A new fluidics method to determine minimum miscibility pressure

Micro and nano-fluidic devices have attracted increasing attention in the oil industry. In this study, we designed a new slim-tube method to determine MMP on a microfluidic chip. The design is significantly different from previous efforts on fluidics chips with an open flowing tube. The new design contains porous media similar to that found in the slim-tube apparatus. The objective is to produce a true multi-contact process in the gas displacement. We tested the new fluidics device at reservoir conditions with three reservoir oils displaced by two hydrocarbon gases and CO2 gas. For pressure lower than MMP, we observed noticeable reservoir oil remained after the injection gas had passed. For pressure higher than MMP, the miscible displacement front was developed. Behind the miscible displacement front, the oil saturation became negligible. We used a camera to detect the oil saturation after gas flooding for each pressure. MMP was determined at the high-resolution transition between miscible and immiscible pressures (similar to the slim-tube determination of MMP from the linear trendline intersection of miscible and immiscible pressures). The new fluidics method is a miniaturization of the slim-tube method on a microfluidic chip. All three microfluidic MMP tests of the selected oils displaced by hydrocarbon and CO2 mixtures generated very close results as that of the slim-tube tests with the same fluids. The new method has imminent business potential due to its reliability, visualization, low cost, low sample requirement, and fast turnaround. The MMP test threshold will be much lower than before, which will significantly benefit many gas-based EOR projects.