Comparative analysis of roller drill bit performance

Currently, roller bits are widely used in rock drilling, which are devices with rotating rollers armed with teeth. There are various approaches in assessing the effectiveness of rock destruction by a roller drilling tool, which can be conditionally divided into structural and technological ones. In addition, all the efficiency factors of the roller bit are related to the correspondence of its characteristics and the drilling process to the properties of the rock it destroys. The article analyzes the operating conditions of the roller bit during drilling of rocks of various hardness. On the example of operation of a two-screw drill bit, the process of power interaction of the toothed weapon with rock is considered depending on various factors, such as the shape and pitch of the teeth, angle of inclination, sharpness of the tooth and others. It is shown that kinematic characteristics of interaction of toothed armament with drilled rock have a significant influence on efficiency of process of face destruction. Keywords: drill bit; drilling tool; destruction; drilling; roller cutter; rock.

The technical solution to reduce the cost of eliminating the seizure of the drill string in the well

The analysis of the nonproductive time when drilling wells is conducted in the paper. it is established that the most of it is associated with the accidents and complications, with the main share (60%)-seizures. The statistical analysis of the reasons for the occurrence of seizures and the effectiveness of methods for their elimination is presented. A drill string disconnector (RBC) developed at the Tyumen Industrial University is proposed for unscrewing drill pipes and freeing them from trapped pipes. Keywords: well; drill pipes; accidents; seizure; drilling tool; drill string break.

Conceptual Control Method of Drilling Rig’s Torsional Vibrations Frequencies

This article focuses on the possibility of using an innovative drilling method for the implementation of underground works, especially where there is no physical possibility of using large working machines. Work on a model carried out under the INDIRES project is discussed. A design of a drilling tool equipped with the proposed technology is presented. The solution in question makes it possible to increase the efficiency of the drilling process, which is confirmed by computer simulations. Also, introductory tests of a drilling process supported by torsional vibration generated by an electromagnetic torque generator provided in the KOMAG laboratory facility show the reduction of the drilling time by almost two-fold. In our opinion, adding torsional vibration acting on the plane of a drilled wall that equals natural frequencies of the drilled material represents a promising new technology for drilling. The presented work constitutes the basis for the development of the proposed technology and allows us to conclude that the developed method will be of great interest to manufacturers of drilling machines and devices.

Definitive Dynamic MWD Surveys Generate Rig Time Savings and Flat Time Reductions in the Middle East

Wellbore surveying is a critical component of any well construction project. Understanding the position of a well in 3D space allows for the wells geological objectives to be carried out while safely avoiding other wellbores. Wellbore surveys are generally conducted using a magnetically referenced measurement while drilling tool (MWD) and taken while static, either before, after or sometimes during the connection. The drillstring is often worked to release trapped torque and time is often taken waiting for the survey to be pumped up. All of this consumes rig time and opens the wellbore up to wellbore instability issues. The application of definitive dynamic surveys (DDS) which are static MWD quality surveys taken while drilling and updated continuously. There is no longer a need to stop and take a static survey eliminating MWD surveying related rig time, reducing drilling risks from additional pumps off time and improving TVD accuracy and directional control. The rig time taken for surveying with and without DDS will be compared between similar wells in the field, and detailed analysis of relative tortuosity between DDS and non-DDS wells will also be conducted. Trajectory control analysis will be reviewed by looking at the difference in the number of downlinks between DDS and no DDS wells and also the deviation from the planned trajectory. An overall analysis of on bottom ROP will be made and an analysis as to the relative differences in TVD between static and DDS survey will be carried out. This abstract will outline the rig time and operational savings from DDS, it will detail the surveying time savings, directional control improvements, TVD placement differences to static surveys and provide costs savings as a comparison to previous similar wells. This will be outlined over a number of wells, divided by sections as the wells are batch drilled and provide an insight into the benefits of DDS on a drilling campaign. Some discussion will be made as to the efficacy of the DDS surveys and how their error model has been developed. DDS is a unique and novel way of taking surveys while drilling, providing static MWD quality without the added rig time costs but at a much higher frequency that the typical once a stand survey program. This paper outlines the cost and process savings associated with using the DDS surveys.

Measurement and Analysis of Downhole Drill String Vibration Signal

Downhole drill string vibration data can provide an effective reference for research drill string vibration during drilling. In this paper, the research group used a storage-type downhole vibration measurement equipment equipped with an orthogonal, three-axis accelerometer to measure and collect drill string vibration signals during drilling in an oil well. Based on the installation characteristics of the sensor, the relationship between the acceleration measurement value of the sensor and the center acceleration value of the drill string is obtained. Then the time-domain signals representative of the vibration in igneous rock drilling is analyzed. It can be found that the occurrence of stick-slip vibration can be judged by the regular wave packets in the time-domain signal, while the time-domain signal of whirl is disorderly. The main frequency of stick-slip vibration in the low-frequency band is 0.1221 Hz and the period of stick-slip vibration is very close to 10 s through Fast Fourier (FFT) and Short-time Fourier transform (DTFT) methods. In the process of whirling, two frequencies, respectively, 0.05341 Hz and 155.5 Hz, play a major role. The frequency 0.05341 Hz is very close to the reciprocal of the period of 20 s when the peak energy spectrum density appears, indicating that the occurrence of whirl is very likely to be related to the natural frequency of the drilling tool. Through further time-frequency analysis, it also can be found that the occurrence of whirl and stick-slip is greatly related to the use of torsional impactors and jars.

Waterway control assembly for rope core drilling rig and its application method

In the process of conventional rope core drilling, the connection and disassembly of waterway occupy a lot of auxiliary time, which seriously affects the drilling efficiency, and even causes drilling or safety accidents. The waterway control assembly and application method for the rope coring rig developed by the author’s team can control the waterway flow direction. It does not need to disassemble the water pipe frequently to control the raising speed of the inner pipe and avoid damaging the drilling tool too fast.Introduction.

New LWD Image Improvement Method to Mitigate Interpretation Risks

With the advancement of LWD (Logging While Drilling) hardware and acquisition, the imaging technology becomes not only an indispensable part of the drilling tool string, but also the image resolution increases to map layers and heterogeneity features down to less than 5mm scale. This shortens the geological interpretation turn-around time from wireline logging time (hours to days after drilling) to semi-real time (drilling time or hours after drilling). At the same time, drilling motion is complex. The depth tracking is on the surface referenced to the surface block movement. The imaging sensor located downhole can be thousands of feet away from the surface. Mechanical torque and drag, wellbore friction, wellbore temperature and weight on bit can make the downhole sensor movement motion not synchronized with surface pipe depth. This will cause time- depth conversion step generate image artifacts that either stop real-time interpretation of geological features or mis-interpret features on high resolution images. In this paper, we present several LWD images featuring distortion mechanism during the drilling process using synthetic data. We investigated how heave, depth reset and downhole sensor stick/slip caused image distortions. We provide solutions based on downhole sensor pseudo velocity computation to minimize the image distortion. The best practice in using Savitsky-Golay filter are presented in the discussion sections. Finally, some high-resolution LWD images distorted with drilling-related artifacts and processed ones are shown to demonstrate the importance of image post-processing. With the proper processed images, we can minimize interpretation risks and make drilling decisions with more confidence.

Innovative Approach to Analysis Drilling Tool Works

Information technologies have long been an integral part of our lives, and the oil and gas industry has also undergone natural IT evolution. Modern technologies have allowed to automate the basic processes and structure the existing order of work, but there are still unresolved problems, one of which is monitoring the full life cycle of drill pipes and predicting the accumulation of fatigue damage. In most cases, the failure of the drill pipes is associated with fatigue destruction, which begins with microcracks as a result of exposure to variable stresses during the construction of the well (drilling). Currently, there are no effective methods to control accumulated fatigue damage or residual durability of the pipe at a given level of stress. In this regard, a system is required for a more reliable assessment of the condition of the drill pipes, which will take into account the whole list of factors influencing the rate of accumulation of fatigue damage in the body of the pipe and will allow to calculate (predict) the accumulated fatigue of the drilling pipes, using data from drilling regimes and well parameters. Understanding the mechanism of accumulation of fatigue wear, which leads to the failure of drilling pipes, makes it possible to manage this process, significantly reduce the cost of maintenance of the drilling pipe fund and reduce incidents with drilling pipes.

Fatigue detection and analysis of drilling tools based on metal magnetic memory method

With the vigorous development of offshore oil and gas resources in the world, underwater extended reach horizontal wells have been widely used. However, due to the complicated stress and serious corrosion of drill pipes in horizontal wells, drill pipes are vulnerable to damage. After a period of service at sea, some drill tools will be placed in coastal areas for a long time. The cumulative fatigue of drilling tools is not easy to master. In the past year or two, drilling tool failure has become more and more frequent. In order to evaluate the fatigue of drilling tools in different periods and master the quantitative fatigue of drilling tools, the metal magnetic memory method has its unique advantages in detecting the stress concentration and early damage of ferromagnetic materials. The self-developed metal magnetic memory detection device is used to detect the drilling tools in the drilling tool base. The results show that the gradient peak value and ladder are used to detect the drilling tools in the drilling tool base. The average degree can be used to classify the fatigue of drilling tools, and the metal magnetic memory method is more than sensitive to various defects of drilling tools, such as penetration, internal corrosion, external corrosion, wall thickness thinning, etc.

Research on Impact Stress Transfer Characteristics of Lunar Rock Coring Drill

In the whole lunar surface drilling and sampling task, it is critical to make the operation of the drilling and sampling impact system efficient and reliable. This paper focuses on how to improve the impact stress obtained at the cutting edge of the drill bit. Firstly, with the objective of maximizing the output impact energy, the design parameters of the percussive mechanism are optimally selected; based on the one-dimensional stress wave transfer theory, the collision input model and transfer models of impact stress in the drilling tool are established. Secondly, in order to verify the above design parameters and theoretical models, the percussive drive characteristics’ test and the transfer characteristics’ tests of impact stress in the drill stem and drilling tool joints are carried out in turn. The experimental results are consistent with the theoretical analysis, which clarifies the transfer characteristics of the impact stress at the various stages of generation, incidence, and transfer to the cutting edge. It was finally found that increasing the percussive frequency and impact energy of the percussive mechanism as well as the contact stiffness of the collision surface can increase the incident impact stress of the drilling tool, while reducing the length of the screw connection between the drill bit and the drill stem can reduce the impact stress loss. This provides a theoretical reference for the design of the percussive mechanism and drilling tools in lunar surface drilling and sampling tasks.