  Citation: Peshkov, G.A.; Chekhonin, E.M.; Pissarenko, D.V. Estimation of the Impact of Basement Heterogeneity on Thermal History Reconstruction: The Western Siberian Basin. Minerals 2022, 12, 97. https:// doi.org/10.3390/min12010097 Academic Editor: Thomas Gentzis Received: 11 November 2021 Accepted: 11 January 2022 Published: 14 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). minerals Article Estimation of the Impact of Basement Heterogeneity on Thermal History Reconstruction: The Western Siberian Basin Georgy Alexandrovich Peshkov 1, * , Evgeny Mikhailovich Chekhonin 1 and Dimitri Vladilenovich Pissarenko 1,2 1 Center for Hydrocarbon Recovery, Skolkovo Institute of Science and Technology, 30/1 Bolshoy Boulevard, 121205 Moscow, Russia; E.Chekhonin@skoltech.ru (E.M.C.); dimitri.pissarenko@totalenergies.com (D.V.P.) 2 TotalEnergies Research and Development, Lesnaya, 125196 Moscow, Russia * Correspondence: Georgy.Peshkov@skoltech.ru Abstract: Some of the simplifying assumptions frequently used in basin modelling may adversely impact the quality of the constructed models. One such common assumption consists of using a laterally homogeneous crustal basement, despite the fact that lateral variations in its properties may significantly affect the thermal evolution of the model. We propose a new method for the express evaluation of the impact of the basement’s heterogeneity on thermal history reconstruction and on the assessment of maturity of the source rock. The proposed method is based on reduced-rank inversion, aimed at a simultaneous reconstruction of the petrophysical properties of the heterogeneous basement and of its geometry. The method uses structural information taken from geological maps of the basement and gravity anomaly data. We applied our method to a data collection from Western Siberia and carried out a two-dimensional reconstruction of the evolution of the basin and of the lithosphere. We performed a sensitivity analysis of the reconstructed basin model to assess the effect of uncertainties in the basement’s density and its thermal conductivity for the model’s predictions. The proposed method can be used as an express evaluation tool to assess the necessity and relevance of laterally heterogeneous parametrisations prior to a costly three-dimensional full-rank basin modelling. The method is generally applicable to extensional basins except for salt tectonic provinces. Keywords: basin modelling; thermal history reconstruction; heterogeneous basement; source rock maturity; gravity anomaly; Western Siberian Basin 1. Introduction Temperature is one of the essential parameters for determining the rate and rank of organic matter maturation [1,2]. The reliability of temporal temperature estimations is determined, primarily, by the reliability of the thermal properties used [3], the boundary conditions and the thermal modelling approach [4–6]. A reliable thermal model of a basin should consider geological processes of equal importance in both the lithosphere and the sedimentary cover and their effects on each other [1,7]. Basin modellers use a number of simplifying assumptions when reconstructing sedi- mentary basin evolution through numerical simulation. One common assumption in most basin models is a laterally homogeneous basement. This assumption is usually connected with a scarcity of data or with its poor quality near the bottom of the basin and/or of the crustal basement. This occurs because the resolution of surveys deteriorates with depth due to the natural limitations of geophysical observations, as well as due to economic con- straints on costly high-resolution surveys. In some cases this may lead to the introduction of “acoustic” [8] or “economic” [9] basements in the model. Thus, due to a lack of data, basin modellers oftentimes introduce a laterally homogeneous crystalline basement instead of a poorly explored bottom part of the sedimentary lithospheric strata. Such an assumption is actually equivalent to populating the model with incorrect thermophysical properties of Minerals 2022, 12, 97. https://doi.org/10.3390/min12010097 https://www.mdpi.com/journal/minerals