Experimental and numerical simulation technique for hydraulic fracturing of shale formations

Hydraulic fracturing is crucial for extracting shale oil and gas. This technique involves creating fractures in rock formations to enhance reservoir development efficiently. Due to the complexity of shale rock, it is important to conduct multiscale investigations into the fracturing process. Despite extensive research, the technology for deep-underground shale hydraulic fracturing continues to advance as it moves deeper underground. This paper explores the existing technical challenges of shale fracturing, review the current status of physical experiments and numerical simulations, and highlight the importance of multiscale numerical simulation methods. Meanwhile, an integrated approach to optimizing fracturing designs for field cases is introduced. Finally, this paper summarizes the challenges and opportunities in shale hydraulic fracturing, aiming to provide fresh insights into the advancements of hydraulic fracturing technology.Document Type: PerspectiveCited as: Huang, L., Liao, X., Fan, M., Wu, S., Tan, P., Yang, L. Experimental and numerical simulation technique for hydraulic fracturing of shale formations. Advances in Geo-Energy Research, 2024, 13(2): 83-88. https://doi.org/10.46690/ager.2024.08.0

Power allocation algorithm of full duplex cognitive relay network based on energy harvesting

To alleviate the shortage of spectrum resources and improve the power utilization of cognitive radio networks,a resource allocation algorithm of full duplex cognitive relay networks with energy harvesting was proposed.In the algorithm,the coefficient for power splitting of the relay and the transmit power of the secondary users were jointly optimized to maximize the throughput of the secondary users under the interference to primary users and energy harvesting constraints.Since the optimization of the algorithm was non-convex,it was transformed into two sub-optimizations,the sub-optimization of the coefficient for power splitting and the sub-optimization of the power transmitted of secondary users,which were the solvable convex sub-optimizations.Then,the final solution of the original optimization was obtained with the iterative algorithm.Simulation results show that the throughput of the proposed algorithm,can obtain 2 times throughput of the networks with half-duplex power splitting algorithm and 1.5 times throughput of the networks with full-duplex time switching algorithm

Investigating the simultaneous fracture propagation from multiple perforation clusters in horizontal wells using 3D block discrete element method

Multi-cluster horizontal well fracturing is one of the key technologies to develop the unconventional reservoirs such as shales. However, the field data shows that some perforation clusters have little production contribution. In this study, a three-dimensional (3D) numerical model for simulating the multiple fracture propagation based on 3D block discrete element method was established, and this model considers the stress interference, perforation friction and fluid-mechanical coupling effect. In order to determine the most appropriate measures to improve the uniformity of multiple fracture propagation, the effect of the geologic and engineering parameters on the multiple fracture propagation in shale reservoirs is investigated. The modeling results show that the geometry of each fracture within a stage is different, and the outer fractures generally receive more fracturing fluid than the interior fractures. The vertical stress almost has no effect on the geometries of multiple fractures. However, higher horizontal stress difference, larger cluster spacing, smaller perforation number, higher injection rate, and smaller fracturing fluid viscosity are conducive to promote the uniform propagation of multiple fractures. The existence of bedding planes will increase the fluid filtration, resulting in a reduction in fracture length. The middle two fractures receive less fluid and the width of them is smaller. Through analyzing the numerical results, a large amount of fracturing fluid should be injected and the proppant with smaller size is suggested to be used to effectively prop the bedding planes. Cluster spacing and perforation number should be controlled in an appropriate range according to reservoir properties. Increasing the injection rate and reducing the viscosity of fracturing fluid are important means to improve the geometry of each fracture

Bed strength in sheared beds of mono- and bi-disperse particles : Dependence on geometrical and mechanical properties of constituent particles

Acknowledgments This work is financially supported by National Science Foundation (U21A20105), China Scholarship Council, China Postdoctoral Science Foundation (2021M692695). FZ thanks LEPS Technology Company, Chengdu, China for providing the temporary plugging materials used in the present experiments and unpublished product specifications. The authors thank the two anonymous reviewers for their comments.Peer reviewe

Water-soluble full-length single-wall carbon nanotube polyelectrolytes: Preparation and characterization

HiPco single-wall carbon nanotubes (SWNTs) have been noncovalently modified with ionic pyrene and naphthalene derivatives to prepare water-soluble SWNT polyelectrolytes (SWNT-PEs), which are analogous to polyanions and polycations. The modified nanotubes have been characterized with UV-vis-NIR, fluorescence, Raman and X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The nanotube-adsorbate interactions consist of π-π stacking interactions between the aromatic core of the adsorbate and the nanotube surface and specific contributions because of the substituents. The interaction between nanotubes and adsorbates also involves charge transfer from adsorbates to SWNTs, and with naphthalene sulfonates the role of a free amino group was important. The ionic surface charge density of the modified SWNTs is constant and probably controlled by electrostatic repulsion between like charges. The linear ionic charge density of the modified SWNTs is similar to that of common highly charged polyelectrolytes

Biotransformation of tobacco-derived Z-abienol into precursors of ambrox by newly identified Acinetobacter tjernbergiae LSC-2

Z-abienol is a labdane diterpene present in tobacco leaves and is a key precursor for producing valuable aroma compounds such as ambrox. This study aimed to identify and characterize a bacterial strain that can efficiently degrade Z-abienol through microbial fermentation. The strain LSC-2 isolated from fresh tobacco leaves was identified as Acinetobacter tjernbergiae based on its morphological features and 16S rDNA phylogenetic analysis. Results of fermentation optimization experiments showed that the highest degradation efficiency of LSC-2 (69.3%) was achieved under the following conditions: 1 mg/mL Z-abienol, 0.5 mg/mL urea as the nitrogen source, pH 7, 30°C, and 150 rpm over 4 days. Whole-genome sequencing and functional annotation revealed that oxidoreductases, especially those from the auxiliary activity enzyme family, play a critical role in Z-abienol degradation. High-performance liquid chromatography and gas chromatography–mass spectrometry analysis confirmed the biotransformation of Z-abienol into various intermediates, including sclareol (211.3 μg/mL), scalaral (89.5 μg/mL), and amberonne (57.0 μg/mL). These intermediates have significant industrial applications, particularly in fragrance, pharmaceutical, and cosmetic industries. Sclareol serves as a key precursor in ambrox synthesis, a widely used fixative in high-end perfumery, whereas scalaral and amberonne enhance the aroma in tobacco and flavor formulations. The findings of this study provide valuable insights into the microbial degradation of Z-abienol, which will help develop a sustainable approach to producing bio-based fragrance compounds. Future studies should focus on enzymatic mechanisms and metabolic engineering strategies to improve the efficiency of biotransformation

The impact of an employee wellness programme in clothing/textile manufacturing companies: a randomised controlled trial

BACKGROUND: The prevalence of health risk behaviours is growing amongst South African employees. Health risk behaviours have been identified as a major contributor to reduced health related quality of life (HRQoL) and the increased prevalence of non-communicable diseases. Worksite wellness programmes promise to promote behaviour changes amongst employees and to improve their HRQoL. The aim of this study was to evaluate the short-term effects of an employee wellness programme on HRQoL, health behaviour change, body mass index (BMI) and absenteeism amongst clothing and textile manufacturing employees. METHODS: The study used a randomised control trial design. The sample consisted of 80 subjects from three clothing manufacturing companies in Cape Town, South Africa. The experimental group was subjected to a wellness programme based on the principles of cognitive behaviour therapy (CBT) as well as weekly supervised exercise classes over six weeks. The control group received a once-off health promotion talk and various educational pamphlets, with no further intervention. Measurements were recorded at baseline and at six weeks post-intervention. Outcome measures included the EQ-5D, Stanford Exercise Behaviours Scale, body mass index and absenteeism.Data was analysed with the Statistica-8 software program. Non-parametric tests were used to evaluate the differences in the medians between the two groups and to determine the level of significance. The Sign test was used to determine the within group changes. The Mann-Whitney U test was used to determine the difference between the two groups. RESULTS: At six weeks post intervention the experimental group (39 subjects) demonstrated improvement in almost every parameter. In contrast, apart from an overall decrease in time off work and a reduction in BMI for all study participants, there was no significant change noted in the behaviour of the control group (41 subjects). Seventy percent of the experimental group had improved HRQoL EQ-5D VAS scores post intervention, indicating improved perceived HRQoL. In comparison, only 58% of the control group had improved HRQoL EQ-5D VAS scores post intervention. There was no significant difference between the two groups at baseline or at six weeks post intervention. CONCLUSION: An employee wellness programme based on the principles of CBT combined with weekly aerobic exercise class was beneficial in improving the perceived HRQoL and changing health-related behaviours of clothing manufacturing employees. However, it cannot be concluded that the EWP was more effective than the once off health promotion talk as no significant changes were noted between the two groups at 6-weeks post intervention.This trial has been registered with ClinicalTrials.gov (trial registration number NCT01625039)

Targeted proteomics-determined multi-biomarker profiles developed classifier for prognosis and immunotherapy responses of advanced cervical cancer

BackgroundCervical cancer (CC) poses a global health challenge, with a particularly poor prognosis in cases of recurrence, metastasis, or advanced stages. A single biomarker is inadequate to predict CC prognosis or identify CC patients likely to benefit from immunotherapy, presumably owing to tumor complexity and heterogeneity.MethodsUsing advanced Olink proteomics, we analyzed 92 oncology-related proteins in plasma from CC patients receiving immunotherapy, based upon the comparison of protein expression levels of pre-therapy with those of therapy-Cycle 6 in the partial response (PR) group and progressive disease (PD) group, respectively.Results55 proteins were identified to exhibit differential expression trends across pre-therapy and post-therapy in both PR and PD groups. Enriched GO terms and KEGG pathways were associated with vital oncological and immunological processes. A logistic regression model, using 5 proteins (ITGB5, TGF-α, TLR3, WIF-1, and ERBB3) with highest AUC values, demonstrated good predictive performance for prognosis of CC patients undergoing immunotherapy and showed potential across different cancer types. The effectiveness of these proteins in prognosis prediction was further validated using TCGA-CESC datasets. A negative correlation and previously unidentified roles of WIF-1 in CC immunotherapy was also first determined.ConclusionOur findings reveal multi-biomarker profiles effectively predicting CC prognosis and identifying patients benefitting most from immunotherapy, especially for those with limited treatment options and traditionally poor prognosis, paving the way for personalized immunotherapeutic treatments and improved clinical strategies

Histological analysis of surgical lumbar intervertebral disc tissue provides evidence for an association between disc degeneration and increased body mass index

<p>Abstract</p> <p>Background</p> <p>Although histopathological grading systems for disc degeneration are frequently used in research, they are not yet integrated into daily care routine pathology of surgical samples. Therefore, data on histopathological changes in surgically excised disc material and their correlation to clinical parameters such as age, gender or body mass index (BMI) is limited to date. The current study was designed to correlate major physico-clinical parameters from a population of orthopaedic spine center patients (gender, age and BMI) with a quantitative histologic degeneration score (HDS).</p> <p>Methods</p> <p>Excised lumbar disc material from 854 patients (529 men/325 women/mean age 56 (15-96) yrs.) was graded based on a previously validated histologic degeneration score (HDS) in a cohort of surgical disc samples that had been obtained for the treatment of either disc herniation or discogenic back pain. Cases with obvious inflammation, tumor formation or congenital disc pathology were excluded. The degree of histological changes was correlated with sex, age and BMI.</p> <p>Results</p> <p>The HDS (0-15 points) showed significantly higher values in the nucleus pulposus (NP) than in the annulus fibrosus (AF) (Mean: NP 11.45/AF 7.87), with a significantly higher frequency of histomorphological alterations in men in comparison to women. Furthermore, the HDS revealed a positive significant correlation between the BMI and the extent of histological changes. No statistical age relation of the degenerative lesions was seen.</p> <p>Conclusions</p> <p>This study demonstrated that histological disc alterations in surgical specimens can be graded in a reliable manner based on a quantitative histologic degeneration score (HDS). Increased BMI was identified as a positive risk factor for the development of symptomatic, clinically significant disc degeneration.</p