SIMULATION STUDY ON OIL SWELLING DURING CO2 INJECTION FOR LIGHT OIL SAMPLES

Carbon dioxide CO2 injection method is one of enhanced oil recovery EOR techniques that is taking the place of interest in oil industry nowadays because of its availability and low cost relatively. Oil swelling during the process of miscible CO2 flooding is the main factor influencing the effectiveness of this method to enhance oil recovery, since it will improve the permeability of the rock when CO2 extracts the residual oil and swells it to let it move leaving more connected pore spaces in the reservoir. The main objective of this study is to determine the swelling factor of some light oil samples having different compositions and properties, and analyse the result to predict factors that affect oil swelling factor so as to technically evaluate the injection process since CO2 injection technique has been widely used in oil industry. CO2 injection evaluation comprises two categories; technical and economical. Technical factor is based on geological, geophysical, engineering and transportation issues. The considered issue in this study is one of the engineering issues which is the effect of CO2 injection on hydrocarbon fluid volume. Oil swelling factor due to CO2 flooding was determined by simulating some lab data using CMG software. A dead oil sample was recombined with methane and CO2 gas after its composition has been identified by gas chromatography analysis. The composition of the other samples has been taken from an SPE paper prepared by Nancy, Italic (1990). Oil samples compositions were entered to the CMG software. Swelling test was run to determine the swelling factor; it was applied for different CO2 concentrations starting from 20% mole, 40% mole, 50% mole, & 60% mole. Constant composition test CCE was run to predict the saturation pressure at each CO2 concentration. The result and output of this simulation were analysed, & graphs have been created for the completion of this project. During this project it was verified that, Based on the technical/ oil swelling factors, CO2 flooding is considered as feasible process up to 60% mole for all oil samples, since the swelling factors did not reach the critical point, beyond which the swelling factor start to decrease.