Performance comparison of novel chemical agents in improving oil recovery from tight sands through spontaneous imbibition

Abstract

Tight sands are abundant in nanopores leading to a high capillary pressure and normally a low fluid injectivity. As such, spontaneous imbibition might be an effective mechanism for improving oil recovery from tight sands after fracturing. The chemical agents added to the injected water can alter the interfacial properties, which could help further enhance the oil recovery by spontaneous imbibition. This study explores the possibility of using novel chemicals to enhance oil recovery from tight sands via spontaneous imbibition. We experimentally examine the effects of more than ten different chemical agents on spontaneous imbibition, including a cationic surfactant (C12TAB), two anionic surfactants (O242 and O342), an ionic liquid (BMMIM BF4), a high pH solution (NaBO2), and a series of house-made deep eutectic solvents (DES3–7, 9, 11, and 14). The interfacial tensions (IFT) between oil phase and some chemical solutions are also determined. Experimental results indicate that both the ionic liquid and cationic surfactant used in this study are detrimental to spontaneous imbibition and decrease the oil recovery from tight sands, even though cationic surfactant significantly decreases the oil–water IFT while ionic liquid does not. The high pH NaBO2 solution does not demonstrate significant effect on oil recovery improvement and IFT reduction. The anionic surfactants (O242 and O342) are effective in enhancing oil recovery from tight sands through oil–water IFT reduction and emulsification effects. The DESs drive the rock surface to be more water-wet, and a specific formulation (DES9) leads to much improvement on oil recovery under counter-current imbibition condition. This preliminary study would provide some knowledge about how to optimize the selection of chemicals for improving oil recovery from tight reservoirs.

The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

“…e contact constitutive model is used to simulate the sliding or opening of the contact. It is very proper to show the failure process of overlying strata after excavation of working face [49,50]. Figure 10 shows the yielding process of the contact.…”

Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

“…Generally, some of tight oil reservoirs are water-wet, so imbibition can happen even if there is no surfactant in the fracturing fluid. However, in some mixed-wet or oil-wet reservoirs, surfactant is usually added into water or the fracturing fluid to promote imbibition by changing the wettability (Begum et al 2017;Alvarez et al 2017;Meng et al 2018;Huang et al 2020). In order to reflect this effect, the capillary force ratio of water to surfactant can be approximated using the Young-Laplace equation assuming constant pore diameter for water and surfactant imbibition,…”

Efficiency Improvement of Heavy-Oil Recovery by Steam-Assisted Gravity Drainage Injection Using New Generation Chemicals

“…The chemicals used in this research are listed in Table . They were selected based on the initial screening studies previously conducted by Bruns and Babadagli , and Huang et al Concentration ranges of these chemical additives were determined based on the IFT results reported by Pratama and Babadagli …”

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