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The paper presents results of surveys of hydrogeological conditions of eighteen heavy oil accumulations. The obtained hydrodynamic and hydrochemical background characteristics of the water-bearing formations above and below production targets were used to understand the man-made impact on the subsurface geological environment. The objectives of the system of hydrological monitoring of the Cheremshan-Bastrykskaya zone heavy oil fields are to prevent possible adverse effects of the thermal recovery process, to control risks, and to meet the requirements of license agreement on subsoil use. The main purpose of the environmental and hydrogeological surveys is to obtain background response characteristics and to evaluate hydrodynamic and hydrochemical changes in water-bearing formations above and below the development targets within and outside the oil drainage boundary with particular emphasis on surface and subsurface fresh water sources. Tatneft system of hydrological monitoring of subsurface water is realized through drilling of observation wells within the extent of the reservoir. Drilling of well pads and testing of water-bearing formations along the cross-section of fresh water zone allowed a conclusion about the inversion of water-bearing intervals of the Sakmarskian and Ufimian formations and made it possible to determine the most water-abundant parts of the cross sections, which can accumulate the injected heat. In terms of chemistry, the range of water types in the zones of active water exchange is very wide – from bicarbonate to chloride types. Sodium bicarbonate type of water is, mainly, characteristic of productive formations, while waters of the sandy-argillaceous Sakmarskian and Ufimian formations are, predominantly of the sulfate type. Monitoring of the concentrations of boron, bromine, ammonium, phenols, and hydrogen sulfide is a tool to determine hydrochemical changes in a productive formation, and in the overlying and underlying formations. References 1. Gareev R.M., Mingazov M.N., Mishanina O.E., Khisamutdinova E.V., Evaluation of ecological state of Lower Kama national park under commercial oil production conditions (In Russ.), Neftyanoe khozyaystvo = Oil industry, 2011, no. 7, pp. 70–73 2. Lesokhozyaystvennyy reglament lesnichestva NP “Nizhnyaya Kama” (Forest management regulations of the forest ranger station of National Park "Lower Kama"), 2017. – 141 p.
3. Order of the Ministry of Ecology and Natural Resources of the Republic of Tatarstan no. 1201-p From 28.10.2016 “Ob utverzhdenii regional'nykh normativov “Dopustimoe ostatochnoe soderzhanie nefti i produktov ee transformatsii v pochve posle provedeniya rekul'tivatsionnykh i inykh vosstanovitel'nykh rabot na territorii Respubliki Tatarstan” (On approval of regional standards "Allowable residual content of oil and its transformation products in the soil after reclamation and other restoration works in the territory of the Republic of Tatarstan”), Kazan', 2016, 6 p. |
