The CO 2 −brine interfacial tension (IFT) is a key parameter affecting the CO 2 storage capacity in saline aquifers and therefore should be accurately characterized to ensure the optimal design of CO 2 sequestration projects. This paper proposed the use of the extreme gradient boosting (XGBoost) trees for the fast and accurate modeling of the CO 2 −brine IFT. Results show that the novel model is capable of not only estimating the IFT but also reproducing the underlying correlation between the IFT and each input variable with remarkably high accuracies. Statistical matrices and point-wise error analyses demonstrate that the new model outperforms previous machine learning (ML) methods significantly. The estimation model was then applied for determining the optimum CO 2 sequestration depth in saline aquifers, which reveals that higher pressure and/or lower geothermal gradients result in a significant increase in the maximum structural trapping capacity that occurs at noticeably shallower formations.
In the present study, Mo was added to Cu–15Ni–8Sn alloy as the fourth element to solve the limitation of service performance of the alloy by composition design. The phase composition, microstructure transformation and mechanical properties of Cu–15Ni–8Sn–xMo (x = 0.3, 0.9, 1.5 wt.%) alloy were systematically studied by simulation calculation and experimental characterization. The results show that the addition of Mo can improve the as-cast structure of Cu–15Ni–8Sn alloy and reduce segregation and Cu–Mo phase precipitates on the surface with the increase in Mo contents. During solution treatment, Mo can partially dissolve into the matrix, which may be the key to improving the properties of the alloy. Furthermore, the discontinuous precipitation of Sn can be effectively inhibited by adding the appropriate amount of Mo to Cu–15Ni–8Sn alloy, and the hardness of alloy does not decrease greatly after a long-time aging treatment. When Mo content is 0.9 wt.%, the alloy reaches the peak hardness of 384 HV at 4 h of aging. These results provide new ideas for composition optimization of Cu–15Ni–8Sn alloy.
The breakthrough of shale oil in North America led to a worldwide energy revolution. Shale reservoirs show multiscale properties and a large proportion of nanopores compared to conventional reservoirs, which makes the imbibition mechanisms of fracturing fluids within shale reservoirs exceptionally complicated. For instance, the fracturing fluid shows a distinct imbibition behavior at different scales. Traditional models face significant challenges in imbibition characterization. Understanding the imbibition mechanisms in shale oil formations from a multiscale perspective can help to make full use of the positive effect and enhance oil recovery. We review imbibition mechanisms in shale reservoirs from the nanoscale to the reservoir scale. The imbibition principles in a single nanopore and the improvement of the traditional characterization models are clarified. Then, at the pore scale, we elaborate on the imbibition laws obtained from the microfluidic chip, pore network model, and direct simulations. We also outline the imbibition dynamics at the core scale, the influences of capillary forces and osmotic pressure, and the variations of the pore structure. Finally, the imbibition behavior at the reservoir scale and field examples considering the imbibition effect are introduced. We analyze the existing problems on each scale and discuss the future trends in this area. This work is expected to help readers systematically understand the mechanisms and behavior of fracturing fluid imbibition in shale oil reservoirs at different scales and accelerate the exploitation of shale resources.
The power transmission auxiliary system is a set of key systems of armored vehicles, which roughly includes a heat dissipation system, a lubrication system, a compressed air system, a heating system, a thermal smoke screen system, and other subsystems. It is characterized by relying on a pipeline connection so that the auxiliary system and the engine, and the transmission system form a closed loop to achieve functional output. The pipeline of the auxiliary system is mainly arranged around the engine, and the main excitation source is the engine. To improve the reliability of the power transmission auxiliary system of armored vehicles and avoid the phenomenon of running, running, dripping, and leaking, this paper mainly proposes a design method based on vibration control for the typical pipelines commonly used in armored vehicles and determines the excitation frequency of the pipelines mainly at 0~500Hz through testing the excitation source, of which the vibration energy of 150Hz~400Hz is the largest and then attenuated with the analysis of pipeline modalities by hammering test method and finite element method. By simulating the pipeline modality, and analyzing its 1st to 6th-order modes, the pipeline is optimized by changing the pipe diameter, changing the bending radius, increasing the pipeline branch, increasing the flexible link, increasing the constraint, etc., so that the pipeline avoids the resonance frequency in the corresponding mode to obtain the best design scheme of the pipeline. The research method in this paper has been successfully applied to the structural design of the test of the armored vehicle auxiliary system pipeline and other model projects. An effective design process has been formed, and the typical pipeline designed by the method has been completed with prototype trial production, bench test, and real vehicle test. The pipeline work performance is good, and the operation is smooth and reliable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.