Masters Theses


"Wellbore instability problems are the cause for the majority of nonproductive time in the southern Iraqi fields' developments. The most severe problem in terms of effort and disbursement which is referred to a pipe sticking in Tanuma shale formation. Examining the drilling data revealed that this phenomenon was mostly related to the shear failure of the wellbore. Thus, a geomechanical analysis and drilling parameters/ practice optimization analysis were performed on a field in southern Iraq based on data from 45 deviated wells. The geomechanics analysis predicted the suitable drilling fluid density to prevent onset shear failure by using the Mogi-Coulomb failure criterion, including thermally and chemically induced stresses and the bedding related failure of the wellbore. While the drilling parameters optimization was conducted by DROPS simulator and multi-regression analysis and resulted in a significant reduction in the shale exposure time to the drilling fluid. The drilling practice analysis was derived based on drilling data from stuck-free well also facilitated in preventing the drilling fluid density reduction by tripping processes. These analyses identified the following areas of improvement. First, the mud weight being used was not changed properly with respect to variation in wells azimuth and inclination. Secondly, anisotropic effects of the stress and strength parameters for this shale formation should be considered in wells trajectory design. Thirdly, the time depended-failure of wellbore was observed in even though the drilling fluid density was appropriately selected. Fourthly, the swabbing effect while tripping was negatively contributed to wellbore stability. Due to limited of published studies regarding wellbore problems in southern Iraqi fields; this research could serve as a significant case history for similar fields"--Abstract, page iii.


Nygaard, Runar

Committee Member(s)

Flori, Ralph E.
Eckert, Andreas


Geosciences and Geological and Petroleum Engineering

Degree Name

M.S. in Petroleum Engineering


Missouri University of Science and Technology

Publication Date

Summer 2016


xv, 113 pages

Note about bibliography

Includes bibliographical references (pages 103-112).

Geographic Coverage



© 2016 Ahmed Alsubaih, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Oil fields -- Production methods -- Analysis
Enhanced oil recovery -- Analysis
Oil shale reserves -- Iraq
Hydraulic fracturing

Thesis Number

T 10944

Electronic OCLC #



Thesis Location