Influence of Imbibition Fracturing Fluid on the Original Water and Methane Occurrence in Actual Coalbed Methane Reservoirs Using the Integrated Device of Displacement and Low-Field Nuclear Magnetic Resonance.

The original water in the coal rock pores plays a controlling role in the occurrence of gas. Furthermore, during the hydraulic fracturing process, pressurized fracturing fluid with a higher pressure than the original pore pressure in the fractures drives the fracturing fluid to infiltrate into the coal rock pores, thereby altering the occurrence pattern of gas and water in the original pores. However, due to the limitations of the indoor simulation device, a systematic conclusion on the impact of the original pore water and imbibition fracturing fluid on coalbed methane reservoirs has not yet been formed. In this paper, an integrated device combining displacement and low-field nuclear magnetic resonance was employed using underground cylindrical coal rock samples as experimental subjects. Experimental conditions were maintained at a temperature of 30 °C, a confining pressure of 23 MPa, and an approximate reservoir pressure of 15 MPa. The initial water saturation levels were altered to 0, 27.88, and 42.18% to replicate the conditions of a coalbed methane reservoir at a depth of approximately 1200 m. Fracturing fluid with a pressure of 18 MPa was injected into the experimental samples to simulate the impact of the fracturing fluid on the original reservoir during hydraulic fracturing. This allowed for a realistic assessment of the influence of initial water saturation and fracturing fluid absorption on the coalbed methane recovery rate in the reservoir. The experimental results indicate that the imbibition process promotes the desorption of adsorbed gas, and the desorption amount of adsorbed gas increases with the increase in the original water saturation. This will result in an increase in the gas pressure within the pore system. The conditions of this experiment, in comparison to the previous ones, more closely resemble real reservoir conditions. This enables a realistic assessment of how the presence of the original water content and the absorption of the fracturing fluid affect gas occurrence within the reservoir.

Effect of Water on Effective Pore Structures for Medium-Rank Coal: Based on the Prefreezing Nitrogen Adsorption-Desorption Experiment.

Water is ubiquitous in coal reservoirs, and its distribution can have a remarkable influence on the effective pore space of methane. This study conducted the combination experiments of moisture equilibrium and prefreezing nitrogen adsorption-desorption to explore the adsorption behavior of water in coal pores and thus to reveal the distribution characteristics of water in pores with different scales as well as the influence of water on pore structures. The results showed that the adsorption mechanism of water vapor undergoes a transition from monolayer to multilayer to condensation with the increase in relative humidity (RH). The occurrence characteristics of adsorbed water in coal pores are controlled by the RH and pore size. When the RH is increased from 0 to 98%, the nitrogen adsorption capacity, specific surface area, and effective pore volume of the samples were all decreased significantly due to the different adsorption modes of water, which is more significant in pores with d < 10 nm. Additionally, the relative pressure corresponding to the branching position of the nitrogen adsorption-desorption curve will be changed with the increase in moisture content. Based on this, it is calculated that the adsorbed water will change the smoothness of the pore wall and the complexity of the pore structure.

Intelligent Nanoplatform with Multi Therapeutic Modalities for Synergistic Cancer Therapy.

Chemodynamic therapy (CDT) has attracted increasing attention in tumor treatment but is limited by insufficient endogenous H2O2. Moreover, it is challenging for monotherapy to achieve a satisfactory outcome due to tumor complexity. Herein, we developed an intelligent nanoplatform that could respond to a tumor microenvironment to induce efficient CDT without complete dependence on H2O2 and concomitantly generate chemotherapy and oncosis therapy (OT). The nanoplatform was constructed by a calcium- and iron-doped mesoporous silica nanoparticle (CFMSN) loaded with dihydroartemisinin (DHA). After entering into cancer cells, the nanoplatform could directly convert the intracellular H2O2 into toxic •OH due to the Fenton-like activity of CFMSN. Meanwhile, the acidic microenvironment and endogenous chelating molecules triggered Ca2+ and Fe3+ release from the nanoplatform, causing particle collapse with accompanying DHA release for chemotherapy. Simultaneously, the released Ca2+ induced intracellular Ca2+-overloading for OT, which was further enhanced by DHA, while the released Fe3+ was reduced to reactive Fe2+ by intracellular glutathione, guaranteeing efficient Fenton reaction-mediated CDT. Moreover, Fe2+ cleaved the peroxy bonds of DHA to generate C-centered radicals to further amplify CDT. Both in vitro and in vivo results confirmed that the nanoplatform exhibited excellent anticancer efficacy via the synergistic effect of multi therapeutic modalities, which is extremely promising for high-efficient cancer therapy.

A pH-responsive dissociable mesoporous silica-based nanoplatform enabling efficient dual-drug co-delivery and rapid clearance for cancer therapy.

The balance between tumor accumulation and renal clearance has severely limited the efficacy of mesoporous silica-based drug nanocarriers in cancer therapy. Herein, a pH-responsive dissociable mesoporous silica-based nanoplatform with efficient dual-drug co-delivery, tumor accumulation and rapid clearance for cancer therapy is achieved by adjusting the wetting of the mesoporous silica surface. At pH 7.4, the synthesized spiropyran- and fluorinated silane-modified ultrasmall mesoporous silica nanoparticles (SP-FS-USMSN) self-assemble to form larger nanoclusters (denoted as SP-FS-USMSN cluster) via hydrophobic interactions, which can effectively co-deliver anticancer drugs, doxorubicin hydrochloride (Dox) and curcumin (Cur), based on the mesopores within SP-FS-USMSN and the voids among the stacked SP-FS-USMSN. At pH 4.5-5.5, the conformational conversion of spiropyran from a "closed" state to an "open" state causes the wetting of the SP-FS-USMSN surface, leading to the dissociation of the SP-FS-USMSN cluster for drug release and renal clearance. The in vitro and in vivo studies demonstrate that the Cur and Dox co-loaded SP-FS-USMSN cluster (Cur-Dox/SP-FS-USMSN cluster) possesses great combined cytotoxicity, and can accumulate into tumor tissue by its large size-favored EPR effect and potently suppress tumor growth in HepG2-xenografted mice. This research demonstrates that the SP-FS-USMSN cluster may be a promising drug delivery system for cancer therapy and lays the foundation for practical mesoporous silica-based nanomedicine designs in the future.