A New Application of Ethylenediamine to Improve CO2 Sweep Efficiency in Extremely-Low Permeability Reservoir

 Gas breakthrough is a common problem in CO2 displacement. This paper provides a new method with ethylenediamine to improve the efficiency of CO2 injection, sealing off the breakthrough channel. Experiments in porous medium model show that the ethylenediamine system can be easily injected into extremely low permeability reservoir, it can react with CO2 and the generated carbonate will reduce the permeability of the flooding region, causing the breakthrough pressure reaches 22MPa, hence, the swept efficiency is improved. Oil displacement experiment with heterogeneous core shows that the recovery factor is improved by 19.8%. Additionally, the ethylenediamine system shows high temperature resistance and CO2 erosion resistance. It also has an advantage of selective plugging, it will not injury the reservoir where CO2 does not pass by as long as we chose the suitable injection speed, prepositive and postpositive slug. So we could control CO2 breakthrough by profile control. Key words:  ethylenediamine; plugging; CO2; heterogeneity; profile contro

Different critical points of chiral and deconfinement phase transitions in (2+1)-dimensional fermion-gauge interacting model

Based on the truncated Dyson-Schwinger equations for fermion and massive boson propagators in QED$_3$, the fermion chiral condensate and the mass singularities of the fermion propagator via the Schwinger function are investigated. It is shown that the critical point of chiral phase transition is apparently different from that of deconfinement phase transition and in Nambu phase the fermion is confined only for small gauge boson mass.Comment: 5 Pages and 3 figure

11-stable fluctuation of the derivative martingale of branching random walk

In this paper, we study the functional convergence in law of the fluctuations of the derivative martingale of branching random walk on the real line. Our main result strengthens the results of Buraczewski et. al. [Ann. Probab., 2021] and is the branching random walk counterpart of the main result of Maillard and Pain [Ann. Probab., 2019] for branching Brownian motion.Comment: 42 pages, 0 figure

Narrow-line-width UV bursts in the transition region above Sunspots observed by IRIS

Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si IV line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as Narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise of one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two datasets (a raster and a sit-and-stare dataset). Among these, four events are short-living with a duration of $\sim$10 mins while two last for more than 36 mins. All NUBs have Doppler shifts of 15--18 km/s, while the NUB found in sit-and-stare data possesses an additional component at $\sim$50 km/s found only in the C II and Mg II lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots.Comment: 8 pages, 4 figures and 1 table, accepted for publication in ApJ