Spontaneous imbibition behavior in porous media with various hydraulic fracture propagations: A pore-scale perspective

Hydraulic fracturing technology can improve the geologic structure of unconventional oil and gas reservoirs, yielding a complex fracture network resulting from the synergistic action of hydraulic and natural fractures. However, the impact of spontaneous imbibition associated with hydraulic fracture propagation on the reservoir matrix remains poorly understood. In this study, combining the Cahn-Hilliard phase field method with the Navier-Stokes equations, pore-scale modeling was employed to capture the evolution of the oil-water interface during dynamic spontaneous imbibition for hydraulic fracture propagation in a two-end open mode. This pore-scale modeling approach can effectively circumvent the challenges of conducting spontaneous imbibition experiments on specimens partitioned by hydraulic fractures. A direct correlation was established between the pressure difference curve and the morphology of discharged oil phase in the primary hydraulic fracture, providing valuable insights into the distribution of oil phase in spontaneous imbibition. Furthermore, it was shown that secondary hydraulic fracture propagation expands the longitudinal swept area and enhances the utilization of natural fractures in the transverse swept area during spontaneous imbibition. When secondary hydraulic fracture propagation results in the interconnection of upper and lower primary hydraulic fractures, competitive imbibition occurs in the matrix, leading to reduced oil recovery compared to the unconnected models. Our results shed light upon the spontaneous imbibition mechanism in porous media with hydraulic fracture propagation, contributing to the refinement and application of hydraulic fracturing techniques.Document Type: Original articleCited as: Zhou, Y., Guan, W., Zhao, C., Zou, X., He, Z., Zhao, H. Spontaneous imbibition behavior in porous media with various hydraulic fracture propagations: A pore-scale perspective. Advances in Geo-Energy Research, 2023, 9(3): 185-197. https://doi.org/10.46690/ager.2023.09.0

Parallelization and I/O performance optimization of a global nonhydrostatic dynamical core using MPI

The Global ‐ Regional Integrated forecast SysTem (GRIST) is the next- generation weather and climate integrated model dynamic framework developed by Chinese Academy of Meteorological Sciences. In this paper, we present several changes made to the global nonhydrostatic dynamical (GND) core, which is part of the ongoing prototype of GRIST. The changes leveraging MPI and PnetCDF techniques were targeted at the parallelization and performance optimization to the original serial GND core. Meanwhile, some sophisticated data structures and interfaces were designed to adjust flexibly the size of boundary and halo domains according to the variable accuracy in parallel context. In addition, the I/O performance of PnetCDF decreases as the number of MPI processes increases in our experimental environment. Especially when the number exceeds 6000, it caused system-wide outages (SWO). Thus, a grouping solution was proposed to overcome that issue. Several experiments were carried out on the supercomputing platform based on Intel x86 CPUs in the National Supercomputing Center in Wuxi. The results demonstrated that the parallel GND core based on grouping solution achieves good strong scalability and improves the performance significantly, as well as avoiding the SWOs

l-2,3-Diaminopropionate: One of the building blocks for the biosynthesis of Zwittermicin A in Bacillus thuringiensis subsp. kurstaki strain YBT-1520

AbstractZwittermicin A (ZwA) is a hybrid polyketide–non-ribosomal peptide that is thought to be biosynthesized from five proposed building blocks, including the 2,3-diaminopropionate. Candidate genes for de novo biosynthesis of 2,3-diaminopropionate, zwa5A and zwa5B, have been identified in a previous study. In this research, zwa5A was interrupted and chemically synthesized 2,3-diaminopropionate was used to feed the zwa5A− mutant. Results showed that feeding with 2,3-diaminopropionate restored the ability of the zwa5A− mutant to produce ZwA. Another non-ribosomal peptide synthase gene, designated orf3, was identified. Amino acid dependent PPi release assay showed that the adenylation domain ZWAA2 of ORF3 acyl-adenylated l-2,3-diaminopropionate effectively. Taken together, it can be concluded that l-2,3-diaminopropionate is indeed one of the building blocks for the biosynthesis of Zwittermicin A

Cloning and characterization of squalene synthase and cycloartenol synthase from Siraitia grosvenorii

AbstractMogrosides and steroid saponins are tetracyclic triterpenoids found in Siraitia grosvenorii. Squalene synthase (SQS) and cycloartenol synthase (CAS) are key enzymes in triterpenoid and steroid biosynthesis. In this study, full-length cDNAs of SgSQS and SgCAS were cloned by a rapid amplification of cDNA-ends with polymerase chain reaction (RACE-PCR) approach. The SgSQS cDNA has a 1254bp open reading frame (ORF) encoding 417 amino acids, and the SgCAS cDNA contains a 2298bp ORF encoding 765 amino acids. Bioinformatic analysis showed that the deduced SgSQS protein has two transmembrane regions in the C-terminal. Both SgSQS and SgCAS have significantly higher levels in fruits than in other tissues, suggesting that steroids and mogrosides are competitors for the same precursors in fruits. Combined in silico prediction and subcellular localization, experiments in tobacco indicated that SgSQS was probably in the cytoplasm or on the cytoskeleton, and SgCAS was likely located in the nucleus or cytosol. These results will provide a foundation for further study of SgSQS and SgCAS gene functions in S. grosvenorii, and may facilitate improvements in mogroside content in fruit by regulating gene expression

Multi-View Broad Learning System for Primate Oculomotor Decision Decoding

Multi-view learning improves the learning performance by utilizing multi-view data: data collected from multiple sources, or feature sets extracted from the same data source. This approach is suitable for primate brain state decoding using cortical neural signals. This is because the complementary components of simultaneously recorded neural signals, local field potentials (LFPs) and action potentials (spikes), can be treated as two views. In this paper, we extended broad learning system (BLS), a recently proposed wide neural network architecture, from single-view learning to multi-view learning, and validated its performance in decoding monkeys' oculomotor decision from medial frontal LFPs and spikes. We demonstrated that medial frontal LFPs and spikes in non-human primate do contain complementary information about the oculomotor decision, and that the proposed multi-view BLS is a more effective approach for decoding the oculomotor decision than several classical and state-of-the-art single-view and multi-view learning approaches

Effects of Rock Fragments on the Soil Physicochemical Properties and Vegetation on the Northeastern Tibetan Plateau

Stony soils are very widely distributed and contain abundant rock fragments (>2 mm), which impose major effects on soil properties and plant growth. However, the role of rock fragments is still often neglected, which can lead to an inadequate understanding of the interaction between plants and soil. Undisturbed soil columns were collected from three alpine grasslands on the Qilian Mountain, and the X-ray computed tomography method was applied to investigate the characteristics of rock fragments. The results showed there was significant difference in number density, volumetric content and surface area density of rock fragment among the three grasslands, and followed the order of alpine meadow > alpine steppe > alpine desert steppe. In addition, the soil organic carbon, total nitrogen, total phosphorus, available phosphorus, N-NH4+, and N-NO3− contents in fine earth all increased with increasing number density, volumetric content and surface area density but to different degrees. Furthermore, positive correlations were observed between the rock shape factor and belowground biomass (R2 = 0.531, p < 0.05), between the rock volumetric content and aboveground biomass (R2 = 0.527, p < 0.05), and between number density and Simpson’s index (R2 = 0.875, p < 0.05). Our findings suggest that within a certain range, the increase in rock fragment content is conducive to soil nutrient accumulation and soil water storage and circulation and changes plant features, which contributes to the growth of plants. In addition, rock fragments should be given more consideration when investigating the relationships between soil and vegetation and their response to climate change in future studies

RECENT CASE NOTES

<p><i>Notes</i>: H-sites and L-sites refer to high-tide-zone sites and low-tide-zone sites, respectively.</p><p>Results of <i>t</i>-test for effects of different stands on aboveground net primary production (ANPP), soil pH, total carbon (TC), organic and inorganic carbon (SOC and SIC, 0–100 cm), and SMBC.</p

Petrology, Physical Properties, and Diagenetic Characteristics of Glutenite Reservoir: An Example from the Upper Urho Formation in Zhongguai Salient, Junggar Basin, China

AbstractThe Upper Urho Formation on the northwest margin of the Junggar Basin is a key formation for oil and gas exploration. Based on the core observation, combined with the analysis of cast thin section, scanning electron microscope, energy dispersive spectrum, X-ray diffraction, fluid inclusion, and porosity-permeability test, the petrological characteristics, physical properties, diagenesis types, and their effects on the physical properties of the glutenite reservoir of Upper Urho Formation were studied systematically. The results show that the lithology of reservoir of the Upper Urho Formation in Zhongguai Salient is mainly conglomerate with a small amount of sandstone. The permeability of conglomerate is generally higher than that of sandstone, and the physical properties of granule conglomerate and fine pebble conglomerate are relatively better. The reservoir experienced complicated diagenesis, mainly including compaction, cementation, and dissolution, also including filler shrink seam and metasomatism. At present, the reservoir of Upper Urho Formation in Zhongguai Salient is mainly at the middle diagenetic stage A period and partly at the middle diagenetic stage B period. The original porosity lost by compaction is the largest, which is the fundamental reason for low porosity and low permeability of reservoir. The influence of cementation on reservoir physical properties has two sides. On the one hand, the development of cementation is the main reason for low porosity and low permeability of reservoir. On the other hand, the early cementation resists compaction to a certain extent and provides a material basis for the later dissolution. The reservoir of Upper Urho Formation in Zhongguai Salient is deeply buried and has experienced strong compaction and cementation, and the reservoir properties are poor, but the secondary pore space formed by dissolution improves the reservoir properties to some extent. The study concluded that the dense glutenite reservoirs of the Upper Urho Formation can develop relatively high-quality reservoirs on a local scale, which is of guiding significance for the exploration of the Upper Urho Formation