Within a single fluid pressure system, fluid migration occurs between different coal measure reservoirs, and the in situ accumulation of coal measure gas (CMG) represents the ultimate outcome of methane undergoing a series of dynamic migration processes. Clarifying the vertical distribution patterns of in situ fluids within coal measure strata is of critical importance for guiding the co-exploration and co-production of CMG. However, direct testing of such distribution patterns remains challenging. Geophysical logging provides an indirect characterization method by evaluating reservoir permeability and gas content. In this study, based on the physical property testing results of coal measure rock samples and their corresponding logging curves from the southeastern margin of the Ordos Basin, a progressive computational model of logging parameters, porosity, and breakthrough pressure was developed for quantitatively evaluating the sealing ability of coal measure strata. Additionally, a comprehensive predictive model for gas-bearing layer was constructed based on the P- and S-wave velocity of rock samples with varying gas-water saturation levels, the logging parameters of density and neutron from coal measure strata, and the logging results of hydrocarbon content. By combining the logging evaluation results of lithology, breakthrough pressure, and gas content, the coal measure strata in the study area were classified into three fluid pressure systems. The reliability of this classification was validated through the analysis of gas characteristic and reservoir pressure differences among the identified fluid pressure systems.

Analysis of the adsorptive behaviour of kaolinite to sodium dodecyl benzene sulphonate (SDBS) at different concentrations can provides a basis for selecting the best concentration. The adsorptive capacity and adsorptive behaviour of kaolinite to SDBS at different concentrations were studied using ultraviolet spectrophotometer, pseudo-first-order adsorption kinetics model, and pseudo-second-order adsorption kinetics model. Scanning electron microscopy with energy dispersive spectrometry (SEM–EDS), X-ray diffraction (XRD), and infrared spectroscopy (FTIR) were used to study the variation characteristics of surface structure, crystallinity indices, and main functional groups on kaolinite before, and after, adsorption. The results show that as the SDBS concentration increase, the adsorptive capacity of kaolinite to SDBS increase. The adsorption process can be accurately fitted by the pseudo-secondary adsorption kinetic model, which means the adsorptive behaviour was mainly chemical in origin. The adsorption of SDBS by kaolinite mainly occurs on the surface. The solidification, lamellar aggregation, and crystallinity index of kaolinite are more obvious after the adsorption of SDBS, but the interlayer spacing of kaolinite did not change to any significant. After the adsorption of SDBS, the intensity ratio of 1000–1008 cm⁻¹ bands changed significantly, indicating the change of the chemical environment, and the adsorptive behaviour was chemical.

The coalbed methane (CBM) resource in the southern Qinshui Basin, North China, is abundant. Proper understanding of the geological control factors on CBM enrichment in Anze Block of southern Qinshui Basin is critical to design efficient CBM development plan in this area. Field and laboratory data including well logging, well testing, hydraulic fracturing, and groundwater chemical analysis of were used to evaluate the characteristics of the hydrodynamic and geostress, and then, the combined effect of hydrodynamic and geostress field on CBM enrichment was analyzed. The results show that the total dissolved solids (TDS) of groundwater in the west is generally lower than that in other areas in the block, and the primary formation water is NaHCO₃-type. The geostress field shows a dominated geostress type in this area, and the western block has a lower value than the eastern block. The strong hydrodynamic field with low TDS also has a lower gas content while the weak hydrodynamic field with high TDS has a higher gas content. Both the TDS value and the horizontal stress differences are positively related to the gas content, indicating that inactive hydrodynamics and large horizontal stress difference of coal reservoir is favorable for CBM preservation.