Effect of Formations Compressive Strength on Drill String Vibrations

Esmaeili, Abdolali; Elahifar, Behzad; Frühwirth, R.; Thonhauser, Gerhard

doi:10.2523/16985-abstract

Cited by 4 publications

(4 citation statements)

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“…Block position, hole depth, hook load, weight on bit, rotary speed of the drill string and torque on bit were recorded in real-time with a sampling frequency of 1 Hz. First and second order frequency moments of all vibrations were calculated in addition (Esmaeili et al, 2013). The vibration sensor sub (Figure 5b) was used to record the drill string vibrations.…”

Section: Methodsmentioning

confidence: 99%

Formation Prediction Model based on Drill String Vibration Measurements Using Laboratory Scale Rig

Esmaeili

Elahifar

Frühwirth³

et al. 2013

All Days

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Characteristics of formations usually cause changes in the drilling parameters such as weight on bit and drill string rotational speed as well as drill string dynamic behavior. When the drill bit breaks up formations, some of the energy dedicated to drilling is transmitted to the drill string as axial, lateral and torsional vibrations. Although these vibrations are affected by the drilling parameters, it has been experienced that vibration measurements can be used to evaluate formations during drilling a well. For this purpose a laboratory scale drilling rig was used to perform numerous experiments. During the drilling operations, several drilling parameters as well as vibrations with three-component accelerometers attached to the drill string were recorded continuously. Numerous uniform concrete and rock samples were drilled by a double roller cone bit. The uniaxial compressive strength of all concretes and rocks were measured prior to the experiments. The tests were executed using different combinations of weight on bit and rotary speed.For a subsequent evaluation statistical features were extracted in a first step from the recorded data in both, the time domain and the frequency domain. Those features formed the base for the formation classification by linear and non-linear models. Although linear models like Bayesian inference are not suited for that challenge, it turned out that non-linear models like neural networks provide excellent results in both, the training and the test data-set. Finally, the application of parameter selection methods showed that mechanical specific energy and rate of penetration in combination with higher order frequency moments of all recorded vibration types play the major role in the formation classification.

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Section: Methodsmentioning

confidence: 99%

Formation Prediction Model based on Drill String Vibration Measurements Using Laboratory Scale Rig

Esmaeili

Elahifar

Frühwirth³

et al. 2013

All Days

Self Cite

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“…The BHA remains constant during the duration of a bit run, thus frequency shifts indicate formation changes and can be used to identify formation tops (Al-Shuker et al, 2011;Esmaeili et al, 2013). For a sensor located near the bit, the spectrum is dominated by the resonances of the BHA and bit-rock interaction.…”

Section: High-frequency Downhole Vibration Data Setmentioning

confidence: 99%

For Better or Worse: Applications of the Transfer Matrix Approach for Analyzing Axial and Torsional Vibration

Shor

Dykstra

Hoffmann

et al. 2015

SPE/IADC Drilling Conference and Exhibition

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The response of the drilling system to axial and torsional vibration inputs has a significant impact on drilling performance. Usually the goal is to minimize dynamic response to limit the effects of potentially damaging phenomena in the low frequency range (e.g. bit bounce and torsional stick-slip) and high frequency range (e.g. axial chatter and torsional resonance). However, in some cases the goal is to maximize dynamic response, for example when introducing oscillation tools to overcome wellbore friction while directional drilling or to free stuck pipe. Whether the intention is to maximize or minimize, a suitable mathematical model is required. The model presented in this study uses the transfer matrix approach to predict how a harmonic vibration input propagates through the remainder of the drillstring. Novel features of the model include the ability to place the excitation source anywhere in the drillstring and to estimate damping effects due to Coulomb friction in directional wells.Model inputs include drillstring and bottom hole assembly composition, well survey data, surface equipment and drilling parameters. Drillstring components are modeled as spring or beam elements and the surface equipment is modeled as a mass-spring system. Bit-formation interaction is modeled as a spring, the stiffness of which can be adjusted to provide a boundary condition ranging from fixed to free. Damping due to material hysteresis and interaction with the drilling fluid is modeled using a velocitydependent term. Coulomb friction is modeled as an equivalent viscous damping coefficient. A harmonic excitation is specified at a given location in the drillstring and the responses at other locations in the system are computed via transfer matrices. This approach allows rapid characterization of the axial and torsional response of the drillstring in the frequency domain and may be applied to analyses of induced oscillation, such as from axial oscillation tools (AOTs), or unintended vibration, such as bit bounce.Case studies show that predicted frequency responses in the axial and torsional domain compare favorably with high sampling rate downhole and surface measurements, respectively. Additional case studies demonstrate how the model has been successfully applied to diagnose and resolve severe axial vibrations while drilling with roller cone bits. Finally, model predictions are compared with downhole acceleration measurements to evaluate effectiveness of axial oscillation tools while drilling with steerable motor systems. Recommended practices for device placement and drillstring configuration are provided based on the findings from these studies.

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“…Ref. [11] investigated the effect of formations compressive strength on drill string vibrations and demonstrated that uniaxial compressive strength of harder formation increases with the magnitude of vibrations and reversely. Ref.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Influence of the Drill String Vibration Cyclic Loads on the Development of the Wellbore Natural Fracture

et al. 2021

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Wellbore instability is one of the most serious issues faced in the drilling process. During drilling operations, the cyclic loads applied on the fractured formation progressively modify the initial parameters (i.e., length and width) of the fractured formation, thus resulting into undesirable wellbore instability. In this paper, using a nonlinear finite element software (ABAQUS) as the numerical simulator, a poro-elasto-plastic model has been established which aimed at analyzing the influence of drill string vibration cyclic loads on the development of the wellbore natural fracture. The numerical results showed that the fracture width as a function of time profiles followed a sinusoidal behavior similar to the drill string vibration cyclic load profiles. For different cyclic load magnitudes with constant number of cyclic loads, the highest percentage increase of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the fracture width increased with the fracture length in the near wellbore region while it globally decreased in the region far away from the wellbore. But for constant cyclic load magnitude with different number of cyclic loads, the biggest percentage increase of the fracture width after integration of cyclic loads was slightly lower representing 63.12% while the oscillating period of the fracture width increased with the number of cyclic loads. The parametric study revealed that the drill string vibration cyclic loads were relatively independent of the fracture length and the bottom hole pressure. However, the fracture width and the loss circulation rates were considerably impacted by the drill string vibration and the highest percentage increase of the loss circulation rate after integration of cyclic loads was 14.3%. This study provides an insight into the coupling of the fracture rock development and the continuous cyclic loads generated by drill string vibrations which is an aspect that has been rarely discussed in the literature.

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Effect of Formations Compressive Strength on Drill String Vibrations

Cited by 4 publications

References 0 publications

Formation Prediction Model based on Drill String Vibration Measurements Using Laboratory Scale Rig

Formation Prediction Model based on Drill String Vibration Measurements Using Laboratory Scale Rig

For Better or Worse: Applications of the Transfer Matrix Approach for Analyzing Axial and Torsional Vibration

Numerical Investigation of the Influence of the Drill String Vibration Cyclic Loads on the Development of the Wellbore Natural Fracture

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