Oil shale in large basins undergoes multiple evolutionary stages, limiting the applicability of a single logging-based prediction model. This study focuses on the oil shale of the Qingshankou Formation in the Songliao Basin, using gamma ray (GR), deep resistivity (LLD), acoustic travel time (DT), neutron porosity (CNL), density (DEN), and depth data as input features. The XGBoost algorithm is employed to develop predictive models for total organic carbon (TOC) content, free hydrocarbon (S1), pyrolyzable hydrocarbon (S2), and maximum pyrolysis peak temperature (Tmax). TOC predictions are further stratified for low-maturity, mature, and high-maturity oil shale intervals. The results show that S2 achieves the highest prediction accuracy (R2 = 0.91), due to its strong correlation with hydrogen index (HI) driven by thermal evolution. TOC prediction accuracy (R2= 0.75) is influenced by combined changes in porosity and organic matter evolution. Tmax prediction (R2 = 0.74) depends mainly on depth and CNL. S1 correlates weakly with all well logs, yielding the lowest accuracy (R2= 0.29). Shale maturity plays a critical role in determining the reliability of TOC prediction models. Low-maturity oil shale exhibits the best TOC accuracy (R2= 0.83), as wellpreserved organic matter and high porosity correlate closely with LLD, DT, CNL, and DEN. In mature oil shale, retained hydrocarbon and reduced porosity weaken logging signals, lowering accuracy to R2 = 0.63. In high-maturity intervals, hydrocarbon expulsion and porosity rebound improve accuracy (R2 = 0.69). Our approach provides a cost-effective, continuous method for evaluating lacustrine oil shale resources. It is particularly applicable to the evaluation of uncored wells.

Oil shale is a type of unconventional energy with abundant reserves. In the in situ mining technology of oil shale, electric heating technology has become a research hotspot due to its multiple advantages, and electric heater is the core of this technology. Despite growing interest in electric heating for in situ oil shale extraction, there remains a lack of comprehensive reviews that focus specifically on the electric heater – its types, performance characteristics, and design optimization strategies. In this paper, the oil shale electric heater is taken as the research object. First, the four mainstream oil shale electric heating technologies – Shell’s in situ conversion process, ExxonMobil’s ElectrofracTM, geothermal fuel cell, and high-voltage power frequency electric heating technology – are analyzed, and their principles, characteristics, and limitations are elaborated in detail. Subsequently, the research status of electric heaters is discussed in depth, covering various types of heaters and their performance, and existing problems are identified. The key role of numerical simulation technology in the optimal design of electric heaters is emphasized. In the future, structural innovation and numerical simulation technology should be leveraged to further optimize the performance of oil shale electric heaters, continuously improving their heat efficiency, thereby promoting their extensive application in industrial fields.

This study investigates the mechanical properties of organic-rich shale from the Lianggaoshan Formation using uniaxial and triaxial tests, nanoindentation, and atomic force microscopy. Key parameters such as elastic modulus and hardness are analyzed with NanoScope Analysis software. The results indicate that flat-laminated shale outperforms corrugated-laminated shale in terms of fracturing potential. As laminae increase, rock strength decreases, enhancing fracability, while thicker laminae hinder fracturing. The elastic modulus trend is clay minerals > calcite > quartz > pyrite, with Young’s modulus negatively correlated with mineral deformation.

In situ conversion technology for oil shale is an innovative method of energy extraction that involves the underground heating of oil shale reservoirs to thermally crack kerogen into oil and gas. This approach avoids the environmental damage and high energy consumption associated with traditional mining methods and offers advantages such as reduced environmental impact, small ecological footprint, and low development costs. In this paper, a variety of in situ conversion technologies, including in situ conversion process (ICP), Electrofrac, geothermic fuels cells process (GFC), and supercritical water heating, are discussed in detail. The paper also analyzes the current state and development trends of in situ conversion technologies in China, and highlights the importance of advancing basic theoretical research and overcoming key technologies to enable large-scale utilization of oil shale resources. Continued research and improvement in in situ conversion technologies will enhance both the efficiency and sustainability of the energy industry.

This study analyzed 25 Chang 7 shale samples from the Ordos Basin, examining geochemical properties, mineral composition, nitrogen adsorption, mercury injection capillary pressure, and NMR T2 and T1–T2 spectra. The results indicate that the shale primarily contains type II1 and II2 kerogen, with mature thermal maturity. Organic-rich shales are enriched in clay and felsic minerals, while organic-lean shales show more dispersed mineral compositions. Nitrogen adsorption classified the shale into four types, with type H2 showing the best properties. The study developed pore size conversion models and clarified the occurrence characteristics of hydrogen nucleus components, providing valuable insights for NMR evaluation of shale reservoirs globally.