Environmental fate of phthalate acid esters in shale gas exploitation areas: Adsorption, degradation, and vadose zone transport dynamics.

Research on the coupled model of fracturing flowback pollution in fractured systems and wellbore of shale gas development under elastic external boundary conditions.

Decoding paleoredox environments and shale gas accumulation in the Niutitang Formation (South China): A pyrite morphology, Fe speciation, and Fe–S isotopes perspective

Selective lithium recovery from simulated shale gas produced water using an ionic liquid extraction system

Unsupervised learning-driven insights into shale gas Reservoirs: Production prediction and strategic applications

Protic ionic liquids as lubricants for water-based drilling fluids in deep shale gas development

Role of multivalent iron in enhancing sodium percarbonate oxidation for alleviating membrane distillation fouling caused by shale gas produced water.

Efficient benzaldehyde degradation by Barnettozyma hawaiiensis and its application in shale gas fracturing flowback fluid treatment: Identification, performance, and mechanisms

Experimental and numerical simulation of dynamic fractionation for methane carbon isotope during shale gas depletion development

Simultaneous recovery of fresh water and ammonia from produced water by membrane contactor coupled with membrane distillation.

Architecting asymmetrical Janus membrane for robust membrane distillation desalination with enhanced anti-fouling performance.

Permeability anisotropy and non-Darcy effect of gas shale: A case study of S1l11-1 sublayer of Longmaxi Formation in Sichuan Basin, China

Shale pores and throats are key factors controlling the enrichment and development efficiency of shale oil and gas. However, the characteristics and formation mechanisms of shale pores and throats remain unclear. Taking the Permian continental shales in the Mahu Sag of the Junggar Basin as an example, this paper studies the formation mechanisms of pores and throats in shales of different lithofacies through a series of experiments, such as high-pressure mercury injection and scanning electron microscopy. The results show that the Permian continental shales in the Junggar Basin are mainly composed of five lithofacies: rich siliceous shale (RSS), calcareous–siliceous shale (CSS), argillaceous–siliceous shale (ASS), siliceous–calcareous shale (SCS), and mixed-composition shale (MCS). The pores in shale are dominated by intergranular and intragranular pores. The intergranular pores are mainly primary pores and secondary dissolution pores. The primary pores are mainly slit-like and polygonal, with diameters between 40 and 1000 nm. The secondary dissolution pores formed by dissolution are irregular with serrated edges, and their diameters range from 0.1 to 10 μm. The throats are mainly pore-constriction throats and knot-like throats, with few vessel-like throats, overall exhibiting characteristics of nanometer-scale width. The mineral composition has a significant influence on the development of pores and throats. Siliceous minerals promote the development of macropores, and carbonate minerals promote the development of mesopores. Clay minerals inhibit pore development. Diagenesis regulates the development of pores and throats through mechanical compaction, cementation, and dissolution. Compaction leads to a reduction in porosity, and cementation has varying effects on the preservation of pores and throats. Dissolution is the main factor for increased pores and throats. These findings provide a lithofacies-based geological framework for evaluating effective porosity, seepage capacity, and shale oil development potential in continental shale reservoirs.

With the continuous advancement of shale gas field development, well productivity following initial hydraulic fracturing often declines due to mechanisms such as proppant embedment and fracture conductivity degradation. However, such wells may still retain significant development potential, making re-fracturing crucial for restoring production and highlighting the critical importance of accurate candidate selection for re-fracturing. To improve the precision of candidate well selection for re-fracturing in shale gas wells, this study focuses on a shale gas block in the Southern Chuan Basin. Through comparative analysis of existing selection methods, 14 key parameters were finalized. The threshold values for some of these key parameters were recalibrated based on the specific geological, engineering, and production characteristics of the target block in the Southern Chuan Basin. Furthermore, the AHP-GRA (Analytic Hierarchy Process-Gray Relational Analysis) weighting method was integrated to achieve a balance between empirical knowledge and quantitative objectivity. Ultimately, a more targeted, comprehensive, and combined subjective–objective methodology for selecting re-fracturing candidate wells was developed. A computational tool developed in Python 3.9 was utilized to evaluate 13 candidate wells in the block, successfully identifying three high-priority wells for re-fracturing implementation. The reliability of this selection result was validated by analyzing production data before and after re-fracturing, confirming that the production performance of the selected wells showed relatively significant improvement post re-fracturing, with a notable increase in recovery factor. This model provides critical decision-making support for the low-cost and large-scale development of shale gas. It holds significant theoretical and practical value for promoting the secondary development of mature shale gas wells and contributes positively to the efficient utilization of unconventional natural gas resources and energy security.

Numerical Simulation of Multicluster Fracture Propagation in Shale Gas Reservoirs under the Coupled Influence of Geological and Engineering Parameters

ABSTRACT The article examines the development of three successive policy proposals for shale gas exploration in France, highlighting the transactional trajectories of each. Using a policy transactional perspective, it demonstrates how policy solutions are shaped by both definition and appropriation. Policy proposals emerge through the redefinition of the problem they address, with this process also assigning roles and identities to various actors, casting them as victims, culprits, or heroes within a causal narrative. This definitional work is further influenced by the appropriation (or lack thereof) of key allies. As such, each proposal reflects a sense of ownership. The rules of appropriation differ depending on the primary debate space in which the proposal is developed. This variation accounts for why some policymakers can adapt their positions, while others cannot.

To clarify the organic matter enrichment regularity of Permian shales in the Kaijiang–Liangping Trough, as well as the differential characteristics of their reservoir lithology, mineral assemblage, and nanopore structure—and thereby provide a geological basis for the exploration and development of Permian marine shales in the eastern Sichuan Basin—core samples from different depths of the Wujiaping Formation and Dalong Formation in Well DY-1H were analyzed using a series of micro–nano technical research methods, including whole-rock X-ray diffraction, major/trace element analysis, conventional porosity-permeability measurement, high-pressure mercury intrusion porosimetry, nitrogen adsorption, and field emission scanning electron microscopy. Research finds that the Dalong Formation shale contains Type I organic matter with high abundance, whereas the Wujiaping Formation shale is dominated by Type II2 organic matter. The Wujiaping Formation experienced stronger terrigenous input and higher weathering intensity, while the Dalong Formation was deposited under persistently anoxic conditions, in contrast to the frequent oxic–anoxic alternations in the Wujiaping Formation. Paleoproductivity indicators suggest higher productivity in the Dalong Formation than in the Wujiaping Formation. Mo/TOC ratios below 4.5 indicate deposition in a strongly restricted water body. Enrichment factors of multiple elements further support the enhanced paleoproductivity of the Dalong Formation. The Dalong Formation shale has higher contents of quartz and carbonate minerals, while the Wujiaping Formation shale has a higher content of clay minerals. The Wujiaping Formation shale is more developed with inorganic micropores, whereas the Dalong Formation shale is characterized by more developed organic nanopores. During the sedimentary period of the Dalong Formation shale, the paleoproductivity was high, the sedimentary waterbody had high reducibility and restriction, and the reservoir was well-developed with nanopores. The Dalong Formation is a more favorable interval for Permian shale gas exploration and development in the Kaijiang–Liangping Trough.

Ethylene, one of the major basic chemicals in the modern chemical industry, has been industrially produced mainly through intensive energy-consuming steam cracking processes from light oil fractions or shale gas operated above 800 °C following the radical mechanism and seriously suffering from high methane selectivity. Herein, we report an efficient catalytic cracking reaction of 1-pentene over a tailored ZSM-5 catalyst at 700 °C with a C2H4/C3H6 ratio of 1.31 and a CH4 selectivity below 5%, which provides an energy-saving and economically viable route for ethylene production from light oil fractions, seamlessly integrating with the existing industrial catalytic cracking processes. Mechanistic studies unveil an interesting type of zeolite catalysis different from the typical acid catalysis following the carbenium ion mechanism, termed as the confined catalytic radical (CCR) mechanism in which 1-pentene dehydrogenates to gaseous pentenyl radicals (C5H9•) at non-acidic [AlO4]0 sites of ZSM-5 in situ formed by dehydrogenation of bridging hydroxyls, whose subsequent reactions confined in ZSM-5 produce more C2H4 than C3H6. These findings significantly broaden the concept and application of zeolite catalysis.

Shale reservoirs contain abundant organic matter, pyrite, and clay minerals, making them highly susceptible to fluid-sensitivity damage; consequently, conventional hydraulic fracturing often yields poor stimulation performance, with low fracturing fluid flowback and rapid post-treatment production decline. Oxidative dissolution, however, can significantly alter the physical properties of shale reservoirs and improve stimulation effectiveness. In this study, nuclear magnetic resonance (NMR), contact-angle measurements, and triaxial compression tests are combined to systematically evaluate the effects of oxidative dissolution on the pore structure, wettability, and mechanical properties of Wufeng Formation shale from the Sichuan Basin. Core-flooding experiments with NaClO solutions show that, as the oxidant dosage (pore volume) increases, shale permeability rises by 66.67–266.67% and porosity by 1.79–9.58%, while the hydrophilic surface fraction increases from 5.45% to 61.73%. These changes are accompanied by a steady reduction in rock strength: the compressive strength decreases by up to 57.8%, and the elastic modulus exhibits a non-monotonic response to oxidation. Oxidative dissolution preferentially enlarges micropores, improves pore connectivity, and strengthens water wetness by consuming oil-wet organic matter and pyrite, which also enhances gel-breaking efficiency. Based on the experimental results, a series of characterization models are developed for oxidized shale reservoirs, including quantitative relationships linking porosity to compressive strength, elastic modulus, and contact angle, as well as a model relating oxidant dosage to microscopic pore structure evolution and imbibition enhancement. Overall, the coupled modifications of pore structure, wettability, and mechanical behavior produced by oxidative dissolution synergistically broaden the effective action range of fracturing fluids, promote shale gas desorption, and improve hydrocarbon seepage, providing a theoretical basis and practical guidance for oxidation-assisted stimulation in shale reservoirs.

Environmental radiological monitoring and risk assessment in shale gas areas.