Document Type : Research Article
Authors
1
School Of Mining Engineering, College Of Engineering, University Of Tehran
2
School of Mining Engineering, College of Engineering, University of Tehran, Therna, Iran
3
School Of Mining Engineering, College Of Engineering, University Of Tehran, Tehran, Iran
10.22034/anm.2023.20594.1609
Abstract
Nowadays, with the increasing human need for energy and oil derivatives, the extraction of this material is increasing day by day. However, the reservoirs, which had few complications and problems in terms of drilling operations and well stability, are running out. In order to answer this need, engineers must extract resources that have more complexity and difficulties in drilling and stability than before. Therefore, the topic of well stability, optimal weight and safe mud window is more important than before. In this research, the well stability analysis and the selection of the optimal weight of the drilling fluid are discussed using analytical and numerical solution methods, by generalizing and modifying the ground reaction curve, which is one of the most important stability analysis methods of underground spaces. First, the ground reaction curve for five circular holes is calculated in the field of hydrostatic and anisotropic stresses, and the effect of parameters such as pore pressure, different ratios of horizontal to vertical stresses, and hole radius on the ground reaction curve is investigated. It was found that the changes of these indices have a direct relationship with the amount of convergence of the hole wall, and with their increase, the amount of convergence of the hole wall increases. Then, using the Mohr-Coulomb analytical relations and the ground reaction curve method in finite difference numerical modeling, the limits of the safe mud window were calculated. According to the numerical method results using the ground reaction curve, the lower and upper limits of the drilling fluid pressure are lower and higher than the lower and upper limits of the drilling fluid pressure using the Mohr-Coulomb analytical method and the numerical method respectively. the numerical method provides a larger safe window than the Mohr-Coulomb analytical method.
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