Interfacial Tension Measurements at Reservoir Conditions Using X-Ray Imaging

Interfacial tension (IFT) is one of the key parameters governing multiphase flow in reservoir. One of standard IFT measurement techniques is pendant drop shape analysis, which includes an acquisition of the drop snapshots in visible light. Hence, the method is limited by optical transparency of an external fluid. Here we present a new approach, which is free from this limitation. It uses X-rays as an illumination source and provides a number of advantages and additional opportunities in the study of fluid interface behavior. Proposed method includes a drop generation inside a uniquely designed X-ray transparent cell for high pressure and temperature (HPHT) measurements placed inside an X-ray scanner and imaging of its evolution with time till equilibrium state. Since X-ray images significantly differ from the classical optical ones, a novel algorithm was developed for accurate drop shape detection and further mathematical processing for IFT value calculation. As a result, an IFT value evolution curve for a pair of fluids is obtained. Depending on relative densities of the fluids, different experimental schemes can be implemented: pendant or rising drop. The method was validated on various neat fluids with well-known IFT values and then was successfully applied for different real fluids systems. This work demonstrates the unique laboratory studies carried out on different liquid-fluid systems showing that the developed methodology works well at elevated pressure and temperature conditions. The developed method unlocks the possibility for an appropriate IFT measurements in surfactant-rich oil-water systems as well as in systems near the phase transition such as gas-condensates at a wide range of thermobaric reservoir conditions and increases feasibility of HPHT measurements due to simplification of the measuring system design.