Experimental and computational failure analysis of drillstrings

Moradi, Shapour; Ranjbar, Khalil

doi:10.1016/j.engfailanal.2008.08.019

Cited by 45 publications

(19 citation statements)

References 8 publications

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“…Many scholars have investigated fractured joints at drilling sites and found that joint fractures caused by thread fracture under the combined action of static and alternating loads are the main causes of downhole accidents [28,29]. Further research found that thread fractures generally occurred at the root of the first turn of the pin joint or the root of the last turn of the box joint, indicating that those two parts are prone to stress concentrations [30][31][32]. These results are in good agreement with the above simulation results.…”

Section: Effect Of the Axial Tensile Loadmentioning

confidence: 99%

Design Optimization for the Thin-Walled Joint Thread of a Coring Tool Used for Deep Boreholes

et al. 2020

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Threaded joints are key components of core drilling tools. Currently, core drilling tools generally adopt the thread structure designed by the API Spec 7-1 standard. However, fractures easily occur in this thread structure due to high stress concentrations, resulting in downhole accidents. In this paper, according to the needs of large-diameter core drilling, a core barrel joint was designed with an outer diameter of Φ135 mm and a trapezoidal thread profile. Subsequently, a three-dimensional simulation model of the joint was established. The influence of the external load, connection state and thread structure on the stress distribution in the joint was analyzed through simulations, from which the optimal thread structure was determined. Finally, a connection test was carried out on the threaded joint. The stress distribution in the joint thread was indirectly studied by analyzing gas leaks (i.e., the sealing effect) under axial tension. According to the test data and the simulation results, the final joint thread structure was optimized, which lays a good foundation for the design of a core barrel.

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Section: Effect Of the Axial Tensile Loadmentioning

confidence: 99%

Design Optimization for the Thin-Walled Joint Thread of a Coring Tool Used for Deep Boreholes

et al. 2020

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“…In drilling of oil and gas wells, severe shock and vibrations occur that are detrimental to the service life of drillstrings and down-hole assembly tools. The causes of these vibrations are due to complex surroundings and a lot of uncertainties include impact and friction at the interfaces of borehole/drillstring and bit/ hard-rock formation, imbalances, drillstring eccentricity or initial curvature in the drill collar sections, various linear or non-linear resonances [1][2][3]. There are three modes of vibration mainly axial, lateral, and torsional, which indicate direction and response of the drillstring when it runs into trouble downhole [4].…”

Section: Introductionmentioning

confidence: 99%

Drillstring Failure: Analytical and Experimental Approach

et al. 2019

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Drilling is one of the costliest activities in oil and gas industry due to the complexity of interactions with downhole rock formation. Under such conditions, the uncertainty of drillstring behaviour increase and hence it becomes difficult to predict the causes, occurrences, and types of failures. Lateral and torsional vibrations often cause failure of Bottom Hole Assembly (BHA), drillstring failure, drill bit and wall borehole damages. In this work, a model is presented to determine the impact of lateral and torsional vibrations on a drillstring during the drilling operation. The model aims to mimic real drillstring behaviour inside a wellbore with regards to its dynamic movements due to multiple real situations such as eccentricity of collars, drill pipe sections, and stick-slip phenomena occurring due to the interaction of the bit and the drillstring with the well formation. The work aims to develop a basis for determining critical operating speeds and design parameters to provide safe drilling procedures and reduce drill string fatigue failure. Lagrangian approach is used in this study to attain drillstring lateral and torsional vibration coupling equations. The nonlinear equations are solved numerically to obtain the response of the system. In this work, we also present a brief description of an in-house constructed experimental setup. The setup has the capability to imitate the downhole lateral and torsional vibration modes. Parameters from the experimental investigations are incorporated for validation of the mathematical models and for prediction of the drillstring fatigue life. Such investigations are essential for oil and gas industries as they provide solutions and recommendations about operational speed, lateral and torsional amplitudes measurements and corrections, and the conditions for avoiding occurrence of natural frequencies of the system. 1

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“…A few researches on DP failure were reported, for example, fatigue failures of DPs caused by vibration [2], erosion wear generated by drilling fluid containing debris [3], static fracture characteristics studied by a cohesive zone model [4]. The effects of impact loading on dynamics responses of DPs with cracks and their fracture failure were rarely studied.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of Dynamic Fracture Behaviour of Drill Pipe Under Various Impact Loads

Zhao

Zhao²,

Zhang

et al. 2018

mech

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In this paper, finite element analysis is conducted to study dynamic responses of a defected drill pipe (DP) under impact loading encountered in working conditions. Longitudinal impact loading such as tensile, eccentric compressive and torsional impact loading and transverse collision loading are considered. A finite element model is firstly developed and validated, and then employed to evaluate the effects of various impact loading on dynamic responses of the defected DP. It is found that the inertial effect due to tensile impact is the most prominent among all the longitudinal impact loadings. In addition, the effect of the transverse collision between the DP and the borehole wall on the driving force of the crack is evaluated. It is concluded that the dynamic effects of the various impact loading frequently exerting on the DP should be taken into consideration for life prediction of DPs. DOI: http://dx.doi.org/10.5755/j01.mech.24.4.19503

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Experimental and computational failure analysis of drillstrings

Cited by 45 publications

References 8 publications

Design Optimization for the Thin-Walled Joint Thread of a Coring Tool Used for Deep Boreholes

Design Optimization for the Thin-Walled Joint Thread of a Coring Tool Used for Deep Boreholes

Drillstring Failure: Analytical and Experimental Approach

Finite Element Analysis of Dynamic Fracture Behaviour of Drill Pipe Under Various Impact Loads

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