Doctoral Dissertations

Keywords and Phrases

Drilling; Fluid losses; Lost circulation; Lost circulation materials; Wellbore strengthening


"Lost circulation is a challenging problem to be prevented or mitigated during drilling. Lost circulation treatments are widely applied to mitigate losses using a corrective approach or to prevent losses using preventive approaches, also known as "wellbore strengthening". The disagreement among the different wellbore strengthening theories and the lack of understanding the strengthening mechanism resulted in the absence of a standardized method to evaluate the effectiveness of lost circulation materials (LCM) for wellbore strengthening application.

An extensive experimental investigation was performed by constructing a high pressure LCM test apparatus to investigate the effects of different parameters on the sealing efficiency of LCM treatments. In addition, hydraulic fracturing experiments, which simulates downhole conditions, were carried out to evaluate the impact of LCM addition on enhancing both; breakdown and re-opening pressure.

The results showed that the sealing efficiency of LCM treatments is highly dependent on the fracture width and the particle size distribution (PSD). Carefully selected LCM blends can seal fractures up to 2500 micron and certain unconventional squeeze LCM can seal wider fractures. A particle size distribution selection criterion for LCM treatments was developed based on a statistical analysis of the experimental results states that D50 and D90 should be equal or greater than 3/10 and 6/5 the fracture width, respectively. The addition of different LCM blends enhanced the breakdown pressure up to 18% and the re-opening pressure up to 210%. Comparing the fractures created by the experiments with analytical models, only one model estimated similar fracture widths"--Abstract, page iii.


Nygaard, Runar

Committee Member(s)

Bai, Baojun
Dunn-Norman, Shari
Wei, Mingzhen
Saasen, Arild


Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Petroleum Engineering


Funding received from Det Norske Oljeselskap ASA under research agreements #37709 and #45343


Missouri University of Science and Technology

Publication Date

Fall 2015


xviii, 165 pages

Note about bibliography

Includes bibliographic references (pages 156-164).


© 2015 Mortadha Turki Alsaba, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Oil wells -- Hydraulic fracturing
Oil fields -- Production methods
Drilling muds

Thesis Number

T 10814

Electronic OCLC #