scholarly journals Studying of speed on the process drill string flattening vertical wells

2019 ◽  
pp. 30-38
Author(s):  
Rasul M. Aliyev ◽  
Shamil M. Kurbanov ◽  
Temirlan M. Umariev
Keyword(s):  
Drill String ◽  
Oil Field ◽  
Vertical Wells ◽  
Service Companies ◽  
Field Service ◽  
Bottom Hole ◽  
Geological Conditions ◽  
Bottom Hole Assembly ◽  
The Cost ◽  
Drill Collar

The issue of vertical wells curvature is important, especially when conducting wells in complex geological conditions of drilling, due to the increasing depth of the wells and the corresponding rise in the cost of drilling. The cause of this circumstance lies in the large time and financial costs while flattening of the bent wells. Moreover, it should be noted that during the subsequent drilling of a curved well the risk of key-seating and the corresponding complications increases. That is why large oil field service companies and drilling enterprises are paying more and more attention to solving the problem of vertical wells curvature. This article is devoted to investigation the effect of rotation of the drill string on the deflecting force on the bit while drilling a vertical well in a rotary way. We suggest using of eccentric drill collars for drilling vertical wells in difficult geological conditions. Also, we create an expression for the dynamic milling force on the bit, taking into account the usage of an eccentric drill collar in the composition of bottom-hole assembly.

scholarly journals Applying modern technologies when drilling directional wells with long horizontal boreholes

2020 ◽  
pp. 13-18
Author(s):  
Kuriachii Aleksandr ◽  
◽  
Kaliagin Sergei ◽  
Keyword(s):  
Horizontal Wells ◽  
Economic Advantage ◽  
Directional Drilling ◽  
Skew Angle ◽  
Service Companies ◽  
Bottom Hole ◽  
Geological Conditions ◽  
Bottom Hole Assembly ◽  
The Given ◽  
Modern Technologies

Introduction. Directional drilling of wells is currently carried out by a rotary steerable system and conventional equipment including a mud motor with an adjustable skew angle. Either of the two methods has particular advantages. Research aim is to analyze the technologies provided by various service companies in the field of directional and horizontal wells drilling in order to provide means of improving the utilization capacity of the conventional bottom hole assembly in long horizontal boreholes. Methodology. When drilling directional wells with a small departure from the vertical and wells with horizontal boreholes up to 500 m long, a preference is given to a mud motor as far as a change in deviation parameters is concerned. This is due to the fact that the mud motor has a significant economic advantage. However, when drilling directional well with complex planned profile or a well with a horizontal borehole of more than 500 m, the mud motor may cause a variety of problems, while a rotary steerable system will allow to avoid some of them. Results. The rotary steerable system is not always economically feasible suggesting a need for an alternative technology with a more advantageous offer on the market of services. A system of pulsed controlled drilling will allow the adjustment of the trajectory of the wellbore when drilling in a rotary mode with conventional equipment for directional drilling, reduce rig time, and improve the borehole quality. Summary. The given technology will make it possible to improve the efficiency of conventional equipment which includes the mud motor for directional wells drilling with complex planned profile and long horizontal boreholes of more than 500 m, as soon as the technology provides the possibility of adjusting the trajectory in a rotary mode. The system of pulsed controlled drilling is developed as an alternative to the rotary steerable system making it possible to significantly reduce construction expenses for wells with complex geological conditions of drilling

scholarly journals Kinematics and dynamics analysis of new rotary-percussive PDM drilling tool

2021 ◽  
pp. 146134842198915
Author(s):  
Jialin Tian ◽  
Xuehua Hu ◽  
Liming Dai ◽  
Lin Yang ◽  
Yi Yang ◽  
...  
Keyword(s):  
Drill String ◽  
Structure Design ◽  
Drilling Process ◽  
Analysis Model ◽  
Drilling Tool ◽  
Stick Slip ◽  
Rate Of Penetration ◽  
Bottom Hole ◽  
Bottom Hole Assembly ◽  
The Impact

This paper presents a new drilling tool with multidirectional and controllable vibrations for enhancing the drilling rate of penetration and reducing the wellbore friction in complex well structure. Based on the structure design, the working mechanism is analyzed in downhole conditions. Then, combined with the impact theory and the drilling process, the theoretical models including the various impact forces are established. Also, to study the downhole performance, the bottom hole assembly dynamics characteristics in new condition are discussed. Moreover, to study the influence of key parameters on the impact force, the parabolic effect of the tool and the rebound of the drill string were considered, and the kinematics and mechanical properties of the new tool under working conditions were calculated. For the importance of the roller as a vibration generator, the displacement trajectory of the roller under different rotating speed and weight on bit was compared and analyzed. The reliable and accuracy of the theoretical model were verified by comparing the calculation results and experimental test results. The results show that the new design can produce a continuous and stable periodic impact. By adjusting the design parameter matching to the working condition, the bottom hole assembly with the new tool can improve the rate of penetration and reduce the wellbore friction or drilling stick-slip with benign vibration. The analysis model can also be used for a similar method or design just by changing the relative parameters. The research and results can provide references for enhancing drilling efficiency and safe production.

scholarly journals The Study of the Interaction of Different Arrangements of the Bottom-Hole Assembly with the Bottomhole and the Borehole Wall

2019 ◽  
pp. 58-68
Author(s):  
Ya. M. Kochkodan ◽  
A.I. Vasko
Keyword(s):  
Differential Equations ◽  
Contact Point ◽  
Point Contact ◽  
Drill String ◽  
Borehole Wall ◽  
Deviation Angle ◽  
Technological Parameters ◽  
Bottom Hole ◽  
Anisotropy Index ◽  
Bottom Hole Assembly

The article presents the main factors affecting the buckling when drilling vertical wells. The authors study analytically the effect of the weight on the bit and the force of the interaction of a drill string with a borehole wall using a uniform-sized arrangement of the bottom-hole assembly and the borehole wall which is located in a deviated wellbore when drilling in isotropic rocks in case the drilling direction coincides with the direction of the force acting on the bit. Differential equations of the elastic axis of the drill string are worked out. The solutions of these equations have given nondimensional dependences between the technological parameters. The authors have obtained the graphical dependences of the distance from the bit to the “drill string - borehole wall” contact point and the normal reaction of the bottom to the bit and the “drill string - borehole wall” clearance. The dependence for identifying the drilling anisotropy index in oblique beds is obtained. An interrelation between the anisotropy drilling index, the zenith angle, the bedding angle, the bottom-hole assembly, the borehole dimensions and the axial weight on the bit has been established. The authors have studied analytically the effect of the weight on the bit and the force of the “drill string - borehole wall” interaction, when installing the centralizer to the bottom-hole assembly. The differential equations of the elastic axis of the drill string with the centralizer in the bottom-hole assembly are obtained. It is established that with the increase in the axial weight on the bit and the “drill collars - borehole wall” clearance, the distance from the bit to the contact point of the borehole wall decreases; whereas with the increase of the deviation angle and the clearance, the pressure force of the column on the walls increases. It has also been established that the anisotropy drilling index reduces the distance from the bit to the point contact both in a slick BHA and in the bottom hole assembly with the centralizer. The presence of a centralizer in the bottom hole assembly increases the distance from the bit to the contact point between the string and the borehole wall, makes it possible to increase the weight on the bit without the risk of increasing a deviation angle.

Implementation of a Bottom-Hole Assembly Program

2007 ◽  
Author(s):  
Kenneth Bhalla ◽  
Lixin Gong ◽  
George McKown
Keyword(s):  
Computationally Efficient ◽  
Efficient Tool ◽  
Shock Absorbers ◽  
Bottom Hole ◽  
Size Number ◽  
Weight On Bit ◽  
Bottom Hole Assembly ◽  
Parametric Studies ◽  
Dip Angle ◽  
Drill Collar

A state of the art windows graphical user interface (GUI) program has been developed to predict and design the bottom-hole assembly (BHA) performance for drilling. The techniques and algorithms developed in the program are based upon those developed by Lubinski and Williamson. The BHA program facilitates in conducting parametric studies, and in making field decisions for optimal performance. The input parameters may include: formation class, dip angle, hole size, drill collar size, number of stabilizers, stabilizer spacing. The program takes into consideration bit-formation characteristics and interaction, drill collar sizes, square collars, shock absorbers, MWD tools, reamer tools, directional tools, rotary steerable systems etc. The output may consist of hole curvature (build up or drop rate), hole angle, weight on bit and is presented in drilling semantics. Additionally, the program can perform mechanical analyses and solve for the bending moments and reactions forces. Moreover, the program has the capability to predict the wellpath using a drill ahead algorithm. The program consists of a mathematical model which makes assumptions of 2-D, static, constant hole curvature resulting in a robust computationally efficient tool that produces rapid reliable results in the field.

Proper Selection of Drill String Bottom-Hole Assembly for Directional Well Drilling

2014 ◽  
Vol 50 (9-10) ◽  
pp. 583-587
Author(s):  
S. A. Zaurbekov ◽  
B. Z. Kaliev ◽  
M. Zh. Muzaparov ◽  
Zh. N. Kadyrov ◽  
A. V. Kochetkov
Keyword(s):  
Drill String ◽  
Proper Selection ◽  
Well Drilling ◽  
Bottom Hole ◽  
Bottom Hole Assembly ◽  
Selection Of

Nonlinear Model for Dynamic Behavior of Drill-String

2002 ◽  
Author(s):  
Hayat Melakhessou ◽  
Alain Berlioz ◽  
Guy Ferraris
Keyword(s):  
Dynamic Behavior ◽  
Degrees Of Freedom ◽  
Initial Position ◽  
Drill String ◽  
Lagrange Equations ◽  
Bottom Hole Assembly ◽  
Drilling Operations ◽  
Set Up ◽  
Mean Time ◽  
Drill Collar

This article is devoted to the study of the contact between the drill-string and the well during drilling operations. The study focuses on the Bottom-Hole-Assembly (BHA), which is submitted to compression. The work is motivated by the need to understand the complex behavior of such a system, in order to improve control their constructive and destructive potentials. The contact, which is supposed to be localized on the drill-collar or stabilizers, is prejudicial and involves a premature abrasive wear of the drill-string, reduction of the rate of penetration of the tool into the rock (ROP) and reduction of the mean time between failure (MTBF). The proposed mathematical model is expressed in terms of four independent degrees of freedom. They include the effects of bending and torsion; the whirling motion of the drill-string as well as the phenomena of friction between the drill-string and the well. The tangential effect is modeled by using Coulomb’s law of friction. The nonlinear equations of the movement are derived using Lagrange equations and are solved numerically to obtain the response. Specific attention is paid to the study of friction and a consistent contact model which is capable of taking into account the rolling of the drill-string, both with and without slip, is included in the model. This paper also presents a parametric study on the influence of the initial position of the string and the friction coefficient of the contact on the dynamic behavior of the structure. An experimental set-up, equipped with two optolineic devices, is used to validate the model.

The Effect of Stick Slip Vibration on the Backward Whirl of Bottom Hole Assembly in Drillstring

2016 ◽  
Author(s):  
Dapeng Zhao ◽  
Sigve Hovda ◽  
Sigbjørn Sangesland
Keyword(s):  
Torsional Vibration ◽  
Borehole Wall ◽  
Stick Slip ◽  
Rock Interaction ◽  
Bottom Hole ◽  
Nonlinear Contact ◽  
Backward Whirl ◽  
Bottom Hole Assembly ◽  
Rotary Speed ◽  
Drill Collar

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.

scholarly journals Methods and technical solutions for keeping the path of a geotechnological borehole

2021 ◽  
Vol 6 (1) ◽  
pp. 42-51
Author(s):  
D. N. Moldashi
Keyword(s):  
Economic Effect ◽  
Drill String ◽  
Soft Rocks ◽  
Bottom Hole ◽  
Ore Bodies ◽  
Drilling Tools ◽  
Wide Range ◽  
Bottom Hole Assembly ◽  
Drilling Conditions ◽  
Technical Solutions

With increasing depth of exploration and process boreholes (at small drilling diameters), the probability of deviation of the borehole path from design trajectory increases many times; i. e. zenith curvature and azimuth deviation of the borehole path occur. Therefore, developing methods for keeping vertical path of the borehole when drilling deeper horizons of ore bodies is a very topical issue. The paper presents the results of developing a new bottom-hole assembly for drilling boreholes in soft rocks using screw casing centralizers, which provide good stabilizing and centering effects to mitigate horizontal departure of the hole axis from the design direction and minimize vertical curvature of the hole path (zenith angle) while maintaining sufficient drill string flexibility. The developed technical solutions provide simplicity of design and ability to adapt to wide range of mining, geological and technological drilling conditions. The feasibility of manufacturing the centralizers by own efforts and the technological feasibility of quick and easy connecting the centralizer with other elements of the bottom-hole assembly have been substantiated. The manufacture efficiency is proved by the use of inexpensive and wear-resistant materials in the centralizer armouring, for which tungsten-cobalt or titanium-cobalt hard-alloy inserts were used. In addition, prevailing volume of borehole drilling in soft rocks allowed using replaceable centering elements, as well as their repair and restoration to increase their service life. The manufactured centralizer has a low production cost due to the design simplicity and the use of inexpensive wearresistant material and will compete in the market of drilling tools and technical devices for drill string stabilization. The economic effect from the introduction of the self-produced centralizers amounted to more than 170,000 tenge per a borehole.

Energy transfer through parametric excitation to reduce self-excited drill string vibrations

2021 ◽  
pp. 107754632110310
Author(s):  
Vincent Kulke ◽  
Georg-Peter Ostermeyer
Keyword(s):  
Energy Transfer ◽  
Parametric Excitation ◽  
High Frequency ◽  
Drill String ◽  
Alternative Methods ◽  
Installation Space ◽  
Energy Output ◽  
Torsional Oscillations ◽  
Bottom Hole ◽  
Bottom Hole Assembly

Drilling a wellbore can result in several types of vibration that lead to inefficient drilling and premature failure of drill string components. These vibrations are subdivided based on their operating direction into lateral, torsional, and axial vibrations. Especially in hard and dense formations, high-frequency torsional oscillations are found in the bottom-hole assembly (BHA). These critical vibrations are induced by a self-excitation mechanism caused by the bit–rock interaction. Self-excitation mechanisms are regenerative effects, mode coupling, or a velocity-dependent torque characteristic at the drill bit. To increase drilling performance and reduce tool failure due to high-frequency torsional oscillations, the critical vibration amplitudes localized at the bottom-hole assembly need to be minimized. Increasing the damping of self-excited systems to affect the energy output during vibration is a common approach to mitigate self-excited vibrations. In drilling systems, the achievable damping is naturally limited by the small installation space due to the drilled borehole diameter. Therefore, alternative methods to influence vibrations are necessary. Applying parametric excitation in self-excited systems can result in a parametric anti-resonance and therefore in an energy transfer within different modes of the structure. This allows, among other benefits, improved utilization of the structural damping. In this article, the influence of additional stiffness–based parametric excitation on self-excited torsional vibration in downhole drilling systems is investigated. For this purpose, a finite element model of a drill string is reduced using the component mode synthesis and analyzed with the goal to mitigate torsional vibrations. The multiple degree of freedom drill string model is investigated regarding the additional energy transfer due to the parametric excitation. Robustness of various parameters, especially with regard to the positioning within the bottom-hole assembly, is analyzed and discussed. Additionally, the problem of multiple unstable self-excited modes due to the nonlinear velocity-dependent torque characteristic in drilling systems is addressed.

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