Doctoral Dissertations

Keywords and Phrases

Frac hit; Gas wells; Multiphase flow; Simulation; Transient; Unloading


"This work seeks to develop a fully step-by-step transient multiphase flow simulation valid for unloading gas wells using nitrogen. It studies the behavior of nitrogen for unloading horizontal gas wells with gas injection in the annulus. The work investigates unloading non-Newtonian fluids such as those which invade offset wells when a frac hit occurs during hydraulic fracturing operations in unconventional wells. The effect of varying tubing depth and injection pressure are included in the study.

Results show that as the plastic viscosity increases, the nitrogen volume and time to unload will be increased. As tubing depth increases, the nitrogen volume and time to unload the liquid will be increased. However, deepening the tubing has the impact of sweeping more fluids from the lateral section and reducing the hold-up in the horizontal section.

As nitrogen injection pressure increases, the nitrogen volume and the time to unload the fluids decrease. Increasing the injection rate of nitrogen will increase the nitrogen volume required to unload but decrease the time to unloading.

Several case studies are simulated using methane as an alternative for nitrogen. The results show that unloading with methane requires a higher volume than nitrogen. Changing the casing size impacts the unloading process as well.

This work serves as a practical guideline for unloading frac hits in unconventional shale play gas wells"--Abstract, page iii.


Dunn-Norman, Shari

Committee Member(s)

Wei, Mingzhen
Flori, Ralph E.
Imqam, Abdulmohsin
Chumkratoke, Chatetha


Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Petroleum Engineering


Missouri University of Science and Technology

Publication Date

Spring 2019


xxxiii, 210 pages

Note about bibliography

Includes bibliographic references (pages 208-209).


© 2019 Miguel Angel Cedeno Moreno, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11520

Electronic OCLC #