Role of Rock Surface Charge in the Carbonated Water Flooding Process

Abstract

SUMMARYCarbonated Water Flooding (CWF) is an alternative EOR method where an oil reservoir is flooded with carbonated (CO2-enriched) water. It is a promising solution for improving oil recovery that benefits from oil viscosity reduction, an increase in oil relative permeability and enhancement of oil mobility. At the same time CWF is a possible mitigation option for the increasing carbon dioxide concentration in the atmosphere and a chance for safe disposal of CO2 underground. We present Bentheimer sandstone surface charge behavior, mainly as a function of the CO2 concentration, in an aqueous solution. To investigate the electrokinetic properties of Bentheimer surface, the coupling coefficient and zeta potential are measured in a streaming potential experiment. The results show that the zeta potential can vary over at least one order of magnitude with different salinities and different CO2 concentrations. It strongly depend on both pore fluid concentration and pH, as well as a set of mineral and temperature specific electrochemical parameters. The results are base case results for the determination of surface behavior of Bentheimer sandstone with presence of oil. The results of the conducted experiment have an application in planning CWF processes, monitoring CO2 sequestration and streaming potential measurements in reservoirs.

Wettability Evaluation of a CO2/Water/Bentheimer Sandstone System: Contact Angle, Dissolution, and Bubble Size

“…However, several studies have reported the wettability alteration of quartz surfaces from strongly to less water-wet in contact with supercritical CO 2 . ,,,, This inconsistency originates from differences in the surface charges of quartz and Bentheimer sandstone. Although Bentheimer sandstone is mainly composed of quartz, even a low content of clay (i.e., 2.5% Kaolinite and so on) plays an important role in the surface charge of particles …”

“…Although Bentheimer sandstone is mainly composed of quartz, even a low content of clay (i.e., 2.5% Kaolinite and so on) plays an important role in the surface charge of particles. 56 For the quartz surface, an increase in contact angle with pressure has been attributed to the decreased charge of the silica surface under the acidic pH of the CO 2 -equilibrated aqueous phase. 12,55,57 The pH of the aqueous phase influences the surface charge of the particles.…”

“…Unlike quartz, the surface charge of Bentheimer sandstone approaches zero at a pH of 8. 56,58 At low pH, the charge of a Bentheimer sandstone surface becomes more positive so that the stability of the water film increases. 56 This means that the pressure induced by the injection of a CO 2 bubble has no effect on the stability of the water film and thus the wettability of the Bentheimer sandstone (as seen in Figure 14).…”

“…56,58 At low pH, the charge of a Bentheimer sandstone surface becomes more positive so that the stability of the water film increases. 56 This means that the pressure induced by the injection of a CO 2 bubble has no effect on the stability of the water film and thus the wettability of the Bentheimer sandstone (as seen in Figure 14). The sequential digital images in Figure 14 show the CO 2 bubble with similar sizes on the Bentheimer rock at subcritical (2.83 MPa), approximately critical (7.51 MPa), and supercritical (12.74 MPa) pressures.…”

Wetting Behavior of CO2–H2O–coal with Different Metamorphic Degrees under In Situ Thermophysical Conditions

“…Effects of components and properties of the coal surface on wettability mainly reflected in organic macromolecules, elemental content, and inorganic minerals. 22 Murata 23 measured the CAs of coal pellets in the atmosphere and reported that CAs depend on the oxygen and hydrogen content of these surfaces. Li et al 24 reported that wettability mainly depends on hydrophilic and hydrophobic groups of coal surfaces.…”