Feasibility Study of Auto Ignition in In-situ Combustion Process

Abstract

Application of in-situ combustion is not widespread for a variety of reasons including the relatively large expense required to evaluate prospects. Moreover, because of the complexity of in-situ combustion processes, their design must be preceded by extensive laboratory investigations to ascertain the burning characteristics of the crude, fuel availability and air requirements. The complexity of the processes has also hindered the development of accurate numerical simulators for performance prediction. In this study KEM reservoir in southwest of Iran was selected as an extra heavy carbonate reservoir. In this work, the potential of auto ignition of heavy oil during in-situ combustion process was studied in KEM reservoir. Also it was aimed to predict experimental work with simulation by implementing valid input data and to investigate the risk of carbonate decomposition due to high temperature.
Thermogravimetry and Differential Thermogravimetry Analysis (TG/DTG) were used to study the kinetics of chemical reaction and determine basic kinetic constants such as the rate constant, activation energy, and frequency factor. TGA test was demonstrated that the carbonate rock decomposition was taken at 650°C. Results showed that the peak of low temperature combustion (LTC) by producing CO was initiated at 275°C when air was injected. Also, enriching the injected air by oxygen lowers the LTC by up to 50°C. Enthalpy of each reaction was obtained by Differential Scanning Calorimetry (DSC). Thus, the values of the Arrhenius kinetics parameters provided the required kinetics data for the numerical simulation the process for the reservoir.
Additionally, combustion tube tests were done using KEM oil and crushed carbonate rock. In forward combustion test, auto ignition has been investigated by the application of enriched air. The forward test was followed by numerical simulation to model the tube. The results of the in-situ combustion tube test were predicted by using a commercial simulator.