A New Technique to Estimate Static Elastic Moduli from Multistage Triaxial Tests

Abstract

Static Young's modulus (E), Poisson's ratio (ν), bulk modulus (K), and maximum compressive strength (MCS) are among the most important parameters in rock mechanics. This work investigates a new approach to accurately estimate static E, ν, K, and MCS from multistage triaxial tests (MST) instead of single stage triaxial tests (SST) in case of having only MST data. Core samples from three zones; Zubair sandstone, Zubair shale, and Nahr Umr shale were obtained from the Rumaila field in Iraq. SST and four stages of MST for each formation were executed, and E, ν, K, as well as MCS, were acquired at each stage of MST and SST. The results showed that the average EMST from four stages of MST provided an underestimate of ESST for Nahr Umr shale and Zubair sandstone while the average EMST for Zubair shale provided an overestimate of ESST. Correction factors were proposed to calibrate the average EMST to ESST which are 1.127, 0.957, and 1.123 for Zubair sandstone, Zubair shale, and Nahr Umr shale, respectively. Average νMST resulted in an overestimate of νSST for Nahr Umr shale and Zubair sandstone while Zubair shale νMST provided an underestimate. Calibration factors were proposed for ν which are 0.645, 1.065, and 0.585 for Zubair sandstone, Zubair shale, and Nahr Umr shale, respectively. The averages of KMST and MCSMST provided an underestimate for KSST and MCSSST. Factors of 1.779, 1.35, and 1.458 were proposed for K for Zubair sandstone, Zubair shale, and Nahr Umr shale, respectively; and factors of 1.466, 1.446, and 1.358 were suggested for MCS for Zubair sandstone, Zubair shale, and Nahr Umr shale, respectively. These results can help to provide a good estimate of E, ν, K, and MCS from MST when the material is limited to perform SST.

Department(s)

Geosciences and Geological and Petroleum Engineering

Comments

3M, Grant None

International Standard Book Number (ISBN)

978-171383912-5

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Rock Mechanics Association, All rights reserved.

Publication Date

01 Jan 2021

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