Microstructural Imaging and Characterization of Organic Matter Presented in Carbonate Oil Reservoirs

More than a half of world's hydrocarbon reserves is presented in carbonate reservoirs. Conventional waterflooding leads to inefficient oil recovery from these reservoirs, because majority of them have mixed or oil-wet wetting properties. It is well documented in literature, that the main reason of oil wetness of carbonate rocks is adsorbed components from crude oil. Although progress has been made in determination of oil components, which have a tendency to react with carbonates, carbonate reservoirs development still remains challenging. Hence, in this study we investigated the distribution of adsorbed oil components on rock surfaces in order to define their influence on fluids flow through porous carbonate samples. This work presents the results for several carbonate core samples taken from the oil zone of an oil reservoir, which mostly consist of calcite with the small impurities of magnesite and quartz. The work provides the standard study of pore structure of samples to assess the solvents influence on pore network of samples using μCT; the method of evaluation of the amount of organic matter adsorbed on calcite using Rock - Eval pyrolysis; the visualization of such matter distribution through samples; and also the results of kinetics experiments in order to evaluate the bond disruption energy between organic matter and surface. Studies have shown that combination of pyrolysis and μCT provides comprehensive and improved data about organic matter.