Downhole-friction-estimation-based rotary speed control for drillstring system with stick-slip vibrations

Author(s):  
Chengda Lu ◽  
Min Wu ◽  
Xin Chen ◽  
Weihua Cao ◽  
Chao Gan ◽  
...  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Yong Wang ◽  
Hongjian Ni ◽  
Yiliu (Paul) Tu ◽  
Ruihe Wang ◽  
Xueying Wang ◽  
...  

Stick-slip vibration reduces the drilling rate of penetration, causes early wear of bits, and threatens the safety of downhole tools. Therefore, it is necessary to study suppression methods of stick-slip vibration to achieve efficient and safe drilling. Field tests show that the use of downhole axial impactors is helpful to mitigate stick-slip vibration and improve rock-breaking efficiency. However, there are many deficiencies in the study of how axial impact load affects stick-slip vibration of a PDC bit. In this paper, based on the two-degrees-of-freedom spring-mass-damper model and similarity theory, a laboratory experiment device for suppressing stick-slip vibration of a PDC bit under axial impact load has been developed, and systematic experimental research has been carried out. The results show that the axial impact force can suppress the stick-slip vibration by reducing the amplitude of weight on bit and torque fluctuations and by increasing the main frequency of torque. The amplitude of impact force affects the choice of the optimal back-rake angle. The impact frequency is negatively correlated with the fluctuation amplitude of the rotary speed. When the impact frequency is greater than 100 Hz, the fluctuation amplitude of the rotary speed will not decrease.


2021 ◽  
Author(s):  
Sherif A. Ezz ◽  
Mohamed S. Farahat ◽  
Said Kamel ◽  
Ahmed Z. Nouh

Abstract Drill string vibrations are one of the most serious problems encountered while drilling as the bit and drill string interaction with formations under certain drilling conditions usually induces complex shocks and vibrations into the drill string components resulting in premature failure of the equipment and reduced drilling penetration rate. In severe cases where shocks and vibrations accumulated into drill string till exceeded its maximum yield or torsional strength, fatigue will occur and thereby increase the field development costs associated with replacing damaged components, fishing jobs, lost-in-hole situations, and sidetracks. Thus, real-time monitoring for downhole generated vibrations and accordingly adjusting drilling parameters including weight on bit, rotary speed, and circulation rate play a vital role in reducing the severity of these undesirable conditions. Vibration optimization must be done incorporation with the penetration rate, as a minimum economical penetration rate is required by the operator. In this study, three penetration rate and vibration level models were developed for axial, lateral, and stick-slip drilling modes using both MATLAB™ Software neural network and multiple regression analysis. It is found that the three models' results for vibration level and penetration rate; as compared with those recorded drilling data; showed an excellent match within an acceptable error of average correlation coefficient (R) over 0.95. The prediction of penetration rate and vibration level is thoroughly investigated in different axial, lateral, and stick-slip vibration drilling modes to be able to best select the optimum safe drilling zone. It is found that the axial vibration could be dampened by gradually increasing the weight on bit and increasing rotary speed while both the lateral and torsional vibrations are enhanced by increasing the rotary speed and decreasing the weight on bit.


1991 ◽  
Vol 113 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Yao-Qun Lin ◽  
Yu-Hwa Wang

The stick-slip vibration is introduced as a new mechanism to explain the large amplitude torsional oscillation of the drill strings in oil and gas well drillings. A record of field data is identified and simulated according to the new mechanism. The analytical results derived from the numerical simulation agree with the field data with 95.6 percent accuracy. The physical phenomenon of the stick-slip vibration of drill string is explained by initiating a phase trace in the phase plane. The beating phenomenon in drilling is interpreted in terms of stick-slip vibration. The effects of viscous damping, rotary speed and natural frequency on the stick-slip vibration are discussed.


Author(s):  
Dapeng Zhao ◽  
Sigve Hovda ◽  
Sigbjørn Sangesland

The whirl phenomena in the bottom hole assembly (BHA) is believed to be formed by the imbalance of the rotational drill collar. Backward whirl is caused by the nonlinear contact between the BHA and the borehole, and can be extremely damaging to the down hole tools and borehole. In the previous studies, a two-degrees-of-freedom lumped parameter model is developed for representing the drill collar in lateral motions (whirl). Due to the bit-rock interaction, the stick slip torsional vibration is very common. In the current work, therefore, the torsional vibration causing fluctuation of rotary speed is taken into account. The simulation results indicate that the drill collar whirls forward at lower constant rotary speed. With increasing rotary speed, the backward whirl is activated by the contact between the drill collar and the borehole wall. The nonlinear contact forces obey the Hertzian contact law, which led to lateral bounce of the drill collar and impact borehole wall chaotically. The modified Karnopp friction model is adopted to simulate the stick slip rotary vibration of the BHA. The different characters of lateral vibrations are identified by a power spectrum density diagram with and without consideration of the stick slip vibration.


2019 ◽  
Vol 86 ◽  
pp. 24-36 ◽  
Author(s):  
Yinan Guo ◽  
Wei Cheng ◽  
Dunwei Gong ◽  
Yang Zhang ◽  
Zhen Zhang ◽  
...  

Author(s):  
Massinissa Derbal ◽  
Mohamed Gharib ◽  
Shady S Refaat ◽  
Alan Palazzolo ◽  
Sadok Sassi

Drillstring–borehole interaction can produce severely damaging vibrations. An example is stick–slip vibration, which negatively affects drilling performance, tool integrity and completion time, and costs. Attempts to mitigate stick–slip vibration typically use passive means and/or change the operation parameters, such as weight on bit and rotational speed. Automating the latter approach, by means of feedback control, holds the promise of quicker and more effective mitigation. The present work presents three separate fractional-order controllers for mitigating drillstring slip–stick vibrations. For the sake of illustration, the drillstring is represented by a torsional vibration lumped parameter model with four degrees of freedom, including parameter uncertainty. The robustness of these fractional-order controllers is compared with traditional proportional-integral-derivative controllers under variation of the weight on bit and the drill bit’s desired rotary speed. The results confirm the proposed controllers effectiveness and feasibility, with rapid time response and less overshoot than conventional proportional-integral-derivative controllers.


2019 ◽  
Vol 10 (02) ◽  
pp. 53-58
Author(s):  
Pristiansyah Pristiansyah

Mechanical workshop in Polman Bangka Belitung has 8 units Ajax Universal Milling Machine Model No. 2A Mark V. The condition of the engine can not be used maximum, for example a milling machine with a serial number FR12. This machine was damaged at the rotary speed control (rpm) and need repairing process. This study aims to analyze the types and causes damage to the rotary speed control, repair the damaged components and assemble the components to make it functioned with the standard engine. This research is devide in several stages, the first stage is analyzing the causes of the damage, the second stage is repairing and re-assembling the damage components. The last stage is testing for the repaired machine vibration by examining and comparing it with standard and permitted vibration machine and another machine which still good. The test results of the vibration machine is 0.884 mm / s rms for the axial direction and 0.938 mm / s rms for the radial direction. The summary, the vibration is still at the allowed limit which is equal to 1.12 mm / s rms and it means the machine is ready to use.


2014 ◽  
Vol 496-500 ◽  
pp. 1226-1230
Author(s):  
Xing He ◽  
Xian Cheng Wang ◽  
Jun Biao Hu ◽  
Zhi Xin Sun

The cooling water of the large power vehicular diesel engine often got high or low and engine could not work in the adaptive thermal conditions in altitude environment. In order to solve the problem, analyzed the refrigeration requirement of the diesel engine on plateau section, suggested the amelioration program from installing the fluid operated pump-mot fan speed regulating device. Base on the coupling simulation model of the diesel engine working process and coolant system, took the 90°C water temperature of the diesel engine as the optimally target value, analyzed the change canon of cooling fan speed form the ambient conditions and the diesel engine work condition, established the cooling fan rotary speed control MAP on plateau section, and regulated the cooling fan speed by the methods of open loop preset controlling and closed loop feedback controlling. That would provide the improved method for the large power vehicular diesel engine working well on plateau section.


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