Roller Cone Bit Research Articles

Development of a supra-bit jet pump for opening a productive formation

The article proposes a jet pump for the bottom hole assembly. The developed supra-bit jet pump provides an additional circulation loop of the drilling fluid above the bottom of the well, which creates a local depression of the formation. In addition, the jet pump grinds the sludge injected from the annular space in the mixing chamber and feeds it to the bridging machine, which is included in the assembly, for temporary isolation of the productive formation. Isolation of the productive formation is necessary to prevent the flow of formation fluids into the wellbore when underbalanced. Grinding of the sludge in the jet pump is ensured by the cross flows of the working and injected liquid, which occur during the angular and eccentric displacement of the working nozzle of the jet pump relative to the mixing chamber. The angular and eccentric displacements of the working nozzle, the roughness of the flowing part of the mixing chamber and the diffuser, at which the pressure losses in the jet pump are insignificant, have been determined. Recommendations are proposed for increasing the efficiency of the jet pump in case of non-stationary operation at the bottom of the well, which occurs as a result of ground vibrations of a roller cone bit and uneven supply of working fluid by mud pumps.

Structural design and sand-discharge performance of the end-face groove of a cone bit

The sealing system of the roller cone bit indirectly determines the overall service life of the bit. However, the sealing part is one of the most easily damaged components of the roller cone bit. It can improve the sealing performance and service life of the bit and reduce the times of tripping during drilling. According to the results of the sealing failure analysis and the end-face position of the cone, the function of the end-face groove structure is defined as expelling most of the rock debris particles from the end face of the cone. The end-face sand-discharge structure is designed through theoretical analysis. Simulations are performed to study the performance of the end-face sand-discharge structure, verify the feasibility of the end-face sand-discharge structure, and obtain the effects of the structural parameters of the end-face sand-discharge structure on the performance of the structure. In the process, a new method of discrete phase particle tracking using simulation software is explored.

Improvement of roller cone drill bit design by using finite element method and experimental study

An approach for increasing the rate of penetration (ROP) of roller cone bits is presented. The proposed approach is based on 3D finite element method (FEM) simulation as well as field test results that were carried out on the Aghajari formation located in the southwest of Iran. In order to reduce the operation time by improving roller cone bit design, the FEM simulation of the complex nature of the contact between the roller cone bit and the formation was performed and the obtained results were compared with the field test data. Results were employed to improve the geometry of the bit profile. Based on the improved design, a roller cone bit was manufactured and employed in the field experiment to assess the performance and to verify the numerical simulation. The results show a positive effect of the improvements on the ROP which leads to a considerable reduction in drilling costs. [Received: September 15, 2021; Accepted: February 26, 2022]

Вплив конструкторсько-технологічних чинників на довговічність вставного твердосплавного породоруйнівного оснащення шарошок тришарошкових бурових доліт

Aim. In the study learning trial was made to make a mathematical model of the assembling process in connections " tungsten carbide insert cutter - cone", while the methods of mathematical statistics were applied. This makes it possible to determine the parameters of the distribution of the closing link. Accordingly, the tension is determined by samples of constituent links. For this purpose, the amount of tension was investigated. Tension affects the change in stress, which characterizes the accuracy of the assembly on the strength of the connection " tungsten carbide insert cutter - cone ". Depending on the magnitude of the insert pressing force, it is customary to estimate the tension in the connection. Method. The analysis of tungsten carbide insert cutter and holes in the layers of bit established that the size errors of the component links of dimensional chains are distributed according to laws that they are similar to the normal law of the distribution of random variables. The test was carried out according to the criteria of Pearson and Kolmogorov Results. The increase in pressing force with an increase in tension is due to an increase in elastic deformation both in the cemented layer and in the core layers of the rolling-cutter row. The extreme nature of the dependence of the pressing force on the amount of tension for the connection " tungsten carbide insert cutter - cone " has been established. This dependence, as a characteristic of the strength in the connection, can be used to design technological pressing operations for roller cone bits steels with different strength indicators. Scientific novelty. a mathematical model of the assembling process of connections " tungsten carbide insert cutter - cone " was made. It makes it possible to determine the parameters of the distribution of the closing link - tension, based on the samples of the component links. The established dependencies make it possible to reasonably and most accurately approach the formation of selective groups of teeth and the marking of holes for them. Practical significance. The appointment of tensions, the value of which exceeds the value of the extreme point, causes the occurrence of unfavorable plastic deformation or destruction of the layers of the shell (which are conjugated along the height of the shank of the insert cutter). They also result to the occurrence of irrational stresses in the body of the tungsten carbide insert cutter. It was established that the tension values have a greater influence on the force of pressing carbide teeth into the holes of roller cone bits steel 9310H (USA), when its hardness value is Rockwell hardness 59-60 compared to Rockwell hardness 48-50. Within the limits of the studied tension values, this dependence is linear.

Performance prediction and multi-objective optimization of metal seals in roller cone bits

Metal seals are the critical component of roller cone bits in oil and gas drilling. The performance of metal seals directly impacts the service life and efficiency of the entire drilling system. How to accurately predict the sealing performance of metal seals with multi-field coupling and optimize the overall sealing performance under the influence of various factors are the main difficulties of this study. A novel thermal-fluid-solid coupling numerical model was established and verified for the new-generation single energizer metal seals (SEMS2). The fluid film characteristics, interface temperatures, and sealing performance of SEMS2 were investigated under different operating conditions, structural parameters, and material parameters by the co-simulation of MATLAB and ANSYS. Based on the coupling analysis results, the significance analysis of the parameters was performed by using the orthogonal test. Furthermore, the multi-objective optimization of SEMS2 was carried out using the Back Propagation Neural Network (BP NN) and three typical multi-objective evolutionary algorithms (MOEAs). By comparison, the elitist non-dominated sorting genetic algorithm (NSGA-II) performed better than the strength Pareto evolutionary algorithm (SPEA2) and region-based Pareto Envelope based Selection Algorithm (PESA-II). The leakage rate and frictional force of SEMS2 were reduced by 52.3 % and 11.0 %, respectively, after multi-objective optimization. The results could provide theoretical support for designing a high-efficiency and long-life sealing system for onshore and offshore drill bits.

Kinetic criteria for evaluating the performance of roller-cone drill bits

Research objective is to work out a method of evaluating the performance of roller-cone drill bits by kinetic criteria. Introduction. It is difficult to determine the absolute criteria for the performance of rock cutting tools. Therefore, the relative values of wear resistance of the cutting structure of roller-cone bits and their relative mechanical rates of drilling are adopted as process criteria. Methods of research. The calculation and analysis of kinetic criteria for evaluating the performance of drill bits have significant differences. Taking them into account is important when studying various modifications of rock cutting tools. The set of kinetic criteria gives a picture of the relative performance of the bit using the model of the well bottom close to the real one. The set of kinetic characteristics (criteria) is conventionally called the kinetic datasheet of the drill bit. The key points of constructing an analytical model of the drill bit operation on the deformable well bottom have been considered. Scope of results. This technique provides for a comparative evaluation of roller-cone drill bits of various modifications, allows for finding feedback, i.e. searching for the appropriate combination of geometrical parameters of the rock cutting tool according to given kinetic characteristics. The versatile approach intended for use in the study of the performance of rock cutting tools allows the most complete and accurate evaluation of the influence of one factor or another on the final result.

Expression of the Self-Sharpening Mechanism of a Roller Cone Bit during Wear Due to the Influence of the Erosion Protection Carbide Coating

Roller cone drill bits are used in drilling larger diameter wells. The drilling efficiency of the roller cone drill bit depends on the wear rate of the materials that forms bit teeth, which crushes the rock at the bottom of the well. To prevent excessive wear, research has largely focused on the study and determination of abrasion-resistant materials. In our work, we investigated the wear mechanism of a roller cone drill bit whose wear-resistant teeth are protected by a hard metal coating welded onto the teeth. The difference between material properties of erosion-protective carbide coating and the tooth steel leads to uneven wear of bit teeth. In order to determine the material changes, we carried out detailed studies of the rock through which drilling was carried out, the drilling parameters and the materials of which the roller cone bit is made. The principle of wear of the tooth materials and their carbide coating, determined by our research, indicated the guidelines which could be basis for the development of abrasion-resistant materials could be carried out, as well as the problem of applying an erosion protection to the teeth of the studied type of roller cone bits.

Mechanical behavior and sealing performance of HAR sealing system in roller cone bits

Mechanical behavior and sealing performance of HAR sealing system in roller cone bits

Research of the kinetics of thickness of the boundary layers of lubricating materials applied to drilling technology

Improving the operational properties of lubricants increases the service life of the mechanisms and increase the durability of rubbing joints, which has a positive effect on the indicators of technical and economic efficiency and equipment safety. Therefore, great attention in tribology is paid to the analysis of the state of friction units in technology and the assessment of their resource characteristics, which makes it possible to increase their service life. The research aim is to study the general provisions on lubricants and lubricants, as well as the features of the boundary layers formation on friction surfaces and the observed patterns. Calculations of the boundary layers thickness using lubricating reagents at different energetic loading of the friction pair were carried out as applied to the roller bearing of a roller cone bit in the medium of cylinder oil 52 and DPS grease. The proposed research methodology made it possible to in-crease the efficiency and effectiveness of the means development for improving the tribotech-nical properties of drilling lubricants.

An empirical model for the drilling performance prediction for roller-cone drill bits

The drilling process is a challenge in the oil and gas industry. These challenges are usually associated with the high costs involved in this process. Technological advances in the past few years, specifically in the drilling process, have allowed the exploitation of oil and gas fields that were uneconomical before. The economic feasibility of drilling a well is directly associated with the accuracy of the plan before the drilling starts, called “well planning”. Therefore, an accurate drilling performance prediction is crucial. Usually, the approaches to drilling performance prediction are divided into two categories: physics-based and data-driven models. Physics-based prediction models, or traditional models, are based on laboratory experiments, being empirical models designed for specific types of drilling parameters. Data-driven models are based purely on data, incorporating either machine learning or the implementation of neural networks to predict the rate of penetration. de Moura et al. (de Moura et al., 2020) developed a new drilling performance prediction model that includes the founder point location for fixed cutter drill bit operations. This model was based on the physics-based prediction approach because it usually presents low complexities and good accuracy. Based on several drilling datasets, the applicability and accuracy of the new model for roller-cone bit operations is discussed. Based on an analysis of the drilling data-sets from drill-off tests and field operations, the linear relationship between the “drillability constant” of the Maurer model and the weight on bit (WOB) was confirmed. The results of this study show that the new model presented high accuracy to predict the drilling performance in 25 distinct scenarios that included roller-cone bits with diameters that varied between 63.50 and 444.50 mm and in different rock specimens with rock strength varying between 30 and 317.16 MPa. • The development of a drilling performance prediction model that includes the location of the founding point is essential for the planning of wells. • Physics-based prediction models have low complexity and good accuracy. • This model showed high accuracy for roller-cone drill bits. • The Maurer's model is restricted to predicting drilling performance before the founding point. • The drillability constant has a linear dependence on the WOB.

Non-linear Axial Vibrations of Composite Drill Strings Considering Interaction of Roller Cone Bit and Polycrystalline Diamond Compact Bit with Rock

Due to the world increasing energy demands, optimizing the drilling system parameters such as the weight on bit (WOB), and the structure of drill string and bit, also vibrations and dynamic behavior of drill strings are of significant interest to researchers and energy industries. Specially, to overcome limitations of drilling operations in oil and gas industry, composite drill strings as high-tech devices are under development. In this research, the fully coupled non-linear axial vibrations of composite drill strings due to the interaction of two common bits namely; Roller Cone (RC) and Polycrystalline Diamond Compact (PDC) with rock, considering the major non-linear terms, the drill string-wellbore contact, the different weight on bit (WOB) and the different composite configurations using the finite element method (FEM) and the Lagrangian approach were studied. This study proved that the different configurations of composite drill strings showed specific dynamic behavior at different conditions. Therefore, composite drill string can be designed for particular purposes. Also, the results imply the remarkable effects of weight on bit (WOB) and type of bits on the axial vibrations of composite drill strings.

Анализ методов диагностики технического состояния шарошечных буровых долот корпусного типа

Анализ методов диагностики технического состояния шарошечных буровых долот корпусного типа

Investigation of hydrodynamic parameters and modernization of PDC drill bit elements

The rapid development of well construction technologies is inherently associated with the improvement of the technology that is used in this case. Tools of a new generation - bits with diamond cutters (PDC) - are widely used, in which technical and economic indicators are significantly better than roller cone bits. Although their design is well developed, the issue of optimizing the operation parameters of jetting nozzles, the design features of which determines the efficiency of well construction, remains relevant. Despite the effectiveness of the existing design of PDC bits, the study of hydrodynamic parameters was carried out using simulation modeling. Such a study makes it possible to assess the hydrodynamic parameters of the bit, develop recommendations for their improvement, which in turn will improve the efficiency of well construction in general. Computer programs designed for simulation of hydrodynamic processes make it possible to determine the necessary parameters with great reliability. However, the accuracy of the obtained result will depend not only on the settings of the grid of finite volumes, the number of iterations, but also on the initial data. Therefore, in the calculation model, in addition to the main parameters, such as the flow rate of the drilling fluid, the pressure at the bottom of the well, the bit rotation frequency, density, temperature and model of the drilling fluid viscosity, the roughness of the surfaces of both the bit and the walls, and the bottom of the well are taken into account. As a result of simulation, the drawbacks of the existing designs of PDC bits were identified, which can be eliminated using the proposed design of the jet nozzle, which: creates a large vorticity of the fluid flow, which positively affects the capture and removal of cuttings; makes it possible to regulate the direction of fluid movement (especially important for nozzles that are located farther from the bit axis), which will improve the removal of cuttings and, accordingly, will prevent it from re-entering the bottom

Change of the Properties of Steel Material of the Roller Cone Bit Due to the Influence of the Drilling Operational Parameters and Rock Properties

The breakdown of the drill bit or rapid decrease of the rate of penetration during the drilling process results in a delay in the progress of drilling. Scientists and engineers are increasingly focusing on research to extend the bit life and improve the drilling rate. In our work, “in situ” drilling parameters were monitored during the drilling process with the roller cone drill bit IADC 136, diameter 155.57 mm (6 1/8"). After drilling, the bit was thoroughly examined to determine the damage and wear that occurred during drilling. The following modern and standardized investigative methods were used: an analysis of rock materials and an analysis of micro and macrostructure materials of the roller cone bit. Analyses were carried out using optical and electron microscopy, a simultaneous thermal analysis of materials of drill bit, analysis of the chemical composition of materials of drill bit, and a determination of the geomechanical parameters of rock materials. The resulting wear, local bursts, and cracks were quantitatively and qualitatively defined and linked to the drilling regime and the rock material. The results of our investigation of the material of the roller cone bit can serve as a good base for the development of new steel alloys, which can resist higher temperatures and enable effective drilling, without structural changes of steel material.

The influence of technological factors during pressing tungsten carbide insert cutter in the cone of the roller cone bits for the reliability connection

One of the key aspects, which are designed to ensure the quality’s production of cones for roller cone bits drill bits with carbide insert cutter are presented. The influence of technological parameters on the formation of holes for planting carbide insert cutter and the assembling operation of the connection tungsten carbide insert cutter-cone. The analysis showed that at the stages of holes reaming operations there are the most problems in quality assurance. Based on numerous experiments on different sizes of carbide insert cutter, it is established that the speed of the pressing process is extremely important. Analysis of cut and disassembled such joints revealed that the walls of the hole have a significant plastic deformation, micro cracks, and in some places chips formed at the bottom of the hole. The parameters of deviation in the roughness of such surfaces were also investigated. If we use the recommendations, then we found that wetting the carbide insert cutter in oxidized paraffin reduces the plastic deformation of the hole’s wall in half. This allows you to increase the tension in the connection. In order to increase the accuracy of the pressing operation, a special device was developed, which allowed accurately orienting the carbide insert cutter before pressing, as well as significantly reducing the shortage. Analysis of the hole’s walls on the steel AISI 9315H revealed that at tensions up to 0.068 mm there was an elastic deformation, then up to 0.148 mm, and then with increasing tension was obtained significant plastic deformation. Theoretically and experimentally substantiated developed methods to improve the technology of drilling bits, which minimizes the deformation of cones and carbide, insert cutters. The main purpose was to determine the empirical dependence, which allows establishing the relationship between the roughness parameters and the amount of tension in the connection cone- carbide insert cutter .

The Design and Analysis of Roller Cone Bit Bearing Ring

Increasing the sealing performance of bearing rings of roller-cone bits plays an important role in reducing the bearing seal failure and improving the service life of drill bits. This paper conducts (1) the structure design of the sealing rings. (2) a simulation on the new designed structure of roller cone bit. The contact pressure together with the equivalent stress of the new tooth bars was analysed by building up the finite element model of the bionic non-smooth surface structure, beyond that the comparisons between the new structure and O type sealing ring were carried out. The results indicate that the ribbed sealing structure is capable of improving the wear resistance, postponing the wear abrasion and ageing, and increasing the service life of rubber ring.

A Method for Optimizing the Structure of the Roller Cone Bit Assembly

A Method for Optimizing the Structure of the Roller Cone Bit Assembly

Characterisation of the Wear of the Roller Cone Drill Bit Caused by Improperly Chosen Drilling Regime

Abstract The rapid drop in the penetration rate or failure of the drill bit during the drilling process delays the drilling process. In our investigation, the ‘in situ’ drilling parameters were monitored during the drilling process along with the roller cone drill bit, which is suitable for drilling in soft rock formations (IADC 136). The drill bit was thoroughly examined to determine its damage and wear occurred during drilling along with decreasing penetration rate. The modern and standardised investigation methods were used to analyse the rock materials and the micro- and macro-structure of the materials of the roller cone bit. The analyses were performed by means of optical and electron microscopes, simultaneous thermal analysis of the steel materials, analysis of the chemical composition of the materials of the drill bit and determination of the geomechanical parameters of the drilled rock. The resulting wear, localised fractures and cracks were quantitatively and qualitatively defined and the parameters were correlated to the drilling regime and the rock material. The results of our investigation of the material of the roller cone bit can serve as a good basis for the development of new steel alloys that can withstand higher temperatures and allow effective drilling without structural changes of the steel material.

On the development of an experimental design and field test of an upper bit tool

The design of upper bit tools has been developed. Such tools provide crushing, sifting and removal of slurry from the bottom when drilling vertical, deviated and horizontal wells with a roller cone bit. The analysis of slurry samples from directional and horizontal wells was carried out to determine rational geometric dimensions of the working channels of the upper bit tool. The design requirements of upper bit tool, ensuring the stability of its operation, are presented.

Lubrication system of a roller cone bit

For drilling roller bits that work with face purging, a device for a circulating lubrication system is proposed through the use of a plunger pump. A constant circulation of the lubricant is realized with a performance proportional to the speed of the bit. The relationship between the parameters of the lubrication system and the purge air pressure with the maximum depth of the well is established. The obtained equations allow us to determine the parameters of the bit journal lubrication system and exclude the penetration of drilling products into the bearing cavity, which will increase the bit life.