Carbonate
reservoirs are susceptible to dissolution and precipitation
effects when an acid solution enters into contact with its matrix
rock, and the main interest with regard to fluid flow and storage
is the alteration of the petrophysical properties, such as porosity
and permeability. Dynamic experiments of injection of carbon dioxide
enriched brine through the outcrop sample (coquina) was carried out
at T = 20 °C and P = 2000 psi
at flow rates of 0.5, 1, and 2 mL/min. X-ray computerized tomography
(CT) was used to determine the porosity of the sample throughout the
test, and rock permeability was evaluated by a series of pressure
transducers installed at a special core holder with six pressure taps.
The results include the variation of the petrophysical properties
along the core sample and its evolution over time. The research covers
experimental and simulation approaches; for instance, the PHREEQC
was used to develop a geochemical model to fit results from calcium
content analysis from effluents and porosity profiles obtained by
CT scan. A very instructive sequence of images documents the formation
of a highly conductive flow channel, initiated and formed as a dominant
wormhole, which dramatically increases permeability and porosity through
the experiment course. The dissolution regime was characterized by
the Damköhler and Péclet numbers. The robust perspective
of this paper showed that it is feasible to estimate the chemical
and physical alterations from laboratory results on future application
in the reservoir field scale by coupling experimental data and numerical
modeling.
Carbon dioxide (CO2) injection in reservoirs promotes reactions which depend on rock nature, brine composition, partial pressure of CO2, reservoir temperature and pressure among other conditions. The reactions may cause changes in the petrophysics properties, including porosity and permeability, that are important parameters to the fluid flow. The present study focus on the effects of carbonated brine injection in carbonate rocks similar to pre salt reservoirs. The effects are evaluated through the changes of the rock absolute permeability provoked by the acidic action of the injected fluid. Experiments were designed to detail permeability changes along the length of a long carbonate core using using a coreholder equipped with multiple pressure taps. The experiments were conducted in dynamic regime, at the temperature of 22°C and at the mean pressure of 2,000 psi, at flow rates of 0.5; 1 and 2 cc/min. The results show significant permeability alterations at the different segments of the sample, which are also highly dependent on the injection rate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.