Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Petroleum Engineering

First Advisor

Adam T. Bourgoyne, Jr


The control of high pressure gas encountered while drilling for hydrocarbon reservoirs is one of the more expensive and potentially dangerous problems of the oil producing industry. When the control of high pressure gas is not accomplished flow of gas from the formation to the wellbore occurs. Once detected, the gas influx is stopped by shutting-in the well. This is the first measure taken in a series of operations which are designed to bring back the well under control. These operations are referred to as well control procedures. Well control simulators are used both for evaluating well control procedures and for training of drilling personnel. Current well control simulators assume that the gas enters a wellbore as a continuous plug and travels at the same velocity of the drilling fluid. Unfortunately, these assumptions often lead to inaccurate results. This study includes a review of the literature on bubble rise velocity in both extended and bounded systems, liquid holdup and flow pattern correlations, and bubble generation. A new method, obtained by applying the minimum energy dissipation principle, was developed to predict the size, shape, concentration, and velocity of gas bubbles within a wellbore during well control operations. The new method was then integrated into a well control simulator computer program that was developed as a part of an ongoing research effort towards the understanding of the behavior of a gas kick for the flow geometry present on a floating drilling vessel. Experiments were performed in a 6000 ft well to determine the accuracy of the computer program. Excellent agreement was seen between the observed and computed results.