Evaluating the petrophysical properties due to the interaction between C 02 - fluids and reservoir rock Evaluación de las propiedades petrofísicas debido a la interacción entre el CO2 - fluidos y la roca del yacimiento

Abstract

This paper developed a methodology to allowed evaluating and understanding the alterations of fluids and reservoir rock due to contact with a system involving C02, by using experimental procedures and correlations, that offered the ability to have an idea of what might happen in the reservoir. Dissolved C02 in the brine, generates carbonic acid, therefore, when a mineral comes in contact with a brine saturated in C02 that wasn't in equilibrium previously, the mineral starts to dissolve in order to achieve equilibrium with the brine. The dissolution of mineral changes the composition of the brine and can lead precipitation of secondary minerals. Interaction rock - fluid depends on the type of formation rock (carbonate or sandstone). Interactions that are generates between C02 - oil, may produce benefits as formation damage. If the ratio resinasphaltene is low, crude oil in contact with the C02 will cause the precipitation of asphaltene, providing a formation damage, which added to the mineral alteration product of interaction with carbonic acid, will affect the permeability and wettability of reservoir rock. However, when increasing the solubility of C02 in oil, this results in a decrease of the oil viscosity increasing oil swelling and reducing superficial tensión, improving oil mobility anddecreasing Sor.