Doctoral Dissertations


Reza Rahimi


"Mechanical wellbore integrity problems while drilling are mainly due to wellbore shear failure or tensile failure. To ensure wellbore integrity, breakout and fracture geomechanical analysis is conducted to estimate minimum and maximum drilling fluid densities. Currently, there is no agreement as to which rock failure criterion to use for estimating breakout or fracture criteria to use for analyzing drilling induced fractures. However, when wellbore integrity issues arise while drilling, mitigation strategies can be applied to rectify these problems.

This dissertation analyzes criteria for wellbore breakout and fracturing. Also, mitigation strategies for breakout and fracturing while drilling were experimentally investigated. Thirteen rock failure criteria were compared based on estimating borehole breakout for field reported wellbore failure cases. Five fracture width models were investigated, compared, and experimentally evaluated. Hydraulic fracturing experiments were carried out to evaluate the impact of LCM addition on enhancing both; breakdown and re-opening pressure. Coal Combustion Residuals particles evaluated as shale inhibitor additive in water-based drilling fluid system using pressure transient test.

The results showed the estimated borehole breakout by Mogi-Coulomb, Modified Lade, and Modified Wiebols Cook criteria is close to field reported shear failure. Carbonell and Detournay's fracture width model estimated close to the measured fracture width of core samples. The addition of different LCM blends enhanced the breakdown pressure up and the re-opening pressure. Using fine grained Coal Combustion Residuals in water-based drilling fluid reduced the pressure transient rate in Catoosa shale samples"--Abstract, page iv.


Nygaard, Runar

Committee Member(s)

Eckert, Andreas
Flori, Ralph E.
Heidari, Peyman
Hogan, John Patrick


Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Petroleum Engineering


Missouri University of Science and Technology

Publication Date

Fall 2016

Journal article titles appearing in thesis/dissertation

  • Comparison of rock failure criteria in predicting borehole shear failure
  • Effect of rock strength variation on the estimated borehole breakout using shear failure criteria
  • Analysis of analytical fracture models for wellbore strengthening applications, an experimental approach
  • Can particle size distribution of lost circulation materials affect the fracture gradient?
  • Experimental evaluation on using fine grained coal combustion residuals for controlling fluid invasion in shales


xvii, 192 pages

Note about bibliography

Includes bibliographic references.


© 2016 Reza Rahimi, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Oil fields -- Production methods -- Analysis
Oil wells -- Hydraulic fracturing
Enhanced oil recovery -- Analysis

Thesis Number

T 11050

Electronic OCLC #