The paper presents the results of an experimental study of the influence of trace amounts of sepiolite/palygorskite clay impurities on the hydrochloric acid – dolomite reaction. Acid dissolution studies were carried out using a rotating disk reactor at a temperature of 30°C and pressure of 10 MPa, which ensured the preservation of carbon dioxide, formed during the acid–rock reaction, in dissolved form. It has been found that the acid dissolution of dolomites that do not contain clay impurities is characterized by high rates and diffusion coefficients, comparable to the characteristics for limestones. At the same time, the presence of a small amount of clay leads to a decrease in the reaction rate by an order of magnitude. Scanning electron microscopy studies showed that a layer of transformed clay residues was formed on the surface of the samples. The presence of this layer prevents acid from reaching the rock surface and significantly reduces the rate of its dissolution. The founded effect of clays on the acid dissolution of carbonates is poorly understood, and for the case of sepiolite/palygorskite is described for the first time. The data obtained can be useful in selecting candidates for acid treatments and improvement of design development. In addition, the research results are intended to stimulate the search for new acid compositions and operating regimes during carbonate rocks acidizing in the presence of clay impurities.
References
1. Hoefner M.L., Fogler H.S., Pore evolution and channel formation during flow and reaction in porous media, AIChE Journal, 1988, V. 34, no. 1, pp. 45–54,
DOI: https://doi.org/10.1002/aic.690340107
2. Fredd C.N., Fogler H.S., Influence of transport and reaction on wormhole formation in porous media, AIChE Journal, 1998, V. 44, no. 9, pp. 1933–1949,
DOI: https://doi.org/10.1002/aic.690440902
3. A.A. Meshcheryakov et al., Justification of optimal acid composition formulation and treatment parameters using physical and mathematical modeling (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2023, no. 8, pp. 104–109, DOI: https://doi.org/10.24887/0028-2448-2023-8-104-109
4. Taylor K.C., Nasr-El-Din H.A., Measurement of acid reaction rates with the rotating disk apparatus, Journal of Canadian Petroleum Technology, 2009, V. 48, no. 6,
pp. 66–70, DOI: https://doi.org/10.2118/09-06-66
5. Salimov V.G. et al., Experimental study of carbonate rocks dissolution rate acid fracturing fluids (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2013, no. 1, pp. 68–71.
6. Lund K., Fogler H.S., McCune C.C., Acidization—I. The dissolution of dolomite in hydrochloric acid, Chemical Engineering Science, 1973, V. 28, no. 3, pp. 691–700,
DOI: https://doi.org/10.1016/0009-2509(77)80003-1
7. Lund K. et al., Acidization—II. The dissolution of calcite in hydrochloric acid, Chemical Engineering Science, 1975, V. 30, no. 8, pp. 825–835,
DOI: https://doi.org/10.1016/0009-2509(75)80047-9
8. Nasr-El-Din H.A. et al., Reaction kinetics of gelled acids with calcite, SPE-103979-MS, 2006, DOI: https://doi.org/10.2118/103979-MS
9. Hyunsang Yoo et al., An experimental investigation into the effect of pore size distribution on the acid-rock reaction in carbonate acidizing, Journal of Petroleum Science and Engineering, 2019, V. 180, pp. 504–517, DOI: https://doi.org/10.1016/j.petrol.2019.05.061
10. Hyunsang Yoo et al., An experimental study on acid-rock reaction kinetics using dolomite in carbonate acidizing, Journal of Petroleum Science and Engineering, 2018, V. 168, pp. 478–494, DOI: https://doi.org/10.1016/j.petrol.2018.05.041
11. Taylor K.C., Nasr-El-Din H.A., Mehta S., Anomalous acid reaction rates in carbonate reservoir rocks, SPE Journal, 2006, V. 11, no. 4, pp. 488–496,
DOI: https://doi.org/10.2118/89417-PA
12. Levich V.G., Fiziko-khimicheskaya gidrodinamika (Physico-chemical hydrodynamics), Moscow – Izhevsk: Publ. of Institute of Computer Research, 2016.
13. Nagy B., Bradley W.F., The structural scheme of sepiolite, American Mineralogist, 1955, V. 40, no. 9–10, pp. 885–892,
DOI: https://doi.org/10.1180/claymin.1954.002.12.15
14. Alver B.E., Sakızcı M., Ethylene adsorption on acid-treated clay minerals, Adsorption Science & Technology, 2012, V. 30, no. 3, pp. 265–273,
DOI: http://doi.org/10.1260/0263-6174.30.3.265
15. Chouikhi N. et al., CO2 adsorption of materials synthesized from clay minerals: A review, Minerals, 2019, V. 9, no. 9, 514 r., DOI: https://doi.org/10.3390/min9090514
