PSI - Issue 47

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Abdullah Al-Ibrahim et al. / Procedia Structural Integrity 47 (2023) 426–436 Abdullah Al-Ibrahim/ Structural Integrity Procedia 00 (2023) 000–000

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1. Introduction The casing of the oil and gas wells is subjected to mechanical wear during the drilling operation. Casing wear is mainly caused by the direct contact of the drilling string with the inner casing wall under the contact loading. Casing wear can cause devastating drilling accidents and a high cost of financial loss Chu et al. (2009). Wear of the casing can lead to several detrimental effects, such as severe casing wear or failure, casing string collapse, distortion, leaking, and the well-being abandoned Jin et al. (2020). Over the past years, many researchers have conducted to study and optimize the wear factor and wear mechanisms. Best (1986) carried out a full-scale test facility using simulations of field conditions, such as forces, and lubricant to discover the main mechanisms present in casing wear. White & Dawson (1987) investigated the casing wear caused by the rotation of non-hard banded tool joints and set the following parameters: two contact forces, water- and oil-based lubricants, and three different casing grades. During the experiment, both the casing wear and the friction forces were measured. After completing the experiment, a wear-efficiency model has obtained to provide good data fit for predicting field wear. Kumar & Samuel (2015) stated that there is no direct correlation between the casing grads based on the laboratory test. Huimei & Yishan (2012) conducted an experimental study with the following factors: mud type and density, rate of penetration, and the grade of the casing where it concluded, mud density, rotational speed, and rate of penetration are all significant elements that impact casing wear, and the wear increases with decreasing penetration rate, increasing rotating speed, or increasing mud density. Zhang (2016) conducted experimental research on casing wear, showed samples of casing worn in the mud and the air, and focused on elements that affect casing wear such as the grade of the casing steel, the rotating speed, and the contact force to the major factor that to be considered and find the dominate wear mechanisms. However, researchers have used the analytical method to calculate the wear factor. Gao et al. (2010) provided an approach to estimate the depth of the wear groove on an intermediate casing. Yu et al. (2018) Obtained an accumulative wear model that, before the casing is run through the dogleg portion, allows for an accurate estimate of the casing wear and its residual strength. Lian et al. (2016) conducted an experimental study to find the effect of the rotation speed, contact load, and casing grade on wear volume and developed a prediction software to find the wear volume and comber it with filed data. In addition, the analytical method and the finite element analysis method are used to show the effect of compound wear on the casing wear collapse strength Jin et al. (2020). Although the fundamental knowledge of casing wear has significantly improved over the past few decades, drilling operations still need a systematic methodology for casing wear prediction and a full understanding of the wear mechanisms Zhang et al. (2016). When studying the wear volume and calculating the wear factor, it is important to find the wear mechanisms which it helps to predict the wear behaviour and optimize worn casing. In the drilling operation, adhesive wear and abrasive wear are two dominant categories of wear mechanisms under the effect of rotational speed and contact load Zhang et al. (2016). Best (1986) defined adhesive wear as a form of solid-phase welding that occurs when materials are transferred from one surface to another while in relative motion and abrasive wear is divided into two categories: two-body abrasion, where the material is removed as a result of a hard tool joint protuberances, and three-body abrasion, where the material is removed as a result of hard mud particles. Mao et al. (2018) studied the effect of the rotation only using a pin on disc machine and found that the behaviour of the wear rate is nonlinear due to the presence of abrasive wear, erosive wear, and corrosive wear. Zhang et al. (2016) found that the increase in wear casing is almost linearly correlated with increasing contact force and rotating speed, and with an increase in casing steel grade, casing wear reduces, and adhesive wear and abrasive wear are two types of casing wear mechanisms observed on the samples. This paper will examine the wear volume and wear mechanisms of different types of casing with several parameters to compare the effect of rotation speed only with the effect of the combined rotational and sliding . 2. Experimental procedure A modified lathe machine with a close feedback loop has been used for this experiment, 3D model of the modified machine can be seen in Figure (1). The lathe machine has been modified by mounting two stepper motors coupled with a gearbox to apply constant normal load and repeated sliding motion. Moreover, an actual tool joint has been