High-Frequency Torsional Oscillation Laboratory Testing of an Entire Bottom Hole Assembly

Drillstring vibration is one of the limiting factors maximizing drilling performance. Torsional vibrations/oscillations while drilling is one of the sever types of drillstring vibration which deteriorates the overall drilling performance, causing damaged bit, failure of bottom-hole assembly, overtorqued tool joints, torsional fatigue of drillstring, etc. It has been identified that the wellbore-drillstring interaction and well face-drill bit interaction are the sources of excitation of torsional oscillations. Predrilling analysis and real time analysis of drillstring dynamics is becoming a necessity for drilling oil/gas or geothermal wells in order to optimize surface drilling parameters and to reduce vibration related problems. It is very challenging to derive the drillstring model considering all modes of vibrations together due to the complexity of the phenomenon. This paper presents the mathematical model of a torsional drillstring based on nonlinear differential equations which are formulated considering drillpipes and bottom-hole assembly separately. The bit–rock interaction is represented by a nonlinear friction forces. Parametric study has been carried out analyzing the influence of drilling parameters such as surface rotations per minute (RPM) and weight-on-bit (WOB) on torsional oscillations. Influences of properties of drillstring like stiffness and inertia, which are most of the times either unknown or insufficiently studied during modeling, on torsional oscillation/stick-slip is also studied. The influences of different rock strength on rate of penetration (ROP) considering the drilling parameters have also been studied. The results show the same trend as observed in fields.

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Analysis of Oscillating Fishing Tool Efficiency for Stuck Assembly Recovery in Field X

10.2118/205829-ms ◽

2021 ◽

Author(s):

Pratama Wangsit Bayuartha ◽

Parluhutan Alvin Sitorus ◽

Rahmat Sinaga ◽

Tomi Sugiarto ◽

Kristoforus Widyas Tokoh ◽

...

Keyword(s):

High Frequency ◽

High Frequency Oscillation ◽

Oil Reserves ◽

Bottom Hole ◽

Successful Case ◽

Probability Of Success ◽

Bottom Hole Assembly ◽

Offshore Field ◽

The Impact ◽

Degree Of Recovery

Abstract As conventional fishing assembly offers a degree of recovery chance, such chance can be increased by utilizing an Oscillating Fishing Tool (OFT). The OFT is a fishing Bottom Hole Assembly (BHA) component that delivers low-magnitude; high-frequency oscillation. The continuous motion that the tool provides complements the impact generated by the fishing jar. This paper reviews the successful case history in Field X, which was in fact the first utilization of OFT for a fishing application in the field. Method of analysis involve comparing fishing sequence without and with the OFT. The OFT was used in Offshore Field X to recover a mechanically stuck 550-meter long Tubing Conveyed Perforating Gun assembly inside 9 5/8" casing that could potentially lead to loss of access into the 6 oil reserves candidate perforation zones. Initially the assembly had been stuck for two days, during which conventional fishing BHA was used to retrieve it to no avail, even after jarring for most of that time. OFT was then incorporated in the final fishing BHA and operated in combination with jarring operation. After around twelve hours of oscillating and jarring, the fish was able to be released from the initial stuck point. When tripping the string out, however, the assembly was stuck at high dog-leg severity area near the surface. At that point, in combination with applying substantial overpull, OFT was utilized further to recover the entire string. Upon fish retrieval, it was evident that post detonation, the TCP gun had swelled into 8.6 inches in diameter. In summary, oscillating and jarring for thirty-six cumulative hours successfully released the swelled TCP gun assembly from the stuck occurrences. In conclusion, the operation showed that the OFT serves as a higher level of fishing tool option that offers a particular excitation mode to the stuck assembly. Stuck assembly in a cased hole presents potential loss of oil reserves. Particularly in offshore application, the situation can also be costly. With reduced chance of recovery as time passes by, operation is hindered from being able to proceed to the next completion phase. The case proved OFT to have played an important role in improving fishing probability of success and should be considered as standard fishing BHA in the future.

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

Journal of Vibration and Control ◽

10.1177/10775463211031065 ◽

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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Bit Design Methodology to Mitigate High-Frequency Torsional Oscillation

10.2118/206353-ms ◽

2021 ◽

Author(s):

Rob Tipples ◽

Sahet Keshiyev ◽

Kian Sheikhrezaei ◽

Prabhakaran Centala

Keyword(s):

Theoretical Model ◽

High Frequency ◽

Laboratory Testing ◽

Design Methodology ◽

Field Data ◽

Laboratory Experiments ◽

Torsional Oscillation ◽

Area Ratio ◽

Design Metrics ◽

Cutter Wear

Abstract This paper reviews field data where high-frequency torsional oscillation (HFTO) was seen on previous bit runs and hypothesizes on features or design metrics that may have directly influenced this vibration. This paper investigates four metrics of bit design: Cutter wear, shear length:shear area ratio, choice of secondary cutter material, and effective backrake. Hypotheses are established linking these metrics to HFTO, and then data from field runs is shown to correlate the hypotheses. At this point, a bit was designed and manufactured to put the HFTO avoidance hypotheses into practice. Prior to laboratory testing, a theoretical model is used to identify resonant torsional frequencies. A series of laboratory experiments followed to test the hypotheses and demonstrated that there is correlation between all factors, but in one case is counter to the hypothesis. This information is of use when selecting or designing bits in environments where HFTO is known to occur. The findings may also assist in explaining performance that's below expectations where HFTO is not able to be explicitly measured.

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Bottom Hole Assembly Design Enhancement Successfully Eliminate Hole Problems and Reduce Significant Drilling Time : South S Field Case Study

Proc. Indon. Petrol. Assoc., Digital Technical Conference, 2020 ◽

10.29118/ipa20-e-71 ◽

2020 ◽

Author(s):

Y. D. Mulia

Keyword(s):

Contact Area ◽

Cost Savings ◽

Assembly Design ◽

Drilling Performance ◽

Bottom Hole ◽

Unconsolidated Sand ◽

Bottom Hole Assembly ◽

Drilling Parameter ◽

Drilling Time

For S-15 and S-14 wells at South S Field, drilling of the 12-1/4” hole section became the longest tangent hole section interval of both wells. There were several challenges identified where hole problems can occur. The hole problems often occur in the unconsolidated sand layers and porous limestone formation sections of the hole during tripping in/out operations. Most of the hole problems are closely related to the design of the Bottom Hole Assembly (BHA). In many instances, hole problems resulted in significant additional drilling time. As an effort to resolve this issue, a new BHA setup was then designed to enhance the BHA drilling performance and eventually eliminate hole problems while drilling. The basic idea of the enhanced BHA is to provide more annulus clearance and limber BHA. The purpose is to reduce the Equivalent Circulating Density (ECD,) less contact area with formation, and reduce packoff risk while drilling through an unconsolidated section of the rocks. Engineering simulations were conducted to ensure that the enhanced BHA were able to deliver a good drilling performance. As a results, improved drilling performance can be seen on S-14 well which applied the enhanced BHA design. The enhanced BHA was able to drill the 12-1/4” tangent hole section to total depth (TD) with certain drilling parameter. Hole problems were no longer an issue during tripping out/in operation. This improvement led to significant rig time and cost savings of intermediate hole section drilling compared to S-15 well. The new enhanced BHA design has become one of the company’s benchmarks for drilling directional wells in South S Field.

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

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/1461348421989156 ◽

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.

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Analytical studies of bottom hole assembly dynamics in directional well while drilling with coiled-tubing system

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1064/1/012076 ◽

2021 ◽

Vol 1064 (1) ◽

pp. 012076

Author(s):

L Z Zainagalina ◽

E Ya Zinatullina ◽

A R Safiullina

Keyword(s):

Coiled Tubing ◽

Bottom Hole ◽

Analytical Studies ◽

Bottom Hole Assembly

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Mechanisms and Mitigation of 3D Coupled Vibrations in Drilling with PDC Bits

10.2118/205904-ms ◽

2021 ◽

Author(s):

Shilin Chen ◽

Chris Propes ◽

Curtis Lanning ◽

Brad Dunbar

Keyword(s):

Torsional Oscillation ◽

Excitation Frequency ◽

Low Frequency ◽

Coupled Vibration ◽

Stick Slip ◽

Rock Interaction ◽

Bottom Hole ◽

New Type ◽

Design Characteristics ◽

Axial Resonance

Abstract In this paper we present a new type of vibration related to PDC bits in drilling and its mitigation: a vibration coupled in axial, lateral and torsional directions at a high common frequency (3D coupled vibration). The coupled frequency is as high as 400Hz. 3D coupled vibration is a new dysfunction in drilling operation. This type of vibration occurred more often than stick-slip vibration. Evidences reveal that the coupled frequency is an excitation frequency coming from the bottom hole pattern formed in bit/rock interaction. This excitation frequency and its higher order harmonics may excite axial resonance and/or torsional resonance of a BHA. The nature of 3D coupled vibration is more harmful than low frequency stick-slip vibration and high frequency torsional oscillation (HFTO). The correlation between the occurrence of 3D coupled vibration and bit design characteristics is studied. Being different from prior publications, we found the excitation frequency is dependent on bit design and the occurrence of 3D coupled vibration is correlated with bit design characteristics. New design guidlines have been proposed to reduce or to mitigate 3D coupled vibration.

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

Prospecting and Development of Oil and Gas Fields ◽

10.31471/1993-9973-2019-3(72)-58-68 ◽

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.

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