Degree
Doctor of Philosophy (PhD)
Department
Petroleum Engineering
Document Type
Dissertation
Abstract
Accurate prediction of gas-liquid hydrodynamics is paramount for well control, yet conventional models struggle with the complexities of non-Newtonian drilling fluids and the unique thermal-hydraulic phenomena in geothermal wells. This dissertation addresses these deficiencies through a comprehensive, two-part investigation that combines novel experimental work with high-fidelity numerical simulation.
Part I focuses on advancing the predictive capability for two-phase flow in shear-thinning fluids. An experimental campaign was performed in a large-diameter vertical flow loop to generate benchmark data for both Newtonian (air-water) and power-law (air-xanthan gum) systems using 4-probe conductivity sensors. This detailed dataset guided the modification of the two-group Interfacial Area Transport Equation (IATE) framework to properly account for non-Newtonian rheology. The adapted IATE was then implemented within a Two-Fluid Model (TFM), and its closure coefficients were systematically tuned by benchmarking simulation results against the experimental data.
Part II investigates hazardous transient events in geothermal well control, with a specific focus on wellbore flashing. A series of case studies using the RELAP5-3D simulator was conducted to identify how, where, and why flashing occurs when restarting circulation in a hot well after a prolonged shut-in. Following this analysis, various mitigation strategies are proposed. One such method, bullheading a steam kick, is examined in detail, revealing that while it is an effective mitigation technique, it introduces a significant challenge: the potential for a severe water hammer that can threaten well integrity.
This research makes a dual contribution: it delivers a validated, rheology-sensitive IATE model for improved hydrodynamic prediction in complex fluids, and it provides a critical analysis of geothermal flashing with practical strategies for managing operational hazards. The work integrates fundamental model development with applied simulation to enhance the safety and predictability of complex drilling operations.
Date
11-17-2025
Recommended Citation
Mahmud, Shahriar, "Hydrodynamic Analysis of Gas-Liquid Flow for Conventional and Geothermal Well Control: Experimental Studies and Simulations" (2025). LSU Doctoral Dissertations. 6926.
https://repository.lsu.edu/gradschool_dissertations/6926
Committee Chair
Chen, Yuanhang