Republic of Iraq Ministry of higher education and scientific research University of Kerbala College of Engineering - Petroleum Dept. Reservoir engineering Name of exp.: - Interfacial tension pendent drop method Supervision by: Dr.Tahseen Al Taei Mr. Salam Khaled Mrs.zahraa radhi By :Ahmed Haider Salam Raad Saad Abbas Ali Mohammed Abd Alhassan Exp date :2023/nov/16 written in :2023/nov/18. The pendant drop (PD) method is an optical method for determining the surface or interfacial tension of a drop of liquid by using the curvature of the drop profile. An advantage when compared with the frequently used methods based on force measurement, such as the Du Noüy ring measurement or the Wilhelmy plate measurement, is the very small sample volume required (approx. 20-60 µL). In addition, measurements are possible throughout a wide pressure and temperature range (up to 690 bars and up to 400°C). Pendant drop method is a widely used technique in numerous applications, such as carbon capture and storage (CCS), enhanced oil recovery (EOR), fields of microfluidics, detergent industries, and quality control in many chemical supplier companies. Due to the importance of the interfacial tension (IFT) and surface tension (ST), defined as the energy difference between fluid-fluid and gas-fluid interfaces at molecular levels for immiscible fluids, respectively, particularly the IFT measurement process should be appropriately performed to eliminate the experimental errors, especially in the reservoir engineering and porous medium. It is measured as N.m−1 or J.m−2 in the SI unit. Measuring this parameter would be properly applicable in determining critical capillary bridges, chemical adsorption of fluid interfaces, and liquid drop stability. Among a wide range of laboratory methods of measuring the IFT and ST, spinning drop, pendant drop, maximum bubble pressure, Wilhelmy plate, Du Nouy ring, and capillary rise are the most common techniques. Pendant drop (A); curved surface segment (B), the radii of the horizontal (green) and vertical (blue) circles of curvature define the surface curvature at point P. The process typically involves the following steps 1. Preparation: The liquids or gas to be tested are prepared and placed in separate containers. The capillary tube or needle is cleaned and filled with the liquid to be dropped. 2. Droplet formation: The capillary tube or needle is carefully inserted into the liquid or gas medium, ensuring that the droplet formed is stable and free from any disturbances. The droplet size is controlled by adjusting the flow rate of the liquid through the capillary. 3. Image capture: A high-resolution camera or microscope is used to capture an image of the pendant droplet. The image should include the droplet shape and any surrounding reference markers or scales. 4. Image analysis: The captured image is analyzed using specialized software to measure the dimensions of the droplet, such as its diameter or contact angle with the reference markers. These measurements are used to calculate the interfacial tension. 5. Calculation: The interfacial tension is calculated using theoretical models, such as the Young-Laplace equation, which relates the droplet shape to the interfacial tension and other parameters. 6. Repeat measurements: Multiple droplets are typically measured and averaged to ensure accuracy and reliability of the results. Benefits of surface tension and interfacial tension in reservoir engineering 1. Enhanced oil recovery (EOR): Interfacial tension plays a crucial role in EOR techniques such as surfactant flooding and polymer flooding. By accurately measuring IFT, engineers can optimize the formulation and concentration of surfactants or polymers to reduce IFT between the injected fluids and the reservoir oil. This leads to improved displacement efficiency and increased oil recovery. 2. Reservoir characterization: The pendant drop method can be used to measure the IFT between different phases within a reservoir, such as oil-water or oil-gas interfaces. This information helps in understanding the wettability of the reservoir rock and designing appropriate production strategies. For example, if the IFT between oil and water is high, it indicates that the rock is water-wet and water flooding might be an effective recovery method. 3. Emulsion stability: Emulsions are often encountered in petroleum production and processing, and their stability is influenced by the interfacial tension between the oil and water phases. By measuring IFT using the pendant drop method, engineers can assess the stability of emulsions and design suitable demulsification processes to separate the oil and water phases efficiently. 4. Fluid behavior prediction: The interfacial tension between oil and gas affects various fluid behaviors in petroleum systems, such as capillary pressure, relative permeability, and multiphase flow patterns. Accurate IFT measurements using the pendant drop method enable engineers to predict these fluid behaviors more reliably, leading to better reservoir management and production optimization. 5. Product quality control: In downstream petroleum operations, such as refining and petrochemical processes, accurate knowledge of interfacial tensions is crucial for product quality control. The pendant drop method allows for quick and reliable measurement of IFT between different liquid phases or gas-liquid interfaces, ensuring that products meet the required specifications. Overall, the pendant drop method for IFT measurement in petroleum engineering provides valuable insights into fluid behavior, reservoir characterization, and production optimization, leading to improved oil recovery, enhanced process efficiency, and better product quality control. Emulsification Interfacial tension also plays a important role in emulsification which is the process of preparing emulsions, which are heterogeneous systems consisting of at least one immiscible liquid intimately dispersed in another in the form of droplets. If two immiscible liquids are in contact with each other, they will tend to maintain as small an interface as possible (as interfacial energy is associated with formation of any interfacial area). Consequently, it is very difficult to mix the two liquids. When they are shaken together, spherical droplets will form, as the liquids tend to maintain as small a surface area as possible and an interfacial tension will be maintained between the two liquids. When a “surface active” ingredient is added, its molecules will tend to be oriented between the two faces with the polar ends in the polar phase and the non polar ends in the non polar phase, which will lower interfacial tension. This will result in miscibility of the two liquids. Procedure • • • • • Fill the cell with oil. Form a pendant drop of water with a syringe (diameter 1.1 mm). Focus the drop and take imaging picture by photo. Measure de and ds, and then calculate S. Determine 1/H from Tab Q/ What is the pendant drop method of interfacial tension? An/Surface and interfacial tension measurements can be performed optically using pendant drop shape analysis Q/ What is the difference between surface and interface? An/ ?In short; surface tension is the property of the liquid in contact with gas phase (usually air). Interfacial tension, on the other hand, is the property between any two substances. Q/Why is interfacial tension less than surface tension? An/Interfacial tensions are weaker than surface tensions because the adhesive forces between two liquid phases forming an interface are greater than that between liquid and gas phases Q/What is the application of interfacial tension? Interfacial tension also plays a important role in emulsification which is the process of preparing emulsions, which are heterogeneous systems consisting of at least one immiscible liquid intimately dispersed in another in the form of droplets Hello winter Source
