit deviations of the three thread parameters of taper, side angle, and pitch is analyzed. Based on this, a total of 12 finite element models of drill pipe joints including various limit deviations and free combinations of internal and external thread limit deviations are established, and the sealing performance of different structures under the action of make-up torque and axial load is analyzed. The results show that the pitch limit deviation has the most obvious influence on the sealing performance of the drill pipe joint, and the yield failure of the contact surface is easy to occur. The existence of taper limit deviation makes the sealing performance of the drill pipe joint significantly reduced when subjected to tensile load. When the change of the limit deviation of the side angle of the internal and external thread teeth is opposite, the plastic deformation occurs locally in the drill pipe joint, which affects the sealing effect. Therefore, it is necessary to control further the tolerance range of the thread parameters of the drill pipe joint to reduce the risk of sealing failure of the drill pipe joint.

Real-Time Detection of Drill Pipe Joints Using Improved YOLOv5x Model Applied to Drilling Operation Images

It is widely known that pipe assembly and disassembly still lacks automation. To enhance drilling efficiency, we propose an autonomous detection and positioning model based on improved YOLOv5x for drill pipe joints. Firstly, we use Activate or Not (ACON) activation function and Convolution Block Attention Module (CBAM) to enhance feature extraction and representation ability. Then, the loss function is changed from Complete IoU (CIOU) loss to Scale-Invariant IoU (SIOU) loss, which increases the accuracy of the bounding box regression. Finally, the predict heads are tailored to be more effective in detecting tiny targets. Following network training, the final drill pipe joint detection model, based on the improved YOLOv5x, achieved an average accuracy of 99.10%, a 3.5% improvement over the base YOLOv5x algorithm. The proposed method effectively promotes the intelligence of oil drilling equipment by quickly and accurately detecting drill pipe joints, consequently enhancing drilling operation efficiency.

Effect of cuttings particle content on the tribological behavior of Fe/DLC at casing and drill pipe joints: A molecular dynamics study

The presence of cuttings in the drilling fluid can exacerbate the wear of drill pipe joints and casing. Diamond-like carbon (DLC) films have ultra-low friction coefficients and high wear resistance, which have excellent research prospects in reducing the wear between drill pipe joints and casing. To investigate the impact of varying particle counts at the interface between Fe bulk and DLC film, this work builds a pertinent molecular dynamics model. The results show that the interfacial friction increases with increasing particle content, which leads to more severe abrasive wear on the Fe bulk and prevents the amorphous structure atoms in the Fe bulk from recovering to a body-centered cubic crystal structure. On the contrary, the DLC film is difficult to be affected by the particle motion because of its good tribological properties. Simultaneously, more silica particles reduce the space for the movement of water molecules and ultimately weaken the lubrication ability of water molecules.

Drill pipe joints fatigue analysis and optimization under special working conditions

Recently, the number of ultra-deep and extended reach wells has continuously increased. The failure of the drill pipe is prominent when drilling. The thickened area of the drill pipe body and the position of the drill pipe joint often appear fatigued, especially the internal thickening zone for the nonlinear structure of the cast component. Fatigue failure occurred at the drill pipe joint due to non-linear contact between the male and female snaps. The fatigue life S-N curves show that the overall life of drilling with high-resistance torsion drill pipe is increased by 136% compared with API drill pipe, though the maximum stress value was reduced by 8.4%. The high-bend drill pipe has an overall life improvement of 174% over the API drill pipe. High flexural drill pipe reduces stress by 10% compared to the maximum value. At the same time, the drill pipe’s fatigue period and safety factor can be improved by adjusting the drilling speed and annulus pressure properly.

Investigation on Cracking Cause of Drill Pipe Joint Used in an Ultra Deep Well

The drill pipe joint cracked during service, resulting in joint failure. The geometric dimensions of thread, chemical composition and microstructure of the drill pipe joint were tested. The geometric dimensions, chemical composition and microstructure were found to comply with the standard requirements. The whole macroscopic fracture didn’t show obvious corrosion product. The tensile properties, Charpy impact properties, and Brinell hardness met the standard requirements. Microstructure of fracture was analyzed, which showed a typical erosion micromorphology with parallel arranged fatigue strips. Through simulation analysis, it was found that the location of cracking was the stress concentration area. The failure mechanism of the drill pipe joint was revealed. The stress concentration led to fatigue cracking at the drill pipe joint. After the fatigue crack penetrated through the wall thickness, the drilling fluid leaked from the inner wall to the outer wall. The flow rate of the leaking drilling fluid is significantly increased. And it is sprayingly leaked, which further leads to fan-shaped erosion damage of the cracked surface from the inner wall to the outer wall.

Wear resistance of carbide-containing deposited layers for drill pipe joints

Wear resistance of carbide-containing deposited layers for drill pipe joints

Sealing performance and failure mechanism of rubber core for conical blowout preventer during the well shut-in process

Blowout preventer reliability is important for safe drilling operation. In order to study the sealing mechanism and failure mechanism of conical blowout preventer, a numerical model of conical blowout preventer was established based on the theory of large deformation of rubber, and the deformation law, stress distribution and sealing performance of rubber core in well shut-in operation were studied. The results show that there are stress concentrations in the contact area between the rubber core and the piston, the grooves in the middle of the adjacent support ribs, and the chamfered corner of the inner wall of the rubber core, the main form of failure at these locations is rubber cracking. Higher stress is present in the neck region of the upper plate and the back region of the lower plate of the support ribs. The inner wall surface of the rubber core gradually produces stripes of wrinkles, and the smaller the size of the sealed drill pipe, the more obvious the wrinkles are. When the drill pipe joint is sealed by the rubber core, there is a sealing buffer zone at the shoulder, and the contact pressure change abruptly. The lower portion of the rubber core’s inner wall serves as the primary sealing area. Increasing the piston displacement appropriately can enhance the sealing performance of the rubber core. The results can provide a theoretical basis for the optimization design of the conical blowout preventer.

Research on a Calculation Model of Cable Tension and Pumping Displacement of a Logging Tool String of Horizontal-Well Drillpipes

Summary With the vigorous development of unconventional oil and gas reservoirs, logging technology of horizontal-well drillpipes has become increasingly important. The improper selection of displacement during the pumping of drilling rods into horizontal wells can lead to accidents such as cable entanglement or tool-string pump detachment. Based on a comprehensive consideration of multiple factors such as drillpipe joints, small gap flow, pressure loss along the pipe, temperature, pressure, tool-string passability, and waterhole diameter variation, a cable tension analysis model for a logging tool string of a horizontal-well drillpipe is established. This model can predict a reasonable pumping displacement by analyzing the tension in the entire wellbore section, thereby avoiding cable entanglement or even tool-string pump detachment accidents during downhole operation. To verify the effectiveness of the model, we analyzed the cable tension during logging operations in Wells M1 and M2 using on-site test data and compared them with the measured tension data. The determination coefficient (R2), mean absolute error (MAE), and root mean square error (RMSE) were used to evaluate the degree of fit and accuracy of the model. The experimental results showed that the model can accurately predict the pumping displacement range before logging operations, ensuring that the cable does not entangle and the tool string is not pumped out during the downhole operation, thus providing effective methods and theoretical guidance for on-site drilling rod-pumping logging operations.

Probing the Effect of Cuttings Particle Size on the Friction and Wear Mechanism at the Casing Friction Interface: A Molecular Dynamics Study.

Cuttings particles of different sizes in the drilling fluid are the leading cause of wear at the casing and drill pipe joints, and diamond-like carbon (DLC) films have excellent research potential in reducing tool wear due to their ultra-low friction coefficient and high wear resistance. In this paper, a corresponding molecular dynamics model was developed using LAMMPS to investigate the effect of silica particles of different particle sizes on the friction and wear mechanisms of Fe/DLC friction pairs at the microscale. The results show that small cuttings particles in a dry environment are more likely to cause interface wear between the casing and drill pipe joint, while in a water environment, the opposite is true. The main reason is that small particles in a dry environment have smaller contact areas and greater indentation depth, leading to greater wear at the friction interface. The movement of water molecules in the water environment will promote the composite movement of large particles, thereby exacerbating the wear of the interface. Moreover, the relevant research results at the micro-scale indicate that DLC films can effectively reduce wear, which provides theoretical support for its application in drill pipe joints.

The Effect of Clamping Force and Friction Coefficient on The Clamping Clamp

In order to study the influence of clamping force and friction coefficient on the stress distribution of drill pipe joint during the buckling process, the nonlinear contact problem and elastoplastic mechanical properties of Φ139.7mm × 9.17mm drill pipe were simulated by finite element analysis method in this paper, and the stress distribution and size of drill pipe joint during the buckling process were obtained. And the effect of clamping force and friction coefficient on the joint of drill pipe. It is found that the stress of drill pipe joint is mainly concentrated in the contact position of drill pipe and the stress value of drill pipe joint shows a trend of increasing. When the friction coefficient is 0.15 and the clamping force is 600KN, although there is stress concentration in the contact position between the clamp teeth and the drill pipe joint, it does not exceed the yield limit of the drill pipe joint, and no plastic deformation occurs. Through the simulation calculation, it is found that the maximum clamping force and the maximum torque are 1200KN and 81.9KN.m respectively. When the torque is fixed, the change of friction coefficient has a great influence on the maximum clamping force of drill pipe joint. With the increase of friction coefficient, the maximum clamping force of drill pipe joint decreases continuously, and the friction coefficient is inversely proportional to the maximum clamping force. The research in this paper enriches the understanding of the buckling process of punching pliers and provides a reference for the rational buckling of pipe string.

Fracture Analysis of Butt Welding Area of 5″ Drill Pipe Internal Thread End in an Oilfield

This paper tested fracture morphology analysis, mechanical properties and chemical, metallographic analysis and micro analysis to find out the factors of fracture in the butt welding area of the internal thread of the 5″ drill pipe, which is made of S135 in the casing pulling process of an oilfield. The results show that the chemical element, tensile strength and yield strength, impact performance, metallographic structure, inclusions in microstructure and grain size of the Fracture drill pipe meet the relevant data of the oilfield and industry standards, but the hardness of the fracture does not meet the requirements of the national standard. The important reason of the fracture of the drill pipe is that the oxide skin was not cleaned before the drill pipe joint was welded with the body. During welding, the oxide skin entered the molten weld metal, and large slag inclusions formed in the weld resulted. The secondary cause is improper subsequent heat treatment of drill pipe weld, which leads to increased weld brittleness and accelerated crack growth. This paper puts forward corresponding countermeasures to improve the quality of the drill pipe’s weld and prevent the failure accidents of drill pipe.

Numerical study of temperature–pressure coupling model for the horizontal well with a slim hole

AbstractHorizontal wells with a slim hole (HW‐SH), characterized by high productivity, high environmental protection, and low cost are gradually being introduced into oil and gas extraction processes in high‐temperature and high‐pressure formations. However, the HW‐SH annulus is narrow, and the distributions of temperature and pressure in the wellbore are very different from those of conventional horizontal wells. Furthermore, the mud properties change under the influence of high temperature and pressure. In this study, a numerical model of the transient temperature‐pressure coupling field in an HW‐SH wellbore was developed based on high‐temperature and high‐pressure performance tests of mud, combined with the characteristics of a narrow annulus in HW‐SH. Subsequently, the effects of the ground temperature gradient, displacement, drill pipe speed, annulus size, and joint size on the temperature‐pressure coupling field were analyzed. Measured data from the HW‐SH drilled in the Mahu field in China were used to validate the developed model. The results showed that the ground temperature had a significant effect on the mud density and rheological properties. As the temperature increased, the mud density decreased, and its rheological properties improved. Although pressure also has a large effect on density, it has a negligible effect on the rheological properties of the mud. The coupled temperature‐pressure field model for HW‐SH considering the effects of the temperature and narrow annulus can predict the annulus temperature and pressure with an accuracy of up to 97%. The ground temperature gradient has the greatest influence on the HW‐SH annular temperature, larger than that of the displacement. In addition, the annular size, rotation speed of the drill pipe, and joint size have almost no influence on the annular temperature. Compared to those of conventional horizontal wells, the rotational speed, annulus size, and joint size of the HW‐SH have a greater impact on the annulus pressure.

Development of a hardbanding material for drill pipes based on high-manganese steel reinforced with complex carbides

In the present study the new “casing-friendly” hardbanding alloy based on high-manganese steel reinforced with complex carbide particles was developed by combining thermodynamic modelling within the CALPHAD approach and first-principles calculations. The alloy, deposited by flux cored arc welding on a steel substrate, has a composite structure consisting of manganese-austenite with the ability to work hardening, fine (up to 5 µm) inclusions of the multicomponent carbide (Nb, Ti, Mo, V) and C the thin layers of (Mo,V)C at the austenite grain boundaries. The comparative wear tests carried out with commercially available hardfacing materials of the Fe-W-C and Fe-Cr-C systems showed that the proposed alloy has the best combination of properties preventing the wear of the drill casing, while its abrasion resistance as well as wear resistance in sliding friction conditions by steel counterbody is close to hypereutectic high chromium alloys. The microhardness tests performed on deformed specimen areas after the friction tests show the presence of a significant hardness gradient in the range of 800-450 HV at a distance of about 300 µm when moving perpendicularly away from the zone of friction contact. During the microscopic observation of the layer deposited with the developed alloy and the interfaces between the deposit and the base steel no cracks, pores delamination were detected indicating a strong metallurgical bonding. The hardbanding process was performed for drill pipe joints with the worn Fe-based high chromium alloy hardbanding after exploitation, which allows the drill pipe to be reused with the same durability.

Casing Wear and Wear Factors: New Experimental Study and Analysis

To understand and quantify casing wear during drilling operations, an experimental setup with real drill pipe joints (DPJ) and casings was designed and used to carry out wear tests, simulating various operating conditions and environments. P110 steel casing samples were tested under dry and wet conditions. Actual field oil- and water-based fluids were utilized to lubricate the contact area at two different side loads (1000 N and 1400 N) and DPJ speeds (115 and 207 rpm). The results show that for the same testing conditions, the casing wear volume and wear factor under water-based lubrication were more than twice those obtained under oil-based fluid testing. As expected, the wear volume and wear factor were highest under dry conditions. Moreover, it was noticed that, as the normal load was increased at a constant rotational speed (rpm), the wear factor increased. On the other hand, raising the rotational speed at the same applied load reduced the casing wear factor, due to the observed absence of adhesive wear and possible localized softening effects at higher speeds. SEM analyses of the worn areas showed that under dry conditions, the main wear mechanisms were abrasion and delamination. However, both adhesive wear and abrasive wear mechanisms were observed under oil-based lubrication. The energy dispersive spectroscopy (EDS) analysis of the worn surface revealed that at higher loads and speeds, a heavy transfer of particles from the oil-based lubricant took place. On the other hand, some contaminants of the water-based lubricant were observed on the worn surfaces.

Failure Analysis of Drill Pipe during Working Process in a Deep Well: A Case Study

The failure of a 101.6 mm drill pipe was studied by combining experimental testing and finite element simulation. The macro analysis, metallographic structure and energy spectrum, chemical composition and a mechanical property test of the failed drill pipe sample were firstly carried out. Then, a three-dimensional finite element model of drill pipe failure was established based on the experimental results. Finally, the failure mechanism of drill pipe was analyzed and the mitigation measures were put forward. The results showed that solids settling sticking was the direct cause of fracture failure of the drill pipe joint. Due to the violent friction and wear between the drill pipe joint and the settled sand, the large amount of heat generated caused the microstructure of the joint material to undergo phase transformation and the bearing capacity to be reduced. Finally, fracture occurs under tensile and torsional loads.

Experimental research on improving the wear resistance and anti-friction properties of drill pipe joints

Purpose The purpose of this study is to solve the oil drill pipe joints and casing excessive wear problems and to improve the drill pipe joint-casing wear resistance and anti-friction properties. Design/methodology/approach On the surface of the drill pipe joints using oxyacetylene flame bead weld (BW) wear-resistant welding wire ARNCO-100XTTM prepares welding layer, high-velocity oxygen fuel (HVOF) Cr3C275-NiCr25 prepares coating and subsonic flame spray and remelt (SFSR) Ni60 prepares coating, then comparing and analyzing the friction and wear of the three types of wear-resistant layers and the casing under the condition of 1.8 g/cm3 mud drilling fluid lubrication. The wear resistance and anti-friction performance of the drill pipe joints were evaluated based on the wear situation, finally revealing its friction and wear mechanisms. Findings Three types of wear-resistant layers can improve the surface wear resistance of drill pipe joints, the wear-resistant layer and the substrate are well combined and the welding layers and coating are both dense and uniform. The wear resistance of the HVOF-Cr3C275-NiCr25 coating is 10.9 times that of the BW-ARNCO-100XTTM weld layer, and the wear resistance of the SFSR-Ni60 weld layer is 2.45 times that of the BW-ARNCO-100XTTM weld layer. The anti-friction properties of SFSR-Ni60 welding layer is the best, followed by HVOF-Cr3C275-NiCr25 coating, and the anti-friction properties of BW-ARNCO-100XTTM welding layer is the worst among the three. Originality/value The research results of this paper have great practical value in the process and material of improving the wear resistance and anti-friction performance of the drill pipe joint casing.

Research on the mechanism of the influence of flooding on the killing of empty wells

In empty well killing, in order to save the time and cost of killing the well, the dynamic replacement method is often used to kill the well. The main problem of the dynamic replacement method for killing wells is how to avoid terrible working conditions caused by flooding, such as gas carrying fluid, killing fluid being brought to the wellhead. Based on the principle of flooding formation and the basic tenets of flooding correlation experiment and dynamic replacement method, this paper incorporates the kill fluid viscosity, surface tension, droplet diameter, inclination angle, drill pipe joint outer diameter, and drill pipe eccentricity into the calculation range and establishes a new mathematical model suitable for dynamic replacement kill. Based on the calculation results, the influencing factors of flooding are analyzed, and the following conclusions are drawn: the increase of dynamic viscosity, gas density in the well, casing pressure, well angle, the outside diameter of drill pipe, the outer diameter of drill pipe joint, and eccentricity of drill pipe can promote the occurrence of flooding; The increase of surface tension, well-killing fluid density, and casing inner diameter have an obstacle to flooding.