Influence of permeability and injection orientation variations on dispersion coefficient during enhanced gas recovery by CO2 injection

This investigation was carried out to highlight the influence of the variation of permeability of the porous media with respect to the injection orientations during enhanced gas recovery (EGR) by CO2 injection using different core samples of different petrophysical properties. The laboratory investigation was performed using core flooding technique at 1300 psig and 50 degree C. The injection rates were expressed in terms of the interstitial velocities to give an indication of its magnitude and variation based on the petrophysical properties of each core sample tested. Bandera Grey, Grey Berea, and Buff Berea sandstone core samples were used with measured permeabilities of 16.08, 217.04, and 560.63 md respectively. Dispersion coefficient was observed to increase with decrease in permeability, with Bandera Grey having the highest dispersion coefficient and invariably higher mixing between the injected CO2 and the nascent CH4. Furthermore, this dispersion was more pronounced in the horizontal injection orientation compared to the vertical orientation with, again, the lowest permeability having a higher dispersion coefficient in the horizontal orientation by about 50%. This study highlights the importance of the permeability variation in the design of the injection strategy of EGR and provides a revision of the CO2 plume propagation at reservoir conditions during injection

Mesh Messaging in Large-scale Protests: Breaking Bridgefy

Mesh messaging applications allow users in relative proximity to communicate without the Internet. The most viable offering in this space, Bridgefy, has recently seen increased uptake in areas experiencing large-scale protests (Hong Kong, India, Iran, US, Zimbabwe, Belarus), suggesting its use in these protests. It is also being promoted as a communication tool for use in such situations by its developers and others. In this work, we report on a security analysis of Bridgefy. Our results show that Bridgefy, as analysed, permitted its users to be tracked, offered no authenticity, no effective confidentiality protections and lacked resilience against adversarially crafted messages. We verified these vulnerabilities by demonstrating a series of practical attacks on Bridgefy. Thus, if protesters relied on Bridgefy, an adversary could produce social graphs about them, read their messages, impersonate anyone to anyone and shut down the entire network with a single maliciously crafted message