Effects of High-Frequency Torsional Impacts on Rock Drilling

Zhu, Xiaohua; Tang, Liping; Tong, Hua

doi:10.1007/s00603-013-0461-0

Cited by 28 publications

(16 citation statements)

References 24 publications

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“…However, the rock's Mises stress is greater than rock's maximum principal stress at the bottom, and rock failure occurs along the direction of maximum principal stress. The pit has tensile stress, shear stress and compressive stress; shale fragmentation mainly depends on tensile and shear stress in PRD, followed by the compressive stress [15,[18][19][20]. The results can be a suggestion to the drilling parameters' optimization.…”

Section: Shale Dynamic Damage Analysis Of Different Elementsmentioning

confidence: 82%

“…The whole process of shale breaking is finished, as show in Figure 10e,f. The numerical simulation of shale dynamic damage can show the entire rock fragmentation process for any drilling condition and provides a basis and system for the design of PRD without complex experimental instruments and field tests, which can reduce the experiment and test costs dramatically [15,26].…”

Section: Dynamic Damage Process Analysis Of Shale Fragmentationmentioning

confidence: 99%

“…The rock fragmentation process of PRD was studied by a plastic strain failure model, which indicated that PRD mainly depends on impact load, but not rotatory load [14]. A numerical model of high-frequency torsional impacts was used to study the rock crushing process and simulate the evolution of damage initiation and propagation [15]. The impact fragmentation of bluestone was studied by using the FEM [12], which focused on multi-type bits.…”

Section: Introductionmentioning

confidence: 99%

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3D Numerical Simulation and Experiment Validation of Dynamic Damage Characteristics of Anisotropic Shale for Percussive-Rotary Drilling with a Full-Scale PDC Bit

Dong

Chen

2018

Energies

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The lower rate of penetration (ROP) is one of the key technical difficulties during drilling of shale reservoirs. Percussive-rotary drilling (PRD) is crucial for increasing ROP. One of the core problems of ROP optimization for PRD are the dynamic damage characteristics of rock fragmentation. By considering the dynamic drilling parameters, a new model for estimating the PRD with a full-scale polycrystalline diamond compact (PDC) bit is established. The mechanical parameters of shale are measured by a wave velocity method. Rock damage characteristics are simulated by using the finite element method. The numerical simulation model is verified by the actual drilling case in LMX shale reservoir in Sichuan (China). The results indicate that rock element damage occurs along the direction of maximum principal stress. The order of decreasing rock damage rate is impact-static load, static load and impact load. When the impact load has the same peak value, and the rock elements in contact with the cutters obtain more energy with load frequency increasing. The rock fragmentation efficiency under a sine wave is higher than rectangular and pulse waves. The rock can obtain more energy to be broken with the increasing impact load duration and peak values. When the impact-static load goes over the rock damage threshold value, the higher the peak value of the impact load is, the more energy the rock will obtain. The higher the lateral vibration amplitude of the drill bit, the lower the efficiency of rock fragmentation. Repetitions of drill bit axial vibration at one indentation point will reduce the ROP, and the axial vibration energy of the drill bit is consumed. Therefore, a small lateral movement and reasonable axial vibration frequency increase the rock breaking efficiency. The ROP was increased through the suppression of drill string and the application of vibration. The study results can be used in the optimization designs of bit trajectory and ROP for PRD tools.Energies 2018, 11, 1326 2 of 23 percussive drilling, and PRD [4,5]. PRD is developed from rotary drilling and percussive drilling. Significant results in understanding the percussive fragmentation mechanism have also been achieved in the laboratory. The rock fragmentation efficiency is not a linear relationship with the drilling parameters, such as weight on bit (WOB), torque on bit (TOB), and rotations per minute (RPM). Experiments examining rock breakage under dynamic and static loads were carried out. PRD is one of the best ways to improve the drilling efficiency of hard formation. The fragmentation investigation of granite is studied by the use of the dynamic and static rock-breaking test device, reasonable load of single cutter cutting rock under the impact-static action was proposed [6][7][8].Energies 2018, 11, x FOR PEER REVIEW 2 of 23 mechanisms. One of the earliest reports of percussion drilling technique occurred in 1940s [3]. Since then different terms have been used, such as downhole hammer, percussion hammer, down-the-hole hammer, percussive drilling, an...

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Section: Shale Dynamic Damage Analysis Of Different Elementsmentioning

confidence: 82%

Section: Dynamic Damage Process Analysis Of Shale Fragmentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

3D Numerical Simulation and Experiment Validation of Dynamic Damage Characteristics of Anisotropic Shale for Percussive-Rotary Drilling with a Full-Scale PDC Bit

Dong

Chen

2018

Energies

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“…Ulterra Drilling Technologies Ltd developed a torsional impact generator for drilling difficult formations. 29 The generator sits in the drillstring above a PDC bit and addresses the stubborn problem of stick-slip vibration by providing auxiliary energy. The hydraulically driven tool applies high-frequency torsional impacts to the drill bit, which ensures steadier rotation and less stickslip vibration.…”

Section: Generator Of Ulterramentioning

confidence: 99%

“…24,25 As a new drilling tool, however, only few researches on both the tool design and theoretical studies can be found. [26][27][28][29] In this research, HFTID tools are presented to study the torsional impact drilling technique. First, theoretical background of this technique for interpreting the mechanism of enhancing the drilling efficiency is presented.…”

Section: Introductionmentioning

confidence: 99%

On the development of high-frequency torsional impact drilling techniques for hard formation drilling

Tang

Zhu

2018

Advances in Mechanical Engineering

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Stick-slip vibration is a big problem that the drilling of deep wells has to face, especially for drilling of tough formations. This type of vibration leads to failure problems, reduces the rate of penetration, and lowers the borehole quality. Suppression techniques for stick-slip vibration, for example, active control method based on real-time measurement, play important roles in improving the drilling efficiency. The high-frequency torsional impact drilling, however, provides a cheaper and more stable way to mitigate stick-slip in many conditions. This work is aimed to study the high-frequency torsional impact generator, which is used to achieve the function, for this new technique. First, state-of-the-art of highfrequency torsional impact generator is studied by schematically illustrating the existing four structures and their operating principles, followed by comments for these structures. Second, theoretical background of the high-frequency torsional impact drilling is presented, showing how the high-frequency torsional impact generator works to mitigate stickslip and improve drilling efficiency. Finally, an optimally designed high-frequency torsional impact generator is schematically described. It is an improved version of the assembly of United Diamond and the improvements are based on results of a series of laboratory experiments.

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