Processes

Intra-platform shoal reservoirs of the Middle Permian Qixia Formation are important targets for deep natural gas exploration in the Sichuan Basin. Core and thin-section observations, well-log interpretation results, and isotope data are integrated to compare reservoir-rock assemblages, pore types, petrophysical properties, and diagenetic features in central and southern Sichuan. Central Sichuan samples are dominated by fabric-retentive and crystalline dolostones containing intercrystalline pores and intercrystalline dissolution pores, with localized vugs and fractures. Southern Sichuan subsurface samples comprise a mixed limestone–dolostone assemblage with pores along grain or crystal boundaries and fractures; moldic pores are observed in regional outcrop samples. Among the interpreted intervals included in the statistics, intervals with porosity ≥5% account for 16.7% in central Sichuan (n = 430) and 7.6% in southern Sichuan (n = 422). Some medium- to coarse-crystalline dolostone groups have higher Sr isotope ratios than the limestone and finely crystalline dolostone groups, consistent with isotopic alteration. Mean δ¹⁸O values are more negative in southern Sichuan regional outcrop samples than in central Sichuan well samples; these differences require interpretation alongside mineral composition and sample setting. Reservoir differences between the two areas are expressed by contrasting precursor lithologies, dolomite replacement textures, and degrees of pore modification, with dissolution and localized filling further modifying pore geometry and preservation.

Nickel contamination in aquatic systems is an important environmental concern, creating a need for efficient and easily recoverable materials for Ni(II) removal from water. This study investigated a commercial macroporous cation-exchange resin (Purolite^® S-930E, IX-P) and its magnetically modified derivative (IX-P-MNp), focusing on the effects of in situ magnetic modification on adsorption performance and process optimization. IX-P-MNp was synthesized by in situ co-precipitation of magnetite within the porous resin structure and characterized using complementary analytical techniques. Batch experiments were conducted to evaluate adsorption kinetics and equilibrium behavior, while the effects of pH, contact time, resin dosage, initial Ni(II), Ca²⁺, and Mg²⁺ concentrations were assessed using a Definitive Screening Design. Magnetic modification reduced the equilibrium time from 6 to 4 h and increased the maximum adsorption capacity by approximately 95%, from 4.44 to 8.65 mg/g according to the Sips model, with comparable values obtained using the Langmuir model (4.49 and 8.87 mg/g, respectively). Contact time was the most influential factor for both materials, while resin dosage and initial Ni(II) concentration also significantly affected Ni(II) removal. For IX-P-MNp, Mg²⁺ concentration and the interaction between pH and initial Ni(II) concentration were additionally significant. Experimental validation showed good agreement between predicted and experimental values for IX-P, whereas greater deviation was observed for IX-P-MNp. Overall, in situ magnetic modification enhanced the adsorption performance of IX-P and provided the additional advantage of magnetic separation, demonstrating the potential of IX-P-MNp for Ni(II) removal from water.

To address the liquid-loading problem at the bottom of deep gas-reservoir wells, a gas-driven jet pump for downhole deliquification was designed, and its key geometric parameters were optimized. Using high-pressure natural gas as the motive fluid, the device achieves stable liquid lifting and continuous drainage through efficient gas–liquid mixing. In this study, the internal flow characteristics of the gas jet pump were numerically investigated using CFD simulations within a steady VOF-RSM multiphase turbulence framework. Published experimental data for a prototype from the open literature were used to validate the numerical model, and the maximum relative deviation between simulation and measurement was 17.5%, satisfying the accuracy requirements for engineering CFD analysis. The effects of three key structural parameters—area ratio, nozzle-to-throat distance, and throat length-to-diameter ratio—on the liquid production rate and pumping efficiency were systematically examined through single-factor sensitivity analysis combined with an orthogonal experimental design. Range analysis showed the following order of influence: area ratio > throat length-to-diameter ratio > nozzle-to-throat distance. The optimal parameter combination was determined as an area ratio of 0.0494, a throat length-to-diameter ratio of 5, and a nozzle-to-throat distance of 7.2 mm. Under this optimized configuration, the maximum liquid production rate reaches 80 m³/d. To achieve a target liquid production rate of 20 m³/d, the required gas injection rate is reduced by 33%, and a peak pumping efficiency of 7.2% is achieved at gas injection rates between 2000 and 3000 m³/d.