bluuebunny/crossref_metadata_2025 huggingface dataset:
Geological Model Coupled with Geomechanics Makes an Impact on Fracturing Stimulation and Field Development Strategy of a Tight Gas Formation in the Sultanate of Oman
Authors: Bate Kevin , Lane Mauricio , Moiseenkov Alexey , Nadezhdin Sergey
Published: February 2021

Appraisal drilling of a recently discovered Cambrian-aged gas field in Oman is indicating that the field may have significant amounts of gas locked in a challenging deep, hot, and highly pressured reservoir environment. The low porosity and permeability values of the Amin reservoir allow the classification of the reservoir as a tight gas sand. The variability of reservoir properties, both spatially and vertically, makes it difficult to standardize perforation and fracture stimulation design which, in turn, complicates delineation of a development plan for the project. One of the difficulties relates to uncertainty in vertical propagation of hydraulic fractures. Fracture height based on evaluation of radioactive tracer logs indicates that vertical barriers to fracture propagation may relate to specific geologic zones in the reservoir. The mapping of the reservoir zones into undeveloped areas of the field would allow selection of primary and secondary production targets based on the specific physical properties of the individual zones. To assume that no barrier to fracture propagation exists between separate production units may lead to attempts to stimulate them synchronously, which would be disadvantageous for several reasons, such as premature screenouts and incomplete coverage of gas-bearing layers. Reserves booking and allocation can also be jeopardized should the fractures propagate into undesired zones.
Understanding Unusual Diagnostic Fracture Injection Test Results in Tight Gas Fields - A Holistic Approach to Resolving the Data
Authors: Naidu R.N.. N. , Guevara E.A.. A. , Twynam A.J.. J. , Rueda J.. , Dawson W.. , Moses E.. , Rylance M..
Published: February 2021

Hydraulic fracturing is a commonly used completion approach for extracting hydrocarbon resources from formations, particularly in those formations of very low permeability. As part of this process the use of Diagnostic Fracture Injection Tests (DFIT) can provide valuable information. When the measured pressures in such tests are outside the expected range for a given formation, a number of possibilities and questions will arise. Such considerations may include: What caused such inflated pressures? What is the in-situ stress state? Was there a mechanical or operational problem? Was the test procedure or the test equipment at fault? What else can explain the abnormal behaviour? While there may not be simple answers to all of these questions, such an experience can lead to a technically inaccurate conclusion based on inadequate analysis.

A recently completed project faced just such a challenge, initially resulting in poor hydraulic fracturing efficiency and a requirement to understand the root causes. In support of this, a thorough analysis involving a multi-disciplinary review team from several technical areas, including petrophysics, rock/geo-mechanics, fluids testing/engineering, completions engineering, hydraulic fracture design and petroleum engineering, was undertaken. This paper describes the evolution of this study, the work performed, the results and conclusions from the analysis.

The key factors involved in planning a successful DFIT are highlighted with a general template and a work process for future testing provided. The importance of appreciating the impact of the drilling and completion fluids composition, their properties and their compatibility with the formation fluids are addressed. The overall process and technical approach from this case study in tight gas fields, will have applicability across similar fields and the lessons learned could help unlock those reserves that are initially deemed technically or even commercially unattractive due to abnormal or unexpected behaviour measured during a DFIT operation.
Predicting Barik Formation Production from Seismic, Khazzan Field, North Oman
Authors: Stiteler T. Chris , Philip M. J.
Published: February 2021

Prediction of areas of good reservoir deliverability has been achieved by the integration of production data, petrophysical analysis, palaeocurrent analyses, core data and 3D seismic data. The key data in this comparative analysis are derived from a petrophysical workflow, which is calibrated to surveillance data and dynamic well test data. These data include porosity, porosity-thickness (PhiH), permeability, and permeability-thickness (KH).

The results of this initial integration are compared with extractions from numerous seismically-generated attribute maps at each well location and used to define preferred seismic PhiH and KH maps. These can be utilised for well planning and further integrated with geocelluar reservoir models.

Additional geological interpretation confirms that trends within the Barik depositional system can be recognised on seismic, defining areas which have the potential to have similar thickness, depositional facies and most likely, similar potential production within them.

This has led to optimisation of the drilling schedule, allowing rescheduling of wells from areas that are now understood to be potentially poor to areas having higher potential, thus increasing efficiency.

Additionally, this work indicates that wells having low production on test conform to areas where low production is predicted, but some wells in the predicted areas of moderate to high production show higher prediction errors than other wells within the same area. This methodology clarifies where differences between predicted and actual measurements occur, allowing the second phase of integration aimed at improving predictions and mitigating risks.
Performance Evaluation of A Horizontal Well with Multiple Fractures Using A Slab Source Function
Authors: Yang Daoyong , Zhang Feng , Styles John A. , Gao Junmin
Published: February 2021

A novel slab source function has been formulated and successfully applied to accurately evaluate performance of a horizontal well with multiple fractures in a tight formation. A semi-analytical method is then applied to solve the newly formulated mathematical model by discretizing the fracture into small segments, each of which is treated as a slab source, assuming that there exists unsteady flow between the adjacent segments. The newly developed function has been validated with numerical solution obtained from a reservoir simulator and then extended its application to a field case. The pressure response together with its corresponding derivative type curves has been reproduced to examine effects of number of stages, fracture conductivity, and fracture dimension under various penetration conditions. The fracture conductivity is found to mainly influence early-stage bilinear/linear flow regime, while a smaller conductivity will force more fluid to enter the toe of the fracture than its heel. Penetrating ratio will impose a significant impact on the pressure response at the early stage, forcing the bilinear/linear flow to the radial flow.
Improvement of Impact Strength of Polyglycolic Acid for Self-Degradable Tools for Low-Temperature Wells
Authors: Okura Masayuki , Takahashi Shinya , Kobayashi Takuma , Saijo Hikaru , Takahashi Takeo
Published: February 2021

Recent increases in the stage count of hydraulic fracturing has increased the time and cost for well completion. Simplifying time-consuming processes is crucial for economic success. The use of degradable materials for components of downhole tools has several advantages, such as eliminating or simplifying the recovery process of the tools. Polyglycolic acid (PGA), a hydrolyzable polymer, is a suitable material for these components. PGA has already been used in frac balls because of its high mechanical strength and appropriate degradation characteristics. However, in low-temperature wells close to the glass transition temperature of PGA, there are problems with tool breakage during installation or stimulation because of the changes in the mechanical properties of PGA at low temperatures.

This paper focuses on the improvement of the impact strength of PGA. A study of modifiers identified the additives that are highly compatible with PGA. Morphological studies of mixtures showed finely dispersed additive domains within a PGA matrix. The impact strength of the mixture was twice as high as that of neat PGA. A formulation was identified that optimized the impact strength while retaining degradability, processability, and machinability similar to that of neat PGA. The improvement of the impact strength broadens the range of applications that PGA tooling is suitable for and helps to reduce the cost and time of the well completion process.
Direct TOC Quantification in unconventional Kerogen-rich Shale Resource Play from Elemental Spectroscopy Measurements: A Case Study from North Kuwait
Authors: Joshi Girija K. , Acharya Mihira N. , Steene Marie Van , Chakravorty Sandeep , Darous Christophe , Al-Azmi Mejbel S. , Dashti Qasem
Published: February 2021

The deep organic-rich calcareous Kerogen of North Kuwait, a continuous 50ft thinly alternating carbonate – organic-rich argillaceous sequence, is not only a source rock but has gained importance as potential reservoirs themselves of typical unconventional category. Resource play or Kerogen characterization relies on quantifying total organic carbon (TOC) and estimating accurate mineralogy. This paper describes the first attempt to directly measure total organic carbon of the Limestone-Kerogen sequence.

For the present study, empirical estimations of TOC have been carried out based on conventional log measurements and nuclear magnetic resonance (NMR). The introduction of a new neutron-induced capture and inelastic gamma ray spectroscopy tool using a very high-resolution scintillator and a new type of pulsed neutron generator for the deep unconventional kerogen resources have provided a unique opportunity to measure a stand-alone quantitative TOC value using a combination of capture and inelastic gamma ray spectra. In this process, Inorganic Carbon Content (ICC) is estimated by using elemental concentrations measured by this logging tool in addition to measuring Total Carbon, and this value is subtracted from the measured total carbon to give TOC.

The advanced elemental spectroscopy tool measurements were first used to determine accurately the complex mineralogy of the layered carbonate and organic-rich shale sequence. Extensive laboratory measurements of core / cuttings data were used to calibrate the petrophysical evaluation and capture the heterogeneity seen on borehole image logs. The final analysis shows considerable improvements compared to conventional empirical estimation. Once the mineralogy is properly determined, the log-derived TOC matches very well with core measured TOC.

This technique has provided a new direct and accurate log-derived TOC for Kerogen characterization. The application has a potential to be used for CAPEX optimization of the coring in future wells. This technique can also be applied in HPHT and High-angle horizontal wells, which can overcome challenging coring difficulties in horizontal wells.
Unconventional Gas Simulation Strategy and Workflow
Authors: Adil Imtiaz , MoG Jamila M. , Harthy Badar Al , Sebastian Herbert M. , Adams John R.
Published: February 2021

Numerous technical publications were written in recent years on the effectiveness of reservoir simulation modeling in developing a tight gas resource. These papers question the applicability of existing numerical simulation methodologies to hydraulically fractured unconventional gas reservoirs. The rapidly changing dynamic flow behavior that occurs as fluids move from poor quality reservoir to a highly conductive fracture and then feed into an infinitely conductive wellbore creates complex solutions which are difficult to fully resolve with conventional reservoir simulation techniques. The lack of well to well dynamic interference during early stages of the production stacks the additional uncertainties around connected gas volume to the wellbore, thereby, increasing the chances of sub-optimal investment decision on well spacing, infill wells and number of fracs during the early stages of the field development.

This paper proposes a reservoir simulation strategy and the workflow for unconventional gas reservoirs. The strategy outlines the need to systematically move from simple to complex modeling solutions while creating a learning loop. It proposes an early modeling focus on single wells in small sector models to understand the impact of stimulation and well design related uncertainties. The paper also identifies a learning stage that allows a progression to the next stage of simulation i.e. sector models. The workflow identified in the paper also presents the disadvantages of how an untimely progression from sector to full field modelling can negatively impact final investment decisions and the field development strategy.

BP has successfully applied this framework in North America and this strategy has been outlined for reservoir simulation related work in the Sultanate of Oman to develop unconventional gas resources in Block 61.
Proppant Transport? Viscosity Is Not All It's Cracked Up To Be
Authors: Gomaa A.M. , Gupta D.V.S. , Carman P.
Published: February 2021

Post-treatment production analyses for hydraulic fracturing treatments with conventional crosslinked gel often indicate that the treatments do not achieve the designed stimulation effectiveness, which could be attributed to non-optimal proppant placement and/or significantly damaged fracture conductivity. Although conventional crosslinked fluids are observed to provide good proppant suspension in laboratory environments, they might not provide the desired proppant transport under downhole conditions. Crosslinked fluids are known to be difficult to clean up, and thus are notorious for imparting gel damage to proppant pack and formation. Surfactant gels have been developed to mitigate some of the issues.

Viscosity measurements are used as the main tool to judge and optimize the performance of both polymer and surfactant based fracture fluids, especially their ability to transport proppant. While efficient proppant transport is essential for successful hydraulic fracturing, recent laboratory work has shown that viscosity alone may not accurately assess proppant transport. The objective of the paper is to investigate and determine the minimum rheological properties required for efficient proppant transport. Thus, combinations of rotational and oscillatory measurements were conducted to better predict the proppant transport characteristics. Also, proppant settling tests were conducted at static and dynamic conditions. A strong correlation was established between fluid's elasticity and its ability to suspend the proppant with a required minimum elastic modulus (G') value to be greater than viscous modulus (G”).

Experimental results show that for two fluids that both have a close viscosity value (similar power law parameters); one fluid with G'>G” while the other one G'< G”, the fluid that has G'>G” behaves as semi-solid material where it deforms instead of flowing when shear stress is applied, while the fluid that has G”>G', flows when shear stress is applied and time to flow depends on viscosity. A proppant particle in a fluid undergoes shear stress due to its density. Therefore, for the fluid G”>G', proppant settles as the fluid moves around it and the speed of settling depends on fluid viscosity, whereas for the elastic fluid (G'>G”), fluid elasticity does not allow the proppant to settle. This observation was confirmed for both polymer and surfactant based fracturing fluids. Additives can be divided into categories that may enhance or reduce fluid elasticity based on their effect on the internal structure of the fluids. For example, breakers tend to significantly reduce the fluid elasticity, even when viscosity reduction is minimized. Data obtained from this study can be used as a guideline to optimize and select the fluid that has ability to carry proppant for field treatment design.
Do Data Mining Methods Matter? : A Wolfcamp “Shale” Case Study
Authors: Zhong Ming , Schuetter Jared , Mishra Srikanta , LaFollette Randy F.
Published: February 2021

Data mining for production optimization in unconventional reservoirs brings together data from multiple sources with varying levels of aggregation, detail, and quality. Tens of variables are typically included in data sets to be analyzed. There are many statistical and machine learning techniques that can be used to analyze data and summarize the results. These methods were developed to work extremely well in certain scenarios but can be terrible choices in others. The analyst may or may not be trained and experienced in using those methods. The question for both the analyst and the consumer of data mining analyses is, “What difference does the method make in the final interpreted result of an analysis?”

The objective of this study was to compare and review the relative utility of several univariate and multivariate statistical and machine learning methods in predicting the production quality of Permian Basin Wolfcamp Shale wells. The data set for the study was restricted to wells completed in and producing from the Wolfcamp. Data categories used in the study included the well location and assorted metrics capturing various aspects of the well architecture, well completion, stimulation, and production. All of this information was publicly available.

Data variables were scrutinized and corrected for inconsistent units and were sanity checked for out-of-bounds and other “bad data” problems. After the quality control effort was completed, the test data set was distributed among the statistical team for application of an agreed upon set of statistical and machine learning methods. Methods included standard univariate and multivariate linear regression as well as advanced machine learning techniques such as Support Vector Machine, Random Forests, and Boosted Regression Trees.

The strengths, limitations, implementation, and study results of each of the methods tested are discussed and compared to those of the other methods. Consistent with other data mining studies, univariate linear methods are shown to be much less robust than multivariate non-linear methods, which tend to produce more reliable results. The practical importance is that when tens to hundreds of millions of dollars are at stake in the development of shale reservoirs, operators should have the confidence that their decisions are statistically sound. The work presented here shows that methods do matter, and useful insights can be derived regarding complex geosystem behavior by geoscientists, engineers, and statisticians working together.
Open-Hole Completion Based Mechanical Diversion of Acid/Chemical Stimulation Operations: Design, Deployment and Field Trial Results
Authors: Carvajal E. I. , Caline Y. , Rylance M. , Rice K. , Waters J. , Wells S.
Published: February 2021

The ubiquitous challenge that is faced by chemical stimulation techniques, of any kind, has always been achieving an economic and efficient distribution of the stimulation solution across the exposed reservoir interval. Many have approached this problem from a chemical perspective and others from the use of additives for mechanical diversion; however the very nature of stimulation itself means that a changing injection profile will make efficient diversion by such techniques uncertain and unpredictable. Instead, rather than relying on serendipitous deployment techniques, the approach described and reported here places true mechanical diversion as part of the well construction process. This paper will completely describe the process and achievements to date, including successful application in a number of horizontal wells completed in the Austin Chalk, as part of an overall deployment plan.

Essentially, this new completion system comprises of multiple pressure actuated assemblies, distributed along the liner/casing. These assemblies, when activated, allow the lateral deployment of forty-foot needles, radially distributed at ninety-degree phasing around the casing, into the unstimulated reservoir. These subs can be precisely located across pre-selected intervals and thereby provide certainty of acid treatment distribution. The acid is pumped through the needles themselves during stimulation; however production takes place through a suite of ports. A bespoke debris basket may be run, after the stimulation treatment, in order to recover a suite of needle deployment indicators. This run, if performed, effectively establishes the success of the deployment.

In order to demonstrate the concept and avoid the high-cost environment of the North Sea, a low cost field trial location was sought and identified. An Austin chalk operator was looked for that had an extensive horizontal candidate well set available for re-completion in open-hole. A number of candidate wells were then identified and the wells were recompleted and stimulated with this new system. This paper will present the entire suite of data related to these deployments, stimulation operations, lessons learned, production impact and potential. This novel technology was greatly assisted, supported and delivered via the Joint Chalk Research (JCR) council, comprising of some ten operating companies that encourage, fund and drive the development of carbonate completion and stimulation solutions.
A Peridynamics Model for the Propagation of Hydraulic Fractures in Heterogeneous, Naturally Fractured Reservoirs
Authors: Ouchi Hisanao , Katiyar Amit , Foster John T. , Sharma Mukul M.
Published: February 2021

A novel fully coupled hydraulic fracturing model based on a nonlocal continuum theory of peridynamics is presented and applied to the fracture propagation problem. It is shown that this modeling approach provides an alternative to finite element and finite volume methods for solving poroelastic and fracture propagation problems and offers some clear advantages. In this paper we specifically investigate the interaction between a hydraulic fracture and natural fractures. Current hydraulic fracturing models remain limited in their ability to simulate the formation of non-planar, complex fracture networks. The peridynamics model presented here overcomes most of the limitations of existing models and provides a novel approach to simulate and understand the interaction between hydraulic fractures and natural fractures. The model predictions in two-dimensions have been validated by reproducing published experimental results where the interaction between a hydraulic fracture and a natural fracture is controlled by the principal stress contrast and the approach angle. A detailed parametric study involving poroelasticity and mechanical properties of the rock is performed to understand why a hydraulic fracture gets arrested or crosses a natural fracture. This analysis reveals that the poroelasticity, resulting from high fracture fluid leak-off, has a dominant influence on the interaction between a hydraulic fracture and a natural fracture. In addition, the fracture toughness of the rock, the toughness of the natural fracture, and the shear strength of the natural fracture also affect the interaction between a hydraulic fracture and a natural fracture. Finally, we investigate the interaction of multiple completing fractures with natural fractures in two-dimensions and demonstrate the applicability of the approach to simulate complex fracture networks on a field scale.
A New Tool for Multi-Cluster & Multi-Well Hydraulic Fracture Modeling
Authors: Zhai Zongyu , Fonseca Ernesto , Azad Ali , Cox Barbara
Published: February 2021

Unconventional gas and tight oil reservoirs require cost-effective fracturing technologies to optimize cost versus productivity and ensure viable commercial development. Horizontal wells together with completion techniques to initiate transverse fractures have been the key to unlocking these vast resources. Variables in the completion design for fracture stimulation in a horizontal well include injection rate, fluid properties, solid loading, well spacing, cluster spacing, and the sequence and timing of pumping stages between wells in a multi-well pad.

An optimized design is critical to improve hydrocarbon production and to reduce the cost. However in current practice, multi-cluster and multi-well design is primarily based on progressive experience and is typically of standardized design in a given area (e.g. the clusters and wells are evenly distributed). This is due in part by the limitations of existing hydraulic fracturing simulators, including: 1. An assumption of planar fractures; 2. Fracture interference within and among stages and adjacent wells is ignored; and 3. Numerical instability when modeling systems with large dimensionless toughness e.g. slick water injection into high-toughness rock.

This paper describes an emerging non-planar 3D fracturing software package with the capability to simulate interference between hydraulic fractures propagating from multiple clusters and multiple wells. Thus, both simultaneous and sequential multiple fracture propagation can be modeled. Furthermore, numerical instability with large dimensionless toughness is solved and makes it possible to predict the fracture geometry equally well for slick water fluids. The case study in this paper shows how fracture interference and proppant distribution occurs within a stage as well as between well and stages. The simulated fracture patterns can be matched with field microseismic data and the simulated pressure trend is in agreement with field operational data. Using this approach, multi-cluster and multi-well designs can be optimized in a manner not previously possible.
Applications of Geomechanics to Hydraulic Fracturing - Case Studies from Coal Stimulations
Authors: Pandey Vibhas J.
Published: February 2021

Modern hydraulic fracture treatments rely heavily on the implementation of formation property details such as in-situ stresses and rock mechanical properties, in order to optimize stimulation designs for specific reservoir targets. Log derived strain and strength calibrated in-situ properties provide critical description of stress variations in different lithologies and at varying depths. From a practical standpoint however, most of the hydraulic fracture simulators that are used for fracturing treatment design purposes today can accommodate only a limited portion of a geologic-based rock mechanical property characterization which targets optimal data integration thus resulting in complexity. By using examples from hydraulic fracture stimulations of coals in a complex but well characterized stress environment (Surat Basin, Eastern Australia) we distil out the reservoir rock related input parameters that are determinants of hydraulic fracture designs and identify those that are not immediately used. In order to understand the impact on improving future fracture stimulation designs, the authors present workflows such as pressure history matching of fracture stimulation treatments and the calibration process of key rock mechanical parameters such as Poisson's ratio, Young's modulus, and fracture toughness. The authors also present examples to discuss synergies, discrepancies and gaps that currently exist between ‘geologic’ geomechanical concepts (i.e. variations in the geometry and magnitude of stress tensors and their interaction with pre-existing anisotropies) in contrast to the geomechanical descriptions and concepts that are used and implemented in hydraulic fracturing stimulations.

In the absence of a unifying hydraulic fracture design that honors well established geologic complexity, various scenarios that allow assessing the criticality, usefulness and weighting of geologic/mechanical property input parameters that reflect critical reservoir complexity, whilst maintaining applicability to hydraulic fracturing theory, are presented in the paper. Ultimately it remains paramount to constrain as many critical variables as realistically and uniquely possible. Significant emphasis is placed on reservoir-specific pre-job data acquisition and post-job analysis. The approach presented in this paper can be used to refine hydraulic fracture treatment designs in similar complex reservoirs worldwide.
Characterizing the Stimulated Reservoir with a Hydraulic Deformation Index Using Tiltmeter-based Surface Microdeformation
Authors: Nanayakkara Asanga S. , Roadarmel William H. , Marsic Scott D.
Published: February 2021

Surface microdeformation monitoring is a fracture diagnostic technology that uses measurements of surface deformation morphology, on the micrometer scale, to geomechanically invert for dislocations and volumetric changes at reservoir depth. Surface microdeformation monitoring is a mature technology that has been successfully applied for more than two decades, using measurements from surface tiltmeter arrays. The conventional deliverables of this fracture-mapping technology have historically been limited to orientation (azimuth and dip) and the volumetric ratios of main fracture components.

This paper introduces a new technique for mapping and characterizing the areal distribution of the main fracture components using surface tiltmeter measurements. The areal distribution of main fracture components is additionally characterized with a hydraulic deformation index (HDI). HDI aids the identification of rock volumes having higher or lower volumetric fracture activity, and thus may provide additional insight into approximate fracture dimensions, productive stimulated reservoir area and where proppant could be located.

This paper describes the process of producing stimulated reservoir characterization (SRC) results with HDI using surface tiltmeter measurements. Synthetic data examples as well as SRC and HDI results derived by applying the new technique to a horizontal well hydraulic fracture stimulation project in the Viking sandstone formation are presented. The paper also includes comparison of SRC and HDI results with downhole microseismic results of the Viking sandstone project.

Surface microdeformation does not require an observation well. Once a precision surface tiltmeter array is installed, it can be used to diagnose multiple stages within the covered area. Hence, the new technique provides an economically viable fracture diagnostic solution for many unconventional reservoir stimulations, such as massive multistage horizontal well hydraulic fracture treatments.
Exploring the influence of the North Pacific Ocean Rossby wave sources on interannual variability of summer precipitation and surface temperature over the Northern Hemisphere.
Authors: Fuentes-Franco Ramon , Koenigk Torben , Docquier David , Graef Federico , Wyser Klaus
Published: February 2021

The influence of Rossby wave sources (RWS) emitted on the Northeastern Pacific Ocean in the Northern Hemisphere during summer is analysed in the ERA5 reanalysis and new large ensemble performed with the EC-Earth3 model. Using extreme years composites of precipitation, surface temperature, geopotential height, we found a causal influence of the Rossby waves generated over the Northeastern Pacific Ocean, on a global climate response. Both the reanalysis ERA5 and the EC-Earth3 model show that RWS triggers wave-like patterns arising from the upper troposphere Northeastern Pacific region. We show that an increased Rossby wave sources intensity is related with negative temperature anomalies over western North America, and positive temperature anomalies over eastern North America concurrently increased precipitation over Northern Europe during summer and sea-ice concentration decrease in the Arctic. We also show that the North Atlantic plays a very important role hindering or permitting that Rossby waves generated in the Pacific reach the Atlantic and modulate the atmospheric conditions over Europe. Such conditions were found in ERA5 and SMHI-LENS during colder and icier conditions over the North Atlantic.
Optimizing sludge dewatering with an alternate pressure and electric field
Authors: Li Yunyi , Huang Xinmiao , Wei Ying , Liu Yangsheng
Published: February 2021

Sludge dewatering is a prerequisite for the subsequent utilization of sludge. However, the existing mechanical dewatering cannot achieve satisfactory water content (< 60%). Herein, pressure and electric dewatering in alternate operation (P/EDWalt) was proposed to improve dewatering efficiency. Compared with conventional simultaneous mode, P/EDWalt performed better in sludge dewatering. Its optimal dewatering conditions were voltage of 30 V for 20 min in two electric dewaterings, and pressure of 0.04, 0.07 and 0.10 MPa in three pressure dewaterings. Such conditions, the water content of sludge was reduced from 83.7% to 53.3%, the dewatering efficiency was 36.3%, and the energy consumption was 0.138 kWh/kgtotal removed water. These phenomena such as electroosmosis, the ohmic heating and electrophoresis facilitated the removal of water in sludge, and the dewatered sludge has good reusability in incineration, landfill and agriculture. Therefore, P/EDWalt could serve as a promising method for the sludge dewatering.
An Unusual Case of chest wall Glomus Tumor presenting with axillary pain: a case report and literature review
Authors: Zanjani Leila Oryadi , Nia Bahman Shafiee , Vosoughi Farzad , Mirzaian Elham , Aghaghazvini Leila , Arabzadeh Aidin
Published: February 2021

Background: Glomus tumor is an uncommon soft tissue tumor. However, as the tumor causes significant disability, its early diagnosis is essential. It involves subungual areas of fingers and toes in most cases, and its extra-digital involvement is rarely seen. To the best of the authors' knowledge, only a few chest wall involvement cases have been reported in the literature. Case presentation: In this paper, we describe a 63-year-old patient with a chest wall glomus tumor presented with axillary paroxysmal pain and limitation in his shoulder range of motion that had been missed for nearly 15 years. His symptoms were relieved immediately following surgical excision.Conclusion: Glomus tumors may involve any part of the human body. It is curable with surgical excision in most cases. Therefore, a correct early diagnosis has paramount importance. A high index of suspicion is needed for early diagnosis, especially when the tumor involves uncommon anatomic areas.
Effects of autoantibody against M2-muscarinic acetylcholine receptor in peripartum cardiomyopathy patients on digoxin additional to standard treatment
Authors: Ma Guiling , Chen Long , Yue Yin , Liu Xiyan , Wang Yidan , Shi Cheng , Song Fei , Shi Wei , Lo Yingshih , Zhang Lin
Published: February 2021

Objectives

To evaluate the effects of autoantibodies against the M2-muscarinic receptor (anti-M2-R) on digoxin additional to standard treatment in peripartum cardiomyopathy (PPCM) patients.
Methods

107 PPCM patients, receiving digoxin and standard treatment regimen for HF, were enrolled between January 1998 and June 2020, who were separated into anti-M2-R negative (n = 59) or positive (n = 48) group according to the anti-M2-R reactivity. Echocardiography and serum digoxin concentration (SDC) were performed regularly. All-cause mortality, cardiovascular mortality and re-hospitalization for heart failure were compared.
Results

103 patients completed the final data analysis, including 46 in the anti-M2-R (+) group and 57 in the anti-M2-R (-) group. Heart rate of the positive group was lower than that of the negative group at baseline (102.7 ± 6.1 vs. 96.0 ± 6.4, p < 0.001). The initial SDC of patients in the positive group was higher than that of patients in the negative group with the same dosage of digoxin (1.25 ± 0.45 vs. 0.78 ± 0.24 ng/mL, p < 0.001). Anti-M2-R (-) patients had better tolerance to metoprolol (38.4 ± 4.6 mg b.i.d. vs. 27.4 ± 5.0 mg b.i.d., p < 0.0001) and digoxin (0.12 ± 0.02 mg/day vs. 0.08 ± 0.04 mg/day, p < 0.0001). The improvement of heart function was obvious in the first year, especially in the first half. Furthermore, anti-M2-R (-) patients showed better improvement than that in anti-M2-R (+) patients. Re-hospitalization for heart failure was decreased in the negative group, but not of all-cause or cardiovascular mortality.
Conclusions

Anti-M2-R maybe a predictor for vagus nerve overactivation and is associated with poor response to digoxin in PPCM patients.
Development and Multicenter Assessment of a Reference Panel for Clinical Shotgun Metagenomics for Pathogen Detection
Authors: Liu Donglai , Xu Teng , Zhou Haiwei , Yang Qiwen , Mo Xi , Shi Dawei , Ai Jingwen , Zhang Jingjia , Tao Yue , Wen Donghua , Tong Yigang , Ren Lili , Zhang Wen , Xie Shumei , Chen Weijun , Xing Wanli , Zhao Jinyin , Wu Yilan , Meng Xianfa , Ouyang Chuan , Jiang Zhi , Liang Zhikun , Tan Haiqin , Fang Yuan , Qin Nan , Guan Yuanlin , Gai Wei , Xu Sihong , Wu Wenjuan , Zhang Wenhong , Zhang Chuntao , Wang Youchun
Published: February 2021

Background Clinical shotgun metagenomics for pathogen detection has been used in diagnosing infectious diseases. However, its technical assessments have been limited to reference standards by individual labs, single experimental workflow and laboratory.Results Here we reported the design and development of a set of reference reagents and reporting metrics dedicated for clinical metagenomics by the National Institutes for Food and Drug Control (NIFDC) of China, and a joint evaluation study including 17 independent laboratories in cross-workflow and cross-platform settings. Our results showed that the performance of metagenomic assays was significantly impacted by the factors of microbial types, host context, and read depth, thus highlighting the importance to take these factors into consideration when designing reference reagents and benchmarking assays. Through this study, we found false positives to be a common challenge across centers, and considerable site and library effects to limited the assay’s quantitative value. Our multicenter study also provided practical guidance of performance that laboratory-developed shotgun pathogen metagenomics tests should aim to detect microbes at 500 CFU/mL (or copies/mL) in clinically relevant host context (10^5 human cells/mL) within a 24h turn-around time, and with a read depth of 20M reads or lower. This collaboration work provided a unique resource comprising nearly 600 billion reads (>5Tb) for technical evaluation in clinical and regulatory settings.Conclusion We demonstrated that the performance of metagenomic assays was significantly impacted by the microbial type, the host context and read depth, which emphasizes the importance to consider these factors when designing reference reagents and benchmarking studies. Across sites, workflows and platforms, false positive reporting and considerable site/library effects were common challenges to the assay’s accuracy and quantifiability. Our study also suggested practical guidance of performance that laboratory-developed shotgun pathogen metagenomics tests should aim to detect microbes at 500 CFU/mL (or copies/mL) in clinically relevant host context (10^5 human cells/mL) within a 24h turn-around time, and with a read depth of 20M reads or lower. This collaboration work provided a unique resource comprising nearly 600 billion reads (>5Tb) for technical evaluation in clinical and regulatory settings.
The Prognostic Value of Myocardial Injury in COVID-19 Patients and Associated Characteristics
Authors: he jian , Zhang Bicheng , Zhou Quan , Yang Wenjing , Xu Jing , Liu Tingting , Zhang Haijun , Wu Zhiyong , Li Dong , Zhou Qing , Yan Jie , Zhang Cuizhen , Weiss Robert G. , Liu Guanshu , Teng Zhongzhao , Sirajuddin Arlene , Qian Haiyan , Zhao Shihua , Arai Andrew E. , Lu Minjie , Zhou Xiaoyang
Published: February 2021

Background: Since December 2019, Coronavirus disease 2019 (COVID-19) has emerged as an international pandemic. COVID-19 patients with myocardial injury might need special attention. However, understanding on this aspect remains unclear. This study aimed to illustrate clinical characteristics and the prognostic value of myocardial injury to COVID-19 patients. Methods: This retrospective, single-center study finally included 304 hospitalized COVID-19 cases confirmed by real-time RT-PCR from January 11 to March 25, 2020. Myocardial injury was determined by serum high-sensitivity troponin I (Hs-TnI). The primary endpoint was COVID-19 associated mortality. Results: Of 304 COVID-19 patients (median age, 65 years; 52.6% males), 88 patients (27.3%) died (61 patients with myocardial injury, 27 patients without myocardial injury on admission). COVID-19 patients with myocardial injury had more comorbidities (hypertension, chronic obstructive pulmonary disease, cardiovascular disease, and cerebrovascular disease); lower lymphocyte counts, higher C-reactive protein (CRP, median, 84.9 vs 28.5 mg/L, p<0.001), procalcitonin levels (median, 0.29 vs 0.06 ng/ml, p<0.001), inflammatory and immune response markers; more frequent need for noninvasive ventilation, invasive mechanical ventilation; and was associated with higher mortality incidence (hazard ratio, HR=7.02, 95% confidence interval, CI, 4.45-11.08, p<0.001) than those without myocardial injury. Myocardial injury (HR=4.55, 95% CI, 2.49-8.31, p<0.001), senior age, CRP levels, and novel coronavirus pneumonia (NCP) types on admission were independent predictors to mortality in COVID-19 patients. Conclusions: COVID patients with myocardial injury on admission is associated with more severe clinical presentation and biomarkers. Myocardial injury and higher HsTNI are both strongest independent predictors to COVID related mortality after adjusting confounding factors. In addition, senior age, CRP levels and NCP types are also associated with mortality. Trial registration: Not applicable.
Light limitation inducing overcompensatory growth of cyanobacteria and function of serine/threonine kinase (STK) genes involved
Authors: Dai Wei , Chen Gao , Bi Xiangdong , Zhong Huairong , Wang Xueying , Dong Shaojie , Lv Dong , Zhang Shulin , Zhang Dajuan , Wang Na
Published: February 2021

The rapid overcompensatory growth that appears when cyanobacteria are supplied with adequate resources after a period of resource deprivation might contribute to the occurrence of cyanobacterial blooms. We investigated the changing characteristics of overcompensatory growth and serine/threonine kinase (STK) genes expression of cyanobacterium Microcystis aeruginosa in response to light limitation. The results showed M. aeruginosa exhibited overcompensatory growth for 2 days after light recovery, during which the increase in growth was inversely related to light intensity. Expression of STK genes, such as spkD, was upregulated significantly at 0.5–4 h after light recovery (P < 0.05). To investigate the function of STK genes in the overcompensatory growth, M. aeruginosa spkD was heterologously expressed in Synechocystis. Transgenic Synechocystis exhibited greater and longer overcompensatory growth than wild-type Synechocystis after light recovery. Relative expression levels of STK genes in transgenic Synechocystis were significantly higher than those in wild-type Synechocystis at 24 h of light recovery (P < 0.05). Heterologous expression of Microcystis spkD might stimulate overcompensatory growth of Synechocystis by affecting its STK gene expression.
Signs and Types of Sports Injuries in Sports Clubs
Authors: Uspuriene Aiste Barbora , Zhiglite Vaida
Published: February 2021

One of the most important factors influencing the quality of sports club services is the competencies of the hired staff. It is also emphasized that special attention must be paid to the competencies of coaches in the field of injury prevention. Research aim – to analyze the literature and to reveal expression and type of sports injuries in sports clubs.
Realistic High-Resolution Body Computed Tomography Image Synthesis by Using Progressive Growing Generative Adversarial Network: Visual Turing Test
Authors: Park Ho Young , Bae Hyun-Jin , Hong Gil-Sun , Kim Minjee , Yun JiHye , Park Sungwon , Chung Won Jung , Kim NamKug
Published: February 2021

Background

Generative adversarial network (GAN)–based synthetic images can be viable solutions to current supervised deep learning challenges. However, generating highly realistic images is a prerequisite for these approaches.

Objective

The aim of this study was to investigate and validate the unsupervised synthesis of highly realistic body computed tomography (CT) images by using a progressive growing GAN (PGGAN) trained to learn the probability distribution of normal data.

Methods

We trained the PGGAN by using 11,755 body CT scans. Ten radiologists (4 radiologists with <5 years of experience [Group I], 4 radiologists with 5-10 years of experience [Group II], and 2 radiologists with >10 years of experience [Group III]) evaluated the results in a binary approach by using an independent validation set of 300 images (150 real and 150 synthetic) to judge the authenticity of each image.

Results

The mean accuracy of the 10 readers in the entire image set was higher than random guessing (1781/3000, 59.4% vs 1500/3000, 50.0%, respectively; P<.001). However, in terms of identifying synthetic images as fake, there was no significant difference in the specificity between the visual Turing test and random guessing (779/1500, 51.9% vs 750/1500, 50.0%, respectively; P=.29). The accuracy between the 3 reader groups with different experience levels was not significantly different (Group I, 696/1200, 58.0%; Group II, 726/1200, 60.5%; and Group III, 359/600, 59.8%; P=.36). Interreader agreements were poor (κ=0.11) for the entire image set. In subgroup analysis, the discrepancies between real and synthetic CT images occurred mainly in the thoracoabdominal junction and in the anatomical details.

Conclusions

The GAN can synthesize highly realistic high-resolution body CT images that are indistinguishable from real images; however, it has limitations in generating body images of the thoracoabdominal junction and lacks accuracy in the anatomical details.