Wettability Changes Due to Nanomaterials and Alkali—A Proposed Formulation for EOR

Abstract

We investigated the usage of two silica nanomaterials (surface-modified) and alkali in enhanced oil recovery through Amott spontaneous imbibition tests, interfacial tension (IFT) measurements, and phase behavior. We evaluated the wettability alteration induced by the synergy between nanomaterials and alkali. Moreover, numerical analysis of the results was carried out using inverse Bond number and capillary diffusion coefficient. Evaluations included the use of Berea and Keuper outcrop material, crude oil with different total acid numbers (TAN), and Na2CO3 as alkaline agent. Data showed that nanomaterials can reduce the IFT, with surface charge playing an important role in this process. In synergy with alkali, the use of nanomaterials led to low-stable IFT values. This effect was also seen in the phase behavior tests, where brine/oil systems with lower IFT exhibited better emulsification. Nanomaterials’ contribution to the phase behavior was mainly the stabilization of the emulsion middle phase. The influence of TAN number on the IFT and phase behavior was prominent especially when combined with alkali. Amott spontaneous imbibition resulted in additional oil recovery ranging from 4% to 50% above the baseline, which was confirmed by inverse Bond number analysis. High recoveries were achieved using alkali and nanomaterials; these values were attributed to wettability alteration that accelerated the imbibition kinetics as seen in capillary diffusion coefficient analysis.

Sorption of Nanomaterials to Sandstone Rock

“…As a way of delimitation, note that fluid-rock interactions in the presence of hydrocarbons were not considered as part of the scope of this work since the particular evaluations and effects we considered and presented in some other works of the authors, such as Saleh et al [1] and Neubauer et al [18].…”

“…A scanning electron microscope (SEM) image of a thin section analysis from the same outcrop is shown in Figure 1a. Pore walls are covered with feldspar or clay [1]. According to the obtained XRD data, the clay is a mix of 92% kaolinite, 7.5% chlorite and 0.7% illite by mass.…”

“…It is well sorted and mainly grain-supported. Limonite is the iron oxide that causes the reddish colour [1,28]. A scanning electron microscope (SEM) image of a thin section analysis from the same outcrop is shown in Figure 1b.…”

“…For the former, nanotechnology provides new and promising applications when applied in reservoir areas, for example, in enhanced oil recovery (EOR) or drilling-related activities. For instance, to reduce formation damage during drilling, as well as to enhance production in mature fields [1][2][3], protect the reservoir formation, reduce fluid loss and prevent shale swelling [4][5][6][7][8][9]. Due to their small size, nanomaterials have the ability to pass through reservoir rock and can be surface active, which is a key requirement for influencing oil-rock-water interfaces.…”

“…Much research has been presented on the application of nanomaterials to recovery oil, including its description and usage [14][15][16][17][18][19]. Various mechanisms are considered when explaining nanomaterial effects, such as wettability alteration due to disjoining pressure [1,20], spontaneous emulsion formation and emulsion stabilisation [17,18], change of interfacial tension (IFT) between reservoir fluids and change of flow properties of the porous medium [1,[14][15][16][17][18][19][20]. Among other mechanisms taking place, nanoparticle adsorption is a very important topic in nanomaterial application.…”