E Kavesian - Ph.D. Candidate, Department of Mining and Metallurgy Engineering
Alireza Yarahamadi Bafghi - Associate Professor, Department of Mining and Metallurgy Engineering
Manouchehr Sanei - Assistant Professor, Department of Mining and Metallurgy Engineering

The instability of the wellbore has significant effects on drilling, causing delays in operations, and increasing costs. Nowadays, with the help of geomechanics and knowledge of the mechanical properties of the formation, the optimal parameters of mud and drilling design can be predicted and determined. A vital stage for optimizing the drilling programs is finding out problematic zones of oil fields. Despite the location and special features of every field, generally, formations that include thick layers of salt and shales have potential dangers for drilling which may even cause heavy costs, forcing extra casing or liner, and may even result in the abandonment of wells. Both Salt and shale have low permeability and mostly show abnormal pore pressure, which must be noticed. Salt shows creep behavior, which causes many problems for wellbore stability. Besides salt, understanding shale behavior and its swelling problems are essential. Salt and shale based on different conditions can be analyzed using various constitutive models, such as elastic, viscoelastic, and viscoplastic. In this paper, a review of previous studies that have been done to analyze and predict the behavior of salt and shale is presented. The paper includes a summation of describing problems related to these rocks and determining rock mechanical properties and studies about these formations.

Problematic zones, Salt, Shale, Creep, Swelling, Constitutive models