The Artinskian productive horizon (P1ar) of the Timan-Pechora oil and gas province is represented by terrigenous-siliceous-carbonate rocks with a complex pore space (fractured, porous and complex reservoir type) and anisotropy of reservoir properties. In P1ar, carbonate-silicite, spongolithic, siltstone-argillaceous lithological-stratigraphic units are distinguished. The main oil and gas production is associated with fractured zones. As a result, the problems of identifying fractured zones and linking them to the stratigraphic intervals of the section become topical. To solve the tasks set, a comprehensive analysis of the core material, reservoir microimager data, standard and special complex of geophysical well surveys were carried out. According to this analysis data the fracture zones are confined to the upper carbonate-silicite part of the Artinskian. The diagnostic signs of rock fracturing are: 1) revealed cracks in the reservoir microimager and core material; 2) high values of Young's modulus and low values of Poisson's ratio; 3) loss of energy of the acoustic signal under the condition of minimum clay content; 4) excess of the interval time of the registered Stoneley wave over the interval time of the model Stoneley wave; 5) anisotropy of acoustic properties due to the splitting of the transverse wave into fast and slow waves when fractures appear.
In a terrigenous-siliceous-carbonate section with a complex type of pore space, such as Artinskian horizon, along with standard open hole logging methods, it is necessary to carry out special research methods. Special methods allow to get a comprehensive understanding of the type of reservoir, its physical properties, more accurately predict fracture intervals, and make decisions on horizontal wells drilling. Directly in the process of horizontal wells drilling, it becomes necessary to identify promising stratigraphic intervals using a limited set of well logging – gamma ray logging (GR) and induction logging (IR). The fractured carbonate-silicite member is marked by low values of GR due to the minimum clay content and high values of electrical resistivity, which are characteristic of siliceous-carbonate rocks. The spongolithic member is characterized by average levels of resistivity and GR. A strategy for designing and drilling horizontal wells for drainage of reservoirs in the upper and middle parts of the P1ar horizon is proposed.
References
1. Gayduk V.V. et al., Model' produktivnosti artinskogo gorizonta (Artinian horizon productivity model), Krasnodar: Publ. of “Rosneft' – NTTs”, 2019, 20 p.
2. Rogozin A.A. et al., Kompleksnoe issledovanie kernovogo materiala (Comprehensive study of core material), Krasnodar: Publ. of “Rosneft' – NTTs”, 2018, 238 p.
3. Alford J., Sonic logging while drilling—Shear answers, Oilfield Review, 2012, Spring, pp. 4-15.
4. Dobrynin S.V., Stenin A.V., Permeability and dynamic porosity estimation by wide-band sonic log (AKSH) (In Russ.), Karotazhnik, 2008, no. 4, pp. 45–49.
5. Gontarenko I.A. et al., Analiz effektivnosti sushchestvuyushchikh metodik dlya vydeleniya pronitsaemykh intervalov po shirokopolosnomu akusticheskomu karotazhu (Analysis of the efficiency of existing techniques for identification of permeable intervals from broadband acoustic logging), Krasnodar: Publ. of “Rosneft' – NTTs”, 2020, 73 p.
6. Filimonov A. et al., Obzor rezul'tatov vypolnennogo kompleksa GIS-GDK-OPK (Overview of the results of the completed wireline formation testers and wireline hydrodynamical well logging tools complex), Shlumberger, 2020, 34 p.
