Flexible Drilling Research Articles

Research on the dynamic behavior of flexible drilling tools in ultrashort-radius radial horizontal wells

A flexible drilling tool is a special drilling tool for ultrashort-radius radial horizontal wells. This tool is composed of many parts and has the characteristics of a multibody system. In this paper, a numerical method for the dynamic analysis of flexible drilling tools is proposed. The flexible drill tool is discretized into spatial beam elements, while the multilayer contact of the flexible drilling tool is represented by the multilayer dynamic gap element, and the dynamic model of the multibody system for the flexible drilling tool’s multilayer contact is established, considering the interaction force between the drill bit and the rock. The nonlinear dynamic equation is solved using the Newmark method and Newton–Raphson method. An analysis of the dynamic behavior of a flexible drilling tool is conducted. The results indicate that the flexible drilling tool experiences vortex formation due to the interaction between the flexible drilling pipe and the guide pipe, leading to increased friction and wear. This situation hinders safe drilling operations with flexible drilling tools. The collision force of the flexible drilling tool near the bottom of the hole is more severe than that of the other tool types, which may lead to failure of the connection.

Operative Effect Comparison of Flexible Drill Guiding vs. Traditional Drill Guiding Template for Lower Cervical Pedicle Screw Insertion: A Retrospective Analysis.

Accurately inserting pedicle screws is the key point of posterior pedicle screw fixation for lower cervical spine (C3-C7) instability. 3D printing technology can improve the accuracy of screw placement. This study compared the safety of 3D-printed flexible drill guiding template vs. traditional rigid drill guiding template for lower cervical pedicle screw insertion. This was a retrospective study. A total of 34 patients who underwent lower cervical pedicle screw fixation from March 2018 to May 2021 were enrolled in this study, and they were divided into the flexible drill flexible drill group and the traditional drill group. A total of 18 patients in the flexible drill flexible drill group underwent pedicle screw fixation assisted by 3D printed flexible drill guiding templates for the lower cervix, and 16 patients in the traditional drill group underwent pedicle screw fixation assisted by 3D printed regular drill guiding templates for the lower cervix. The length of the incision and intraoperative blood loss during surgery were recorded and compared for the two groups. The grade, deviation of the screw entry point, deviation of the screw medial angle and screw length were measured and compared after surgery for the two groups by independent-sample tests. There was a significant difference in the length of the incision and blood loss between the two groups (P < 0.05). There was a significant difference between the two groups for grade (P = 0.016). The deviation of the screw entry point was 0.65 ± 0.50 mm in the flexible drill group and 0.78 ± 0.83 mm in the traditional drill group. The deviation of the screw medial angle was 2.14 ± 1.78 in the flexible drill group and 4.23 ± 2.51 in the traditional drill group, with a significant difference between the two groups (P < 0.05). Compared with regular guiding techniques, lower cervical pedicle screw placement assisted by multistep navigation templates and flexible K-wires results in less trauma and better safety.

Design of Flexible Drill Pipe with Ultra-Short Radius in Sidetrack Horizontal Well Based on the Snake Bone Directional Variability

Design of Flexible Drill Pipe with Ultra-Short Radius in Sidetrack Horizontal Well Based on the Snake Bone Directional Variability

Research on Multi-Body Collision Dynamics of Ball Cage Flexible Drill Pipe Considering Borehole Curvature

A ball cage flexible drill pipe is a new type of ultra-short-radius drilling tool, which consists of multiple flexible joints hinged together. During the drilling process, the flexible members will come into contact and wear, which reduces the efficiency of load transfer. The multi-body collision contact dynamics model was proposed to study the performance of the ball cage flexible drill pipe. The method considered the influence of the borehole curvature. The kinematic equations of the ball cage flexible drill pipe were established. The Lankarani–Nikravesh collisional contact model was used to characterize the normal contact force, and the Coulomb friction model was used to describe the tangential contact force. The multi-body motion state of the flexible drill pipe was simulated, the contact force distribution of the flexible drill pipe during the motion cycle was analyzed, and the influence of the borehole curvature radius on the size of the flexible joints and the contact force was studied. The results show that the running form of the ball cage flexible drill pipe shows a “folded” shape compared with the initial form; the contact force of different flexible joints is in a state of fluctuation; the normal contact force is much larger than the tangential contact force; the matching relationship between the borehole curvature and the length and radius of the flexible joints is derived, which provides criteria for the design of the flexible joints to ensure the reliability of the flexible drill pipe in large curvature borehole; the borehole curvature has an important influence on the collision contact force and load transfer efficiency of flexible drill pipe.

Design of Flexible Drilling and Milling Tool for Composite Wing Beam of Aircraft

To solve the disadvantages of traditional processing tooling, such as long processing cycle, low production efficiency, and easy deformation during the processing of large-size composite wing beams, a drilling and milling tooling for flexible positioning of composite wing beams of multiple types of aircraft is proposed based on the structural characteristics and manufacturing technology requirements of a certain type of aircraft wing spar combined with flexible tooling design technology. And a modular mobile clamping unit with automatic control is designed. Then the practical problems such as the difficult clamping and positioning of large-size wing beams, the deformation and vibration during processing are solved by the flexible drilling and milling tool. The results of the current design are helpful to improve the processing efficiency and shorten the manufacturing period of the wing beams.

Simulation and Field Studies on an Innovative Downhole Machine Designed for Ultrashort-Radius Horizontal Well Drilling Engineering

Ultrashort-Radius Horizontal Well (URHW) drilling engineering plays an important role in increasing the recovery factor of old oilfields. By sidetracking old wellbores at a very high build-up rate, the URHW can effectively exploit the residual oil near old wellbores. Currently, the main problem faced in URHW drilling engineering is the reduced torque received by drill bits owing to the increased friction between the flexible drilling assembly and wellbore as the horizontal section extends, which greatly limits oil production from a single trip. To tackle this problem, we proposed an innovative machine design, a Dynamic Flexible Drill Rod (DFDR), to provide extra torque near the drill bit to extend the horizontal section of the URHW. The interior structure and working principle of the DFDR were illustrated. The mechanical properties of the DFDRs critical load-bearing part were examined via simulation. The torque and pressure loss characteristics were analyzed using computational fluid dynamics. Corresponding modifications were made to optimize the design, with model machines produced accordingly. Field trials were carried out based on old wellbores in Chunliang District, Shengli Oilfield. The DFDR-based technique extended the URHWs horizontal section in this area by 13.38% on average.

Design and application of weight-on-bit control system for drilling process: A variable-gain integrated controller with multiple-model parameter estimation

Controlling weight-on-bit is essential in the drilling process, which determines the rock-breaking performance, drill bit wear, and wellbore quality. This paper aims to develop a weight-on-bit control system for field implementation, using a variable-gain integrated controller and a multiple-model parameter estimator. First, a weight-on-bit dynamic model for controller synthesis is derived according to the real drilling scenario. Then, the integrated controller is designed with two parts: a variable-gain proportional–integral controller and a dynamic output feedback controller, which separates the design of the system’s high-order from low-order parts. The controller gain is tuned through a multiple-model parameter estimator, which estimates uncertain parameters related to rock strength. The established control system is implemented in a typical electrical drilling rig. It meets the requirement of adapting to different formations, considering the flexible drill string and the variable feed motor speed threshold. Numerical and field application results confirm the effectiveness of the developed system.

A robust integrated control design for weight-on-bit fluctuation suppression in drilling process subject to fractured formations

Fractured formations lead to insufficient contact or loss of contact between the drill bit and rocks, which subsequently causes notable fluctuation in weight-on-bit due to flexible drill strings. This paper presents a robust integrated control design to suppress weight-on-bit fluctuation. First, a finite element drill-string longitudinal model is employed as the basis of control design, which has been verified using actual run data. The integrated controller contains a proportional–integral (PI) controller and a dynamic output feedback controller, dealing with the system’s first-order and high-order dynamics. The dynamic output feedback controller only needs to focus on the system’s high-order dynamics since the controller synthesis is based on the pre-designed PI controller. The controller decreases the flexible mode amplitude from disturbance to the output channel through H-infinity loop shaping, making the closed-loop system less flexible. The numerical results demonstrate that the developed approach can effectively suppress weight-on-bit fluctuation due to drill-string flexibility when drilling in fractured formations.

Research on well selection and layer selection methods for tapping the remaining oil at the top of thick oil layers using ultra-short radius lateral drilling horizontal wells

The flexible drilling method of ultra-short radius sidetrack horizontal wells is an effective method to utilize the remaining oil at the top of thick oil reservoirs. By analyzing the current status of the SZ oilfield well network, development stage and sand body development characteristics, combined with the characteristics of ultra-short radius lateral drilling horizontal well technology, the areas and formations suitable for ultra-short radius lateral drilling horizontal well tapping are identified, and the criteria for selecting wells and formations for ultra-short radius lateral drilling horizontal wells are established, which is a guide for the application of this technology.

Design and simulation analysis of impact-resistant flexible drill pipe for rock-breaking rig

In the process of drilling and coring by the rock-breaking rig, the drill rod is affected by the intermittent impact force, which reduces the efficiency of the rig to break the rock and increases the cost of the drilling and coring. Therefore, it is very important to improve the impact resistance of the drill pipe during the rock-breaking process. To achieve this goal, a flexible design of the drill pipe was carried out, and a dynamical model of the drilling rig based on a series elastic actuator was established. Considering the dynamic performance of the system, a torque feedforward link is introduced and a control model based on the force source is established. The influence of the equivalent inertia of the transmission system and the series elastic actuator damping coefficient on the system stability was analyzed by drawing the frequency domain characteristic curve of the system. By using the control and Simulink simulation software, the electromechanical simulation of the model is carried out, and the torque step tracking response of the system is obtained. A torque feedforward link is introduced to establish the control model of the system based on force source. Through dynamic simulation software ADAMS, dynamic and static impact simulation experiments were carried out on the system. The results show that when a force of 200 N is applied to the output end of the drill pipe in the tangential direction, the maximum moments received by the joint under static and dynamic environments are 34.1 N·m and 57.9 N·m, respectively. When the impact force disappears, the time required for the flexible drill pipe to reach a stable state is only 0.15 s, which verifies that the series elastic actuator–based drill pipe model can alleviate the impact of the external environment and protect the internal structure of the rig.

Design and Performance Research of Flexible Drill Pipe Joint Based on Bionic Theory

Fatigue fracture is the main failure form of mining drill pipe joints, which directly leads to the occurrence of drill pipe drop accidents. Based on the principle of engineering bionics, the spine structure and kinematic behavior characteristics of cheetah were studied; the bionic design and trial production of drill pipe joints were carried out. For the bionic drill pipe joint, it separates the torsion transmission function from the connection function, and when the torsion transmission function of the joint fails, the connection function is still effective, so as to achieve the effect of “breaking the bones and connecting the ribs.” The mechanical and flow field properties of the bionic drill pipe joint were analyzed. Mechanical test results showed that, for the bionic drill pipe joint, the average tensile capacity was 555.48 kN and the average torsion capacity was 8914.13 N·m, which met the mechanical performance requirements. The flow field numerical simulation results showed that, when the drilling fluid velocity field and pressure field were stable and change evenly, there is no risk of leakage. The study results can provide a new research idea for the research and development of mine drill pipe joint with long life and antidropping function.

Retrospective in silico evaluation of optimized preoperative planning for temporal bone surgery

PurposeRobot-assisted surgery at the temporal bone utilizing a flexible drilling unit would allow safer access to clinical targets such as the cochlea or the internal auditory canal by navigating along nonlinear trajectories. One key sub-step for clinical realization of such a procedure is automated preoperative surgical planning that incorporates both segmentation of risk structures and optimized trajectory planning.MethodsWe automatically segment risk structures using 3D U-Nets with probabilistic active shape models. For nonlinear trajectory planning, we adapt bidirectional rapidly exploring random trees on Bézier Splines followed by sequential convex optimization. Functional evaluation, assessing segmentation quality based on the subsequent trajectory planning step, shows the suitability of our novel segmentation approach for this two-step preoperative pipeline.ResultsBased on 24 data sets of the temporal bone, we perform a functional evaluation of preoperative surgical planning. Our experiments show that the automated segmentation provides safe and coherent surface models that can be used in collision detection during motion planning. The source code of the algorithms will be made publicly available.ConclusionOptimized trajectory planning based on shape regularized segmentation leads to safe access canals for temporal bone surgery. Functional evaluation shows the promising results for both 3D U-Net and Bézier Spline trajectories.

P15. Power-assisted pedicle screw placement decreases screw wobble

P15. Power-assisted pedicle screw placement decreases screw wobble

360 Degree Flexible Drilling Machine

Nowadays, the drilling machine is developing very fast with more uses and application. In basic drilling machine, the machine work in particular direction which is the limitation in this machine. And there is more problem like space between the drill and job is very less. In this project we are working on the flexible drilling machine which can work in any direction and can be adjust as per choice. And drilling machine work automatically that can make work easier and can done more accurately. It is mounted on the flat surface as like table which can rotate in any direction, move up and down. It will reduce the setting time and capital for the operation. And in this drilling machine, we use permanent magnetic chuck which is attached to drilling machine.

Two-layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in The Wellbore

Two-layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in The Wellbore

Unloading wave in the cylindrical network from nonlinear elastic fibers

Aims of research. Investigation of a wave of unloading in a cylindrical network of nonlinear elastic fibers. Given the many options for wave propagation in cylindrical networks, an attempt is made to solve the problem of continuous waves. Methods. The movement of the network in the axial direction is cornsidered. nonlinear elastic fibers; To a basis of a cylindrical system are accepted: an individual vector i r parallel wave of unloading; cylindrical network; to a cylinder axis, j r · an individual vector of a tangent to cross-section section continuous waves of the cylinder, k · an individual vector perpendicular to the previous ones, x - is the coordinate in the direction of the axis of the cylinder, y - is the length of an arc of the circumference of the cylinder. The problem reduces to a hyperbolic system of equations under appropriate conditions. Since the wave speed increases when the net is stretched, the stretch wave will obviously be discontinuous. In order to study continuous waves, the problem of wave propagation is solved when unloading a pre-stretched cylinder from a nonlinear basis. The problem is solved by the method of characteristics. Results. The results are illustrated with calculations and can be used at calculations of various flexible pipes, including flexible drilling.

Microfracture in Hip Arthroscopy. Keep It Simple!

Despite all the advances in hip arthroscopy, microfracture is still the workhorse for treating focal and full-thickness cartilage lesions. The success of this treatment is owed to its reliability and simplicity. Given the structure of the hip joint, however, there are challenges to this procedure using a conventional microfracture pick. This note presents our current and preferred microfracture technique using a curve drill guide and flexible drill. This method offers greater range of access to different regions of the joint with ease, thus ensuring a reproducible and quicker procedure with less risk.

Design and Fabrication of 360° Flexible Drilling Machine

Design and Fabrication of 360° Flexible Drilling Machine

Vibration suppression and output constraint of a variable length drilling riser system

In this paper, we mainly concentrate on the control issue of a variable length drilling riser under condition of unknown disturbances and output constraint. The studied flexible drilling riser system with variable length, variable tension, variable speed and restricted boundary output is essentially a nonlinear distributed parameter system. For achieving the vibration suppression and ensuring the boundary output within the constrained range, an appropriate control scheme with output signal barrier is put forward by integrating boundary control method, barrier Lyapunov function with finite-dimensional backstepping technique, where disturbance observer is employed for coping with the boundary disturbance. Moreover, the Lyapunov’s synthetic method is applied for the steadiness research of the studied flexible drilling riser system, and the simulations are presented to display the usefulness of proposed control scheme.

On the development of a new flexible drill for orthopedic surgery and the forces experienced on drilling bovine bone.

This article presents the construction of a flexible drill which is designed to cut a curved canal in the bone or remove bone materials, to improve the outcome of orthopedic surgery and to facilitate minimally invasive. This article reports the design of the flexible drill and uses it in an experimental rig to evaluate the drilling force generated when cutting bovine bone. The experiments facilitate the measurement of action forces between the mill bits when moving the tip toward or across a bone sample in various configurations caused by bending the flexible drill sheath to enable cutting of a curved path of variable radius in the bone. The reaction force represents the force trying to deflect the mill bit tip away from the bone sample surface and must be resisted in order to continue cutting without deflection or buckling of the tip during the drilling of curved pathways. The experiment shows the flexible drill can cut bones in both configurations and experienced a maximal force of 3.4N in the vertical configuration and 0.54N in lateral configuration. The experimental results show that the flexible drill designed is able to produce sufficient force at variable bending angles to perform the required tasks for bone cutting.