High-porosity sandstones are highly susceptible to the development of deformation bands under tectonic stress. However, limited studies have been conducted on factors controlling the structures and physical properties of these bands. By combining a systematic literature review and experimental analysis, we investigate the macro- and micro-structural characteristics and deformation mechanisms of these bands in high-porosity sandstones. Furthermore, we analyze the primary and secondary factors governing the structural and physical property evolution of these deformation bands, as well as the mechanisms by which these factors operate. The results indicate that effective normal stress and shear displacement serve as the primary factors controlling the structural and permeability evolution of the deformation bands. Specifically, the effective normal stress significantly reduces the permeability by intensifying grain breakage and modifying the boundary morphologies of shear zones. In contrast, shear displacement predominantly governs the thickening and structural stratification of the deformation bands. Notably, such controlling effect exhibits a pronounced nonlinear evolutionary trend, with a critical displacement threshold observed. The secondary controlling factors include the mineral composition, initial porosity, grain size, sorting degree, clay content, and strain rate of surrounding rocks. Under certain geological conditions, these factors modulate the structural morphology and physical property parameters of the deformation bands. The evolution of the deformation bands consists of five stages: non-deformation, initial deformation, initial stratification, stratification transition, and stable formation. Each stage exhibits regular variations in the microstructural parameters of the deformation bands, including band thickness, grain-size distribution, grain roundness, and grain orientation. With increasing stress level and displacement, the deformation bands experience significantly intensified grain breakage and pronounced enrichment of fine-grained matrix. This leads to porosity reduction of up to a maximum of 70% and permeability decreases of two to three orders of magnitude. The evolutionary patterns of the structures and physical properties of the deformation bands derived from laboratory tests are highly consistent with data from field outcrops. Future research on the of deformation bands should focus on computed tomography (CT)-based three-dimensional structural modeling, thermal-hydrological-mechanical-chemical (THMC) multi-field coupling simulations, and machine learning-based modeling for predicting structures and permeability.

Deformation band research has long been hindered by limited understanding of structural characteristics and physical properties during actual deformation processes. To address these knowledge gaps, this study systematically reviews experimental simulation methodologies through integrated approaches. Combining field observations with our newly developed ring shear tests for consolidated rocks, we investigate: formation mechanisms of deformation bands; key controlling factors including effective normal stress, shear displacement, clay content, mineral composition, porosity, particle size distribution, sorting, and cementation; comparative evaluation of experimental techniques (ring shear vs. direct shear vs. triaxial shear vs. sandbox modeling). Our analysis reveals two critical experimental parameters: effective normal stress and shear displacement. Notably, the advancement of consolidated rock-specific ring shear apparatus enables centimeter-scale displacement simulations, significantly enhancing deformation band experimentation. Current challenges in field measurement, image analysis, and 3D modeling are discussed with proposed solutions. Future directions emphasize: in-situ permeability testing, quantitative analysis frameworks, cementation dynamics, and numerical simulation optimization. This work aims to highlight deformation bands' crucial role in fluid migration and reservoir preservation while providing methodological guidance for designing simulation experiments. The compiled experimental protocols and analytical techniques offer researchers a systematic reference for deformation band investigations.

Helium (He) is considered an indispensable rare resource due to its critical applications in high-tech fields such as low-temperature superconductivity, magnetic resonance imaging, and aerospace. However, the sources of helium and its accumulation processes in hydrocarbon basins remain unclear. The Hetianhe gas field, as China's first supergiant He-rich gas field, provides a natural laboratory for studying the mechanisms of helium enrichment. By analyzing the primary gas components and noble gas data from natural gas wells in the Hetianhe gas field, and comparing these with geological data from known He-rich gas fields worldwide, a detailed anatomy of the Hetianhe helium-rich gas field is conducted from three aspects: generation, migration, and accumulation. The Hetianhe gas field is not only uniformly rich in helium but also shows promising exploration potential. Helium tends to accumulate in structural highs within the field. Quantifying the helium isotope ratios (R/Ra) reveals that the helium in the Hetianhe gas field is of typical crustal origin. From a "source-reservoir dual control" perspective, it is calculated that 62% of the helium is sourced from the basement helium source rocks, while 38% comes from sedimentary helium source rocks. The study indicates that the Paleoproterozoic granite basement provides a sufficient helium source, with the fault systems serving as effective migration pathways for helium. The concentration of ⁴He and ²⁰Ne in natural gas is positively correlated, which reflects the close relationship between He migration and groundwater. In addition, N₂ and He in natural gas in the Tarim Basin show a good positive correlation, which further indicates that ⁴He dissolves into the groundwater system before degassing into a gas reservoir and that the variations in the ⁴He concentration in the gas phase are caused by the difference of natural gas lateral migration and charging intensity. Notably, a comparison with the reservoir characteristics of globally recognized He-rich fields reveals that "shallow depth, low pressure, and high structural uplift" are key geological factors for helium accumulation.

Fault zones play a key role in controlling subsurface fluid migration, influencing hydrocarbon accumulation, CO₂ sequestration, and geo-energy storage safety. Most previous experimental studies, however, have been restricted to static outcrop or core observations, which fail to capture the progressive evolution of fault zone structures in time as a response to changing stresses. Moreover, existing analogue experiments often use unconsolidated sediments, which cannot accurately represent brittle faulting in consolidated rocks, and quantitative analyses remain limited. To address these challenges, a new method based on ring-shear experiments was developed to physically simulate fault zone formation in consolidated sandstones. The method simulates shear deformation under variable stress and displacement conditions, followed by multi-scale quantitative analyses, including computed tomography imaging, thin section analysis, and porosity-permeability testing under confining pressure. This comprehensive testing routine allows to quantify changes in fault zone thickness, particle and pore size distributions, and grain orientations during progressive deformation and depending on shear parameters. The results demonstrate systematic relationships between effective normal stress, shear displacement, and fault zone structural attributes. The fault zone thickness shows a nonlinear trend with stress, while cataclasis and compaction intensify with increasing displacement. This work provides a methodological foundation for future applications in fault seal analysis, fluid flow modeling, and numerical simulation, offering a practical reference for petroleum systems studies, hydrogeology, and underground gas storage including CO₂ and hydrogen.

The Archean buried-hill metamorphic reservoirs in the Bohai Bay Basin are examples of metamorphic rocks having faults with diverse strikes as a consequence of multi-phase tectonic evolution. For faults in metamorphic rocks, no method that accounts for the properties of metamorphic rocks exists for evaluating fault sealing capacity. To elucidate the mechanisms controlling sealing capacity, our study pioneers a novel methodology termed the Mylonite Gouge Ratio (MGR) method. This method integrates neutron density log responses, petrophysical characteristics, and corresponding depth-specific rock thin-section analyses to assess lateral fault sealing capacity. Application of this set of rules and procedures to metamorphic faults in the basin's Archean strata reveals two critical findings: spatially, the Block X exhibits elevated MGR values indicative of superior sealing efficiency; temporally, Yanshanian NE-trending faults demonstrate enhanced sealing capacity compared to Himalayan EW-trending counterparts, with pre-Yanshanian and syn-Yanshanian tectonic activities facilitating paleo-fluid migration while current sealing conditions favor hydrocarbon preservation. The new method provides a tailored framework for evaluating fault sealing in metamorphic rocks, where conventional methods designed for sedimentary sequences are often inapplicable. This study establishes a new theoretical model for fault-sealing analysis in complex metamorphic reservoirs, with implications for deep hydrocarbon exploration and development.