Tiantian Zhang,Xiangchun Chang,Xiaoyong Wen,Zhiwen Li,Qianru Yang,Zhiping Li,Caspar Daniel Adenutsi,Mingwei Gao,Qing You
Hydraulic fracturing has been proposed as a potential technology for the development of low-permeability oil reservoirs and also has promising application prospects offshore. In this study, a novel SiO 2 -enhanced seawater-based temperature-resistant clean fracturing fluid was formulated. The fracturing fluid main agents, additives and reducing agents were screened. Besides, the physical and chemical properties (rheology) as well as application (i.e., sand-carrying, gel-breaking, dynamic fluid loss, dynamic damage and anti-swelling) performance of the proposed SiO 2 -enhanced seawater-based temperature-resistant clean fracturing fluid were systematically investigated. It was revealed that 3.2 wt% AASB-17+1.92 wt% NaSal+0.1 wt% SC-107+0.1 wt% TS3 was the optimal SiO 2 -enhanced seawater-based clean fracturing fluid system formula. The SiO 2 -enhanced seawater-based temperature-resistant clean fracturing fluid exhibited remarkable rheological characteristics , the temperature and shear resistance was increased by 28 %, with a maximum temperature resistance of 90ºC. This system can be applied to the fracturing development of most oil reservoirs in the Bohai Bay. In addition, the presence of SiO 2 nanoparticles significantly improved the sand-carrying properties of the proposed clean fractuirng fluid system. The experimental results also suggested that the SiO 2 -enhanced seawater-based temperature-resistant clean fracturing fluid showed excellent performance of shear recovery (fixed shear viscosity recovery rate was 100 %), gel breaking (30 min,1 mPa·s), filter loss ( C w =4.75×10 −4 m/min 1/2 ), anti-swelling (anti-swelling rate was 77.78 %) and salt tolerance. This study provides fundamental technical support for the application of SiO 2 -enhanced seawater-based temperature-resistant clean fracturing fluid in offshore fracturing.
Solid-state lithium batteries (SSLBs) are promising energy-storage devices. However, the low ionic conductivity of solid electrolytes and poor interface stability are two challenges to their commercial application. To alleviate these problems, we investigated three different composite modes of ZIF-8 and SiO2: (1) mechanical mixing of ZIF-8 and mesoporous SiO2 (ZIF-8+SiO2); (2) mesoporous SiO2 spheres adsorbed on the surface of ZIF-8 (ZIF-8/SiO2); (3) mesoporous SiO2 shell deposited on the surface of ZIF-8 (ZIF-8@SiO2). In particular, ZIF-8@SiO2/IL was obtained when ZIF-8@SiO2 with a hierarchical pore structure was used as the host of the Li+-containing ionic liquid (IL). By combining ZIF-8@SiO2/IL as a filler with polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide, the composite electrolyte (PZS-3) showed excellent performance. PZS-3 showed a high ionic conductivity (2.35 × 10−4 S cm−1 at 30 °C), wide electrochemical stability window (5.5 V), and high Li+ transference number (0.6), and excellent compatibility with the Li metal and electrodes. An SSLB composed of LiFePO4/PZS-3/Li exhibited outstanding cycling stability with an initial discharge capacity of 155.6 mA h g−1 at 0.2 C and capacity retention of 96.5% after 100 cycles. This novel design strategy offers a promising approach for MOFs composited with other inorganic materials to construct prospective hierarchical Li+ channels.
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