The process of studying the hydrophobization of carbonate rock with organic acids includes the preparation of samples and their treatment with compositions of carboxylic and naphthenic acids. To reproduce reservoir conditions, adsorption was carried out at a temperature of 70 °C. During the study, the time of contact of the rock with acids was varied (1, 14 days); the operation of washing with toluene after aging in acids was used. The assessment of the change in the wetting properties was carried out by the static contact angle by two methods: scanning electron microscopy in the "natural environment" mode (ESEM) and sessile drop method on a DSA30S device from Kruss. The correctness of the contact angle measurement was confirmed on standard samples: glass (hydrophilic) and teflon (hydrophobic). A change in the wettability of carbonate plates from hydrophilic to hydrophobic after aging in solutions of palmitic and stearic acids has been achieved. In the case of palmitic acid, the wetting angle increases as the holding time increases. Washing samples with toluene after aging in acid has a hydrophilizing effect - the contact angle is reduced by 30% compared to samples without washing. It is possible that toluene washes away some of the acid molecules that have reacted with the molecules adsorbed on the rock surface and formed a monolayer. The fact of acid adsorption on the rock surface was confirmed by the method of pyrolitic two-dimensional chromatography – mass spectrometry (pyro-GC-GC-MS). An increase in the holding time in palmitic acid leads to an increase in the concentration of palmitate anions detected in the products of rock pyrolysis. After 14 days of exposure, a signal of decay products of aggregates of the palmitic acid molecule was recorded, which makes it possible to assume layer-by-layer adsorption of the acid on the rock surface. The obtained results became the basis for the method development for controlled calcite aging with solutions of carboxylic acids.
References
1. Kuramshin R.M., Chernitskiy A.V., Gula E.V., Differential estimation of oil reserves based on carbonate reservoir classification (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 5, pp. 48–50, DOI: 10.24887/0028-2448-2019-5-48-50
2. Gomari S.R., Hamouda A.A., Effect of fatty acids, water composition and pH on the wettability alteration of calcite surface, Journal of Petroleum Science and Engineering, 2006, V. 50, pp. 140–150, DOI:10.1016/j.petrol.2005.10.007
3. Fernø M.A., Torsvik M., Haugland S., Graue A., Dynamic laboratory wettability alteration, Energy Fuels, 2010, V. 24, pp. 3950–3958, DOI:10.1021/ef1001716
4. Sachdeva J.S., Sripal E.A., Nermoen A. et al., A laboratory scale approach to wettability restoration in chalk core samples, Proceedings of E3S Web Conf. (SCA 2018), 2019, V. 89, DOI: 10.1051/e3sconf/20198903003
5. Kumar S., Burukhin A.A., Cheremisin A.N., Grishin P.A., Wettability of carbonate reservoirs: effects of fluid and aging, SPE-201834-MS, 2020, DOI: 10.2118/201834-MS
6. Thomas M.M. at al., Adsorption of organic compounds on carbonate minerals: 1. Model compounds and their influence on mineral wettability, Chemical Geology, 1993, V. 109, pp. 201–213, DOI: 10.1016/0009-2541(93)90070-Y
7. Graue A., Aspenes E., Bognø T. et al., Alteration of wettability and wettability heterogeneity, Journal of Petroleum Science and Engineering, 2002, V. 33(1–3), pp. 3-17, DOI: 10.1016/S0920-4105(01)00171-1
8. Buckley J.S., Liu Y., Monsterleet S., Mechanisms of wetting alteration by crude oils, SPE-37230-PA, 1998, DOI: 10.2118/37230-PA
9. Mihajlović S., Vučinić D., Sekulić Ž., Milićević S., Kolonja B., Mechanism of stearic acid adsorption to calcite, Powder Technology, 2013, V. 245, pp. 208–216, DOI: 10.1016/j.powtec.2013.04.041
10. Ivanova A., Cheremisin A.N., Khayrullin M., Sansiev G., Microstructural imaging and characterization of organic matter presented in carbonate oil reservoirs, SPE-195456-MS, 2019, DOI: 10.2118/195456-MS
11. Zimon A.D., Adgeziya zhidkosti i smachivanie (Liquid adhesion and wetting), Moscow: Khimiya Publ., 1974, 416 p.
12. Mihajlović S., Sekulić Ž., Daković A. et al., Surface properties of natural calcite filler treated with stearic acid, Ceramics-Silikaty, 2009, V. 53, pp. 268–275.
