CT Experiments and Image Processing for the Water-Oil Displacement at Pore Scale

AbstractWe established a CT experimental method for the study of the water-oil displacement at pore scale. The microscopic core model made up of reservoir coring materials could truthfully reflect the surface property and pore structure of reservoir rocks. We scanned the core model at different water flooding stages using SkyScan1174v2 CT scanner, and high resolution images were obtained. The present paper adopted a new image segmentation method, which depends on the discriminatory analysis constrained by the measured porosity and oil saturation. This new method improved the accuracy of image segmentation. We utilized the new algorithm to carry out the segmentation of pores and residual oil from the scanning images. The segmentation results were in agreement with those measured from the core experiments

Numerical study of the fluid fracturing mechanism of granite at the mineral grain scale

Hydraulic fracturing is an essential technique for reservoir stimulation in the process of deep energy exploitation. Granite is composed of different rock-forming minerals and exhibits obvious heterogeneity at the mesoscale, which affects the strength and deformation characteristics of rocks and controls the damage and failure processes. Therefore, in this paper, based on the discrete element fluid-solid coupling algorithm and multiple parallel bond-grain based model (Multi Pb-GBM), a numerical model of a granite hydraulic fracturing test is established to study the evolution of hydraulic fractures in crystalline granite under different ground stress conditions. The main conclusions are as follows. The crack propagation of hydraulic fractures in granite is determined by the in situ stress state, crystal size, and mineral distribution, and the ground stress is the main controlling factor. The final fracture mode affects the maximum principal stress and shear stress, and the generation of cracks changes the distribution of the stress field. The hydraulic fracturing initiation pressure decreases with decreasing crystal size. The influence of the crystal size on the crack inclination angle is mainly reflected in local areas, and the general trend of the fissure dip angle distribution is along the direction of the maximum in situ stress. This study not only has important theoretical significance for clarifying the propagation mechanism of hydraulic fractures but also provides a theoretical basis for deep reservoir reconstruction and energy extraction

Degradation of norfloxacin by red mud-based prussian blue activating H2O2: A strategy for treating waste with waste

The massive accumulation of red mud (RM) and the abuse of antibiotics pose a threat to environment safety and human health. In this study, we synthesized RM-based Prussian blue (RM-PB) by acid solution-coprecipitation method to activate H2O2 to degrade norfloxacin, which reached about 90% degradation efficiency at pH 5 within 60 min and maintained excellent catalytic performance over a wide pH range (3−11). Due to better dispersion and unique pore properties, RM-PB exposed more active sites, thus the RM-PB/H2O2 system produced more reactive oxygen species. As a result, the removal rate of norfloxacin by RM-PB/H2O2 system was 8.58 times and 2.62 times of that by RM/H2O2 system and PB/H2O2 system, respectively. The reactive oxygen species (ROS) produced in the degradation process included ·OH, ·O2- and 1O2, with 1O2 playing a dominant role. The formation and transformation of these ROS was accompanied by the Fe(III)/Fe(II) cycle, which was conducive for the sustained production of ROS. The RM-PB/H2O2 system maintained a higher degradation efficiency after five cycles, and the material exhibited strong stability, with a low iron leaching concentration. Further research showed the degradation process was less affected by Cl-, SO42-, NO3-, and humic acids, but was inhibited by HCO3- and HPO42-. In addition, we also proposed the possible degradation pathway of norfloxacin. This work is expected to improve the resource utilization rate of RM and achieve treating waste with waste

Intermediates Transformation of Bornite Bioleaching by Leptospirillum ferriphilum and Acidithiobacillus caldus

Bioleaching experiments, electrochemical tests, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were conducted to investigate the intermediates transformation of bornite by Leptospirillum ferriphilum and Acidithiobacillus caldus. The bioleaching experimental results showed that the presence of L. ferriphilum and A. caldus significantly accelerated the bornite bioleaching. In addition, the intermediate species of bornite bioleaching with these two kinds of bacteria were similar. Electrochemical analysis indicated that the dissolution of bornite was an acid-consuming process. The results of XRD showed that intermediate species, namely covellite (CuS), mooihoekit (Cu9Fe9S16) and isocubanite (CuFe2S3), were formed during bornite bioleaching, and a mass of elemental sulfur was formed in the late stage of bioleaching. The Cu 2p photoelectron spectrum revealed that Cu was present in the form of Cu (I) during the bornite bioleaching. Additionally, the S 2p3/2 photoelectron spectrum suggested that S2− and S22− were gradually converted to Sn2−/S0, and the formation of elemental sulfur hindered the further dissolution of the bornite

Tolerance to CR to compare the integrity of the cell wall.

<p>Wild-type, Δ<i>mopex19</i> and complemented strains were cultured on CM supplemented with 200 μg/ml CR for 5 days.</p

<i>MoPEX19</i> gene deletion and mutant complementation.

<p>(A) Diagram showing that the 1.22-kb <i>MoPEX19</i> coding region was replaced by the 1.36-kb <i>HPH</i> cassette. An inner fragment within the deletion region was used as the probe for Southern blotting. Scale bar = 500 bp. (B) Total genomic DNA was isolated from the wild-type (lane 1), ectopic transformants (lanes 2 and 3), and potential Δ<i>mopex19</i> mutants (lanes 4–8, Δ<i>mopex19-11</i>, Δ<i>mopex19-14</i>, Δ<i>mopex19-20</i>, Δ<i>mopex19-32</i> and Δ<i>mopex19-44</i>), digested with <i>Sac</i>I and subjected to Southern blotting. A 3943-bp hybridization band was detected in the wild-type, whereas 4971-bp bands were present in the five potential mutants, consistent with the gene deletion events. Ectopic transformant generated two bands, one of which was in equal size to the wild-type. (C) Gene transcription analysis of wild-type (Guy-11), Δ<i>mopex19-11</i> and Δ<i>mopex19-44</i>, and Δ<i>mopex19-</i>com by quantitative PCR. <i>MoPEX19</i> transcripts were detected in similar abundance in the wild-type and complemented strains, but were completely undetectable in the mutants.</p