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For more than a century, matrix acidizing has been one of the most common methods to enhance productivity of oil producing wells. Domestic and foreign researchers have developed numerous modifications of acidizing systems and plenty of technologies to inject them into formations. The treatments are carried out with varying degree of success depending on concrete geological settings and reservoir conditions. The effectiveness of matrix acidizing of sandstone and carbonate reservoirs penetrated by vertical and horizontal wells depends on a number of factors. Natural factors are the type of a reservoir, geological setting, macro- and micro-heterogeneity of a reservoir, physical and chemical properties of formation fluids, reservoir pressure and temperature, oil- and water saturation, structure of residual reserves in the well drainage area, well interference, etc. Operational and engineering factors are associated with proper selection of candidate wells, effective preparation works on the wellsite, proper selection of acidizing system, engineering design, acid and other chemicals retention time, the completion method and the quality of completion jobs, competence of staff, whether reservoir energy is maintained or not, well design, optimal bottomhole pressure and reservoir pressure (underbalance), duration of aftereffect, etc. Low success of matrix acidizing is attributed, mainly, to poor distribution of acid in the reservoir, plugging of pore space by chemical reactions’ products, shallow acid penetration, etc. Innovative treatment methods to enhance production from heterogeneous carbonate reservoirs are in high demand. The paper discusses two promising methods – foam-acid treatment and selective large-volume acidizing. References 1. Khisamov R.S., Musabirov M.Kh., Yartiev A.F., Uvelichenie produktivnosti karbonatnykh kollektorov neftyanykh mestorozhdeniy (Increase in productivity of carbonate reservoirs of oil fields), Kazan': Ikhlas Publ., 2015, 192 p. 2. Glushchenko V.N., Silin M.A., Neftepromyslovaya khimiya (Oilfield chemistry), Part 4. Kislotnaya obrabotka skvazhin (Acid treatment of wells): edited by Mishchenko I.T., Moscow: Interkontakt Nauka Publ., 2010, 703 p. 3. Musabirov M.Kh., Sokhranenie i uvelichenie produktivnosti neftyanykh plastov (Preserving and increasing the productivity of oil reservoirs), Kazan': FEN Publ., 2007, 424 p. 4. Silin M.A. et al., Kislotnye obrabotki plastov i metodiki ispytaniya kislotnykh sostavov (Acid formation treatment and methods for acid compositions testing), Moscow: Publ. of Gubkin Russin State University of Oil and Gas, 2011, 120 p. 5. Patent no. 2638668 RF, MPK E 21 B 43/24, Method of thermofoam-acid treatment of near-well zone of carbonate reservoir, Inventors: Ismagilov F.Z., Khabibrakhmanov A.G., Novikov I.M., Latypov R.R., Nafikov A.A., Podavalov V.B., Nig"matullin M.M., Gavrilov V.V., Nig"matullin I.M., Musabirov M.Kh., Abusalimov E.M., Dmitrieva A.Yu., Musabirova N.M., Orlov E.G., Yarullin R.R. 6. Patent no. 2308475 RF, MPK S 09 K 8/74, Composition for acid treatment of critical zone of formation (Variants), Inventor: Musabirov M.Kh. |
