An apparatus (and method) for characterizing interfacial tension between a non-wetting phase fluid and a wetting phase fluid of a slug flow employs a capillary structure that is configured to contain a slug of the non-wetting phase fluid of the slug flow. The slug has a leading edge meniscus and a trailing edge meniscus, and the capillary structure has a venturi-like section. A pressure sensor is configured to measure differential pressure between first and second locations of the capillary structure. The first location is disposed upstream of the leading edge meniscus of the slug with the leading edge meniscus of the slug contained within the venturi-like section. The second location is disposed downstream of the trailing edge meniscus of the slug. Data processing means is configured to derive a measure of interfacial tension based upon the differential pressure measured by the pressure sensor and, optionally, geometry of the capillary structure.

The invention relates to a system and a process for analyzing the interaction between a drop of fluid which is immiscible in an ambient medium and a surface, this surface being another drop of fluid or else alternatively a solid surface. The system also comprises processing means suitable for determining, according to data collected by an image acquisition and processing device, a value of interfacial tension of the drop after a contact between the drop and the surface, and a value of pressure difference between the internal pressure of the drop and the pressure in the ambient medium without having to know the position of the apex of the drop. The invention also relates to a device for forming drops and bringing drops into contact and to a device for forming a drop of fluid and bringing a drop of fluid into contact with a solid surface for the purpose of analyzing them by means of the appropriate system.

A method of measuring a minimum pressure for gas bubble generation (MPGBG) value of a capillary tube is disclosed. The capillary tube has an inlet and an output portion including an outlet. The inlet is connected to a regulated pneumatic system, configured to supply a gas to the inlet under pressure. The output portion is immersed in a liquid. The gas is supplied to the inlet under a range of pressures including a higher pressure range and a lower pressure range. In the higher pressure range, gas bubbles are generated in the liquid from the outlet. In the lower pressure range, no gas bubbles are generated in the liquid from the outlet. A value of the minimum pressure for gas bubble generation (MPGBG) for the liquid is determined. Other methods include a method of measuring and storing MPGBG values of capillary tubes, methods of selecting at least one capillary tube from a plurality of capillary tubes, and a method of cutting a capillary tube to a desired MPGBG value.

A method for determining interfacial tension of a hydrocarbon in a brine fluid, the method including injecting a first brine fluid into a test cell, the first brine fluid having an initial ionic composition, injecting a hydrocarbon fluid into the test cell, contacting the hydrocarbon fluid with the first brine fluid, forming a droplet, measuring the interfacial tension of the hydrocarbon fluid in contact with the first brine fluid, at least partially displacing the first brine fluid with an inert gas, measuring a ionic composition salinity of the displaced first brine fluid in an ionic chromatograph, and comparing the measured ionic composition salinity to the initial ionic composition.

A method for determining interfacial tension of a hydrocarbon in a brine fluid, the method including injecting a first brine fluid into a test cell, the first brine fluid having an initial ionic composition, injecting a hydrocarbon fluid into the test cell, contacting the hydrocarbon fluid with the first brine fluid, forming a droplet, measuring the interfacial tension of the hydrocarbon fluid in contact with the first brine fluid, at least partially displacing the first brine fluid with an inert gas, measuring a ionic composition salinity of the displaced first brine fluid in an ionic chromatograph, and comparing the measured ionic composition salinity to the initial ionic composition.