Rock-Cutting Performance Experimental Research of Particle Water Jet Based on Orthogonal Experimental Method

Particle Impact Drilling is an efficient drilling technology for deep-well hard formation which cuts rock mainly by high-speed spherical particle impacting rock with the help of hydraulic action and mechanical action. In order to determine main influence factors and their order of priority, the orthogonal experiment was designed and the experimental data was analyzed with both the general method and the variance method. The analysis indicates that the order of priority of the main influence factors of particle water jet rock-cutting performance is pump pressure ps, impacting range S, particle mass concentration ω, confining pressure P and particle diameter dp. Moreover, ps is highly important and S and ω are important. In addition, high ps, moderate S, moderate ω, moderate dp and low P could effectively promote particle water jet to impact and cut rocks. Key words: Deep hard formation; Particle impact drilling; Particle water jet; Rock-cutting performance; Orthogonal experiment method; Analysis of varianc

Geology-engineering integration to improve drilling speed and safety in ultra-deep clastic reservoirs of the Qiulitage structural belt

The Qiulitage structural belt in Tarim Basin has a large reservoir burial depth and complex geological conditions. Challenges such as ultra-depth, high temperature, high pressure and high stress lead to significant problems related to well control safety and project efficiency. To solve these key technical issues that set barriers to the process of exploration and development, a drilling technology process via the integration of geology and engineering was established with geomechanics as the bridge. An integrated key drilling engineering technology was formed for improving the drilling speed and safety of ultra-deep wells, including well location optimization, well trajectory optimization, formation pressure prediction before drilling, stratum drillability evaluation, and bit and speed-up tool design and optimization. Combined with the seismic data, logging data, structural characteristics, and lithology distribution characteristics, a rock mechanics data volume related to the three-dimensional drilling resistance characteristics of the block was established for the first time. The longitudinal and lateral heterogeneities were quantitatively characterized, providing a basis for bit design, improvement and optimization. During the drilling process, the geomechanical model was corrected in time according to the actual drilling information, and the drilling “three pressures” data were updated in real time to support the dynamic adjustment of drilling parameters. Through field practice, the average drilling complexity rate was reduced from 18% to 4.6%, and the drilling cycle at 8,500 m depth was reduced from 326 days to 257 days, which comprised significant improvements compared to the vertical wells deployed in the early stage without considering geology-engineering integration.Cited as: Chen, C., Ji, G., Wang, H., Huang, H., Baud, P., Wu, Q. Geology-engineering integration to improve drilling speed and safety in ultra-deep clastic reservoirs of the Qiulitage structural belt. Advances in Geo-Energy Research, 2022, 6(4): 347-356. https://doi.org/10.46690/ager.2022.04.0

Vibration Characteristics of Rock Under Harmonic Impact

Modal analysis of rock is done in this study, and the results of numerical analysis are presented. Meanwhile, the amplitude-frequency characteristic curve of rock in steady state response is investigated based on the principle of vibration. In addition, indoor experiments are carried out to further analyze the vibration characteristics of rock under harmonic impact. Three main control parameters are considered, including drilling way, excitation frequency and impacting amplitude.Our investigations confirm that the rock has different resonant frequencies and vibration modes in different orders for free vibration system, and there is only one resonant frequency for a rock with one degree of freedom. Based on theoretical analysis and indoor experiments, it can be concluded that the vibration amplitude under resonant frequency of rock is significantly higher than that under non-resonant frequency and in conventional drilling. Also, the vibration response of rock is in the harmonic form by the harmonic impact, and increases with the increase of the impacting amplitude.The vibration characteristics of rock by harmonic impact are validated by numerical analysis and experimental results. Harmonic vibration impact drilling can greatly enhance the vibration amplitude of rock, and further improve the rate of penetration

Feasibility Study on Resonance Enhanced Drilling Technology

With the increasing of well depth, the hardness of rock increases which will lead to rock is difficult to be broken. Therefore, Resonance Enhanced Drilling as one of new efficient drilling technologies is presented to improve the efficiency of drilling. The paper is focused on the feasibility study on Resonance Enhanced Drilling, showing the results of the numerical analysis and presenting the implementation methods of the technology. Two kinds of numerical simulations are performed, including modal analysis and harmony analysis of rock and indenter. Also, the excitation frequency is optimized under the actual operation conditions to analyze whether Resonance Enhanced Drilling can be achieved.Our investigations confirm that both rock and drill bit can be resonant, and there are different resonant frequencies and vibration modes in different orders which are only related to their inherent characteristics. In addition, when the rock drilled is resonant and easily broken, the drill bit will not be destroyed. As a result, the Resonance Enhanced Drilling can be achieved and the optimization of excitation frequency is the resonant frequency of rock drilled.We suggest that although there are some methods and apparatus have been proposed to achieve resonance drilling technology, more researches are still needed to be conducted to further understand the rock breaking mechanism and promote the realization of the Resonance Enhanced Drilling

Modeling of System Energy of Rock Under Harmonic Vibro-Impact

Hamiltonian function is proposed and the modeling of system energy of rock under harmonic vibro-impact is undertaken in this study. The modeling includes two aspects, namely, energy equation of rock system with no damping and the one with damping. Also, the results of numerical simulation are presented. Four main control parameters are considered, including natural frequency of rock, impact frequency, impact force, damping coefficient.It is confirmed that the system energy of rock will increase with the increase of natural frequency impact frequency and impact force. While impact force, damping coefficient and stiffness of rock will mainly decide the vibration amplitude of system energy

The Micro Vibration Equation of Rock and Its Analysis in Flat Indenter Basing on the Principle of Least Action

Impact frequency of drill tools, vibration displacement of rock and other factors play a key role on the impact efficiency of vibration and rock breaking effect in the percussion drilling. In this paper, the micro vibration equation of rock in the impact of indenter was established based on the principle of least action. Then the relationship among vibration displacement of rock and quality and natural frequency of rock, impact force and impact frequency of indenter and time were analyzed. The results show that the curve of vibration displacement is kind of shape of cosine function, its size fluctuates up and down in the equilibrium position with the changes in various factors; The greater the impact of flat indenter is, The smaller the quality of rock is, the greater the vibration displacement of rock is; The closer the impact frequency of indenter and natural frequency of rock are, the greater the vibration amplitude of rock is, and it is significantly higher than the situation which the difference of impact frequency of indenter and natural frequency of rock is large

Efficacy and safety of a novel 450 nm blue diode laser versus plasmakinetic electrocautery for the transurethral resection of non-muscle invasive bladder cancer: The protocol and result of a multicenter randomized controlled trial

ObjectivesTo be the first to apply a novel 450 nm blue diode laser in transurethral resection of bladder tumor (TURBt) to treat patients with non-muscle invasive bladder cancer (NMIBC) and evaluate its efficacy and safety during the preoperative period compared to the conventional plasmakinetic electrocautery.Materials and MethodsRandomized controlled trial (RCT) in five medical centers was designed as a non-inferiority study and conducted from October 2018 to December 2019. Patients with NMIBC were randomized to the blue laser or plasmakinetic electrocautery group for TURBt. As the first study to evaluate this novel blue laser device, the primary outcome was the effective resection rate of bladder tumors, including effective dissection and hemostasis. The secondary outcomes were the perioperative records, including surgical time, postoperative indwelling catheter time, hospital stay length, blood loss, reoperation rate, wound healing and adverse events.ResultsA total of 174 patients were randomized to either the blue laser group (85 patients) or plasmakinetic electrocautery group (89 patients). There was no statistical significance in the clinical features of bladder tumors, including tumor site, number and maximum lesion size. Both the blue laser and plasmakinetic electrocautery could effectively dissect all visible bladder tumors. The surgical time for patients in the blue laser group was longer (p=0.001), but their blood loss was less than that of patients in the control group (p=0.003). There were no differences in the postoperative indwelling catheter time, hospital stay length, reoperation rate or other adverse events. However, the patients undergoing TURBt with the blue laser showed a faster wound healing at 3 months after operation.ConclusionThe novel blue laser could be effectively and safely used for TURBt in patients with NMIBC, and this method was not inferior to plasmakinetic electrocautery during the perioperative period. However, TURBt with the blue laser may provide the benefit to reduce preoperative blood loss and accelerate postoperative wound healing. Moreover, longer follow-up to confirm recurrence-free survival benefit was required