Experimental Investigation of Absorption and Desorption of Gas in Riser During MPD Well Control

Abstract

In this experimental work, the absorption and desorption of CO2 (Carbon Dioxide) in oil using a laboratory scale low-pressure experimental apparatus was conducted to study the dissolution behavior of gas in the oil. Estimating the concentration and rate of CO2 transfer from/to a non-aqueous column of static fluid is very important to understand the dissolution of natural gas in an oil-based mud within a well. Studying how natural gas dissolves in an oil-based drilling fluid is of great significance due to risks that a gas kick in an oil-based mud poses to equipment and workers’ health and safety once it is in the riser. By understanding the variables associated with this phenomena, better field practices can be developed and implemented to predict the dynamics of an influx and determine the best course of action when handling the influx. A laboratory scale experimental apparatus was designed and built to inject CO2 at the bottom of a seven-foot static column of VO. The apparatus has five test chambers that can be closed individually to isolate and measure the concentration of dissolved CO2 in oil in each of the sections. As a part of the experiment, the the backpressure applied to the column of oil was varied to observe how pressure affects the mass transfer due to absorption and desorption within the oil column. The amount of gas injected was 1.0 liter per minute of CO2 with a back pressure of the apparatus ranging from 40 to 80 psi. The results of this study will influence further experiments and testing using larger scale equipment involving the dissolution of natural gas within various oil-based drilling fluids at higher pressures. This study also allows for the development of an initial time-dependent mass transfer model which will also be used for predicting dissolution dynamics of Methane in diesel for future large-scale testing.