Laboratory Geomechanical Characterization of the Zubair Shale Formation


Zubair formation consists of approximately 55% shale, which causes almost 90% of wellbore problems, due to shale instability. To solve this problem, it is necessary to understand the rock mechanical properties and the response of shale. However, little data is available related to shale sections due to the additional cost of acquiring and preparing shale samples. The main objective of this study is to measure the rock mechanical properties of shale samples retrieved from the Zubair Formation in Southern Iraq. Extensive testing, including a number of shale characterization and rock mechanical tests were conducted on well-preserved core samples from Zubair shale. The core samples characterization included the porosity, structure, texture, and mineralogy, using the free water content method, a scanning electron microscope image, a thin section photograph, and X-ray diffraction analysis. Consolidated undrained triaxial tests were conducted to determine the static rock mechanical properties. The measured rock mechanical properties gave a good indication of the strength and stability of the shale around the wellbore. Consequently, it can be used to solve shale instability problems, optimize drilling processes, seal integrity evaluation, and improve fracturing operations across the Zubair shale formation.

Meeting Name

52nd U.S. Rock Mechanics/Geomechanics Symposium (2018: Jun. 17-20, Seattle, WA)


Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Drilling fluids; Oil field equipment; Borehole stability

Document Type

Article - Conference proceedings

Document Version


File Type





© 2018 American Rock Mechanics Association (ARMA), All rights reserved.

Publication Date

01 Jun 2018

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