Low Salinity Injection Fluids With Additives For Enhanced Oil Recovery From Clastic Reservoirs: The Macro to Pore Scale Studies

The core of the present work is the studies of the use of additives in low salinity water for their suitability for injection into oil-bearing sandstone reservoirs to improve the oil recovery performance in an enhanced oil recovery process by this method. This work carried out various investigations to find out the possibilities to mitigate the shortcomings of the existing process of low salinity water injection enhanced oil recovery

In situ wettability investigation of aging of sandstone surface in alkane via x-ray microtomography

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Wettability of surfaces remains of paramount importance for understanding various natural and artificial colloidal and interfacial phenomena at various length and time scales. One of the problems discussed in this work is the wettability alteration of a three-phase system comprising high salinity brine as the aqueous phase, Doddington sandstone as porous rock, and decane as the nonaqueous phase liquid. The study utilizes the technique of in situ contact angle measurements of the several 2D projections of the identified 3D oil phase droplets from the 3D images of the saturated sandstone miniature core plugs obtained by X-ray microcomputed tomography (micro-CT). Earlier works that utilize in situ contact angles measurements were carried out for a single plane. The saturated rock samples were scanned at initial saturation conditions and after aging for 21 days. This study at ambient conditions reveals that it is possible to change the initially intermediate water-wet conditions of the sandstone rock surface to a weakly water wetting state on aging by alkanes using induced polarization at the interface. The study adds to the understanding of initial wettability conditions as well as the oil migration process of the paraffinic oil-bearing sandstone reservoirs. Further, it complements the knowledge of the wettability alteration of the rock surface due to chemisorption, usually done by nonrepresentative technique of silanization of rock surface in experimental investigations

Recent advances in carbon dioxide geological storage, experimental procedures, influencing parameters, and future outlook

The oxidation of fossil fuels produces billions of tons of anthropogenic carbon dioxide (CO2) emissions from stationary and nonstationary sources per annum, contributing to global warming. The natural carbon cycle consumes a portion of CO2 emissions from the atmosphere. In contrast, substantial CO2 emissions accumulate, making it the largest contributor to greenhouse gas emissions and causing a rise in the planet\u27s temperature. The Earth\u27s temperature was estimated to be 1 °C higher in 2017 compared to the mid-twentieth century. A solution to this problem is CO2 storage in underground formations, abundant throughout the world. Millions of tons of CO2 are stored underground into geological formations annually, including deep saline aquifers. However, these geological formations have minute concentrations of organic material, significantly influencing the CO2 containment security, fluid dynamics, and storage potential. Examining the wetting characteristics and influencing parameters of geological formations is pertinent to understanding the supercritical CO2 behavior in rock/brine systems. Wettability is an important parameter governing the ability of injected CO2 to displace formation water and determine the containment security and storage capacity. Previously, many studies have provided comprehensive overviews of CO2-wettability depending on various factors, such as pressure, temperature, salinity, formation type, surfactants, and chemicals. However, mineral surfaces in these wettability studies are chemically cleaned, and natural geological storage conditions are anoxic (containing organic molecules) where reductive conditions ensue. A severe gap exists in the literature to comprehend the effects of organic material for determining the CO2 storage capacities and how this effect can be reversed using nanomaterial for increased CO2 storage potential. Therefore, we conducted a thorough literature review to comprehend the recent advances in rock/CO2/brine and rock/oil/brine systems containing organic material in different geo-storage formations. We also present recent advances in anoxic rock/CO2/brine and rock/oil/brine systems that have employed nanomaterial for wettability reversal to be more water-wet. This comprehensive review is divided into four parts: 1) reviewing CO2 emissions and geological systems, 2) recent advances in direct quantitative experimental procedures in anoxic rock/CO2/brine systems and effects of organic contaminations on experimental methodology and their controls, 3) effects of organics and nanomaterial in rock/CO2/brine and rock/oil/brine systems, and 4) the future outlook of this study

Streaming and zeta potentials of basalt as a function of pressure, temperature, salinity, and pH

The electric surface charge of basalt in contact with filing fluids (e.g. water and CO2) has broad range of applications in varied fields such as gas geological storage sites, geothermal systems, and hydrocarbon reservoirs. The surface charge at the interface between a solid surface (e.g. rock) and liquid (e.g. aqueous solution) can be quantified by the zeta potential, thus zeta potential measurement is a useful technique for interpreting wetting characteristics of rock-fluid systems. However, there is no data for zeta potentials of basaltic rocks in presence of aqueous solutions or how zeta potentials may be affected by pressure, temperature, salinity, or pH. Thus, streaming potential measurements were performed to determine the zeta potential of basaltic rocks in the presence of aqueous NaCl solution at pore pressures (1.72 MPa to 6.9 MPa), temperatures (298 K and 323 K), brine salinities (1 wt% NaCl to 3.5 wt% NaCl), and pH values (4 to 10). Also, the effects of mineralogy and CO2-presence (dead and live brines) on the zeta potential were evaluated. The results showed that the zeta potential remained constant versus pressure, while it increased (became less negative) with increasing temperature and salinity, and decreased (became more negative) with increasing pH. This study provides key fundamental data and thus improves fundamental understanding of basalt-water-CO2 interactions, thereby aiding in the improvement of various industrial applications, including gas geo-storage schemes and geothermal energy production

Effect of CO2 flooding on the wettability evolution of sand-stone

Wettability is one of the main parameters controlling CO2 injectivity and the movement of CO2 plume during geological CO2 sequestration. Despite significant research efforts, there is still a high uncertainty associated with the wettability of CO2/brine/rock systems and how they evolve with CO2 exposure. This study, therefore, aims to measure the contact angle of sandstone samples with varying clay content before and after laboratory core flooding at different reservoir pressures, of 10 MPa and 15 MPa, and a temperature of 323 K. The samples’ microstructural changes are also assessed to investigate any potential alteration in the samples’ structure due to carbonated water exposure. The results show that the advancing and receding contact angles increased with the increasing pressure for both the Berea and Bandera Gray samples. Moreover, the results indicate that Bandera Gray sandstone has a higher contact angle. The sandstones also turn slightly more hydrophobic after core flooding, indicating that the sandstones become more CO2-wet after CO2 injection. These results suggest that CO2 flooding leads to an increase in the CO2-wettability of sandstone, and thus an increase in vertical CO2 plume migration and solubility trapping, and a reduction in the residual trapping capacity, especially when extrapolated to more prolonged field-scale injection and exposure times