Protection of drilling equipment against vibrations during drilling

The article is devoted to the study of important problem of influence of vibrations on drilling and drilling equipment. Vibration can adversely affect the condition of equipment, reducing its durability and productivity, as well as creating the risk of breakdowns and accidents for workers. Various vibration protection methods and technologies are considered, such as use of shock absorbers, vibration dampers, active control and intelligent control systems. The main attention is paid to methods of measurement and analysis of vibration spectrum, which allow to understand the nature of vibrations and to determine their main parameters. This helps to establish criteria for evaluating the level of vibration for drilling equipment and to make necessary protection decisions. Application of modern technologies and innovative approaches, such as the use of intelligent control and management systems, allows to achieve better results and reduce the impact of vibrations on drilling and drilling equipment. In general, the implementation of vibration protection systems in drilling is an important step in improving the quality and safety of work, saving equipment and reducing maintenance costs. The use of modern technologies and innovative approaches helps to achieve optimal drilling productivity and efficiency, which is a key success factor in well drilling.


Introduction
The problem of impact of vibrations on drilling equipment is extremely relevant and critically important for the drilling industry.Vibrations are caused by the interaction of the rock-breaking tool with the rocks, which can lead to negative consequences for equipment, workers, and drilling efficiency.Increased vibration load accelerates wear and tear of drilling equipment, which leads to unanticipated shutdowns and repairs, and increases maintenance costs.In addition, vibrations can affect the quality of the wellbore, causing its distortion, discontinuity of rocks and other defects that have a negative impact on the production of oil or gas.Also, high vibration intensity can create dangerous conditions for workers, causing loss of control over equipment, increasing the risk of accidents and injuries.
The sources of vibrations during drilling can be related to various aspects of the drilling process and rock properties.Vibrations can occur both as a result of mechanical contact between various equipment elements, and as a result of the interaction of the drilling tool with the rock.
One of the main sources of vibration during drilling is the rotational motion of the drilling tool, such as the bit or the drill string.These rotational movements create uneven wear and stress on the drill tool and can cause vibrations in the system.The interaction of the drill bit with the geological rock, uneven wear of the drill bits during drilling can cause uneven resistance and can also cause vibrations.This can occur due to different degrees of wear on the surfaces of the drills, which leads to uneven contact with the rock, and the properties of the rock can vary at different depths, which creates uneven conditions for drilling [1][2][3][4][5].
Measurement of the parameters of the vibration spectrum is an important stage in the analysis of the vibration state of the drilling equipment.This process allows you to get detailed information about the nature and intensity of vibrations at various points of the equipment and determine the causes of vibrations for further improvement of the vibration management system.Measuring the spectral characteristics of vibrations allows you to identify the main frequencies, amplitudes, and phase shifts of vibrations.Spectrograms can be presented in the form of amplitude-frequency or frequency-time diagrams.To measure the parameters of the vibration spectrum, various technical means are used, such as vibrometers, vibration analyzers, acceleration, and speed sensors, as well as special software tools for data processing and analysis.The results of the measurements make it possible to detect unwanted vibrations and develop effective measures for their management, which helps to ensure stable operation of the equipment and increase the productivity of the drilling equipment [5][6][7].
Determining the criteria for assessing the level of vibrations for drilling equipment is an important task for assessing its condition and operational efficiency.The evaluation criteria allow to set limits of permissible vibrations, which must not be exceeded to ensure the safety, stability, and reliability of the equipment.Assessment of the level of vibrations for drilling equipment is usually carried out on the basis of measurements and analysis of data obtained with the help of vibrometers, vibration analyzers and other technical means.Comparison of the measured values with the established limit values helps to determine the condition of the equipment and develop measures for its optimal functioning and protection [7][8][9].
Technologies and methods of vibration protection are important for increasing the efficiency of drilling equipment and ensuring its durability.They allow to reduce the impact of vibrations on the equipment and ensure stable and safe operation.The use of shock absorbers and vibration dampers helps to reduce the level of vibrations and ensure the stability and safety of drilling equipment.Their correct selection and adjustment can increase the performance and durability of equipment, as well as reduce maintenance and repair costs.Optimal use of these devices is an important step in ensuring efficient and safe drilling [9][10][11][12][13][14].
Consequently, the impact of vibration on drilling equipment has serious implications for drilling productivity, safety, and efficiency.Understanding this impact is essential to the development and implementation of systems and technologies that will protect drilling equipment from vibrations and improve productivity and safety.And the improvement of vibration protection systems is an important step in the development of drilling and increasing the productivity of drilling equipment.Prospects and improvement of vibration protection systems are important directions in the development of drilling technologies and improvement of equipment productivity.With the ever-increasing requirements for drilling efficiency and safety, researchers and engineers continue to work on improving innovative vibration protection systems.For example, an optimally selected mode allows you to maintain stable contact of the bit with rocks and minimize deviations from the specified drilling path [15][16][17][18].
Accordingly, the goal of the work is to develop an approach to reduce the impact of vibration sources through proper regulation of drilling process parameters, which is an effective approach to ensure optimal productivity and reduce the negative impact of vibrations on drilling equipment.This approach should involve the use of various technologies and methods that allow controlling the parameters of the drilling process in order to minimize vibrations.

Methods
Active vibration control systems use sensors and actuators to measure and compensate for vibrations.These systems allow automatic adjustment of the protection system parameters depending on the operating conditions and vibration dynamics.This can improve the adaptability of the system and allow it to effectively cope with changing drilling conditions.The integration of artificial intelligence into protection systems will allow more accurate analysis of data from vibration sensors and the development of optimal management strategies.
The use of appropriate control algorithms allows you to adapt the parameters of the drilling process during its duration.This allows you to respond to changing drilling conditions and maintain an optimal operating mode, which helps reduce the impact of vibrations.Machine learning algorithms can predict and avoid unwanted vibration modes, improving performance and reducing the risk of breakdowns.Upto-date information from sensors helps to ensure more accurate and quick adjustment of the protection system parameters.
Let's consider the use of an intelligent system when drilling with the Bottom Hole Assembly (BHA) and Rotary Controlled System (RCS) and PDC Bit (Polycrystalline Diamond Compact Bit).
Vibration measurement sensors during drilling, which are used to record vibrations during drilling are placed in a 1.5 m long translator made of non-magnetic steel.In addition to vibration data, acoustic cavernometer and acoustic impedance data are also recorded.In the well, the translator was located at a distance of 84 m from the bit, that is, behind other log sensors during drilling.
The vibration sensor includes 3-axis accelerometers, gyroscopes, and magnetometers [1,2].Magnetometers provide absolute measurement of the angular position of the dynamic translator.Continuous measurements of the angular position of the dynamic translator are used to calculate angular velocities and accelerations.
In a typical situation of torsional vibrations, the rotation frequency can reach 300-400 rpm in a fraction of a second.For example, at 360 rpm the drill string rotates 6 times per second, and at a sampling rate of 10 Hz this means that there will be 216° between each sample, while for a sampling rate of 200 Hz there will be 10.8° between each value, as shown in figure 1.
The rotation frequency of the drill string, obtained with the help of high-frequency magnetometers, is estimated by the rotation frequency on the surface.The scatter of downhole rotation frequency values can be used as a visual indicator to determine the surface rotation frequency values at which there was intermittent rotation at the hole, helping to identify the surface rotation frequencies at which strong torsional vibrations occurred at the hole.

Results and discussion
It has been found that, as a percentage of downhole BHA turnover relative to surface turnover, it is close to zero up to 100 rpm at the surface but tends to increase at higher turnovers.As can be seen, there is a rather large difference at 170 rpm above the bump and on the bump, which is probably explained by the occurrence of torsional vibrations that occur when the BHA speed reaches values of 170 rpm.In all these cases, the BHA rotation frequency in the well stabilized after some time, but transient processes contributed to the larger change observed in the diagram.
The frequency spectrum of the BHA rotation frequency in the well can give some insight into the intensity of torsional vibrations.Using the Fast Fourier Transform for torsional vibrations also allows you to visualize the dominant frequencies over time on the spectrogram graph [15].The example shown in figure 1 taken during the period of time when torsional vibrations were observed.Dark blue indicates low power spectral density, while cyan, green, and yellow correspond to higher power spectral density.
In the example, the top drive starts rotating at 50 rpm, which causes torsional vibrations of the BHA with a fundamental frequency of 0.08 Hz and a harmonic at 0.16 Hz.As the top drive rpm increases to 140, a single peak frequency of 0.14 Hz is observed.Once the velocity in the well begins to stabilize, the power spectral density peaks are no longer visible, appearing as a single-tone spectrum.
A high-energy sequence of torsional vibration as the top drive revolutions from 10 to 30 rpm.Three dominant harmonics (0.08 Hz, 0.15 Hz and 0.22 Hz) are identified in this sequence.For torsional vibration on potholes, one peak in the frequency spectrum is observed, as shown in figure 2. The peak of the frequency spectrum appears at the moment when there is a slow increase in the rotation frequency of the upper drive from 120 to 140 rpm, when the torsional vibration persists after a short period of lower vibration levels.When the number of revolutions of the upper drive increases to 160 rpm and the torsional vibration is suppressed, the power of the low-frequency spectral component decreases, despite some residual changes in the number of revolutions of the BHA in the well.In figure 2 dark blue in the lower graph indicates low power spectral density, answer higher power spectral density.
Higher frequencies are sometimes observed when the number of revolutions of the top drive is 140 rpm and above.These harmonics appear in both wells in the same frequency ranges, as shown in figure 3. Histograms in figure 3 were generated by finding the maximum power spectral density for the selected time window of the BHA rotation data in the well and estimating the corresponding frequencies.Two ranges are distinguished: a range of 0.1-0.4Hz, which is observed both during the occurrence of torsional vibration and without it, and a second range of 4.5-6 Hz for sequences without torsional vibration.The peaks in the second range are about twice the speed of the top drive (e.g. 6 Hz for 180 rpm on the surface).In works [10][11][12][13][14] with description of the transitional hydromechanical model, it is mentioned that the transition from static to kinetic friction is a source of negative damping, which can lead to situations of torsional vibration when the speed of the top drive is insufficient.This situation is observed in many cases of starting the top drive.The recommended starting procedure for the top drive is often to gradually increase the rotational speed until the nominal rotational speed is reached.The motivation for this practice is to be careful with the casing and open-well formations while accelerating the drill string rotation.Nevertheless, if we look at the rotation speed of the BHA as measured by the high-frequency magnetometer (figures 3 and 4).
The maximum values of BHA rotation during torsional vibrations reach 200 rpm (rotation speed of the top drive 30 rpm).
As a rule, the peak rotation speed of the BHA is more than twice the speed of the top drive.For example, we can see in figure 4, that for a top drive speed of 30 rpm, the peak rotation speed of the BHA reaches 200 rpm.Thus, instead of being gentle with the casing and open-well formations, low top drive speeds tend to produce very high peak rotation rates during which intense rotation of the drill string can occur.As you can see, when the speed of rotation of the top drive is more than 140 rpm, the torsional oscillations of the BHA are quickly dampening vibrations.You can also notice that the rotation in the well is delayed for about 10 seconds.Figures 3 and 4 show the measured speed of rotation of the BHA in the wellbore and the moment on the rotor when the command was sent to change the mode of operation of the RCS of the well.
As you can see, there is no serious torsional vibration during drilling.However, by the end of the command transfer to the RCS, a rather strong torsional vibration occurs.After that, almost every procedure of sending a command to the RCS is accompanied by a strong torsional vibration, except for a few cases when the speed of the top drive is maintained at 180 rpm.A possible explanation for these observations could be the interaction between the transport of the drilled rock and the torque, when short-term mudding occurs due to the change in the flow rate of the drilling fluid, which occurs through the command reference to the RCS.A decrease in fluid velocity in a larger diameter well makes it difficult to keep the slurry in a suspended state.Since the typical flow rate used for drilling is just under 1900 l/min, top drive speeds below 160 rpm may increase the risk of poor slurry transport.During the RCS command, the flow rate is periodically reduced to 1500 l/min and for this flow the top drive speed must exceed 170 rpm to ensure sufficient sludge transport capability.
From the analysis of the high-frequency measurements, the conclusion is suggested that with long and elastic drill strings, it is better to start the rotation of the top drive directly to a value that exceeds the minimum drilling threshold, than to increase the speed of the top drive-in cascades from low rotation frequencies.This limits the duration of torsional vibration and the associated risk of intense swirling conditions in the drill string above the RCS.When it is necessary to use a low flow rate, for example, due to losses in formation rocks with natural fractures, absorption, it is reasonable to maintain the speed of rotation of the top drive above the threshold value necessary for the transportation of slurry in a suspended state when performing the procedure of sending the command to the RCS.This is due to the fact that that reduced flow can destabilize the transport of drilled rock and lead to side effects of mechanical forces applied to the drill string that can contribute to torsional vibrations.In addition, it is important to choose a combination of top drive flow and speed that will be suitable for proper transport of the drilled rock.Otherwise, there is an additional risk of torsional vibrations in the drill string.The use of active vibration control makes it possible to achieve a high level of protection of drilling equipment against the negative effects of vibrations.This approach allows you to effectively compensate for vibrations and ensure the stability and safety of equipment operation.In addition, active control allows you to increase the productivity and durability of the equipment, which in turn reduces the costs of operation and maintenance.However, the implementation of active vibration control may require certain costs for technology and system maintenance, but these costs are many times justified by increased efficiency and reliability of the equipment.
Let's group in the table 1 information on ways to diagnose vibration modes in real time and potential methods of combating vibrations by changing drilling parameters that can be applied when using intelligent systems.That allows you to influence vibration processes directly in the drilling process without the use of additional equipment.From this we can conclude that the use of intelligent vibration control and management systems provides opportunities to improve the quality and productivity of drilling, reduce the cost of equipment maintenance and repair, and ensure the safety of workers.

Conclusions
Thus, the implementation of intelligent control and management systems in drilling, which allow active control of vibrations, is a promising direction in the fight against vibrations.Intelligent systems based on modern technologies of artificial intelligence, machine learning and data analysis allow for more accurate and effective control of the vibration process.They can work in real time, providing constant monitoring and response to changes in drilling conditions and parameters.This allows you to react faster and more accurately to vibration cases and avoid possible problems.These systems can automatically control the parameters of the drilling process, such as revolutions, forces, supply of flushing fluid, etc., and optimize the parameters of the drilling process to reduce the impact of vibrations on the equipment and improve work productivity by providing optimal conditions for reducing the impact of vibrations.Using data analysis and machine learning algorithms, intelligent systems can predict possible vibration risks and develop strategies to prevent problems, detect vibration anomalies and automatically stop the drilling process in case of dangerous situations.Enable selective control of loads on equipment, which helps to minimize wear and tear, as well as more efficient use of resources, such as fuel, materials, providing optimal conditions for equipment operation.
With the constant development of technologies and the expansion of the capabilities of intelligent systems, their implementation in drilling becomes an even more promising and effective solution to protect drilling equipment from the effects of vibrations, allows you to achieve better results and reduce the impact of vibrations on drilling equipment and drilling.Further research and development in this field has great potential to improve the efficiency and quality of well drilling, ensuring stable and safe working conditions.

Figure 1 .
Figure 1.Examples of the frequency spectrum in time for the sequences of torsional vibrations above the pothole that occur at different revolutions of the top drive on the surface.

Figure 2 .
Figure 2. Torsional vibrations during drilling in a well.

-Figure 3 .Figure 4 .
Figure 3. Starting the top drive during drilling.The maximum values of BHA rotation during torsional vibrations reach 200 rpm (top drive -20 and 30 rpm).

Table 1 .
Detection of vibration and methods of combating it using active control.