## 2 Oil Shale Properties
### Porosity/Permeability and Saturation Evolution  
Permeability of oil shale changes as it undergoes heating and compression [14; 15]. The permeability-time curves for columns of confined fragments prepared from different grades of Green River oil shales show that as compressive strain increases with time, the columns' pore geometry, porosity, and permeability undergo concurrent changes. [PERSON] (2017)continues studying the permeability and porosity evolution of Green River oil shale during retorting [16]. The permeability is calculated from porosity using a modified Kozeny-Carman relation, and it increases as the fraction of oil shale retorted increases. The porosity decreases as the grade of oil shale increases and as kerogen conversion occurs during in situ retorting. Compaction during diagenesis can also affect porosity [14]. Using numerical simulations, [PERSON] (2014) described porosity permeability and saturation distributions during the ICP process [17]. Porosity, permeability, and saturation undergo significant changes driven by converting solid kerogen (and any reactive minerals) into fluids. Results show that the ICP process increases the porosity and permeability above their original values by opening up pore space through kerogen conversion. This effect is somewhat counteracted by competing factors such as compaction and coking. The degree of compaction is influenced by stress history, including zero lateral strain and a vertical load that increases with pattern depth and decreases overburden stiffness. Lack of vapor space can retard compaction. The triggers for compaction during ICP are kerogen softening, grain loss through pyrolytic conversion, and fluid pressure decrease. The evolution of porosity results in the development of permeable regions within ICP well patterns. As the high temperatures from the ICP process propagate away from the heaters, a kerogen-depletion front leads the product-generation front, resulting in the development of permeable pathways that connect the producer well to the pyrolyzing regions. This permeable network is established relatively early in the ICP, suggesting that pre-ICP measures to enhance oil-shale permeability may not be necessary. During ICP, there is a window of increased oil saturation, which results in a period of enhanced heavy-oil flow towards producer wells, leading to a period of greater heavy fractions in the produced oil. Conditions that may enhance this in situ peak of oil saturation include lesser initial porosity, lesser initial gas saturation, lesser initial water saturation, greater hydrocarbon richness (both kerogen and native bitumen), lesser reactive mineral content, and greater magnitude of compaction [17]. The changes in porosity, permeability, and saturation observed during the ICP process have significant implications for the efficiency and output of oil production from oil shale reservoirs. [PERSON] and [PERSON] (2021) experiment measuring The permeability of Fushun oil shale, which exhibits distinct patterns as temperature increases [18]. Below 200 \({}^{\circ}\)C, the oil shale is nearly impermeable. From 200 \({}^{\circ}\)C to 350 \({}^{\circ}\)C, the permeability gradually increases but then sharply decreases at 350 \({}^{\circ}\)C. Between 350 \({}^{\circ}\)C and 400 \({}^{\circ}\)C, the permeability shows mixed behavior among the samples. From 400 \({}^{\circ}\)C to 500 \({}^{\circ}\)C, the permeability varies with different trends for each sample. Finally, from 500 \({}^{\circ}\)C to 600 \({}^{\circ}\)C, the permeability of all samples increases, reaching a maximum at 600 \({}^{\circ}\)C. Results indicate that permeability variations are influenced by factors such as thermal cracking, organic matter pyrolysis, and the development of fractures and pores within the oil shale [18]. In addition to the general permeability and porosity, [PERSON] et al. (2016) provided pore size distributions in oil shale under different conditions. With increasing temperature, the distribution of pore sizes in oil shale undergoes changes.