Mud Motor PDM Dynamics: An Analytical Model

2021 ◽  
Author(s):  
Robello Samuel ◽  
Fedor Baldenko ◽  
Dmitry Baldenko
Keyword(s):  
Transient Behavior ◽  
Drill String ◽  
Critical Speeds ◽  
Coupled Oscillations ◽  
Unbalanced Force ◽  
Positive Displacement ◽  
Bending Stresses ◽  
Equivalent Mass ◽  
Conservative Estimation ◽  
Lateral Displacements

Abstract In a fast drilling environment, suchas shale drilling, refining advanced technologies for preventing downhole toolfailures is paramount. Challenges are still very much associated with complex bottom-hole assemblies and the vibration of the drill string when used with a downhole mud motor. The mud positive displacement motor with various lobe configurations and designs becomes an additional excitation source of vibration. Further, it affects the transient behavior of the performance mud motor. Unbalanced force exists because the center ofmass of the motor rotor does not coincide with the axis of rotation.Further, the vector of full acceleration of the center of the rotor can be decomposed into two perpendicular projections—tangent and normal—which aretaken into account and integrated intothe full drill string forced frequency modelas force and displacement at the motorlocation. The paper includes two models, first one to predict the critical speeds and the second one to see the transient behavior of the downhole parameters when the mud motor is used.The model also considers the effect of the stringspeed. The unbalanced force is more pronounced at the lower pair or lobe configuration as compared to the higher pairlobe configuration because of the larger eccentricity. The unbalance is modeled in terms of an equivalent mass of therotor with the eccentricity of the rotor. Also, the analysis provides an estimation of relative bending stresses, shear forces, lateral displacements and transient bit rpm, bit torque, and weightone bit for the assembly used. Based onthe study, severe vibrations causing potentially damaging operating conditionswhen transient downhole forcing parametersare used for the vibration model.It has been found that when a mud motor isused using static forcing parameters may not provide the conservative estimation of the critical speeds as opposed totransient parameters. This is because coupled oscillations fundamentally can create new dynamic phenomena, which cannot be predicted from the characteristics of isolated elements of the drilling system.

Continuous Improvement: Rotary Steerable System with Electromagnetic Telemetry as Approach to Reduce Well Time

2021 ◽  
Author(s):  
Farit Rakhmangulov ◽  
Pavel Dorokhin
Keyword(s):  
Drill String ◽  
Telemetry System ◽  
Drilling Process ◽  
Construction Time ◽  
Horizontal Section ◽  
Well Drilling ◽  
Positive Displacement ◽  
Drilling Tools ◽  
Combined Use ◽  
Logging While Drilling

Abstract One of the main challenges from operating companies is the continuous reduction of well construction time. During drilling, considerable time is spent on static measurements to determine the wellbore location and to verify that the actual well path matches the planned one. The electromagnetic telemetry system (EMT) allows the taking of static directional survey measurements during connections, when the drill string is in slips. Transmitting commands to the rotary steerable system (RSS) through the EMT does not cause the drilling process to stop, which also reduces well construction time. The work describes well drilling experience with the use of the electromagnetic channel for communication with the rotary steerable system and the positive displacement downhole motor not only in horizontal section but in all well sections, starting from the top hole. Combined use of the complete logging while drilling tools (LWD) with this type of the telemetry system is a valuable finding. The article describes BHA, operational principles of this type of the telemetry system, and problems which may arise during operation.

Analysis of Some Factors Related to Permissible Horizontal Motions of a Floating Drilling Vessel

1970 ◽  
Vol 10 (03) ◽  
pp. 229-236 ◽  
Author(s):  
John E. Hansford ◽  
Arthur Lubinski
Keyword(s):  
Fatigue Damage ◽  
Water Depth ◽  
Drill Pipe ◽  
Drill String ◽  
Blowout Preventer ◽  
Bending Stresses ◽  
Cumulative Fatigue Damage ◽  
Vessel Motion ◽  
Pipe Bending ◽  
Rotary Drive

Abstract Horizontal vessel motions (drift, sway or surge) result in the bending of the drill-string members in the vicinity of the rotary-drive bushing at the vessel and at the blowout preventer close to the sea floor. Allowable horizontal vessel motions are calculated as a function of hookload, using both cumulative fatigue damage and drill-pipe strength as criteria for drilling and for pulling stuck pipe. The presently used rule limiting horizontal vessel motion to 5 percent of water depth is shown to be too restrictive in some cases and too lenient in others. Introduction When drilling from a floating vessel, the rotating drill string is subjected to fatigue damage caused by reversing stresses which arise from heave, roll, pitch and horizontal motions of the vessel. In Ref. pitch and horizontal motions of the vessel. In Ref. 1, the effect of drilling-vessel roll and pitch on the cumulative fatigue damage of the kelly and the first joint of drill pipe below the kelly are examined. As a continuation of that investigation, the present study covers the effect of horizontal motions of the vessel on the drill string. Horizontal departure from over the borehole may be oscillatory (sway or surge), static (drift), or most often, some combination of the two. An accepted limit of horizontal vessel motion of 5 percent of the water depth has been suggested mad percent of the water depth has been suggested mad frequently followed. In reality, the allowable motion is strongly influenced by the hookload. Motions greater than 5 percent of water depth are often permissible, and under some conditions, motions permissible, and under some conditions, motions should be limited to less than 5 percent of water depth. The purpose of this paper is to suggest maximum permissible motions imposed by drill-pipe fatigue damage and pipe strength, as a function of hookload. IDEALIZED SYSTEMS Fig. 1 shows an idealized system, highly exaggerated for explicitness. Although pipe bends are shown quite acute, bending stresses were properly defined mathematically. The pipe bending properly defined mathematically. The pipe bending at the rotary-drive bushing (labeled RDB in Fig. 1) is relieved in most cases by a gimbaled bushing and largely taken by the kelly, a more durable member. Therefore, the point of most severe damage is in the area of the blowout preventer rams (labeled BOP). SPEJ P. 229

A Novel Model for Catenary Drilling and Drill String Induced Stresses

2017 ◽  
Author(s):  
Catalin Teodoriu ◽  
Arash Asgharzadeh
Keyword(s):  
Great Depth ◽  
Drill String ◽  
Directional Drilling ◽  
Horizontal Section ◽  
Horizontal Drilling ◽  
Deep Wells ◽  
Bending Stresses ◽  
Novel Method ◽  
Extended Reach Drilling ◽  
Novel Model

Petroleum engineers are aware of the advantages of directional and horizontal wells. In case of intermediate deep wells, the preference is the customary solution, in which a well is drilled vertically to the kick off point, and then moved directionally to the reservoir level. Nowadays, due to the advent of extended reach drilling, this approach does not satisfy the meant goal anymore. In extended reach drilling, the concern lies on the drill pipe’s strength. Because of the great depth of the borehole, the torque and tension below the drill floor increase and could reach the drill pipe’s strength. Therefore, in order to extend the wellbore reach, it is necessary to minimize the torque and drag. Several authors have mentioned that catenary profile may help reduce torque and drag. The purpose of the paper is to analyze the mechanics of the drill string, and to understand the stress distribution along the drill string and the geometry of the well configurations while bringing the borehole from a vertical to a horizontal position. . This will be achieved by means of an analytical comparison between the catenary profiles and the conventional well configurations. A novel catenary profile which improves the previous models is also presented in this paper. The modified catenary has a larger curvature of the drill string; particularly in the upper parts of the borehole the bending stresses are small. The modified catenary profile, which resembles a free hanging cable, can be a novel method in directional drilling of deep and extended reach wells. Thus, the build rate in the modified catenary is being continuously increased until it reaches the desired position. It is different from conventional methods used especially in horizontal drilling to connect the vertical and the horizontal section, where the build rate is kept constant. The focus of this paper lies on the study of catenary’s geometry as a complex well path and the induced stress. Different approaches are used and compared.

scholarly journals Torsional vibrations in reciprocating engine shafts

1925 ◽  
Vol 109 (749) ◽  
pp. 99-119 ◽  
Keyword(s):  
Large Amplitude ◽  
Critical Speed ◽  
Practical Calculation ◽  
Torsional Vibrations ◽  
Connecting Rod ◽  
Elastic Vibrations ◽  
Critical Speeds ◽  
Reciprocating Engine ◽  
Complicated System ◽  
Equivalent Mass

It is well known that, in the case of reciprocating engines, there are certain critical speeds of running at which the torsional vibrations in the shaft become large in amplitude and introduce an element of danger into the system. Fairly simple methods have been devised for the practical calculation, from the constants of the machinery, of the location of these critical speeds. In these methods, the reciprocating parts of the engine are replaced by an “equivalent mass” which is assumed to contribute to the elastic vibrations of the shaft in exactly the same way as do the actual, rather complicated, system of crank, connecting-rod, piston and piston-rod. It is the main purpose of this paper to examine the correctness of this equivalence. In two particular cases examined by the author, the automatic records of the shaft vibrations at about a critical speed showed a large amplitude at the expected point, but the period of the vibration was twice that anticipated. This anomaly is examined on p.116 and the conditions of its existence exhibited.

Identification of a Laboratory Slide Drilling Experiment: The Relationship Between the Top Drive Rotation and the Tool-Face Angle

2019 ◽  
Author(s):  
Kaidong Chen ◽  
Xiaoyu Zhong ◽  
Zaibin Cheng ◽  
Yingjie Lu ◽  
Qiuhai Lu
Keyword(s):  
Drill String ◽  
Directional Drilling ◽  
Experiment Data ◽  
Angular Rotation ◽  
Single Input Single Output ◽  
Positive Displacement ◽  
Single Output ◽  
One Step ◽  
Single Input ◽  
The Relationship

Abstract Slide drilling refers to the technology of creating a predetermined non-vertical wellbore with a bent housing positive displacement motor (PDM). It is widely adopted in the area of directional drilling. In practical drilling operation, the top drive on the ground introduces an angular rotation to the top of the drill string, and the PDM at the bottom of the drill string rotates accordingly. When the bend is pointed to the desired direction, the adjustment of the PDM stops and the drill string slides without rotation to make a deviation. Up till now, the relationship between the top drive displacement and the direction of the bend, namely the tool-face angle (−180° ∼ 180°), is still unclear. In this research, an indoor slide drilling experiment is carried out, and the nonlinear relationship between the top drive input and the tool-face output is recorded. The hysteretic phenomenon observed is consistent with the in-field experience, and a single-input-single-output (SISO) system is established to describe this relationship. The Volterra/ Wiener neural network (VWNN) is introduced to identify this system, and provides a one-step prediction of the tool-face output. The predicted tool-face output is verified by the experiment data.

Modeling and Analysis of Drillstring Vibration in Riserless Environment

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Robello Samuel
Keyword(s):  
Mathematical Formulation ◽  
Careful Consideration ◽  
Operating Conditions ◽  
Drilling Process ◽  
Analysis Model ◽  
Modeling And Analysis ◽  
Bending Stresses ◽  
Downhole Tool ◽  
Lateral Displacements ◽  
Well Data

Riserless drilling poses numerous operational challenges that adversely affect the efficiency of the drilling process. These challenges include increased torque and drag, buckling, increased vibration, poor hole cleaning, tubular failures, poor cement jobs, and associated problems during tripping operations. These challenges are closely associated with complex bottomhole assemblies (BHAs) and the vibration of the drillstring when the topholes are drilled directionally. Current methods lack proper modeling to predict drillstring vibration. This paper presents and validates a modified model to predict severe damaging vibrations, analysis techniques, and guidelines to avoid the vibration damage to BHAs and their associated downhole tools in the riserless highly deviated wells. The dynamic analysis model is based on forced frequency response (FFR) to solve for resonant frequencies. In addition, a mathematical formulation includes viscous, axial, torsional, and structural damping mechanisms. With careful consideration of input parameters and judicious analysis of the results, the author demonstrates that drillstring vibration can be avoided by determining the 3D vibrational response at selected excitations that are likely to cause them. The analysis also provides an estimate of relative bending stresses, shear forces, and lateral displacements for the assembly used. Based on the study, severe vibrations causing potentially damaging operating conditions were avoided, which posed a major problem in the nearby wells. The study indicates that the results are influenced by various parameters, including depth of the mud line, offset of the wellhead from the rig center, wellbore inclination, curvature, wellbore torsion, and angle of entry into the wellhead. This study compares simulated predictions with actual well data and describes the applicability of the model. Simple guidelines are provided to estimate the operating range of the drilling parameter to mitigate and avoid downhole tool failures.

Correlation averaging of two-dimensional crystals: basic strategy and refinements

1986 ◽  
Vol 44 ◽  
pp. 136-139
Author(s):  
W. Baumeister ◽  
R. Rachel ◽  
R. Guckenberger ◽  
R. Hegerl
Keyword(s):  
Low Dose ◽  
Signal To Noise Ratio ◽  
Real Space ◽  
Fourier Domain ◽  
Two Dimensional ◽  
Signal To Noise ◽  
Unit Cells ◽  
Lateral Displacements ◽  
Established Technique ◽  
Crystalline Array

IntroductionCorrelation averaging (CAV) is meanwhile an established technique in image processing of two-dimensional crystals /1,2/. The basic idea is to detect the real positions of unit cells in a crystalline array by means of correlation functions and to average them by real space superposition of the aligned motifs. The signal-to-noise ratio improves in proportion to the number of motifs included in the average. Unlike filtering in the Fourier domain, CAV corrects for lateral displacements of the unit cells; thus it avoids the loss of resolution entailed by these distortions in the conventional approach. Here we report on some variants of the method, aimed at retrieving a maximum of information from images with very low signal-to-noise ratios (low dose microscopy of unstained or lightly stained specimens) while keeping the procedure economical.

Conservative Estimation of Whole-body Average SAR in Infant Model for 0.3-6GHz Far-Field Exposure

2009 ◽  
Vol 129 (12) ◽  
pp. 2102-2107 ◽  
Author(s):  
Akimasa Hirata ◽  
Yoshio Nagaya ◽  
Naoki Ito ◽  
Osamu Fujiwara ◽  
Tomoaki Nagaoka ◽  
...  
Keyword(s):  
Whole Body ◽  
Far Field ◽  
Field Exposure ◽  
Conservative Estimation

An Analytical Transient Tire Model

2001 ◽  
Vol 29 (2) ◽  
pp. 108-132 ◽  
Author(s):  
A. Ghazi Zadeh ◽  
A. Fahim
Keyword(s):  
Transient Behavior ◽  
Stability Control ◽  
Vehicle Stability ◽  
Tire Model ◽  
Steering Angle ◽  
First Order ◽  
Vehicle Stability Control ◽  
Proposed Model ◽  
Depth Study ◽  
And Performance

Abstract The dynamics of a vehicle's tires is a major contributor to the vehicle stability, control, and performance. A better understanding of the handling performance and lateral stability of the vehicle can be achieved by an in-depth study of the transient behavior of the tire. In this article, the transient response of the tire to a steering angle input is examined and an analytical second order tire model is proposed. This model provides a means for a better understanding of the transient behavior of the tire. The proposed model is also applied to a vehicle model and its performance is compared with a first order tire model.

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