Design and Analysis of a Novel Rotary Percussion Drilling Tool in Petroleum Exploration

Transcription

1 Journal of Applied Science and Engineering, Vol. 20, No. 1, pp (2017) DOI: /jase Design and Analysis of a Novel Rotary Percussion Drilling Tool in Petroleum Exploration Lingchao Xuan*, Zhichuan Guan and Huaigang Hu School of Petroleum Engineering, China University of Petroleum Huadong, Shandong, P.R. China Abstract The rotary percussion drilling technology is one of the effective ways to improve the rate of penetration in deep well drilling. The common shortcomings of impact tools used today are the low impact force and the instability of impact frequency. Therefore, a novel rotary percussion drilling tool powered by positive displacement motor was designed. Its principle is that, the PDM drives a hammer piston to rotate, meanwhile the piston hits the anvil to generate impulse load. The dynamic model of this tool shows that, the impact load is influenced by the spring s storage energy, and the impact time is closely related to the piston s mass. The impact frequency is the product of the rotary rate of the PDM and the number of piston s teeth. Experiments showed: the tool s impact frequency is 25.7~37.6 Hz, and the peak value of impact force is 20~42 kn. The research showed the calculation model has a high accuracy compared with the testing data. The tool s impact parameters are in range of the optimal value of previous research, and this novel tool has great potential in increasing the ROP in deep well drilling. Key Words: Rotary Percussion, Piston with Teeth, Contact Surface, Impact Force, Dynamic Model, Percussion Test 1. Introduction Nowadays, with the oil reservoir becoming more and more sophisticated and deep, the fast and safe drilling technology becomes an urgent need of oil exploitation. Experience over the few decades has proved that rotary percussion drilling technology is an effective way to improve the rate of penetration (ROP) in drilling deep and ultra-deep wells [1,2]. This technology can improve the depth of bit teeth forced into the formation, and generate large broken cutting. The impact load, impact frequency and other parameters of the rotary percussion tool have a significant influence on the ROP of deep well [3]. In practice, the impact energy of the percussion tool usually is set at J, impact force is set at kn; some *Corresponding author. xuanlingchaoboy@163.com research shows that the optimal impact frequency of the rotary percussion tool is set at a range of Hz [4,5]. The ROP of rotary percussion drilling is generally 40% higher than that of common drilling [6]. The rotary percussion drilling also has the benefits of saving costs and cutting accidents. Study found that the rotary percussion tools used today have some common shortcomings. The impact force is too small in contrast with the bit weight, and the impact frequency is unstable and potentially useless for fast drilling [7,8]. Also, it is difficult for some tools to adjust the working parameters to match with the complicated formations. This paper s objective is to design a novel rotary percussion drilling tool powered by positive displacement motor (RPDTPDM) to overcome these problems. A dynamics model was established to simulate the impacting process of this percussion tool. Meanwhile, compre-

2 74 Lingchao Xuan et al. hensive properties of this tool s prototype were measured and analyzed through ground experiments. The results show that this novel tool has great potential in increasing the ROP of deep well drilling. 2. The Novel Rotary Percussion Drilling Tool Positive displacement motor (PDM) is a dynamic tool that uses the hydraulic energy of drilling fluid. It has been widely used in common and directional drilling with advantages of stable performance and long life [9]. The cam mechanism is used to change the continuous motion into intermittent motion. With good performance of impact resistance, the cam has been widely used in mechanical field [10]. By analyzing the structure and feature of the PDM and the cam mechanism, a novel rotary percussion tool powered by PDM was designed. 2.1 The Structure As shown in Figure 1, this novel rotary percussion drilling tool powered by PDM is made up of three parts: the upper part is a high-speed positive displacement motor, the middle part is the cardan shaft and bearings, and the lower part is the impact components. The impact components consist of a hammer piston, an anvil and some disc spring. The contact faces of the piston and anvil are designed like teeth. The anvil s rotation is restricted by the torsion shell with a hexagonal shape. The end of anvil is connected with the drill bit by tubing joint. The profile of the teeth is designed as modified trapezoid curve, which is suitable for light-load and high-speed rotation [11]. 2.2 The Working Principle In the drilling operation, this rotary tool is connected with the drill bit and the drill collar. Through the upper joint, shell, anvil and lower joint, the bit weight and torque are transmitted to the drill bit. The PDM drives the hammer piston rotating with high speed, meanwhile the piston periodically hits the anvil to produce impact load. When these two impact components are staggered, the piston climbs along the anvil s teeth, and the piston forces the spring to compress and store the energy. When the hammer piston reaches the top of the anvil s teeth, the piston will fall quickly, and impact the anvil with high velocity. When one impact process is finished, the hammer piston powered by the PDM will climb the slope of the teeth, hit the anvil and produce impact load again. 3. Dynamic Model of the Tool s Impact Process In order to analyze the working principle and working state of the novel rotary percussion drilling tool, a dynamic model was established. 3.1 Calculation Model of the Piston s Velocity In drilling operation, the hammer piston rises along the inclined plane of teeth, meanwhile the spring is further pressed with energy storage. Finally, the piston drops and hits the anvil with a high velocity. The drop process of the hammer piston with spring acceleration meets: (1) The spring is always pressed to the cam, so the boundary condition is that: (2) Figure 1. Structure of rotary percussion drilling tool powered by PDM. 1: upper joint; 2: anti falling; 3: PDM; 4: shell of shaft; 5: cardan shaft; 6:bearings; 7: driving shaft; 8: spring; 9: hammer piston; 10: anvil; 11: lower joint.

3 Design and Analysis of a Novel Rotary Percussion Drilling Tool in Petroleum Exploration 75 Finally, the velocity function v(t) of the hammer piston was obtained: (3) Note: K M Mg KTL K T 1 ; T And also, the final speed of the cam before impact was obtained: (4) 3.2 Calculation Model of the Impact Load The impact process of the piston and anvil transforms the kinetic energy of the piston into the stress wave of the anvil. Because the profile of the six teeth is complex, so the impact process transits gradually from contact of some points to full contact. Therefore the impact load increases gradually, reaches the peak and then subsides gradually, not as a rectangular form. This phenomenon works in conditions such as a spring installed between the piston and anvil, as shown in Figure 2. Apparently, the deformation coefficient of these contact surfaces is related to the material of impact components, the profile of the teeth, and the thickness of the oil slick. This deformation coefficient of contact surfaces usually is measured by experiments. The interaction of these three components meets that: (5) Finally, the function of impact load was obtained: (7) 2 KC 4mz Note: ; 1 2mz MKC Further analyzing the function of the impact load, the peak value of the impact load F max was obtained: 3.3 Calculation Model of the Impact Frequency (8) The impact frequency of this tool is the product of the rotary speed of PDM and the number of the piston s teeth. The rotary speed increases with the flow rate increase of drilling fluid [12]. The flow rate of the motor is set as 25 L/s~32 L/s, and the rotary speed ranges 255 r/min~364 r/min. In percussion drilling, the best impact frequency usually is about 30 Hz. Therefore, the structure of piston and anvil was designed with six teeth. 4. Calculation and Analysis of the Tool s Impact Characteristics (9) The tool s main structural parameters affecting impact properties include: the compression and stiffness of the spring, the mass of hammer piston, and the deformation coefficient of contact surfaces. Using the single factor method, the influencing rule of every parameter on the impact load were obtained. Note: dl ( vc vz); mz Az E dt Initial condition of impact process is that: (6) Figure 2. Mechanical model of impact process.

4 76 Lingchao Xuan et al. 4.1 The Influence of Spring on the Impact Load As shown in Figure 3(a), the impact load grows gradually and subsides gradually; the waveform is similar to the sinusoidal function. With gradual increase in the amount of spring compression, the value of impact load increases commensurately. The action time of a single impact remains the same while changing the spring s compression, so the impact time is unaffected by the spring performance and velocity of the piston. Increasing the amount of spring compression, the peak of the impact load increases gradually, and the growth trend is like a power function as shown in Figure 3(b). The methods of increasing the amount of spring compression, using a spring with large stiffness, all can increase the peak value of impact load. 4.2 The Influence of Piston s Mass on Impact Load According to Figure 4(a), the peak value of the impact load stays the same while changing the piston s mass, and the fluctuation range of the impact load is less than 3%. Increasing the mass of the piston will reduce the final velocity of the piston, but also will improve the collision effect of the contact surfaces. Finally, changing the mass of piston does not significantly affect the peak of impact load. Increasing the piston s mass in a proper range, can improve the action time of a single impact significantly, as seen in Figure 4(b). This phenomenon can improve the depth of the bit teeth penetrating into the for- Figure 3. The influence of spring compression on impact load. Figure 4. The influence of piston s mass on impact load.

5 Design and Analysis of a Novel Rotary Percussion Drilling Tool in Petroleum Exploration 77 mation, and increase the volume of broken rock effectively [13]. 4.3 The Influence of Contact Surfaces on Impact Load Keeping the cam s mass and final velocity unchanged, Figure 5(a) bears the influence of the deformation coefficient of contact surfaces on the impact load. A deduction was made that the deformation coefficient of the teeth has a significant effect on the impact load and the action time. It plays a role in adjusting the waveform of impact force. Figure 5(b) reveals that the peak value of impact load can be improved while the action time can be reduced by increasing the deformation coefficient of the teeth. Therefore, optimizing the profile of the teeth is very helpful in adjusting the waveform of impact load, and also helpful in improving the tool s adaptability to complex formations. 5. Experimental Test In order to study and improve the tool s performance, the impact properties of the rotary tool were tested by ground experiments. The prototype of this novel tool was fixed on the pedestal, the force sensor was installed at the end of the tool, and the F-1600 mud pump was used to drive the PDM. While changing the amount of spring compression and the flow rate of the mud pump, the prototype s impact load was recorded by high-speed multichannel data gathering system. The study and comparison of the measured data and calculated value in same working conditions were also carried out. 5.1 Impact Load in Single Impact Process As shown in Figure 6(a), under the same working condition, the calculated value of the impact load has a high similarity with the measured data. The waveform of the dynamic model is more close to the sinusoidal curve, and the measured data has some random noise. Increasing the amount of spring compression, the peak value of the tool s impact load was improved subsequently because of the increasing of the velocity of piston. The measured data showed that the action time of impact process slightly increases from 3.95 ms to 4.45 ms. In general, the impact load of the calculation model is remarkably similar to the measured data, so the calculation model can offer great assistance in adjusting this tool s performance. 5.2 Impact Load in Continuous Impact Process The working state of this tool with continuous impacting is shown in Figure 6(b). For a single curve, the time interval of two impact processes is the same, which is determined by the stable rotary speed of motor; and the fluctuation of the peak value of impact load is less than Figure 5. The influence of teeth s deformation coefficient on impact load.

6 78 Lingchao Xuan et al. Figure 6. The analysis of the testing value of the tool s impact process. 10%. This suggests that the impact process of this tool is obviously periodic and repeatable, because every process of piston falling and teeth impacting is exactly the same. Two measured data under different working conditions proved that, the tool s impact frequency can be adjusted by the flow rate of drilling fluid, and the tool s impact load can be changed by the mount of spring compression. 5.3 Tool s Comprehensive Properties By changing the tool s working condition many times, the multi-properties of the prototype were measured and studied, as shown in Table 1. The peak value of impact load is kn, and it is 0.2~0.4 times of the bit weight in common drilling, so it can improve the volume of rock broken by bit teeth. The impact frequency is 25.7~37.2 Hz, and the tool s pressure loss is 1.1~1.2 MPa. The dynamic model of impact process has a high accuracy compared with the testing results. The impact load and impact frequency of this tool are in the range of the optimal value of the rotary percussion drilling. Therefore, this novel tool has great potential in improving the rate of penetration in deep well drilling. 6. Conclusions A new idea of utilizing a spatial cam powered by the positive displacement motor to produce impact load periodically was proposed. And a novel rotary percussion drilling tool for petroleum exploration was made based on this principle. Based on the dynamics theory, the calculation model of the impact process was established. The calculated results show that the peak value of the impact load is affected by the spring compression, and the impact time increases with the increase of piston s mass. Under the same working conditions, the dynamic model of the tool has a high accuracy compared with the testing data, so it is help- Table 1. Comprehensive properties of the rotary percussion drilling tool powered by PDM Impact load Spring compression Flow rate of mud Frequency Calculation Testing Action time m L/s kn kn Hz ms

7 Design and Analysis of a Novel Rotary Percussion Drilling Tool in Petroleum Exploration 79 ful in improving the tool s adaptability to the complex formations. The impact frequency of this percussion tool is 25.7~ 37.2 Hz, which is adjusted by the flow rate of drilling fluid. The peak value of impact load is 20~42 kn, and is 0.2~0.4 times of the bit weight. The waveform of the impact load is close to the sinusoidal curve, and the impact action time is about 4.2 ms. The impact load and impact frequency of this tool are in range of the optimal value of previous research. This novel tool has great potential in improving the ROP in deep well drilling. Acknowledgment This work was supported by the National Science and Technology Major Project Foundation of China The safe & fast drilling technologies for complicated formations in western China (No. ZX05021). Nomenclature M The cam s mass, kg s The cam s displacement, m t time, s g Acceleration due to gravity, m/s 2 K T The stiffness of spring, N/m L y The spring compression, m The velocity of cam, m/s H The height of cam s teeth, m) max The final velocity of cam, m/s F Impact load, N l Spring of contact surfaces, m C The velocity of cam in impact, m/s Z The velocity of anvil in impact, m/s K C Deformation coefficient of contact surfaces, N/m m Z The shock resistance of anvil, kg/s A Z Area of anvil, m 2 Density of anvil, kg/m 3 E Young modulus of anvil, Pa F max The peak value of impact load, N f Impact frequency, Hz n The rotary rate of PDM, r/s N The number of cam s teeth References [1] Tao, X. H., Effective Measures for Improving the Penetration Rate of Deep Well, Oil Drilling & Production Technology, Vol. 23, No. 5, pp. 4 8 (2001). [2] Ostasevicius, V., Gaidys, R., Rimkeviciene, J. and Dauksevicius, R., An Approach Based on Tool Mode Control for Surface Roughness Reduction in High-frequency Vibration Cutting, Journal of Sound and Vibration, Vol. 32, No. 9, pp (2008). doi: /j.jsv [3] Wang, R. J., Hydraulic Rotary Percussion Drilling, The Geological Publishing House, Beijing (1988). [4] Zhang, Y. L., The Development and Application of Rotary Percussion Drilling Tool, Oil Field Equipment, Vol. 30, No. 5, pp (2001). (Chinese) [5] Ni, H. J., Han, L. J. and Ma, Q. M., Study on Downhole Vibration Drilling Tool Induced by Hydro-pulse, Oil Drilling & Production Technology, Vol. 28, No. 2, pp (2006). (Chinese) [6] Labus, T. J. and Savanick, G. A., An Overview of Water Jet Fundamental and Application, Water Jet Technology Association, Saint Louis (2001). [7] Jian, Z. J., Zhang, W. H. and Liu, G. H., Current Status and Developing Trend of Research on Hydraulic Hole Hammer for Oil Drilling, China Petroleum Machinery, Vol. 29, No. 11, pp (2001). [8] Wiercigroch, M. and Wojewoda, J., Vibrational Energy Transfer Via Modulated Impacts for Percussive Drilling, Journal of Theoretical and Applied Mechanics, Vol. 46, No. 3, pp (2008). [9] Chen, J. S. and Zhai, Y. H., Theoretical Evaluation of an Impulsive-load Generate, China Petroleum Machinery, Vol. 29, No. 4, pp (2001). [10] Su, Y. N., Research and Application of Positive Displacement Motor, Petroleum Industry Press, Beijing (2001). [11] Liu, C. Q., Liu, Q. L. and Cai, C. W., Practical Design

8 80 Lingchao Xuan et al. Manual for Cam Mechanism, Science and Technology Press, Beijing (2013). [12] Nawafleh, M. A., Al-Kloub, N., Tarawneh, M. and Younes, R. M., Reduction of Vibration of Industrial Equipments, Jordan Journal of Mechanical and Industrial Engineering, Vol. 4, No. 4, pp (2010). [13] Xiong, Q. S., Huang, Z. Q. and Kun, K., Experimental Research on a New Type of Hydro-efflux Hammer in Drilling Deep and Ultra-deep Wells, Natural Gas Industry, Vol. 28, No. 12, pp (2008). Manuscript Received: Mar. 2, 2016 Accepted: Jun. 17, 2016