Influence of temperature and interfacial tension on spontaneous imbibition process

“Spontaneous imbibition is a mechanism that can significantly contribute to the production rate and final oil recovery in fractured and stratified reservoirs. This mechanism is affected by rock and fluid properties and it has been reported by several authors to be strongly dependent on interfacial tension (IFT) and contact angle. Both magnitudes are influenced by system temperature. In this work a laboratory study is performed on the influence of IFT and temperature on production rate and oil recovery for a given rock-fluid system. All sequences were performed on rock and fluid samples from Argentine basins. Rock samples were of medium permeability (56.1 to 83.1 mD) and porosity ranging from 18.7 % to 22.9 %. The fluids used were formation water and medium viscosity oil (45 cp at standard conditions). The samples were carried to irreducible water saturation before performing the imbibition tests resembling the assumed reservoir condition. Initial tests were designed including representative water, oil and rock samples at several temperature levels. Another sequence of tests were performed with the addition of variable amounts of water dispersed surfactant. A noticeable influence of experimental conditions was found on the final results. As part of the tests, the same final temperature was reached through single and several steps observing the differences in overall performance.”