20 ITB J. Eng. Sci. Vol. 39 B, No. 1, 2007, 20-27 Received May 29 th , 2006. Laboratory Experiments on Enhanced Oil Recovery with Nitrogen Injection S. Siregar, A. D. Hidayaturobbi, B. A. Wijaya, S.N. Listiani, T. Adiningrum, Irwan & A.I. Pratomo Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology Abstract. Based on previous studies, nitrogen injection could recover oil up to 45-90% of initial reserves. Although this method has a very good ability to produce oil, sometimes the operation pressure is higher than leak off formation pressure. In this study, operation pressure used a low pressure to solve this problem under immiscible process. Objective of this study is to determine the effect of injection pressure and displacement rate on oil recovery performance of continuous one dimensional nitrogen gas injection with a slim tube apparatus. The effect of nitrogen gas-oil contact on the gas composition was investigated using Gas Chromatograph Mass Spectrometer apparatus. In the experiments, nitrogen gas was injected into an oil sample of 38.5 o API gravity at various rates: 20 cc/hr, 30 cc/hr and 36.66/hr under 1500 psi pressure, and then at 20 cc/hr undr 2500 psi pressure. The results showed that an increase in injection rate increased oil recovery factor. The recovery factor lies between 40-54% of original oil in place. Gas analysis before injection and at the injection outlet showed a change of composition. when oil was contacted by nitrogen, indicating that some molecular mass transfer had taken place. Keywords: nitrogen injection; immiscible process; molecular mass transfer. 1 Introduction In the year 1970’s, enhanced oil recovery (EOR) became a popular and important technique in the petroleum industry. The declining of oil production and languid of new oil reserves combined with the rising demand for oil, had become a reason for EOR techniques to develop. Furthermore the high demand for oil and gas, which was not equalized by the production, made a significant rising in oil and gas prices. Now, EOR techniques become one of the top priorities for technology development in petroleum industry [1]. EOR method consists of secondary and tertiary recovery. Those methods are used for increasing hydrocarbon recovery from the reservoir with changing fluid characteristics sometimes even changing reservoir characteristics. There are two classical secondary recovery methods that we still use today. These methods are water injection and gas injection that have proven to increase oil and gas recovery.