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Gas flooding has become a mature technique for light to medium crude oil recovery. It is often applied after a water flood is no longer economic to recover capillary trapped oil. Miscible/Immiscible gas injection or gas flooding is the Enhanced oil recovery (EOR) approach considered in this research which is a favorable alternative due to the extremely low permeability nature of the reservoir formation. In any gas injection design, one of the most important parameters is minimum miscibility pressure (MMP). MMP is the lowest pressure at which gas and oil become miscible at a fixed temperature. MMP is an important parameter that determines the type of flooding whether it will be miscible or immiscible flooding and consequently the efficiency of oil displacement by gas. The MMP is important because when gas and oil are miscible, the pore scale efficiency (or displacement efficiency) is 100% in the absence of dispersion. Hence, knowledge of MMP is essential in gas flooding designs. The experimental methods available for determining MMP are both costly and time consuming. Therefore, the use of correlations that prove to be reliable for a wide range of fluid types would likely be considered acceptable for preliminary screening studies. Four types of gases will be used- Carbon dioxide, Dry gas, Liquefied Petroleum gas (LPG) and Nitrogen. The selection of the gas which is best fit for a specific field depends upon the physical properties of the oil reservoir such as temperature, viscosity and the API gravity. Most of the MMP correlations evaluated in this study considered the effect of fluid composition properly. In most cases, Equation of state (EOS) based models are more conservative in predicting the MMP. The screening methods are used to identify any reservoir that could be a candidate for a miscible injection job. Experimental MMP measurements should be conducted for specific gas-injection and specific reservoir for efficient and effective oil recovery. The screening criterion indicates that the CO2, LPG, dry gas (DG) flooding are applicable in the entire thirty reservoirs. It showed only four fields are eligible for N2 flooding (Raguba, Jebel, LDM and Ghani). Immiscible process is only choice for Haram field. For CO2 a comparison between the calculated and the laboratory values of minimum miscibility pressure indicates that the Holm-Josendal and Mungan, Glaso and Eakin & Mitch give close results. For LPG MMPs Eakin and Maklavani give nearby values of minimum miscibility pressure but should be confirmed with an experimental data performed on the field. In the absence of any measured site-specific MMP data, Empirical correlation could be used as an effective and convenient 'predictive tool to guess the MMP for initial design calculations. It is also conducted that CO2 flooding is applicable in Libya oil reservoirs. The results obtained from the studied reservoirs will be the bases and guidelines for gas flooding for the oil companies in Libya. A new piece of software was developed using Excel and VBA (Visual Basic for Applications) to be used as an automated AI (Artificial Intelligence) tool in screening the fields for suitable method of gas flooding EOR technology.
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