There is a lot of laboratory and field experiments confirmed the effectiveness of gas methods for enhanced oil recovery (EOR). However, a wide range of reservoir conditions, characteristics and properties of produced and injected fluids, injection technologies, along with a wide variety of research methods, leads to difficulties to compare the results obtained by different authors for different fields.
The article discusses topical issue to improve the methodology of filtration experiments on oil by gas displacement using slim-tube models of the reservoir. The geometric parameters of the models, fluid filtration rates, and other characteristics of the experiments affecting the result vary in studies performed by different authors. The authors compared some methods to determine the possibility and correctness of comparing the results. The key features of experimental determination the minimum oil-gas miscibility pressure and the selection of the optimal gas composition under given thermobaric conditions are detected, and the order of their implementation is optimized. It is noted, the special attention should be paid to the sampling of heavy oil and its stability while mixing with the injection gas. The stability of oil displacement process is an important condition of filtration experiments at high filtration rates, i.e. removing of gravitational and viscous influence by using slim tube with a length more than 12 m. Increase of the slim tube length reduces the experimental error due to an increase in the volume of fluids. Two approaches are considered – oil displacing from short slim-pipe model (6 m long) with reservoir filtration rates and displacement with increased rates from the slim tube of increased length (18 m). The reproducibility of the final results of the displacement is shown, which indicates the achievement of the stability of the oil displacement process in both cases.
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