Presented at CMTC 149958, Carbon Management Technology Conference, 7-9 February, 2012, Orlando, Florida/
Carbon Dioxide Sequestration in Sandstone Aquifers: How Does It Affect the Permeability?
CO2 will potentially cause formation damage when injected in sandstone formations, due to the precipitation of reaction products that are generated by the reaction between carbonic acid and different clays and feldspars, which often exists in sandstone formations. Several parameters affect these interactions including pressure, temperature, brine composition, CO2 injection rate, and overall injection scheme. This paper addresses the effect of the temperature and injection scheme on the permeability reduction generated in the sandstone cores due to CO2 injection. A core flood study was conducted using Berea sandstone cores. CO2 was injected under supercritical conditions at a pressure of 1,300 psi, and at temperatures ranging from 70 to 250°F at injection flow rate of 5.0 cm3/min. Core effluent samples were collected and the concentrations of calcium, potassium, magnesium, aluminum, iron, and silicon ions were measured. Precipitated material collected in the effluent samples were analyzed using XRD and XRF. Core permeabilities were measured before and after the experiment to evaluate the damage generated. A significant damage, between 35 and 55% loss in core permeability, was observed after CO2 injection. For shorter WAG injection the damage was higher, decreasing the brine volume injected per cycle the damage was less. At higher temperatures, 200 and 250°F, more damage was noted than at 70°F. Two mechanisms of damage were identified: damage occurred due to the precipitation of the reaction products, and damage due to the migration of clay particles, which were attached by the dissolved cementing materials.