The basic prerequisites and factors leading to changes in petrophysical models of reservoirs of the fields at the late stage of development are considered on the example of oil fields at the platform part of the Republic of Bashkortostan. These oil fields are characterized by a limited complex of well log data, low and uneven removal of the core, lack of complex of the laboratory research, lack of accurate reference of the core to the depth. These disadvantages contributed to a significant difference in the approved parameters by the neighboring fields which are located in the same lithofacies zones. A prerequisite for reviewing of the reservoir model of the carbonate layer of Tournaisian Stage of some fields is a mismatch of the dynamics of watering in the oil deposits with equal effective thicknesses. Different rate of watering attests the heterogeneity of the reservoir. Analysis of production availability revealed deposits with low reserve multiplicity, while the decline in production in these deposits is not observed. The logical explanation is the underestimation of the pore volume. Significant factors which need to be taken into account for changing the traditional view of reservoir properties are noted during the revising of the petrophysical models. They include the problem of selection of analogues in conditions of low core removal, the typification of reservoirs by lithological and structural features, and the influence of the properties of modern research (methods and techniques) of the core. Also the analysis of the influence of changes in the petrophysical model on the volumetric parameters which are obtained from the interpretation of geophysical well data is shown in this proposed article. In most cases, a decrease in the leads of reservoir boundary values to an increase in the effective thickness and a decrease in the weighted average porosity. The application of modern methodological approaches to the creation of petrophysical models leads to a differentiated assessment of the quality of the reservoir and should be accompanied by changes of dynamic parameters.
References
1. Khusainova A.M., Burikova T.V., Privalova O.R. et al., The influence of structural and lithological features on the saturation model of Middle Carboniferous reservoirs of the Republic of Bashkortostan (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2016, no. 8, pp. 74–77.
2. Khusainova A.M., Burikova T.V., Savel'eva E.N. et al., Razrabotka interpretatsionnoy modeli pri rayonirovanii karbonatnykh kollektorov turneyskikh otlozheniy (na primere mestorozhdeniy Respubliki Bashkortostan) (Development of an interpretation model for the regionalization of carbonate reservoirs of the Tournaisian deposits (on the example of deposits in the Republic of Bashkortostan)), Collected papers “Aktual'nye nauchno-tekhnicheskie resheniya neftedobyvayushchego potentsiala PAO ANK “Bashneft'” (Current scientific and technical solutions to the oil production potential of Bashneft PJSC), 2016, V. 124, pp. 68–75.
3. Privalova O.R., Khusainova A.M., Amineva G.R., Analiz elektricheskikh svoystv i nasyshcheniya dlya razlichnykh petroklassov po dannym GIS karbonatnykh otlozheniy srednego i nizhnego karbona (Analysis of electrical properties and saturation for various petroclasses according to well log data of carbonate deposits of Middle and Lower Carbon), Proceedings of petrophysical scientific workshop “Sovremennye podkhody k interpretatsii GIS, issledovaniy kerna i petrofizicheskogo modelirovaniya” (Modern approaches to the interpretation of well log data, core research and petrophysical modeling), Tyumen', 2017, p. 9.
4. Shumatbaev K.D., Privalova O.R., Amineva G.R., Dvorkin A.V., Razdelenie karbonatnykh kollektorov po dobychnomu potentsialu v usloviyakh ogranichennogo kompleksa GIS, na primere mestorozhdeniy RB i NAO (Division of carbonate reservoirs by the production potential in conditions of a limited well log complex, on the example of the deposits of the Republic of Bashkortostan and the Yamalo-Nenets Autonomous District), Proceedings of petrophysical scientific workshop “Sovremennye podkhody k interpretatsii GIS, issledovaniy kerna i petrofizicheskogo modelirovaniya” (Modern approaches to the interpretation of well log data, core research and petrophysical modeling), Tyumen', 2017, p. 10.
5. Chervyakova A.N., Zubik A.O., Dushin A.S. et al., Methodological approaches, experience and prospects of Tournaisian stage oil deposits development by horizontal wells at Znamenskoye oil field (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, no. 10, pp. 33–35.
