Roller Bit Research Articles

Computerized design of blasting parameters based on drillability index of jointed rock mass in roller bit drilling in open pit mines

Blastability of rocks mainly depends on their strength (hardness) and jointing. Rock drillability is found both by Russian and foreign scientists using the rock strength and elasticity characteristics. In the meanwhile, practice shows that jointing in rock masses with joint sizes of 0.1–0.5 m increases the rate of drilling. Consequently, when determining the rate of roller bit drilling and drillability of rock mass, the jointing parameters of rocks should be taken into account. This article presents the found relations for finding the roller bit drilling rates, drillability index and the main blasting parameters in open pit mining in jointed rock masses. The relation of the roller bit drilling, drilling techniques and drillability index includes the hardness factor and the parameters of jointing. The formula of the drillability index of jointed rock mass is obtained. The validity of the relations is proved by the comparison of the calculation results with the physicotechnical properties of rocks, as well as with the Wenco system data on drilling in Verninsky Open Pit Mine of Polyuszoloto. Using the drillability index, the formulas are obtained for determining the powder factor and explosive charge weight per hole. On the whole, based on the drilling data, a dedicated software program is designed for determining the drilling index and the main blasting parameters in open pit mines at the preset fragmentation quality for jointed rock mass.The authors express their gratitude to V. I. Volkov, I. V. Rykov and N. N. Zakharov, specialists from Verninsky OPM, for their help in these studies.

Tricone drill bit performance evaluation

The process of drilling can be addressed from the points of technique and technology. Technique means engineering, design and manufacture of rock-breaking drilling tools. Technology includes selection of the optimal drill tool designs in compliance with the physical and mechanical properties of rocks at the bottomhole, and in accord with the optimal modes of drilling. Roller bit drills are used in execution of 70 % of total exploration and production drilling in the world. The drill bits of this kind can actually and greatly enhance efficiency of the whole drilling process. Extremely complex kinematics of bit work in drilling, as well as high impacts applied to the bits in drilling in rocks of different hardness, viscosity, plasticity and abrasivity make the drill bit one the most complex and high-loaded mechanisms which operate under conditions of high vibrations, in a confined space and in the medium of abrasive drilling fluid. Extremely complex conditions also exist in operation of drill bits with removal of chippings and with cooling of the tool components by feeding compressed air to the bottomhole. In recent years, as the design basis is improved, and new materials and technologies appear, designers pay much attention to the design optimization and fabricability improvement of drill bits. To this effect, it is required to take into account the axial load, rotation frequency, hole diameter, rock hardness factor, as well as physical and mechanical properties of rocks a function of drilling depth. In estimation of energy inputs, it is required to validate a more effective design of a drill bit. The authors study a few operating modes of tricone drill bits, and give recommendations on their design improvement, productivity enhancement, reliability increase and life extension.

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.

Improving drilling speed and borehole quality in ultra-deep complex formations through rock mechanics research

Halahatang oilfield in Tarim Basin is a typical ultra deep fractured vuggy carbonate reservoir, which is the main production area of crude oil in Tarim Basin. The wellbore instability is serious in Triassic and lower strata (the borehole enlargement rate is 22% - 31%). Due to the complex rock characteristics, the drilling cycle for single well is long (124 days on average), and it is difficult to speed up. Based on the log interpretation curves, the calculation methods of pore pressure, collapse pressure and fracture pressure profiles established, and the spatial distribution characteristics of three pressures in this area were analysed; The rock drillability, rock hardness, compressive strength and abrasiveness of the roller bit and PDC bit single well measured by laboratory tests. Based on the statistical regression method, the relationship between the above drilling rock mechanical parameters and logging acoustic time difference and the formation drillability profile single were studied. The research results guide the drilling design optimization and operation of 15 wells in Ha 8 and Ha 12 blocks, The average drilling cycle is reduced by 21% (from 124 days to 98 days), and the hole enlargement rate is reduced from 24% to less than 10%.

Effect of Heat Treatment on the Structure and Properties of the Carburized Layer of the Legs of Three-Ball Drill Bits

The effect of time-temperature parameters of heat treatment on the structure and properties of carburized case and the core of 19CrMnNiMo steel was studied. The critical points were determined by dilatometric analysis: Ac1 = 740°C, AC3 = 835°C. It was established, that after carburizing at 940 °C, prequench to 890 °C with oil cooling, quenching at 790 °C and tempering at 180 °C, martensite structure of carburized case with uniformly distributed carbides and the least amount of retained austenite is formed. The hardness of carburized case decreases smoothly from the surface into the depth, in proportion to the decrease in the carbon concentration and amounts to 60-50 HRC. The technological process of heat treatment of drill bit legs made of 19CrMnNiMo carburized steel providing minimal amount of retained austenite in structure, absence of carbide network and combination of optimum mechanical properties which is proved by a real on-site experiment is developed. Temperature conditions of carburizing, quenching and low tempering are recommended for the production of legs of roller bits.

Titanium in Cast Cu-Sn Alloys-A Review.

The article reviews the progress made on bronze alloys processed through various casting techniques, and focuses on enhancements in the microstructural characteristics, hardness, tensile properties, and tribological behaviour of Cu-Sn and Cu-Sn-Ti alloys. Copper and its alloys have found several applications in the fields of automobiles, marine and machine tools specifically for propellers in submarines, bearings, and bushings. It has also been reported that bronze alloys are especially used as an anti-wear and friction-reducing material to make high performance bearings for roller cone cock bits and warships for defence purposes. In these applications, properties like tensile strength, yield strength, fatigue strength, elongation, hardness, impact strength, wear resistance, and corrosion resistance are very important; however, these bronze alloys possess only moderate hardness, which results in low wear resistance, thereby limiting the application of these alloys in the automobile industry. The major factor that influences the properties of bronze alloys is the microstructure. Morphological changes in these bronze alloys are achieved through different manufacturing techniques, such as casting, heat treatment, and alloy addition, which enhance the mechanical, tribological, and corrosion characteristics. Alloying of Ti to cast Cu-Sn is very effective in changing the microstructure of bronze alloys. Reinforcing the bronze matrix with several ceramic particles and surface modifications also improves the properties of bronze alloys. The present article reviews the techniques involved in changing the microstructure and enhancing the mechanical and tribological behaviours of cast Cu-Sn and Cu-Sn-Ti alloys. Moreover, this article also reviews the industrial applications and future scope of these cast alloys in the automobile and marine industries.

Influence of bit size on stability bottom drill column balance when drilling a horizontal well

The article raises the question that if you change the bit type, the "critical length" of the lower part of the drill string change too. For the first time, the issue of the stability of the lower part of the drill string when drilling a horizontal section of the wellbore was formulated and solved, taking into account the features of the bit designs (roller bit, wing bit, PDC bit) and the mechanism of rock destruction in well drilling. The research uses the generally accepted provisions of the linear theory of elasticity of materials, the theory of stability of rods and shells. It is assumed that the lower part of the drill string is a heavy elastic rod, experiencing the combined action of the forces of the pipe's own weight and the axial load on the bit, and the twisting moment from the rotor table acting on the pipe string is not taken into account. To find the "critical length" of the lower part of the drill string, simple approximate formulas are obtained that take into account the bit size, drill collar and axial load.

Research on variation law of geophysical drill-bit downhole flow field under the interaction of multiple hydraulic factors.

Mountain geophysical prospecting operations play an important role in the entire petroleum exploration field. Geophysical drill-bit is the main tool for mountain geophysical prospecting operations. Its hydraulic structure directly affects the downhole flow field and then affects the chip removal efficiency and drilling efficiency of the bit. At present, most of the scholars' research is focused on Poly Diamond Crystalline bit, roller bit, etc., and the research on geophysical drill-bit is less, and most of them study the downhole flow field based on the change of single hydraulic structure. The primary objective of this research is to study the variation law of the downhole flow field under the interaction of multiple hydraulic structure factors. The drilling time and cuttings size of two geophysical drill-bits with different hydraulic structures are compared, and the key hydraulic structure factors are selected for analysis. Using numerical simulation software, take different levels of key hydraulic structure parameters and carry out orthogonal experiments. Under the interaction of various factors, study the flow field distribution in the flow channel, the downhole, and the annulus area of the shaft lining. The hydraulic structure of the geophysical drill-bit is closely related to the drilling speed and chip removal efficiency. When multiple hydraulic factors are changed, the diameter of the flow channel is the best when it is 10-12.5 mm, the inclination of the flow channel should be set as close as possible to the center of the downhole, and the length of the chip groove increases, the movement of cuttings is more stable. Variation law of downhole flow field under the interaction of multiple hydraulic factors is studied. This study provides a basis for the hydraulic structure design and optimization of the geophysical drill-bit.

Improving accuracy and technology for manufacturing tricone roller bits

As a result, the control of the process of basing a roller bit in a chuck was experimentally tested and introduced into production by measuring the gap between the working surface of the restrictive ring and the calibrating surface of the cone in order to increase the accuracy of drill bit manufacturing. Bits with a diameter close to the lower limit value can be machined in a chuck with a restrictive ring of reduced diameter. Height differences of the cones are reduced by introducing into the production the method of group interchangeability of sections in height, measured in a direction parallel to the axis of the bit.

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.

Information technology of ultrasonic assembly and pressing of joints

The paper considers the issues of increasing the efficiency of forming press connections by using additional ultrasonic vibrations introduced during the pressing process. A distinctive feature of the proposed approach is the use of ultrasonic vibrations simultaneously both for technological purposes to improve the efficiency of Assembly of press connections, and for indirect non-selective diagnostics of formed connections by analyzing vibrations directly in the Assembly process. The developed algorithm and device for ultrasonic pressing of teeth of a roller bit with an assessment of the quality of pressing on diagnostic indicators is presented.

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.

Analysis of the roller bit lubrication system

The results of most studies conducted in the field of improving the reliability and performance of roller drill bits indicate the main cause of their failure, which is the failure of the bearing unit. We believe that work on improving the reliability and performance of roller bits lies in the modernization of existing or the development of fundamentally new lubrication systems for roller bits.

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.

About transition processes in blasthole drilling at quarries

As a system, the mining enterprise develops under constantly changing conditions of the external and internal environment. These conditions affect the state of the most important drilling subsystem: blasthole drilling technology, safety, performance, power consumption of the boring rigs and roller bits used. The main transition processes as necessary responses of the subsystem to changing conditions were identified as a result of fragmentary data analysis showing decisions taken over the past 15-20 years, which increase drilling activity efficiency and safety of smaller quarries of Russia, which contain a significant amount of material resources. The main transition processes contribute to the growth of drilling performance and consist of changing the following: bit design for specific rocks; drilling method; drilling mode; boring rig design; controlled parameters of drilling process and rock properties redetermination; parameters of maintenance and repair system. Based on the performed analysis, the systematization results of the main factors predetermining the need for transition processes implementation in the “drilling operations” subsystem were obtained and presented. The proposed approach allowed to reveal a holistic picture of the main interacting factors in the “drilling operations” subsystem. Based on the factors systematization presented in the article it is possible to envisage changes of individual factors depending on changes of other factors, not functionally related directly when planning drilling operations.

Elements to improve theory of roller cutter bit with chisel teeth

The article deals with solving the problem of determination in the first approximation of the time of the interaction of tricone bit tooth with the rock and the maximum dynamic impact force. Considered the roller bit teeth are of types Sh and B. The shape of the bottom hole after the previous penetration the rock is adopted as having spherical mounds between paths. It is believed that deformations during the impact of the tooth occur only in the area of ​​the mounds, neglecting the masses of the rock material being deformed. The concept of the consolidated mass of the part of the rock, which is disintegrated and sections of the mass of the drill string with a roller bit is introduced. Separate consideration is given to determining the time and maximum impact force at the stages of sinking the rock and the raising of the tooth from it. In raising the plastic deformation of the material of the rock and its elastic return are taken into account. The determination of these parameters is carried out both without considering the moment of inertia of the roller bit, as well as taking into account this moment. It is shown that during the oblique impact of the tooth on the mound, taking into account the moment of inertia of the roller bit, it is necessary to know the coefficient of friction of the rocks over the tooth and the initial acceleration of the roller bit. In this case, the normal and the tangential component of the force of the specified impact of the tooth on the mound is considered separately. Were suggested analytical dependences for determination of the normal and tangent component of the shock interaction force module, as well as their maximum value.

Modern drilling technologies used for the making bored piles under the conditions of dense urban area

The parameters of drilling boreholes (including depth, diameter, angle of borehole inclination, cross-section) that are currently used for the making bored piles under the conditions of dense urban area, have been considered. The review about modern technologies of drilling boreholes used for making bored piles has been prepared. The updated classification of drilling technologies used for the making bored piles, which taking into account the nature of the removal of the destroyed rock and the movement of the drilling tool, the type of drilling tool, as well as the method of mounting the borehole walls, has been proposed. The classification, according to the nature of removal of the destroyed rock, distinguishes technologies providing or not providing the removal of destroyed rock. According to the nature of movement of the drilling tool, the rotary, shock and vibration technologies, as well as a static indentation technology, can be identified. According to the type of drilling tools, the classification divides methods into hollow drill stem with sacrificial drill bit and soil compactor and displacement tools with a starter auger section, augers, drilling buckets, core barrels, belling buckets, roller, impact and three-way bits, grabs. According to the methods of well casing, the technologies can be divided into the ones, allowing and not allowing the casing of well.

Adaptive model of the control of roller bit drilling process

The article is devoted to research of the features of roller-bit drilling process control under incomplete information caused by random variation of the drilled rocks properties. It is proposed to optimize control model of the roller-bit drilling process parameters that uses the correction values of axial force and rotational speed of drill bit. The optimization method of operating parameters of roller-bit drilling process is developed and based on the correcting values of axial force and bit rotational speed depending on the technical characteristics of the drilling unit and physic and mechanical rocks properties. The proposed method allows determining the maximum headway per drill bit, drilling speed and its ratio corresponding to the optimum efficiency of the roller-bit drilling process, required for adaptive control of process parameters. The structure of intelligent automated control system of roller-bit drilling process with an adaptive element is developed and this system can adjust and maintain the values of operating parameters correspondingly actual rocks properties for effective process control.

Modified calculation model for loads of bearing systems for tricone roller bits

Abstract The article presents a modified calculation model of loads of cone bearing systems in tricone roller bits. The presented model includes the actual nature of the loads of a tricone roller bit and the effect of these loads on the construction of individual elements of the cone bearing systems. The presented calculation model was created in order to develop a computer program that allows the calculation and verification of structural parameters of cone bearing systems even at the stage of their initial design. It will allow an optimal selection of these parameters to geological properties of drilled rocks.

Back-to-back endurance design procedure for elements of roller bit bearing

Back-to-back endurance design procedure for elements of roller bit bearing