Experimental investigation of dynamic interfacial interactions at reservoir conditions

Much of the research on wettability in the existing literature has been done using stocktank oils and at ambient conditions. The main objective of this study is therefore to examine the validity of ambient measurements in inferring in-situ reservoir wettability. For this purpose, Drop-Shape-Analysis for interfacial tension and Dual-Drop-Dual-Crystal (DDDC) contact angle measurements have been carried out using dolomite rock, Yates reservoir stocktank and live crude oils and Yates synthetic brine at Yates reservoir conditions of 82oF and 700 psi. Two types of surfactants (nonionic and anionic) in varying concentrations have been used to study the effect of surfactants on wettability alteration in Yates reservoir. Dynamic behavior of interfacial tension (IFT) of crude oil - brine are mainly caused by the polar components or surfactants in the liquids. The oil composition especially light ends, and brine composition also have effect on it. A four-staged model was adapted from the literature to explain this time-dependent behavior of IFT. An advancing contact angle of 156o measured for dolomite rock, Yates stocktank oil and Yates synthetic brine in the absence of surfactants showed the strongly oil-wet nature. Experiments with Yates live crude oil at reservoir conditions indicated weakly water-wet behavior with a water-advancing angle of 55o For oil-wet stocktank oil system, the anionic surfactant was able to alter wettability from strongly oil-wet (156o) to less oil-wet (135o). No significant wettability alterations were observed with the nonionic surfactant in the stocktank oil containing system. However, for water-wet live oil system, the nonionic surfactant injection altered the wettability to intermediate-wet and the anionic surfactant altered it into strong oil-wet. The oil-wet behavior observed with Yates live oil due to anionic surfactant indicates the ability to this surfactant to form continuous oil-wet paths for mixed-wettability development. These experiments clearly indicate the need to use live crude oils at reservoir conditions for in-situ reservoir wettability determination. Furthermore, these experiments provided clear evidence that the surfactants used altered wettability to either intermediate-wet or mixed-wet, which could result in potential oil recovery enhancements in field applications

The Role of Wettability Alteration in Subsurface CO2 Storage: Modeling and Numerical Analysis

This dissertation is aimed to provide mathematical frameworks to assess the large-scale deployment of CO2 in a subsurface formation, where the formation wettability is assumed to be altering through exposure time to the wettability-altering agent. Particularly, this thesis addresses: upscaling the pore-scale process to the macroscale laws, developing an alternative time-stepping method, and quantifying the upscaled models for the subsurface CO2 storage technology. These three components are organized to investigate and understand the effect of the wettability change on the interaction of CO2-water in a porous medium. Wettability refers to the tendency of a fluid to be in contact with the solid surface over the other fluid. This property changes due to many factors (e.g., reservoir temperature, pressure, pH, fluid compositions, and exposure time to the reactive fluid), and the change in wettability is known as wettability alteration. Wettability alteration (WA) takes place at the pore scale, but strongly controls the fluid-fluid interaction that is observed at the macroscale. One of the goals of this thesis is to develop a mathematical framework that upscales the effect of exposure time-dependent WA process to Darcy-scale models such as capillary pressure and relative permeability functions also known as saturation or \textit{flow functions. The upscaling processes introduce a pore-scale WA mechanism that follows a sorption-based model as a function of WA agent and exposure time to a WA agent. This model is then coupled with a bundle-of-tubes (BoT) model to simulate time-dependent WA-induced capillary pressure and relative permeability data. The resulting saturation functions are then used to quantify the WA-induced dynamic components of the saturation functions. More importantly, this part of the study also draws a clear relationship between the pore-scale and upscaled model's behaviors. The developed saturation functions are non-local in time. Coupling these functions adds extra complexity and non-linearity to the solution process of the multi-phase flow model. This thesis develops a monotone fixed-point iterative linearization scheme to approximate the solution for the resulting non-standard model. The scheme treats the capillary pressure function semi-implicitly in time and introduces an L-scheme type stabilization term in both the saturation and pressure equations. The convergence of the scheme is proved theoretically. The theoretical convergence analysis and numerical results show that the scheme is linearly convergent. However, the proposed linearization scheme shows flexibility for the choice of time-step size for reasonably large alteration (possibly jumps) in the capillary pressure function (i.e., saturation discontinuity). Furthermore, the scheme is designed so that it can be combined with Newton's method in a straightforward manner. This may improve the convergence rate of the scheme. The third part of this study concerns the full compositional flow model, where the saturation functions are dependent on solvents (e.g., dissolved CO2 in water), phase saturation, and exposure time to the solvent. Here, we quantify the role of the exposure time-dependent WA processes on the applicability of CO2 storage in saline aquifers. To do so, we design horizontal and vertical CO2-water flow scenarios. For the horizontal flow scenario, we compare the CO2-water front locations for static (i.e., initial-wet condition) and WA induced dynamic saturation functions based on the capillary number. The analysis shows that the CO2 front scales well with the capillary number. More precisely, the effect of WA on the CO2 front movement decreases while the capillary number increases. On the other hand, the integrity of the caprock is evaluated with and without WA effects in the saturation functions for the vertical flow scenario. We design a correlation model that can be used to forecast the total CO2, caused by WA, in the caprock for a given rate of WA dynamics, caprock permeability, entry pressure, and of course time.Doktorgradsavhandlin

Analysis of wettability alteration in low salinity water flooding using a zeta potential-based model

This study introduces a zeta potential-based model which connects low salinity water flooding oil recovery to the reservoir wettability. The model assumed that the reservoir wettability is controlled by the electrostatic forces that exist between rock-brine and oil-brine interfaces. Therefore, it links the wettability to the zeta potentials present at the corresponding interfaces. Using the model, various literature oil recovery data were simulated and then statistically compared the trend of the oil recovery factor with the trend of the wettability indicator values. The Pearson correlation coefficient was used for the statistical analysis. The results from the suggested model were compared with the outputs computed from other pre-existing models for wettability alteration. The simulation outcome indicated that a strong relationship exists between reservoir wettability and the zeta potentials produced at the rock-brine and oil-brine interfaces. The Pearson correlation coefficient calculated for the suggested model exceeded 0.7 for all the experimental cases simulated. However, most of the other pre-existing models showed weak relationships between the wettability indicator values and the oil recovery factor, with some models producing the Pearson correlation coefficient below 0.2. This study highlights the role of zeta potentials at the rock-brine and oil-brine interfaces on the wettability alteration during low salinity water flooding. The suggested model can be utilized in the decision making and implementation of low salinity water flooding works.Cited as: Boampong, L. O., Rafati, R., Haddad, A. S. Analysis of wettability alteration in low salinity water flooding using a zeta potential-based model. Capillarity, 2023, 7(2): 32-40. https://doi.org/10.46690/capi.2023.05.02

Analysis of wettability alteration in low salinity water flooding using a zeta potential-based model

Peer reviewedPublisher PD

Evaluation of CO2 and Carbonated Water EOR for Chalk Fields

Imperial Users onl

Evolution and interfacial dynamics of thin electrolyte films in oil-brine-carbonate rock systems due to chemical equilibrium disruptions

Open Access through the ACS Agreement. ACKNOWLEDGMENTS The authors thank the Petroleum Technology Development Fund (PTDF), Nigeria for funding this project.Peer reviewedPublisher PD

Pore scale mechanisms of carbonated water injection in oil reservoirs

Concerns over the environmental impact of carbon dioxide (CO2) have led to a resurgence of interest in CO2 injection (CO2I) in oil reservoirs, which can enhance oil recovery from these reservoirs and store large quantities of CO2 for a long period of time. Oil displacement and recovery by CO2I has been studied and applied in the field extensively. However, CO2I lacks acceptable sweep efficiency, due to the large viscosity contrast between CO2 and resident reservoir fluids. Various CO2I strategies e.g. alternating (WAG) or simultaneous injection of CO2 and water have been suggested to alleviate this problem. An effective alternative strategy is carbonated (CO2-enriched) water injection. In carbonated water, CO2 exists as a dissolved as opposed to a free phase, hence eliminating the problems of gravity segregation and poor sweep efficiency. In this thesis, the results of an integrated experimental and theoretical investigation of the process of carbonated water injection (CWI) as an injection strategy for enhanced oil recovery (EOR) with the added value of CO2 storage are described. High-pressure micromodel technology was used to physically simulate the process of CWI and visually investigate its EOR potential, at typical reservoir conditions. Using the results of these flow visualisation experiments, the underlying physical processes and the pore-scale mechanisms of fluid-fluid and fluid-solid interactions during CWI were demonstrated to be oil swelling, coalescence of the isolated oil ganglia, wettability alteration, oil viscosity reduction and flow diversion due to flow restriction in some of the pores as a result of oil swelling and the resultant fluid redistribution. A mathematical model was developed that accounts for the pore-scale mechanisms observed during the micromodel experiments. In this study, some of the micromodel experimental observations were interpreted and the impact of some of the pertinent parameters on CWI and CO2I processes was studied. The results predicted by the model were linked to the results obtained using a new relationship developed based on the dimensional analysis technique. To examine and investigate the effect of CWI on wettability, micromodel experiments, designed only to observe possible variation of contact angles and spontaneous imbibition displacement mechanisms due to CW, were performed. Contact angle measurements were also conducted to quantify different tendencies of CW and water to wet solid surfaces, using three different solid plates with different salinity of the aqueous phase, under different pressure and temperature conditions. Two other important parameters affecting the performance of CWI, i.e. CO2 solubility in water and its CO2 diffusion coefficient, were also experimentally studied and estimated. A mathematical model was developed to estimate CO2 diffusion coefficient from the corresponding experimental results. The results of this research show that CWI is an effective and efficient injection strategy that offers great potential for enhanced oil recovery and at the same time a unique solution to the problem of reducing CO2 emission

Application of Nanotechnology in Chemical Enhanced Oil Recovery and Carbon Storage

Nanofluids gaining increased importance in science and industry including enhanced oil recovery. In this work, the ability of nanoparticles to alter the wettability of oil-wet surfaces towards water-wet at reservoir conditions and the synergistic effect of nanoparticle-surfactant combinations on nanofluid interfacial properties and nanofluid stability were systematically examined using several nano-silica dispersions. This study not only presents novel nanofluid formulations for wettability alteration but also introduced the first insight into nanoparticle-surfactant interactions in saline environments

Wettability Alteration During Low Salinity Water Flooding in Carbonate Reservoirs: An Experimental and Theoretical Study

The aim of this research is to achieve a more comprehensive understanding of the underlying mechanisms of Low Salinity Effect in carbonate reservoirs through systematic analysis of physical, chemical, and geochemical factors that affect the oil-brine-carbonate interactions during low salinity waterflooding. This research presents several hypotheses and suitable strategies for validating these hypotheses to fill the knowledge gaps that were identified in the literature. The outcome of this research can have significant implications for field application of LSWF