bluuebunny/crossref_metadata_2025 huggingface dataset:
Financial-cum-industrial Groups of Eastern Ukraine and the State of Industry in Donetsk and Lugansk Regions
Authors:   Primakov National Research Institute of World Economy and International Relations (IMEMO), Russian Academy of Science, 23, Profsoyuznaya Str., Moscow, 117997, Russian Federation, Krivogouz M.
Published: November 2020

The article examines the origin and the evolution processes of the main financial-cum-industrial holdings in the South-East Ukraine. The author analyses the modern state of the regional industry after an outbreak of the civil conflict in Ukraine and asserts that serious damage was done to the industrial development of the Donetsk and Lugansk regions. The conclusion is made that the system of unofficial ties between business and the state remains an integral part of the Ukrainian business processes.
Investment Activity of the World’s Leading Countries in Kazakhstan
Authors:   Kazakhstan Institute for Strategic Studies under the President of the Republic of Kazakhstan 4, Beybitshilik str., Astana, 010000, Republic of Kazakhstan, Dodonov V.
Published: November 2020

The article examines trends in the inflow of foreign investments from countries that are Kazakhstan’s leading partners in this area. Changes in the dynamics of foreign investments incoming flows in terms of their gross and net inflows, the state and changes in their typical and sectoral structure are analyzed. The situation as a whole and in relation to each of six largest investor countries of Kazakhstan is considered. It also examines the inflow of investments from the selected countries into manufacturing industry – a key branch in the context of the modernization of the Kazakhstan economy.
ETNOMÍDIA INDÍGENA: discurso e conflitos de representação do Covid-19 no Portal do CIR
Authors: Araújo Bryan Chrystian da Costa , Santi Vilso Junior
Published: November 2020

A presente pesquisa reflete sobre as práticas etnomidiáticas levadas a cabo pelo portal do Conselho Indígena de Roraima (CIR) durante a pandemia do Covid-19, a fim de entender como a organização constrói sentidos sobre a doença. Para isso, primeiro identificamos os princípios da Etnocomunicação Indígena, a partir de Baniwa (2012) e Tupinambá (2016), para depois empregar a conceituação de Representação de Hall (2003) e Soares (2007) e a Análise de Discurso de Pêcheux (1997) e Souza (2014) para examinar o corpus de estudo, constituído por 15 publicações textuais sobre o Covid-19, realizadas pelo CIR entre 21 de março e 21 de abril de 2020.
You are Welcome Here: Considerations of Diversity, Equity, and Inclusion for Embracing New Ecologists
Authors: McGill Bonnie M. , Foster Madison J. , Pruitt Abagael N. , Thomas Samantha Gabrielle , Arsenault Emily R. , Hanschu Janaye , Wahwahsuck Kynser , Cortez Evan , Zarek Kaci , Loecke Terrance D. , Burgin Amy J.
Published: November 2020

Ecology is working to face its colonial roots and institutional inequities. As we build more diverse, equitable, and inclusive (DEI) institutions we must work to support new ecologists by empowering them with the knowledge and tools to succeed. Undergraduate research experiences (UREs) are critical for a student’s professional and interpersonal skill development and key for recruiting more diverse groups of students to ecology. Here, we highlight DEI dimensions of a URE in ecology, acknowledge safety considerations for field ecology, including harassment and assault, and provide tools to support the URE. This is written primarily for all URE students and secondarily for their advisors. We welcome students from underrepresented groups and encourage allyship from students from non-underrepresented groups. After reading this paper, we hope that all students feel more confident and excited about their URE and that advisors see how to improve DEI in their lab.
The Beneficial Potential of Genetically Modified Stem Cells in the Treatment of Stroke: A Review
Authors: Salehi Mohammad Saied , Safari Anahid , Pandamooz Sareh , Jurek Benjamin , Hooshmandi Etrat , Owjfard Maryam , Bayat Mahnaz , Zafarmand Seyedeh Shaghayegh , Miyan Jaleel , Borhani-Haghighi Afshin
Published: November 2020

The last two decades have witnessed a surge in investigations proposing stem cells as a promising strategy to treat stroke. Since growth factor release is considered as one of the most important aspects of cell-based therapy, stem cells over-expressing growth factors are hypothesized to yield higher levels of therapeutic efficiency. In pre-clinical studies of the last 15 years that were investigating the efficiency of stem cell therapy for stroke, a variety of stem cell types were genetically modified to over-express various factors. In this review we summarize the current knowledge on the therapeutic efficiency of stem cell-derived growth factors, encompassing techniques employed and time points to evaluate. In addition, we discuss several types of stem cells, including the recently developed model of epidermal neural crest stem cells, and genetically modified stem cells over-expressing specific factors, which could elevate the restorative potential of naive stem cells. The restorative potential is based on enhanced survival/differentiation potential of transplanted cells, apoptosis inhibition, infarct volume reduction, neovascularization or functional improvement. Since the majority of studies have focused on the short-term curative effects of genetically engineered stem cells, we emphasize the need to address their long-term impact.
The Generations of Sequencing Technologies: An Overview
Authors: Adesiyan Ayobami , Kade Emmanuel , Ifeakachukwu Iyebeye , Oladimeji Kafayat , Sowunmi Kehinde , Oladipupo Temitope
Published: November 2020

The world has now entered into a replacement era of genomics due to the continued advancements within the next generation high throughput sequencing technologies, which incorporates sequencing by synthesis-fluorescent in place sequencing (FISSEQ), pyrosequencing, sequencing by ligation using polony amplification, supported oligonucleotide detection (SOLiD), sequencing by hybridization alongside sequencing by ligation, and nanopore technology. Great impacts of those methods are often seen for solving the genome related problems of plant and Animalia which will open the door of a replacement era of genomics. This might ultimately overcome the Sanger sequencing that ruled for 30 years. NGS is predicted to advance and make the drug discovery process more rapid.
QSAR Model for Predicting the Cannabinoid Receptor 1 Binding Affinity and Dependence Potential of Synthetic Cannabinoids
Authors: Lee Wonyoung , Park So-Jung , Hwang Ji-Young , Hur Kwang-Hyun , Lee Yong Sup , Kim Jongmin , Zhao Xiaodi , Park Aekyung , Min Kyung Hoon , Jang Choon-Gon , Park Hyun-Ju
Published: November 2020

In recent years, there have been frequent reports on the adverse effects of synthetic cannabinoid (SC) abuse. SCs cause psychoactive effects, similar to those caused by marijuana, by binding and activating cannabinoid receptor 1 (CB1R) in the central nervous system. The aim of this study was to establish a reliable quantitative structure-activity relationship (QSAR) model to correlate the structures and physicochemical properties of various SCs with their CB1R-binding affinities. We prepared 15 SCs and their derivatives (tetrahydrocannabinol [THC], naphthoylindoles, and cyclohexylphenols) and determined their binding affinity to CB1R, which is known as a dependence-related target. We calculated the molecular descriptors for dataset compounds using an R/CDK (R package integrated with CDK, version 3.5.0) toolkit to build QSAR regression models. These models were established and statistical evaluations were performed using the mlr and plsr packages in R software. The most reliable QSAR model was obtained from the partial least squares regression method via external validation. This model can be applied in vivo to predict the addictive properties of illicit new SCs. Using a limited number of dataset compounds and our own experimental activity data, we built a QSAR model for SCs with good predictability. This QSAR modeling approach provides a novel strategy for establishing an efficient tool to predict the abuse potential of various SCs and to control their illicit use.
Impacts of bioturbation by Venus clam Cyclina sinensis (Gmelin, 1791) on benthic metabolism and sediment nutrient dynamics in a shrimp-clam polyculture pond
Authors: Nicholaus Regan , Lukwambe Betina , Mwakalapa Eliezer Brown , Yang Wen , Zhu Jinyong , Zheng Zhongming
Published: November 2020

Dynamics of benthic inorganic nutrients are key biogeochemical components of sediment metabolism and ecosystems. This study investigated the roles of the bivalve Cyclina sinensis (Gmelin, 1791) and its influence on benthic metabolism, nutrient fluxes and sediment oxygen consumption (SOC) in a shrimp-clam polyculture system in comparison with shrimp culture ponds without incorporating clams, in Ningbo Zhejiang China. The benthic inorganic nutrients fluxes (ammonium-NH4+, nitrate plus nitrite-NO3-+NO2- and phosphate-PO43-) and SOC were measured across the sediment-water interface with dark incubation experiments. The results showed that there were significantly higher nutrient fluxes from the sediment into the overlying water (p<0.05) in the treatment ponds in the order of NH4+ > PO43- > NO3- + NO2-. The SOC varied significantly (p<0.05) and was three-times higher than that of the control ponds. Water quality (dissolved oxygen, pH, chlorophyll-a and salinity) recorded showed slight variations over time but were not significantly different (p>0.05) between the control and treatment ponds. Sediment organic matter and chlorophyll-a concentration measured in the shrimp-clam ponds varied significantly (p<.05) as compared to control ponds. The results of this study suggest that the bioturbation activities by C. sinensis promoted the SOC, sediment organic matter degradation and mineralisation process that increased the exchange of nutrients and oxygen uptake between the sediment and the overlying water.
Effect of incorporation of green tea extract in icing medium on the quality and shelf life of Nemipterus japonicas (Bloch, 1791) in chilled storage
Authors: Hassan F , Geethalakshmi V.
Published: November 2020

The present study was aimed at investigating the effect of inclusion of green tea leaf (GTE) extract (at 3 and 6% levels) in the icing medium employed during the chilled storage (2±1°C) of Japanese threadfin bream Nemipterus japonicus.Fish stored in normal ice (NI)was treated as control. Changes in microbiological, biochemical and sensory quality characteristics were monitored during the period of storage. Multivariate comparison was performed using principal component analysis (PCA) for the mean sensory, microbiological and chemical attributes. Samples stored in normal ice (NI) had only 8 days shelf life whereas both 3% GTE and 6% GTE stored samples had a shelf life of 16 days. From an economic point of view 3% GTE can be adopted for preservation of fish and there was no significant difference in the parameters between 3 and 6% GTE levels. Visualisation by PC plots clearly separated the investigated samples according to storage conditions, thus indicating the importance of GTEI treatment. The present study indicated that the application of GTE in ice (GTEI) is a promising technique to increase the shelf life of N.japonicus in chilled condition and hence the technique can be commercially exploited.
Utilisation of isoelectric precipitation to recover fish protein isolate from seafood processing waste
Authors: Sasidharan Abhilash , Michu V. J. , Pradhan Chiranjiv , Sabu S.
Published: November 2020

Threadfin bream (Nemipterus japonicus) is an important marine fish species used in the preparation of surimi. The waste generated from surimi production contains large quantity of recoverable proteins, which could be utilised for byproduct development. In this study, Isoelectric precipitation (IEP) technique as a method to recover proteins from fish processing waste was attempted. The alkali aided IEP process extracted the fish protein isolate (FPI) efficiently with a yield of 84.13±0.11%. The highest protein yield was recorded at a homogenised sample to water ratio of 1:9. Maximum protein content was found at pH 13 with 19.63 ±0.52% yield. FPI extracted had higher protein content, less ash and low lipid contents compared to the fish processing waste. The mean yield and protein composition of FPI extracted atdifferent treatments of pH and sample to water ratiowere found to be significantly different (p<0.05). Sample to water ratio of 1:9 and pH 13 was found to be the best combination among the different treatments attempted for FPI extraction from threadfin bream processing waste.
Development of dietary fibre incorporated tuna sausage employing response surface methodology and quality evaluation during chilled storage using multivariate control charts
Authors: Joshy C. G. , Aswathy K. S. , Zynudheen A. A. , Greeshma S. S. , Ninanand George , Ravishankar C. N.
Published: November 2020

In the present study, dietary fibre incorporated functional sausage was prepared by optimising the ingredients viz. tuna mince, wheat and oats dietary fibre using response surface methodology. D-optimal mixture response surface experimental design with 13 runs was formulated for the development of dietary fibre incorporated tuna sausage. The optimum combinations of sausage were found to be 62.5% fish mince, 2.5% wheat and 5% oats fibre and 66.8% fish mince and 1.6% of oats and wheat fibre each. The quality evaluation of combination sausage prepared at optimum conditions along with control sample was carried out based on biochemical, physical and sensory parameters during storage in chilled condition at 2°C. Storage stability studies of the optimised sausage samples indicated a shelf life of 14 days under chilled conditions. Multivariate statistical control charts based on T2 and PSE statistics were developed to monitor quality variations during storage.
Climate change drivers influencing Indian mackerel fishery in south-eastern Arabian Sea off Kerala, India
Authors: Zacharia P U , Sajna V.H. , Rojith G. , Roshen G.N. , Joseph Dhanya , Kuriakose Somy , George Grinson
Published: November 2020

The Indian mackerel Rastrelligerkanagurta(Cuvier, 1816) is one of the most important marine fishery resources along the south-eastern Arabian Sea along the coast of Kerala, south India. The effect of selected environmental variables on the Relative effort (Effort) and weighted catch per unit effort (cpue)of the fish were investigated using simple correlation and Path analysis. Six major oceanographic variables, namely sea surface temperature (SST), sea surface chlorophyll-a concentration (SSC), sea surface salinity (SSS), Precipitation (Pr) Indian Ocean Dipole (IOD) and Southern Oscillation Index (SOI) (ENSO index) were selected for the present study. Among these SST had the highest direct negative effect (-0.282, p<0.01), followed by SSS (-0.152, p<0.1) and IOD (-0.006, p<0.01). The highest positive direct effect on the cpue was exhibited by Pr (0.514, p<0.001) followed by SSC and SOI (0.178, p<0.01). The environmental variables also exerted indirect effects on cpue through Effort. The residual variance indicated that there are spurious effects exerted by environmental variables not included in the study. According to the coefficient of determination (R2), the relative importance of the influence of causally dependent environmental variables on the cpue of Indian mackerel is Pr> SSC >SSS.
Biometry, length-weight and length-length relationships of flathead sillago Sillaginopsis panijus (Hamilton, 1822) (Perciformes: Sillaginidae) from the north-western Bay of Bengal
Authors: Pradhan Suraj Kumar , Roul Subal Kumar , Ghosh Shubhadeep , Tripathy Pritam , Jaiswar A. K. , Bhusan Sashi , Nayak B. B.
Published: November 2020

Biometry, length-weight relationships (LWRs) and length-length relationships (LLRs) of Sillaginopsis panijus (Hamilton, 1822) were investigated in the Indian coast of north-western Bay of Bengal. Altogether 622 specimens were collected between August 2018 and September 2019 from landings by trawls (30-35 mm mesh size), gillnets (15-55 mm mesh size) and shore seines (7-15 mm bag mesh size). The total length and weight of the specimens ranged from 7.8-40.3 cm and 2.9-506 g, respectively. The LWR established was W=0.0048 L3.059 for males, W=0.0032 L3.185 for females and W=0.0047 L3.0645 for indeterminates, indicating positive allometric growth pattern. All the LWRs were highly significant (p<0.001, r2≥0.977). The highest coefficient of correlation (r) was observed for total length against fork length (0.999) and lowest for head length against eye diameter (0.951). The fin formula was expressed as D1 X, D2 I + 24-28, P 17-22, V I + 5, A II + 25-27, GR 2-3/6-9. The study provides the first detailed account of the biometric relationships of S. panijus in the north-western Bay of Bengal, which can be used as baseline information for subsequent biological and population based studies in the region.
Induced spawning and embryonic development of striped murrel Channa striata (Bloch, 1793) under indoor conditions using salmon gonadotropin releasing hormone analogue (sGnRHa)
Authors: Rawat Anurag , Raizada Sudhir , Yadav Kailash Chandra , Sahu Vikash
Published: November 2020

Ten successful trials on induced breeding of the striped murrel Channa striata (Bloch, 1793) under indoor conditions were carried out during July-August 2019. Brooders reared in cement tanks,(males weighing in the range of 290-700 g and females 220-600 g), were used in a set of 2:2 male to female ratio for induced breeding with salmon gonadotropin releasing hormone anologue (sGnRHa) and dopamine antagonist commercial formulation. Each brooder set was kept in an FRP tank (13’x3’x14’’) along with submerged macrophyte Hydrilla verticillata, which was sparsely spread all around the tank. Maturity of brooders was screened on the basis of secondary sexual traits. The brooders were given hormonal injection after 6 h of acclimatisation under indoor conditions @ 1 ml kg-1 body weight (containing sGnRHa 20 µg ml-1 and domperidone 10 µg ml-1) to both the sexes. Natural spawning occurred in all ten sets within 21.5+3.2 h (17-26 h) of injection. In all the tanks, two separate egg masses were observed with 30-95% fertilisation. Approximately 0.14 million eggs were scooped out from the tanks and reared in round plastic tanks (70 l) for hatching, where hatching occurred within 17-26 h post-fertilisation (hpf) with hatching rates of 50.76 to 93.18% at 28+2oC. The embryonic development was recorded under a stereo-zoom microscope in live condition under controlled temperature conditions and described with digital images. The study revealed that induced breeding of C. striata can be undertaken in FRP tanks under indoor conditions for mass-scale seed production, which will provide a platform for diversification of this high valued fish species for large scale farming practices in ponds as well a new species for culture in recirculatory aquaculture system (RAS) and biofloc technology (BFT).
Análise econômica da produção de Pitaya na agricultura familiar do sul de Santa Catarina
Authors: Pires Eliton , Krauze Carlos
Published: November 2020

Conhecer o custo de produção é uma das ferramentas mais importantes para subsidiar o planejamento e a tomada de decisão na agricultura. A pitaya é uma fruta exótica que tem despertado o interesse de produtores e consumidores no Brasil. Neste trabalho foram analisados os dados econômicos de pomares de pitaya de quatro propriedades com características de agricultura familiar na região do extremo sul do estado de Santa Catarina, seguindo a metodologia da Conab. O custo médio de produção ficou em R$ 1,53/kg e o preço de venda foi superior a R$ 4,00/kg.  As propriedades analisadas se mostraram eficientes, com lucratividade acima de 60%. Porém, foram identificados espaços para cortes de custos, como a introdução de novas cultivares e a utilização de produtos fitossanitários, máquinas e implementos adequados tecnologicamente à cultura da pitaya.
A Novel Workflow of Greenhouse Gas Capture and Utilization in Well Health Issue
Authors: Haq Bashirul , Hossain M. Mozahar
Published: November 2020

Liquid load issue is commonly found in the gas condensate reservoir. In this regard we consider a novel workflow consisting: (i) CO2 capture from fossil fueled power plants, (ii) inject the captured CO2 into the well and (iii) investigate the effects of CO2 injection in well health. This communication reports, the issue identification and verification, as well as the effects of high purity CO2 on surface tension, minimum miscible pressure (MMP) and well productivity.

ScCO2 will be obtained from a chemical-looping combustion (CLC) integrated power plant. The novel CLC method includes the application of a solid oxygen (O2) carrier to supply O2, instead of air, to carry out the fuel combustion, thereby almost pure CO2 can be delivered without any energy penalty for separation. The captured CO2 needs to be brought in ScCO2 condition before injection. A mathematical workflow model was developed to identify and verify liquid loading issue. In addition, surface tension, and density were measured at high pressure and temperature to analyse the influence of supercritical CO2 in recovery and liquid loading.

As indicated above, this study comprises with three major aspects (i) captured/compressed of CO2 from a power plant and (ii) use of ScCO2 in gas condensate reservoirs and (iii) impact of pure CO2 in the well health. In CO2 capture, a thermodynamic parametric models analysis has been conducted using natural gas as fuel, and nickel oxide as a solid oxygen carrier.

The influence of temperature in fuel and O2 ratios are examined by the Gibbs free energy method to determine the combustion product composition. It reveals that CO2 is purified up to 99.5% in the fuel combustion cycle which is nickel (Ni) based O2 carrier. The result is agreed with the experimental studies.

The workflow model identified and varied liquid loading in an active well. Surface tension (ST) between Arabian condensate and ScCO2 was measured and found that ST continued to decrease with increasing pressure. Dynamic miscibility value was determined at high pressure and temperature.
A Bonded 3D LBM-DEM Approach for Sand Production Process
Authors: Xia Tian , Feng Qihong , Wang Sen , Zhao Yunchang , Xing Xiangdong
Published: November 2020

Due to the long-term fluid-solid interaction in waterflooding, some sand particles forming the reservoir formation detach from the rock and migrate with fluid in the reservoir, which will cause many problems such as borehole instability and casing collapse. However, the mechanism for sand production process is not clear. Therefore, it is very urgent to find out the mechanism for this process. This paper presents a coupled lattice Boltzmann method and discrete element method (LBM-DEM) to study the sand production process of the formation. The method has been validated by simulating the sedimentation of single particle. Simulation of sand production process is conducted and the effect of cementation type, cementation strength and injection rate are investigated. During the simulation, sand particles will detach from the reservoir and the formation will reach a steady state after a period of time. Strong force chain rupture can be recognized, which is the main reason for sand detachment. Besides, force chain reorganization can be identified. The total number of produced sand first increases and remain constant after the force chain reorganization. Reservoir with clay cement produces more sand than that with carbonate cement. For the same cementation type, reservoir with lower cementation strength produces more sand than the higher one. Moreover, higher injection rate leads to more sand production than the lower injection rate. The proposed method presents simulations of sand production process at a pore-scale level which is the best scale level to describe the phenomena. Compared with experimental method, it doesn't need too much labor and can reveal the mechanism of this process. This method not only can be widely used in the study of sand production process but also can deal with other problems such as proppant migration in fracturing and gel particles migration in profile control, which is very important to the oil field development.
Estimating Coal Permeability Using Machine Learning Methods
Authors: Salehi Cyrus , Zhong Ruizhi , Ganpule Sameer , Dewar Steven , Johnson Raymond , Chen Zhongwei
Published: November 2020

Bulk permeability of coal is a critical parameter in coalbed methane (CBM) or coal seam gas (CSG) well completion designs and field development planning. The estimation of permeability can be made by well testing either during drilling or production; however, well tests are costly, time sensitive and resource-intensive. Therefore, field-wide estimates are often dependent on production data history-matching, which has a high degree of uncertainty.

In this paper, we present a new attempt to apply machine learning approach to estimate coal permeability using drilling data. We first extract important parameters from well test analyses, which are obtained using a packer element testing (PET) tool from four wells in the Surat Basin, Australia. Then drilling data from the wells are processed and fed into different artificial neural networks (ANNs), which include multi-layer perceptrons (MLP), convolutional neural network (CNN), and recurrent neural network (RNN). Two types of models are constructed: regression model with permeability values, and classification model with permeability class intervals (i.e., low, medium, and high permeability values). The evaluation metrics include R2 for regression models and confusion matrix for classification models.

Results show that the drilling mud losses are generally higher in coal layers and lower in interburden formations. The predicted medium and high coal permeabilities from MLP and CNN are in good agreement with measured permeability values from PET data. For the classification task, the CNN achieved an overall accuracy of 99%. Thus, an improved coal permeability map with a higher resolution and less calibration against PET data can be developed quickly to aid production data history matching. The developed machine learning model demonstrated a potential to be applied to new wells to predict the coal permeability for the Surat Basin as well as other CSG appraisal projects. This model can allow more rapid optimisation of well spacing, improved downhole pump design, more targeted well stimulation, and overall project economics.
Sand Monitoring in Gas Wells: Enhanced Methodology of Sand Sampling via Combination of Online Sand Sampler and Acoustic Sand Monitors to Determine Max Sand Free Rates for Identification of Quick Gain Opportunities and to Quantify Sand Production
Authors: Kunasekaran Sarran Raaj , Sidek Sulaiman , Ambrose Jonathan , Mackie Alex
Published: November 2020

Sand production from wells are one of the operators’ biggest nightmare as the cascading effect can cause some major harm to the surface equipment as well as lead to a costly cleanup effort. Sand sampling in gas wells is considered a rare activity due to the difficulty of containing the gas flow. The objective of this paper is to elaborate on why this activity is crucial to be performed in sand prone gas wells and more importantly the value it can bring to the asset owner. The paper will also elaborate further on the benefits of coupling the online sand sampler with the acoustic sand monitors to improve accuracy and reliability of readings

The paper will elaborate the major difference in sampling for oil wells and gas wells. Operators of oil fields have the liberty of sampling from an existing sampling point to obtain the sand count. However, obtaining the sand count in a gas well is not as straight forward as it is for oil wells hence the importance of this activity. Quantification of sand produced in gas wells are also a challenge as only amount of sand is reported from the desander flushing. The paper will contain a detailed procedure on the methods to quantify sand production as well as the process flow to determine the max sand free rates safely to meet the objectives of this project.

Some of our wells were ‘accused’ of producing sands at certain flowrates. Since the wells were not equipped with any type of permanent sand monitoring equipment, there were no conclusive ways of proving that the wells were sand free. Due to that, the wells flowrates were curtailed to protect the asset from the effect of sand production. With the completion of this activity, we could conclusively prove that the wells were free from producing sands at the existing rates. On top of that, from the process of determining the max sand free rates (MSFR) this activity gave us enough confidence to produce our wells at a proved sand free rate. In conclusion, not only does this activity allow us to prevent further production deferments, this activity also allows us to increase production by beaning up the wells if possible

This is a very flexible method that can be used as the main method to sample sand in gas wells. It is a very cost-effective method as well as logistically friendly to mobilize to even offshore fields.
Is Chemical EOR Finally Coming of Age?
Authors: Delamaide Eric
Published: November 2020

Chemical flooding is one of the classical EOR methods, together with thermal methods and gas injection. It is not a new method; indeed, the first polymer flood field pilots date back to the 1950s while the first surfactant-based pilots can be traced back to the 1960s. However, while both gas injection and thermal methods have long been recognised as field proven and are being used at a large scale in multiple fields, it is not the case for chemical EOR.

Although there have been over 500 polymer flood pilots recorded, and almost 100 surfactant-based field tests, large scale field applications are few and far between. This situation seems to be evolving however, as more and more large scale chemical projects get underway. This paper proposes to review the status of chemical EOR worldwide to determine whether it is finally coming of age.

The status of chemical EOR projects worldwide will be reviewed, focusing on recent and current large-scale field developments. This will allow to establish what is working and where the industry is still encountering difficulties. This review will cover North America, South America, Europe, the Middle East, Asia and Africa.

It is clear that polymer flooding is now indeed becoming a well-established process, with many large-scale projects ongoing or in the early stages of implementation in particular in Canada, Argentina, India, Albania and Oman in addition to China. Strangely enough, the US lags behind with no ongoing large-scale polymer flood.

The situation is more complex for surfactant-based processes. At the moment, large-scale projects can only be found in China and – although to a lesser extent – in Canada. The situation appears on the brink of changing however, with some large developments in the early stages in Oman, India and Russia. Still, the economics of surfactant-based processes are still challenging and there is some disagreement between the various actors as to whether surfactant-polymer or alkali-surfactant polymer is the way to go.

This review will demonstrate that polymer flooding is now a mature technology that has finally made it to very large-scale field applications. Surfactant-based processes however, are lagging behind due in part to technical issues but even more to challenging economics. Still there is light at the end of the tunnel and the coming years may well be a turning point for this technology.
Integrating Reservoir Characterisation, Diagnostic Fracture Injection Testing, Hydraulic Fracturing and Post-Frac Well Production Data to Define Pressure Dependent Permeability Behavior in Coal
Authors: Johnson Raymond L. , You Zhenjiang , Ribeiro Ayrton , Mukherjee Saswata , Salomao de Santiago Vanessa , Leonardi Christopher
Published: November 2020

Defining pressure dependent permeability (PDP) behaviour in coalbed methane (CBM) or coal seam gas (CSG) reservoirs using reservoir simulation is non-unique based on the uncertainty in coal properties and input parameters. A diagnostic fracture injection test (DFIT) can be used to investigate bulk permeability at a reservoir level and at lowered net effective stress conditions. As coal has minimal matrix porosity and under DFIT conditions cleat porosity is fluid saturated with reasonably definable total compressibility values, the DFIT data can provide insight into PDP parameters. At pressures above the fissure opening pressure, pressure dependent leak off (PDL) behaviour increases exponentially with increasing pressure. Many authors have noted that with decreasing pressure PDP declines exponentially with increasing net effective stress. Thus, PDP behaviour can be defined by PDL.

In this paper, we show how combined analyses, using typically collected field data, can be used to better define and constrain the modelling of PDP. We illustrate this process based on a well case study that includes the following data: fracture fabric and porosity reasonably defined from image log and areal core studies; DFIT data acquired under initial saturation conditions; hydraulic fracturing data; and longer term production data. These analyses will be integrated and used to constrain the parameters required to obtain a rate and pressure history-match from the post-frac well production data.

This workflow has application in other coal seam gas cases by identifying key variables where hydraulic fracturing performance has been unable to overcome limitations based on pressure or stress dependent behaviours and often accompanied by low reservoir permeability values. While this is purposely targeting areas where only typically collected field data is available, this workflow can include coal testing data for matrix swelling/shrinkage properties or other production data analysis techniques.
Direct Approach for Contact Angle Measurement of Neutral Wet HSP Proppants
Authors: Al-Boghail Fawaz , Al Moajil Abdullah , Al-Arawi Abeer , Al-Darwish Sajad
Published: November 2020

Neutral wet proppant plays a pivotal role in maximizing the flow back of fracturing fluids and the recovery of produced hydrocarbons. An accurate and repeatable contact angle measurements are extremely challenging because of proppant spherical shape and small size. This paper presents a methodology of direct contact angle measurements in spherical particles examined with high strength coated ceramic proppant.

20/40 and 25 HSP non coated proppants were used for the study. Coating material was applied to the proppant sample to obtain non-wetting characteristics. KRUSS Drop shape Analyzer was utilized to measure the contact angle using a modified pendent drop method. Step by step procedure is detailed and possible sources of errors were identified, and recommendations were introduced accordingly.

HSP coated proppant showed contact angle measurements of 117-120° and 84-114° with deionized water and hydrocarbon samples, respectively. Ideally, a neutrally wetted surface would have a contact angle of 90°. This indicates that the proppant is neutral to slightly oil-wet. Wetting characteristics are dependent of hydrocarbon type. For instance, Condensate 2 have a contact angle of 102.3° indicating neutral wetting characteristics, whereas Condensate 3 shows contact angle of 84.5° indicating slightly oil-wet character. Geometry of hydrocarbon droplets modified the adhesion tension of oil, nevertheless had insignificant effect with water drops. For example, tripling the droplet size of Condensate 2 and Diesel resulted in increment in contact angle values of 12° and 15°, respectively.
New Method of Well Integrity Screening for Carbon Dioxide Storage Well
Authors: Zulkarnain Nurul Nazmin , Abu Bakar Mohd Azuan , Zakaria Nur Atiqah
Published: November 2020

The issue of global warming is widespread nowadays with an increase in the surface temperature of the earth. Carbon dioxide, CO2 emission from industrial energy is one of the contributing factors to this issue. The concept of CO2 storage is one of the potential solutions to achieve zero CO2 emissions from the oil and gas industry. In order to have an effective cost solution, existing wells are suggested as CO2 injection wells. Therefore, the structures of the existing wells are assessed to observe the sustainability of the well towards CO2 injection since the wells previously drilled without considering their potential secondary life.

Well screening is carried out through 19 development wells in the RSK field. The method used in this screening including; information gathering through the master database, selection of screening criteria and risk quantification. The screening criteria consist of cement quality and quantity, casing metallurgy and wellhead grade. The screening results will be categorized under three different risks; low, high and unknown-risk. Each of the categories and the evaluation methods will be discussed in-depth in this paper.

The assessment resulted in 44% of low-risk well, 50% of the high-risk well and the remaining 6% of the unknown-risk well. The high-risk well is when the well does not meet one or more screening criteria set out, while the low-risk well clearly shows the well fit all the standard as CO2 compliance well. The unknown-risk is classified when there is no sufficient information to do the evaluation. It can be observed that most of the high-risk wells are from the first drilling campaign, while the latest campaign contributes to most of the low-risk well. To reduce the severity of high-risk well, squeeze cementing, geopolymer cement, wellhead modification and workover can be suggested. At the same time, detailed report searching from operators and service companies can be recommended to unknown-risk well.

The study is a quick look well screening for CO2 storage well. In order to strengthen the screening result; reservoir continuity, caprock integrity and comprehensive well assessment concentrating on packer integrity, tubing integrity, injection pressure, internal and external pressure and corrosiveness of injection fluid can be carried out to transform the high-risk well into a low-risk well and classifying the unknown-risk into a specific class.
Utilizing Surface Microseismic Monitoring to Improve Understanding of Natural Fractures in Sichuan Shale Gas Play
Authors: Jing Cui , Chen Yanyan , Jing Xianghui , Wang Bing , De Heng , Huang Zheyuan , Wen Ran , Zhang Caiyun , Zhou Nie
Published: November 2020

The highly complex geology of the Sichuan Shale gas play, especially in relation to natural fracture systems at different scales, affects the hydraulic completion efficiency and performance. Ant-tracking-based workflows and borehole image data are regularly used to optimize completion campaigns, but bridge-plug-stuck and screen-out risks are still high. The lack of sufficient understanding and accurate identification of the natural fracture systems are the major challenges to address these engineering risks.

Surface microseismic monitoring campaigns were conducted over several wells of the Changning field, Sichuan Basin, China. The surface receivers were placed in a radial pattern to record microseismicity generated by hydraulic fracturing. The failure mechanism of all mapped microseismic events (i.e., strike, dip, rake, etc.) was extracted using a moment tensor inversion (MTI) method. Improved understanding of the natural fracture systems and their influence during the hydraulic fracturing process has been achieved by integrating the regional geological data, pumping data and MTI results.

Several hydraulic fracturing cases that stimulated near natural fracture systems were investigated. The microseismic monitoring results show that (i) most of the hydraulically induced fractures located in the vicinity of the natural facture or fault did not propagate along the regional maximum stress direction, (ii) the bridge plug got stuck and (iii) screen-out happened frequently in these areas. Moment tensor inversion reveals that (i) the dominant failure mechanism of the natural fractures different from hydraulically induced fractures, (ii) more than one group of natural fractures develop along different directions.

Real-time adjustments of the pumping schedule and bridge-plug settings were conducted to reduce engineering risks based on the improved understanding of natural fractures, which proved effective. The innovation of using surface microseismic monitoring results to improve understanding of natural fractures and reduce the engineering risks in real time represents a key step forward to mitigate natural fracture influence and improve the effectiveness of stimulation.
The First 7-in. Single-Trip Multizone STMZ Gravel Pack Completion Best Practices and Lessons Learned in Malaysia Offshore
Authors: Bakar Hasmizah , Faris W Hassan W M , Kumar Suman , Faliq Jamal Ajmal , Magna Bela Sunanda , Fiqri Hairi Helmi , Latif Nurlizawati , Hashim Saharul , Tham Dennis , Shahabuddin Syukri
Published: November 2020

A 7-in. single-trip multizone (STMZ) gravel pack system was installed successfully in two wells in the T field, Sarawak offshore. This paper highlights the system performance and knowledge obtained during this first-time installation performed in Malaysia. The most common sand control techniques established in the H, I, and J sands of this mature field include stacked gravel pack, 9 5/8-in. single-trip multizone gravel pack, and openhole standalone sand screen (OHSAS) systems. Internal gravel pack completions have provided proven, robust sand control for the sand-prone reservoirs in the T field and can save four to five days of rig time depending on the well configuration, compared with the standard stacked gravel pack completion, which was initially planned during the field development plan (FDP) stage. This paper presents the extensive technical works performed post-FDP approval to ensure the change from the 7-in. stacked gravel pack to the 7-in. single-trip multizone gravel pack completion was executed safely and efficiently and most importantly able to maximize the recoverable reserves from the multiple unconsolidated reservoirs. The technical challenges, such as unexpected drilling of additional zones, limited annulus clearance between the 7-in. liner and gravel pack tool string to reverse out proppant efficiently, intersands spacing, and gross sand interval constraints within certain tolerance because of bottomhole assembly (BHA) limitations, are also discussed. The 7-in. single-trip multizone gravel pack installation helped reduce rig time and provided a cost savings of nearly USD 1.1 million. Subsequently, the two oil-producing (OP) wells (two OP wells and four OP strings) are producing sand-free at higher than expected reserve and flow rates.
Using Alcohol-Treated CO2 to Reduce Miscibility Pressure during CO2 Injection
Authors: Saira Saira , Yin Hang , Le-Hussain Furqan
Published: November 2020

CO2 injection is one of the most promising enhanced oil recovery (EOR) techniques because it can also reduce greenhouse gas through CO2 sequestration. However, effectiveness of CO2 injection dependent on CO2 miscibility. If reservoir is depleted, reservoir pressure is usually not high enough to achieve miscible or near-miscible conditions during CO2 injection in oil reservoirs. In this paper we investigate whether the required miscibility pressure can be reduced by substituting CO2 with alcohol-treated CO2.

Experimental measurements of interfacial tension (IFT) and swelling behavior were made using a high-pressure and high temperature visual cell at 70 °C. Two sets of fluid pairs were used (i) pure CO2 and oil, and (ii) alcohol-treated CO2 and oil. Two types of oil were used: a mixture of 35% hexane and 65% decane (C6-C10 mixture), and pure decane (C10). Ethanol and methanol alcohols were used to prepare alcohol-treated CO2 (a mixture of alcohol and CO2 equilibrated at experimental pressure and temperature). The experiments were matched using an equation of state to provide a quantitative measurement of the miscibility pressures. This study has identified that capillary rise method can be used for IFT measurements down to 0.04 mN/m. The conventional pendant drop method can only be used for IFT values greater than 1 mN/m. For IFT values greater than 1 mN/m, both methods are in close agreement. Validation of IFT simulated model with experimental IFT results showed a good agreement. Results showed that for pure C10, ethanol-treated CO2 cause 0.4 mN/m to 1.5 mN/m IFT reduction leading to 1.1 MPa minimum miscibility pressure (MMP) reduction and methanol-treated CO2 cause 0.4 mN/m to 2.2 mN/m IFT reduction leading to 0.2 MPa MMP reduction. While for C6-C10 mixture, ethanol cause 0.02 to 1.42 mN/m reduction in IFT and methanol cause 0.02 to 0.2 mN/m. Both alcohol have similar reduction of 1.1 MPa in MMP. Results also suggest that alcohol-treated CO2 leads to a better oil swelling behavior for both type of oil which helps to release oil from rock pore. However, ethanol presence in alcohol-treated CO2 shows more oil swelling than methanol. Experimental observations reveal that alcohol-treated CO2 is effective than pure CO2 for IFT reduction and enhancing oil swelling. Furthermore, experiments should be performed using real field crude oil.
Quick Caprock Integrity Analysis for CO2 Storage Sites in Malaysian Fields.
Authors: Mohd Ali Siti Syareena , W. Zairudin W. Ahmad , Abu Bakar Zainol Affendi , Kantaatmadja Budi Priyatna , Ismail Issham
Published: November 2020

The purpose of this research work is to establish a quick method for caprock integrity assessment for carbon dioxide (CO2) storage site selection. There are three main components to evaluate a seal potential which are through seal capacity, seal geometry, and seal integrity. This research work focuses on evaluation of seal characteristics through its pressure behaviour and evidence of potential leakage. Various logs data such as gamma ray, sonic logs, density logs, and resistivity are utilized to establish 1D pore pressure analysis. At the same time mud logs data are used to investigate the similarity of hydrocarbon from reservoir and seal (if any). In this study, two mature brownfields namely Camos and Zhann have been identified and evaluated for their seal characteristics, thickness, environment of deposition and pressure regimes differences in order to determine their seal effectiveness through integration of pore pressure analysis, background gas or gas while drilling evidence and seal capacity from Mercury Injection Capillary Pressure (MICP) data. Camos field, a depleted carbonate field in Sarawak Basin with continuous seal shows an overpressure regime with gas chimney in immediate seal above it. Meanwhile Zhann field, a depleted clastic field in Malay Basin shows slight overpressure in deeper reservoirs and hydrostatic in most of the multistack sand reservoirs. Both fields show the evidence of effective seal through their own geological characteristics, pore pressure and gas component analysis. Nevertheless, both fields have their own challenges to be converted to potential storage sites. A detailed understanding and analysis are required for seal integrity evaluation which can lead to better plan establishment that may further reduce risks during selection of CO2 injection site and help to execute future well or field monitoring design.