caa a22 4500 606225951 CHVBK 20210128101150.0 cr unu---uuuuu 210128e20150301xx s 000 0 eng 10.1007/s10553-015-0576-y doi (NATIONALLICENCE)springer-10.1007/s10553-015-0576-y Leak-Off Model Considering the Effect of CO2 in Acid Hydrofracking of Naturally Fractured Carbonate Reservoirs [Elektronische Daten] [Zhi-feng Luo, Bo-heng Hou, Ping-li Liu, Zheng-ku Wang, Nian-yin Li] Carbonate reservoirs are generally highly heterogeneous and fractured. Acid leak-off (infiltration) in acid hydrofracking is particularly serious because it reduces the acid efficiency and limits the fracture length from acid etching. As a result, a favorable reservoir away from the wellbore may fail to be connected, leading to poor results after acid hydrofracking. In this work, a new three-phase (oil—gas—acid) model of acid leak-off (infiltration) in acid hydrofracking of a reservoir that considers dissolution of rock by acid, changes in the width of natural fractures, and the effect of CO 2 was developed and a numerical calculation method was also given. The model allows precise description of the characteristics of acid leak-off in acid-fractured carbonate reservoirs. The results show that the mechanism of acid infiltration into fractured and porous (permeable) reservoirs differs widely. The acid penetrates deep into the reservoir mainly via wide natural fractures and only thereafter through microfissures and the matrix. The acid reacts most vigorously with the rock in wide fractures, leading to further widening of the natural fractures and increased infiltration of the acid into the fractures, which causes deeper penetration of the acid into the fractures. CO 2 reduces the acid leak-off rate, which is less at higher CO 2 concentrations. Springer Science+Business Media New York, 2015 acid leak-off nationallicence acid hydrofracking nationallicence fractured reservoirs nationallicence carbonate reservoir nationallicence acid—rock reaction nationallicence wormholes nationallicence carbon dioxide nationallicence Luo Zhi-feng National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut Hou Bo-heng National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut Liu Ping-li National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut Wang Zheng-ku Chongqing University of Science and Technology, 401331, Chongqing, China aut Li Nian-yin National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut Chemistry and Technology of Fuels and Oils Springer US; http://www.springer-ny.com 51/1(2015-03-01), 66-78 0009-3092 51:1<66 2015 51 10553 https://doi.org/10.1007/s10553-015-0576-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10553-015-0576-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Luo Zhi-feng National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut NATIONALLICENCE 700 1- Hou Bo-heng National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut NATIONALLICENCE 700 1- Liu Ping-li National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut NATIONALLICENCE 700 1- Wang Zheng-ku Chongqing University of Science and Technology, 401331, Chongqing, China aut NATIONALLICENCE 700 1- Li Nian-yin National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China aut NATIONALLICENCE 773 0- Chemistry and Technology of Fuels and Oils Springer US; http://www.springer-ny.com 51/1(2015-03-01), 66-78 0009-3092 51:1<66 2015 51 10553