## 5 Conclusions  
Rock samples from the Bazhenov Formation were subject to the combustion tube experiment and analyzed by the suite of both conventional laboratory (pressure-decay porosimetry and permeametry) and novel non-destructive techniques such as NMR relaxometry. To supplement the NMR results, we utilized 2D pyrolysis to study the distribution of OM after combustion and SEM to characterize the changes in the rock porous structure. In summary, the following points can be highlighted:  
1. The gas pressure-decay technique revealed a significant increase of porosity (on average, for 9 abs. % of porosity) and permeability (on average, for 1 mD) of core samples after the CT experiment. Samples located in high-temperature zones showed a direct correlation between the measured parameter and the combustion temperature. However, the changes were also conditioned by the initial properties of the core plugs, such as rock lithology and OM properties. 2. The NMR T\({}_{1}\)-T\({}_{2}\) fluid identification scheme was proposed by the results of preliminary research conducted on five core samples with a similar lithological type and reservoir properties. We applied the proposed scheme in the analysis of the T\({}_{1}\)-T\({}_{2}\) maps obtained for samples before and after combustion. Interpretation of the maps allowed us to categorize the total fluid saturation into several fluid types (bitumen and adsorbed oil, structural and adsorbed water, and mobile oil in inorganic porosity) and estimate the changes induced by thermal exposure. 3. Rock-Eval pyrolysis was performed in 1D and 2D testing modes, which elicited detailed knowledge on combustion front propagation inside the core plugs from different combustion tube zones. 2D pyrolysis technique demonstrated the relatively uniform distribution of OM inside the core plugs after CT. In addition, values of S0 and S1 indicated a certain amount of oil remaining in rock samples. We explain it as newly generated synthetic oil, which was trapped in the pores due to hindered migration in low-permeability rock. It can lead to the inaccurate interpretation of laboratory-scale combustion experiments involving crushed rock samples since a significant amount of generated oil remains in the core material and is not accounted for in the final material balance. 4. SEM of rock samples revealed that heating of the organic-rich shales leads to at least two processes: the transformation of OM during the heating with the formation of new voids and the formation of micro and nanofractures in the mineral matrix. All these alterations increase the porosity and homogeneity of pores distribution in the rock. 5. NMR T\({}_{2}\) results included the determination of fluid saturation of the sample, as well as the pore size distribution before and after the combustion experiment. For low-permeability samples, NMR and Rock-Eval pyrolysis proved to be useful and reliable tools in determining the saturation of fragile core plugs and types of hydrocarbons in the rock, which can be applied in the assessment of the amount of displaced oil. In turn, conventional porosimetry also demonstrated satisfactory results in the estimation of open porosity and permeability of the rock. In summary, the results of this preliminary research can prove a solid base for the new protocol of laboratory thermal air injection modeling, including non-disruptive testing of consolidated core samples. Conceptualization, A.M., A.C.; methodology, A.M., P.M., E.K., A.B. ; experimental investigation, A.M., P.M., E.K. and T.K. ; project supervision, A.C.; workflow control, A.M., T.K. ; analysis, A.M., P.M., T.K. ; resources, A.C.; data curation, A.M., E.K., T.K., A.C.; writing and editing, A.M., P.M., T.K., A.C. All authors have read and agreed to the published version of the manuscript.