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The rotary system of drilling equipment enables the drill string and the drill bit to rotate, thereby penetrating the earth's strata and drilling a wellbore. It is mainly composed of the rotary table, top drive device, drill string, drill bit, and related control systems. The following is a detailed introduction for you: Ⅰ. Main Components Power Source: It provides power for the rotary system. Commonly used ones are diesel engines and electric motors. Large-scale drilling platforms may use multiple diesel engines or electric motors working jointly to meet the power demands of different drilling conditions. Transmission Device: It includes gear transmission, chain transmission, hydraulic transmission and other devices. Its function is to transmit the power of the power source to the drill string, so that the drill string drives the drill bit to rotate. For example, in the rotary table rotary system, the power is transmitted from the power source to the rotary table through gear transmission, and then the rotary table drives the kelly to rotate; in the top drive system, the power is directly transmitted to the top drive device at the top of the drill string through hydraulic or electrical transmission devices. Drill String: It is composed of drill pipes, drill collars, etc., and is an important component connecting the drill bit and surface equipment. It transmits the rotational power from the surface to the drill bit at the bottom of the well. At the same time, during the drilling process, it also plays the roles of conveying the drilling fluid and supporting the drill bit. Drill Bit: It is a tool that directly acts on the rock. According to different geological conditions and drilling requirements, there are various types, such as roller cone bits, PDC (Polycrystalline Diamond Compact) bits, etc. The drill bit, through various cutting structures, rotates and cuts the rock under the drive of the drill string to form a wellbore. Ⅱ. Rotary Table Structure: It is mainly composed of a driving device, a turntable, a main bearing, a sprocket, a braking device, etc. The driving device generally uses an electric motor or a hydraulic motor, and transmits the power to the turntable through the sprocket and chain. The main bearing supports the turntable to enable it to rotate smoothly. The braking device is used to stop the rotation of the turntable when necessary. Working Principle: The driving device provides power, drives the turntable to rotate through the sprocket and chain. There are square bushings on the turntable, and the kelly is inserted into the square bushings. As the turntable rotates, the kelly drives the drill string and the drill bit to rotate together, thus achieving the purpose of breaking the rock. Application Scenarios: It is widely used in various types of onshore and offshore drilling platforms. It is a commonly used rotary component in traditional drilling equipment, especially showing good applicability in the drilling operations of some shallow and medium-deep wells. Ⅲ. Top Drive Device Structure: It is usually composed of a drilling rotary swivel, an electric motor, a gearbox, a main shaft, a balance system, etc. The swivel provides a passage for high-pressure drilling fluid for the drill string. The electric motor serves as the power source, and transmits the power to the main shaft through the gearbox, and the main shaft drives the drill string to rotate. The balance system is used to balance the weight of the top drive device and reduce the load on the derrick. Working Principle: The electric motor drives the gearbox, and the output shaft of the gearbox is connected to the main shaft, driving the main shaft to rotate, and then driving the drill string and the drill bit connected below the main shaft to rotate. At the same time, the drilling fluid enters the inside of the drill string through the swivel and is ejected from the drill bit, realizing the circulation and cuttings-carrying functions of the drilling fluid. Application Scenarios: It is widely used in the drilling operations of deep wells, ultra-deep wells and complex formations. It can improve the drilling efficiency and reduce the time for making up drill pipes. It is especially suitable for situations where frequent tripping of the drill string and control of complex wellbore trajectories are required. Ⅳ. Drill String Structure: It is mainly composed of drill pipes, drill collars, heavy-weight drill pipes, etc. The drill pipe is the main component of the drill string, usually made of high-strength steel pipes, and is used to connect the drill bit and the wellhead equipment, transmitting torque and drilling fluid. The drill collar is located at the lower part of the drill string, close to the drill bit. It has a relatively large weight and is used to apply the drilling pressure to the drill bit to ensure that the drill bit can effectively break the rock. The heavy-weight drill pipe is used between the drill pipe and the drill collar to adjust the weight and stiffness of the drill string.  Working Principle: In the rotary system, the drill string rotates with the rotation of the rotary table or the top drive, transmitting the torque from the wellhead to the drill bit, enabling the drill bit to cut the rock. At the same time, the inside of the drill string is the passage for the drilling fluid. The drilling fluid flows downward from the inside of the drill string under the action of the pump, and after being ejected from the drill bit, it carries the cuttings back to the wellhead. Application Scenarios: It is applicable to various drilling operation environments. Drill strings are indispensable for drilling operations from shallow wells to deep wells, and from onshore to offshore drilling platforms. Different well depths, formation conditions and drilling process requirements will require the selection of drill strings of different specifications and materials. Ⅴ. Drill Bit Structure: The structure varies according to different types. A common roller cone bit is composed of cones, legs, bearings, etc. There are teeth on the cones, and the rock is cut through the rolling of the cones and the breaking action of the teeth. The PDC bit uses diamond compact slices as cutting elements, which are fixed on the bit body. Working Principle: During the rotation of the roller cone bit, the cones roll and come into contact with the rock surface, and the teeth produce impact and extrusion effects on the rock, causing the rock to break. The PDC bit relies on the high hardness and wear resistance of the diamond compact slices to break the rock by cutting, and has a relatively high drilling efficiency. Application Scenarios: The roller cone bit is suitable for various hardness formations, especially performing well in hard formations and abrasive formations. The PDC bit has obvious advantages in soft to medium-hard formations and can achieve rapid drilling. Ⅵ. Control System of the Rotary System Structure: It includes an operation control console, sensors, a controller, etc. The operation control console is the interface for operators to control the rotary system. It is equipped with various buttons, knobs and a display screen, which are used to set parameters such as the rotation speed and torque. Sensors are distributed in various key parts of the rotary system, such as the electric motor, gearbox, drill string, etc., and are used to monitor the running status of the system in real time, such as the rotation speed, torque, temperature, etc. The controller precisely controls each component of the rotary system according to the settings of the operator and the information fed back by the sensors. Working Principle: The operator sets the working parameters of the rotary system through the operation control console. The controller, according to these set values and the actual operation data fed back by the sensors, adjusts the rotation speed of the electric motor, controls the start and stop of the braking device, etc., so that the rotary system operates in the set working state. For example, when the sensor detects that the torque of the drill string is too large, the controller will automatically reduce the rotation speed of the electric motor to prevent the drill string from being damaged due to overload. Application Scenarios: In various drilling operations, the control system plays a vital role. It can ensure the safe and efficient operation of the rotary system and adapt to different drilling process requirements and changes in formation conditions. Ⅶ. Common Faults and Solutions of the Rotary System of Drilling Equipment are as follows: Faults of the Rotary Table The rotary table rotates inflexibly or there is a jamming phenomenon Reasons: The main bearing of the rotary table is worn or damaged, resulting in an increase in the rotation resistance; the chain is too tight or the sprocket is worn, affecting the power transmission; there is foreign matter stuck between the turntable and the base; the clearance between the square bushing and the kelly is too small or the wear is uneven. Solutions: Check the main bearing, and replace it in time if it is worn or damaged; adjust the tightness of the chain, check the wear condition of the sprocket, and replace the sprocket if necessary; clean up the foreign matter between the turntable and the base; check the matching condition of the square bushing and the kelly, adjust the clearance or replace the worn parts. The rotary table leaks oil Reasons: The seals are aged or damaged, resulting in the leakage of lubricating oil; the oil pool level is too high, and the lubricating oil overflows from the seals; the oil pipe joint is loose or damaged, causing oil leakage. Solutions: Replace the aged or damaged seals; check the oil pool level and adjust it to an appropriate height; tighten the oil pipe joint, and replace the joint in time if it is damaged. Faults of the Top Drive Device Faults of the top drive motor Reasons: The motor is overloaded or overheated, resulting in the burnout of the motor winding; the motor bearing is damaged, causing the vibration and noise of the motor; there are faults in the electrical control system, such as contactor faults, line short circuits, etc., affecting the normal operation of the motor. Solutions: Check the load condition of the motor, avoid overload operation, and improve the heat dissipation conditions of the motor; replace the damaged motor bearing; check the electrical control system, and repair or replace the faulty contactors, lines and other components. The top drive swivel leaks water Reasons: The seals of the swivel are worn or aged, resulting in the leakage of the drilling fluid; the wash pipe is worn, affecting the sealing effect; the connection part between the central pipe and the gooseneck pipe is loose or the seal is damaged. Solutions: Replace the seals of the swivel; check the wear condition of the wash pipe and replace the wash pipe in time; tighten the connection part between the central pipe and the gooseneck pipe, and replace the seal if it is damaged. Faults of the Drill String Drill pipe fracture Reasons: The drill pipe is used for a long time, and the fatigue damage accumulates; the drill pipe is subjected to excessive torque, tension or bending force during the drilling process; there are defects in the drill pipe material or problems in the processing quality. Solutions: Regularly perform flaw detection on the drill pipe, and timely find and replace the drill pipes with fatigue damage; optimize the drilling parameters to avoid the drill pipe from bearing excessive loads; strictly control the purchase quality of the drill pipe and select high-quality drill pipes. Drill string sticking Reasons: The performance of the drilling fluid is not good, the filtration loss is large, and a thick mud cake is formed on the wellbore wall, resulting in an increase in the friction between the drill string and the mud cake; the wellbore trajectory is irregular, and there are places with a large dogleg severity, causing local stress concentration of the drill string; the drill string remains stationary for a long time, and adhesion occurs between the drill string and the wellbore wall. Solutions: Adjust the performance of the drilling fluid, reduce the filtration loss, and improve the quality of the mud cake; optimize the wellbore trajectory and reduce the dogleg severity; regularly move the drill string to avoid long-term stationary. Faults of the Drill Bit The drill bit wears too quickly Reasons: The drill bit is not properly selected and is not suitable for the current formation conditions; the drilling parameters are not reasonable, such as excessive drilling pressure and too high rotation speed; the performance of the drilling fluid is not good, and the lubrication and cooling effects on the drill bit are poor. Solutions: Select the appropriate drill bit type according to the formation lithology; optimize the drilling parameters and reasonably adjust the drilling pressure and rotation speed; improve the performance of the drilling fluid and enhance its lubrication and cooling effects. Drill bit balling Reasons: The viscosity and yield point of the drilling fluid are too high, the cuttings are not easy to be discharged, and they adhere to the drill bit; the water holes of the drill bit are blocked, the displacement of the drilling fluid is insufficient, and the drill bit cannot be effectively cleaned; the formation lithology is prone to water absorption and swelling, and a mud cake is formed and adheres to the drill bit. Solutions: Adjust the viscosity and yield point of the drilling fluid to improve its cuttings-carrying capacity; check the water holes of the drill bit, clean up the blockages, and ensure the normal displacement of the drilling fluid; for formations prone to water absorption and swelling, add anti-swelling agents and other treatment agents to improve the formation conditions.

The main differences between the kelly drive and the top drive are as follows: Ⅰ. Main differences Structural Location:The kelly drive device is mainly composed of a rotary table, a swivel, a kelly, etc. The rotary table is on the drill floor and cooperates with the kelly through a kelly bushing. The top drive drilling system is generally installed at the top of the derrick and includes components such as the swivel-drilling motor assembly, the motor support/guide trolley assembly, and the drill pipe make-up and break-out assembly. Driving Method:The power of the kelly drive device comes from the ground rotary table. It drives the kelly to rotate through the kelly bushing, and then drives the drill string and the drill bit. The top drive is directly driven by the drilling motor installed at the top of the derrick to rotate the top of the drill pipe. Drilling Mode:The kelly drive device adopts single joint drilling. After drilling a length of one kelly (about 9 meters), a joint connection operation is required. The top drive adopts stand drilling. A stand is usually composed of three drill pipes, with a length of approximately 28 meters Well Control Operation:In the case of well kicks and other situations during tripping operations with the kelly drive device, the kelly needs to be lifted out first, and then blowout preventers and other equipment are connected to establish a well control circulation channel. The top drive is generally equipped with two sets of internal blowout preventers, which can connect the drill string quickly, close the annular blowout preventer, and establish the mud circulation within a short time. Automation Degree:The kelly drive device has a relatively low degree of automation, and more manual operations are required for operations such as connecting drill pipe joints. The top drive has a high degree of automation, and many operations can be automated or remotely controlled. The following is a detailed introduction to these two types of products to help you find more suitable equipment: Ⅱ. Kelly Drive The kelly drive device usually refers to the rotary table drive device because in drilling operations, the rotary table generally drives the kelly to rotate. The following is an introduction to the kelly drive device. Structural Composition Transmission Part: It mainly includes components such as the coupling, the input shaft of the chain box, the chain, and the sprocket. Its function is to introduce and transmit power. For example, in the ZP375 rotary table drive device, the power of the motor is transmitted to the rotary table through these components, and then drives the kelly. Support Part: It includes the rotary table beam, the chain box, etc., which are responsible for the positioning and installation of the rotary table, the chain box, the transmission parts, etc., providing stable support for the entire drive device. Control Part: It mainly includes components such as the disc brake, the gas circuit and electrical circuit valves, and the pipelines, which are used to control the operation and speed regulation of the rotary table, and realize the control of the rotation speed and start/stop of the kelly. Working Principle:Taking the ZP275 rotary table drive device as an example, this device uses an AC variable-frequency motor as the power source and adopts a modular structure with chain transmission. After the motor is started, the generated power is transmitted to the input shaft of the chain box through the coupling, and then through the transmission of the chain and the sprocket, the power is transmitted to the rotary table. When the rotary table rotates, the kelly that cooperates with the rotary table bushing rotates accordingly, and then transmits the torque to the drill pipe, driving the drill bit to carry out the drilling operation. Application Scenarios:It is widely used in traditional rotary table drilling operations. Whether it is onshore drilling or offshore drilling, as long as the drilling rig uses the rotary table to drive the kelly for drilling, a kelly drive device is required. For example, in some shallow well drilling and drilling operations under ordinary geological conditions, the kelly drive device can meet the basic drilling requirements. Ⅲ. Advantages of Kelly Drive The kelly drive device has the following advantages: Simple and Reliable Structure Simple Composition: It is mainly composed of basic components such as the rotary table, the kelly, and the swivel. There are no complex intermediate transmission links or too many auxiliary devices, and the structure is relatively simple, making it easy to manufacture, install, and maintain. High Stability: This simple structure makes the connection and cooperation between various components relatively direct. During the drilling process, it can stably transmit power and torque, reducing the possible failure points caused by a complex structure, and has high working reliability. Easy to Operate Familiar Operation Process: Drilling workers are very familiar with its operation process and can master it proficiently after simple training. For example, when connecting drill pipe joints, only a conventional threaded connection operation between the kelly and the drill pipe is required, without the need for complex equipment and technology. Direct Control Method: By controlling the rotation speed and direction of the rotary table, the rotation of the kelly and the drill string can be directly controlled, and then the drilling speed and direction of the drill bit can be controlled. The control method is intuitive and simple, facilitating operators to make timely adjustments according to the actual drilling situation. Good Cost-effectiveness Low Equipment Cost: Compared with some advanced top drives, etc., the equipment procurement cost of the kelly drive device is relatively low. There is no need to purchase high-end equipment such as expensive top drive systems, which has a great cost advantage for some drilling projects with limited budgets. Low Maintenance Cost: Due to its simple structure, its maintenance work is relatively easy, and the required maintenance equipment and tools are also common, resulting in a low maintenance cost. Daily maintenance mainly involves inspecting, lubricating, and replacing vulnerable parts of the rotary table, the kelly, and other components, without the need for professional high-tech personnel and special maintenance facilities. Ⅳ. Disadvantages of Kelly Drive The kelly drive device has the following disadvantages: In Terms of Drilling Efficiency Frequent Joint Connection: The length of the kelly is limited, usually about 9 meters. A joint connection operation is required every time a certain distance is drilled, which will consume a lot of time and reduce the overall drilling efficiency. Slow Tripping Speed: During the tripping process, the kelly needs to be removed from or installed at the wellhead, and the operation is relatively complicated, resulting in a slow tripping speed. Especially when dealing with complex situations such as stuck pipes, the drill string cannot be connected quickly for processing. In Terms of Operation Safety High Labor Intensity: Operations such as connecting drill pipe joints require a lot of physical labor by workers. Workers need to operate frequently at the wellhead, and the labor intensity is relatively high. Moreover, working in such a high-intensity state for a long time is likely to cause fatigue, increasing the risk of operational errors. High Safety Risk: Since a large number of operations by workers are required near the wellhead, such as connecting the kelly and operating the rotary table, there are many dangerous areas around the wellhead. For example, high-pressure mud may spray out, and the drill string may rotate accidentally, which poses a great threat to the safety of operators. In Terms of Power Transmission and Control Torque Loss: The power is transmitted from the rotary table to the kelly, and then to the drill string and the drill bit. There are multiple connection parts in the middle, resulting in a certain torque loss and reducing the power transmission efficiency. Especially in deep wells or situations with high torque requirements, this torque loss may be more obvious, affecting the rock-breaking effect of the drill bit. Low Control Precision: The control of the rotation speed and torque of the kelly drive device is relatively rough, and it is difficult to achieve precise control. In some situations where precise control of drilling parameters is required, such as directional drilling and horizontal drilling, the kelly drive device may not be able to meet the requirements, making it difficult to control the wellbore trajectory. Equipment Wear Severe Drill Pipe Wear: The drill pipe and the drill bit rotate together. The deeper the drilling, the more drill pipes are used, and the greater the weight driven by the rotary table. The wear of the drill pipe also increases exponentially. Ⅴ. Top Drive Drilling System The top drive drilling system, abbreviated as the “top drive”, is a new type of drilling equipment that emerged in the 1980s. It is known as the third revolution in the field of drilling equipment and is one of the three major technical achievements of modern drilling equipment. Structural Composition Swivel-Drilling Motor Assembly: It is the core component, which combines the swivel and the drilling motor to provide the rotation power and the mud passage for the drill string. Motor Support/Guide Trolley Assembly: It moves along the guide rail and can serve as the support beam for the motor, guiding the up and down movement of the top drive. Drill Pipe Make-up and Break-out Assembly: It includes components such as the torque wrench, the internal blowout preventer and the starter, the elevator link connector and the torque limiter, the elevator link tilting device, and the swivel head, etc., to realize the make-up and break-out operations of the drill pipe. Balance System: It prevents the thread damage during the make-up and break-out of the joints and helps the pin joint to pop out from the box joint during the break-out operation. Cooling System: Generally, the air cooling method is adopted to dissipate heat for components such as the drilling motor. Control System of the Top Drive Drilling Device: It realizes various operation controls of the top drive to ensure the safe and efficient operation of the operation Working PrincipleThe motor of the top drive transmits the power to the main shaft through the reduction gearbox. The main shaft drives the swivel to rotate, and then makes the drill pipe connected to the swivel generate a rotational movement, realizing the breaking of the formation by the drill bit. At the same time, under the action of the mud pump, the mud enters the inside of the drill pipe through the central passage of the swivel, and then sprays out from the nozzles of the drill bit, carrying the cuttings back to the surface, completing the mud circulation process, playing the roles of cooling the drill bit, carrying the cuttings, and stabilizing the wellbore. As an important piece of equipment in the field of oil drilling, the top drive has many characteristics and advantages, which are mainly reflected in the following aspects: In Terms of Drilling Efficiency Reducing the Time for Connecting Drill Pipe Joints: Traditional drilling uses the kelly drive, and the drill pipes need to be connected one by one. However, the top drive can adopt stand drilling. Generally, a stand is composed of three drill pipes, which greatly reduces the frequency and time of connecting drill pipe joints. In deep well and ultra-deep well drilling, it can significantly shorten the drilling cycle. Continuous Mud Circulation: During the operation of connecting drill pipe joints or tripping, the top drive can realize the continuous circulation of the mud. There is no need to interrupt the circulation frequently as in the traditional way, which helps to maintain the stability of the wellbore, reduce the occurrence of downhole complex situations, and also saves the time consumed for restoring the circulation. Rapid Directional Drilling: In directional drilling operations, the top drive can adjust the direction of the bottom hole assembly more quickly and accurately. Through the cooperation with the downhole power drilling tool and the measurement while drilling system, it can efficiently complete operations such as directional deflecting and azimuth changing, improving the efficiency and accuracy of directional drilling. In Terms of Operation Safety Reducing the Risk of Manual Operation: It has a high degree of automation. Many dangerous operations that originally required manual operation, such as connecting and disassembling drill pipes at the wellhead, can be completed by the automation system of the top drive, reducing the working time and frequency of workers in high-pressure and high-risk environments, and reducing the labor intensity and safety risk. Equipped with Safety Protection Devices: It is equipped with a variety of safety protection functions, such as torque overload protection, overcurrent protection, and the braking system, etc. When abnormal situations occur during the drilling process, such as the torque suddenly increasing and exceeding the set value, the protection device will be activated immediately to stop the operation of the equipment, avoiding accidents such as the drill pipe being twisted off and the equipment being damaged, and ensuring the safety of personnel and equipment. Convenient for Well Control Operation: In case of emergency situations such as well kicks and blowouts, the top drive can quickly realize the connection between the drill pipe and the blowout preventer, rapidly establish the well control circulation channel, and timely control the pressure in the well, effectively preventing the expansion of the accident and improving the reliability and timeliness of well control. In Terms of Drilling Quality Precise Control of Drilling Parameters: It can precisely control the rotation speed, torque, and weight on bit of the drill pipe. Operators can adjust these parameters in real time according to different formation conditions and drilling process requirements, so that the drill bit always remains in the best working state, which helps to improve the drilling quality and reduce the occurrence of problems such as well deviation and well collapse. Realizing Back Reaming and Tripping Reaming: During the drilling process, if situations such as unstable wellbore and hole shrinkage are encountered, the top drive can conveniently carry out back reaming or tripping reaming operations. By rotating the drill pipe and moving it up and down, it can trim the wellbore, remove the cuttings bed and obstacles in the well, ensure the regularity and smoothness of the wellbore, and create good conditions for subsequent operations such as cementing and logging. In Terms of Economic Benefits   Reduction of Comprehensive Costs: Although the initial purchase cost of the top drive is relatively high, due to its ability to improve drilling efficiency, reduce downhole accidents, and lower labor costs and maintenance costs, etc., from the perspective of the entire life cycle of the drilling project, it can significantly reduce the comprehensive cost and improve the economic benefits. Increase of Oil and Gas Recovery Rate: Through efficient and high-quality drilling operations, the top drive can better realize the exploration and development of oil and gas reservoirs, increase the production and recovery rate of oil and gas wells, and provide a strong guarantee for the long-term stable production and economic benefit improvement of oil and gas fields.