Axial Excitation and Drill String Resonance as a Means of Aiding Tubular Retrieval - Small Scale Rig Testing and Full Scale Field Testing

Forster, I.; Grant, Robert

doi:10.2118/151096-ms

Cited by 6 publications

(3 citation statements)

References 4 publications

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“…Typical tool sizes are 1-11/16 in through 8 in Outer Diameter (OD) to suit a variety of applications. (Forster and Grant, 2012) If the induced axial excitation frequency coincides with the natural frequency/resonance of the drillstring/BHA…”

Section: Fig 1 -Axial Excitation Tool Designmentioning

confidence: 99%

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Drilling with Induced Vibrations Improves ROP and Mitigates Stick/Slip in Vertical and Directional Wells

Clausen

Schen

Forster

et al. 2014

IADC/SPE Drilling Conference and Exhibition

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For years drillers have been taught to mitigate all vibrations in the drillstring while drilling to maximize Rate of Penetration (ROP), limit bit damage, and extend bit life. While limiting lateral vibrations and stick/slip are proven ways to improve performance and maintain directional control, in recent years it has been conclusively proven in the field that inducing axial agitation with specialized downhole tools can significantly improve lateral reach. Currently, however, the benefits of downhole oscillation tools have not been thoroughly studied for other performance gains, such as improved ROP in non-directional wells.An extensive research study, including lab and field testing, found that a low-frequency, benign axial vibration can increase the ROP significantly in all well types. Initial laboratory experiments were performed by inducing axial vibrations into the drilling process on a small scale drill bit in hard rock. Dramatic improvements in ROP and drilling efficiency were observed, with the added benefits of improved bit life and an unexpected reduction in stick/slip. This lab experiment was later tested in the field by utilizing a proven downhole oscillation tool in an active Bottom Hole Assembly (BHA) to create the effect that was simulated in the lab. The field tests showed the same results as the lab tests: significant performance gains were observed in several test wells using the downhole oscillation tool as compared to offset data. In addition, this same downhole oscillation tool showed drastically improved directional control when run above a Rotary Steerable System (RSS) tool, and stick/slip was practically eliminated with no negative effect on bit life or BHA reliability.High-speed sensor data collected at the bit during both the lab and field tests will further demonstrate the validity of the theory. Testing for a hard-rock application with roller cone bits is forthcoming, as the data indicates possible performance gains in this environment as well.Overall, the study revealed many benefits, such as improving well placement, reducing Non-Productive Time (NPT) and time to Total Depth (TD) by preventing BHA component damage through beneficial axial vibrations from the downhole oscillation tool. The data indicates that "benign vibration" can drastically improve drilling performance. Induced Vibration Theory and Application Background (Forster and Grant, 2012)Theoretically, any drilling assembly which provides a fluctuating axial load application focused downhole will improve drilling efficiency. The axial excitation will improve drilling efficiency by breaking static friction, both in the BHA and at the bit. Once static friction is overcome and stead-state dynamic friction results, the Weight on Bit (WOB) required will be a fraction of the WOB required under normal drilling conditions, and load transfer will improve.

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Section: Fig 1 -Axial Excitation Tool Designmentioning

confidence: 99%

“…This same method will now be applied to drilling applications using the AET. (Forster and Grant, 2012) …”

Section: Time In Milliseconds Fig 9 -Bit Response With Increased Resmentioning

confidence: 99%

See 1 more Smart Citation

Drilling with Induced Vibrations Improves ROP and Mitigates Stick/Slip in Vertical and Directional Wells

Clausen

Schen

Forster

et al. 2014

IADC/SPE Drilling Conference and Exhibition

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Practical Approach to Functional Testing and Analytical Modeling of Axial Oscillation-Supported Drillstrings

Omojuwa

Ahmed

Acquaye³

2019

Journal of Energy Resources Technology

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Drillstrings that include one or more axial oscillation tools (AOTs) are referred to as axial oscillation-supported drillstrings. Downhole vibrations induced by these tools in the drillstring are the most efficient method for friction reduction and improving axial force transfer in high-angle and extended-reach wells. Functional testing of axial oscillation tools prior to downhole operations and modeling the dynamic response of axial oscillation-supported drillstring systems are required to predict the performance and functionality of AOTs. This study presents a practical approach for functional testing of axial oscillation tools and a new analytical model for predicting the dynamic response of axial oscillation-supported drillstrings operating at surface conditions. The axial oscillation-supported drillstring is modeled as an elastic continuous system subjected to viscous damping, frictional contact, and displacement (support excitation). The functional test is a unique experimental test procedure designed to measure the pressure drop, pressure fluctuations, and axial displacement of an axial oscillation tool while varying the flow rate and the spring rate of the tool. The introduction of the spring rate as a variable in the new model and functional testing is unique to this study and not considered in the existing literature. Axial displacement and acceleration predicted from the new model closely agrees with the results obtained from the functional tests. The accuracy of the model is also validated with the results of two previously published functional tests. The comparisons demonstrate an average deviation of approximately 14.5% between predictions and measurements. The axial displacement and pressure drop of AOT increased with flow rate or oscillation frequency. The amplitude of axial displacement increased with frequency because of increased pressure drop.

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Investigating the Benefits of Induced Vibrations in Unconventional Horizontals via Nonlinear Drill String Dynamics Modeling

Wilson

Heisig

2015

SPE/IADC Drilling Conference and Exhibition

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Inducing vibrations while drilling is a relatively new concept that shows promise in directional applications. Instigating motion of the drill string, particularly in the sections lying on the low-side of the wellbore, can lead to substantial improvements in managing the two limiting factors of the long horizontal wells that are typically associated with today's unconventional shale plays: removal of formation cuttings from the borehole, and frictional drag between non-rotating drill strings and the wellbore wall. Minimizing these effects, by introducing controlled vibrations, increases the overall drilling efficiency and reduces the cost associated with the well. The difficulty in implementing such actions, however, is consistency. Because the behavior of drilling assemblies is inherently nonlinear, it has been difficult in the past to reliably predict their response to dynamic events. This, in turn, creates a challenge when trying to optimize the performance of arbitrary Vibration Inducing Devices (VIDs). This paper presents a detailed analysis of the fully coupled, three-dimensional, nonlinear behavior of drill strings under the action of induced vibrations. Specific focus is given to the dynamic characteristics of a drill string, during horizontal drilling operations, in long unconventional wells and how this behavior affects the success of the well. The response of the drill string, due to induced axial and lateral oscillatory motions, is examined through linearized dynamic analysis and nonlinear timedomain simulations. Solutions obtained from the study provide a clearer understanding of the dynamics experienced down-hole and lead to suggestions for improved practices when drilling with lateral VIDs, particularly with regards to hole-cleaning. Further insights into the sliding and rotational behavior of the drill string, while using these types of tools, are drawn from animated modeling results. Finally, the future applications of this technology are discussed.

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Axial Excitation and Drill String Resonance as a Means of Aiding Tubular Retrieval - Small Scale Rig Testing and Full Scale Field Testing

Cited by 6 publications

References 4 publications

Drilling with Induced Vibrations Improves ROP and Mitigates Stick/Slip in Vertical and Directional Wells

Drilling with Induced Vibrations Improves ROP and Mitigates Stick/Slip in Vertical and Directional Wells

Practical Approach to Functional Testing and Analytical Modeling of Axial Oscillation-Supported Drillstrings

Investigating the Benefits of Induced Vibrations in Unconventional Horizontals via Nonlinear Drill String Dynamics Modeling

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