bluuebunny/crossref_metadata_2025_split huggingface dataset:
Switching from Water Injection Scheme to Gas Injection Scheme for Improved Oil Recovery in a Niger Delta Oilfield
Authors: Akpabio Julius U. , Jackson Benson E. , Udie Celestine A. 
Published: July 2019

Abstract
The ‘JEB’ oilfield has been in operation since 1992 with 24 oil producing Wells, 8 water injection Wells and no gas injection. From inception, the field was producing at the rate of 27 MSTB/D. The gas produced was 34,333.7 SCF/D which was being flared but later supplied to the Nigeria Liquefied Natural Gas (NLNG) for export. The field had very weak aquifer support and therefore had been water-flooded from early days of its production. With high water cut, it was necessary to find ways of reducing water production and increasing oil production. The study involved field data gathering, history matching of the field data and prediction of future production. Production rates from the different production schemes were simulated for fourteen years. The cumulative oil production of gas injection, water alternating gas (WAG) injection and gas alternating water (GAW) injection schemes were 4.28 MMMSTB, 3.29 MMMSTB and 3.15 MMMSTB respectively representing an incremental recovery of 38%, 6%, and 1%. The cumulative water production of gas injection, WAG injection and GAW injection were 2.65 MMMSTB, 6.52 MMMSTB and 6.90 MMMSTB respectively, which represent 64%, 10% and 5% reduction in produced water. The economic analysis showed gas injection as the best alternative injection scheme for the field with internal rate of return (IRR) of 19.26 %, while the IRR of WAG and GAW injection schemes were 12.09 % and 11.22 % respectively. Also, at 15% discount rate, the gas injection scheme had the best result with a Profitability Index (PI) greater than 1, a positive Net Present Value (NPV) while all other injection schemes had negative NPV and PI was less than one. The possibility of changing a field from water injection to gas injection has been explored, hence, before embarking on any enhanced oil recovery scheme, other alternatives should be evaluated.
Utilization of Big Data Analytics and Advanced Formation Modelling for Detection of Kicks in Drilling Operations
Authors: Isemin Isemin. A. , Nkundu King-Akanimo B. , Agwu Okorie E. 
Published: July 2019

Abstract
A Kick, the influx of formation fluid into the wellbore while drilling, poses a major challenge to drilling operations and can spiral out of control into blowouts with severe fatal, fiscal and environmental consequences. Kicks characteristically have a higher occurrence when drilling in relatively unexplored formations and with the combined factors of a waning era of easy oil and increasing energy demand, the consequent push for petroleum exploration in unconventional formations demands better techniques to detect and control kicks. This work has detection of kicks as its objective. Traditional methods of detecting kicks by monitoring drilling mud levels in the tanks has proven to be cumbersome and error prone and it leaves little time for an effective response. Thus, the use of analytics of real time drilling data and advanced formation modelling is presented as an approach to create a better representation of the drilling environment sub-surface and identify potential threats of a kick along the course of drilling (with respect to the trajectory as well as decisions to be made following that course). The methodology seeks to create a comprehensive model that defines relevant physical parameters whose values can be used as data sets which describe the ongoing drilling process and its relationship with the background formation with the aim of bringing forth information which would give a representation of consequent events. Notable parameters include, porosity, rock density, drill string hook load, weight on bit (WOB), mud density, formation fluid resistivity, rate of penetration, ultra sound speed across media, drilling trajectory amongst others, all relative to time. The background formation is aptly described in discretized grid blocks and is then cross-matched with the real-time data from the drillstring to double-check the actual position of the drillstring at any point in time. The interactions of the formation with the drillstring trajectory are computed as described by the grid blocks in contact with the drill string trajectory as well as adjacent grid blocks. The data describing the formation can be regularly updated to represent whatever sensitive changes that might have occurred in the formation while drilling. This solution, though notably complex is well within the capacity computing power available in the upstream petroleum industry and shows great promise to eliminate all the disastrous consequences that arise from late detection of kicks.
Digital Rock Core Simulation of Waterflooding, Showing the Impact of Rock Heterogeneity on Oil Production
Authors: Olofinnika Oluwakemi 
Published: July 2019

Abstract
Digital rock special core analysis has been used in recent times as an alternative to laboratory special core analysis (SCAL) but has failed to deliver the level of accuracy required by service companies. Current research suggests the dominant role of capillary pressure heterogeneity in flow characterization compared to viscous and gravity forces. However, the irreversible changes in relative permeability (hysteresis) during strategies for hydrocarbon recovery, have not been integrated.
Hence, capillary heterogeneity and hysteresis were incorporated in numerical corefloods of primary waterflooding. Heterogeneity in the Bentheimer and Berea cores used for this study, were defined by a 3D spatial variation in capillary entry pressure obtained from experiments. Steady state Decane drainage preceded waterflooding. Capillary numbers were obtained across a range of rates depicting capillary to viscous dominated flow regimes, controlled by rock heterogeneity and distance from the well.
Simulation results showed a dominance of heterogeneity in lowering oil production especially in the Berea-characterized by increased capillary strength-than the corresponding Bentheimer case. Hysteresis accelerated but decreased ultimate oil recovery, with greater impact in viscous (higher rates) than capillary dominated conditions (lower rates). Capillary number increased nonlinearly with flow rate. Also, residual oil saturation increased from low to high rates until a considerable decline ensued beyond threshold rates for which viscous pressure drop exceeded 60–3 times the highest capillary entry pressure in the Bentheimer and Berea cores respectively.
Thus, the significant influence of capillary heterogeneity on oil production and the use of digital cores to estimate the irreversible oil trapping effects of hysteresis within heterogeneous rock sections is highlighted. This gives insight into effective enhanced oil recovery strategy to capture capillary trapped oil across core to field scales.
Estimating and Modeling of Spatial Variability of Volumetric Attributes of a Nigerian Heavy Oil and Bitumen Deposit
Authors: Mosobalaje Olatunde O. , Orodu Oyinkepreye D. , Ogbe David O. 
Published: July 2019

Abstract
Deposits of heavy oil and natural bitumen have been long-discovered in the Dahomey basin south-western Nigeria. However, inconsistency in estimates of volumes of hydrocarbon contained in these deposits has inhibited commercial interest in the deposits. The inconsistency is attributable to the little or no consideration for spatial variability in those studies. This work is therefore motivated by the need for spatially-coherent geomodels leading to reliable volumetric estimates. An existing database of porosity, depth-to-top and thickness attributes of a section of the deposits located at Agbabu is the subject of this work.
This work conducted exploratory spatial data analysis (ESDA) as well as empirical variogram estimation, interpretation and modeling of the attributes. Here, the estimation and interpretation of empirical variogram faced a number of challenges with potentials to render the estimates uninterpretable, unstable and inconsistent with geologic information. These include presence of spatial outlier data, clusteredness of variogram clouds, data paucity, and irregular distribution of point-pairs on variogram clouds. Spatial outliers were either removed or correlated with existing geologic information. The clusteredness issues were resolved using a machine-learning – aided variogram estimation technique recently proposed. Variogram cloud binning approach was deployed to handle irregular distribution of point-pairs. In attempting to deploy an automatic fitting algorithm, cases of insufficient empirical points leading to lack of convergence were encountered. Such cases were resolved by adopting a combination of manual and automatic fitting approaches.
Ultimately, this work presents a three-dimensional anisotropic (zonal) porosity variogram model and two-dimensional anisotropic (geometric) models for the depth-to-top and thickness variograms. These models are suitable inputs to spatial interpolation algorithms in generating maps of these volumetric attributes.
Interpreting Downhole Pressure and Temperature Data from ESP Wells by Use of Inversion-Based Methods in Samabri Biseni Field
Authors: Adesanwo Moradeyo , Bello Oladele , Zhu David , Owen Barthemeaus , Ogu Bob , Ossai Jennifer Chimuanya , Iwo George 
Published: July 2019

Abstract
Increasing need for improved efficiency, service life and cost reduction using downhole real-time streaming sensor data is making electrical submersible pump (ESP) well operation management one of the most important issues in production optimization and improved oil recovery. Expanding the benefit of the downhole sensors is currently driving the need for embracing dynamic data-driven application systems (artificial intelligence, machine learning and deep learning) and big data tools by Oil and Gas industry to gain competitive advantage. One of the shortcomings for conventional data driven approach is that artificial intelligence (machine and/or deep learning) algorithms are totally decoupled from physics based modeling due to the lack of domain knowledge. As OEM for ESP, we have an industry proven ESP system simulator that can be used to generate training dataset for scalable data driven monitoring of ESP systems. Correct interpretation of temperature and pressure data can lead to improved accuracy of continuous downhole flow performance characteristics and reservoir properties such as static reservoir pressure and productivity index, which are key information to control and optimize ESP-based well production. In this work, a physics-based data driven model and inversion-based methods for model calibration and updating are developed for ESP well monitoring. The model is used as a forward engine and an inversion procedure is then added to interpret the measured data to estimate reservoir pressure, productivity index, downhole multiphase flow rates, and perform production allocation to improve hydrocarbon recovery and mitigate water/gas breakthrough risk. The new modeling framework introduces a fast and accurate forward model that incorporates specific measurements response functions for the physics-based data driven simulation model of permanent downhole gauge data in the ESP wells. Multiple inversion methods are used to interpret the downhole-measured data. Under the assumption of a subsurface multiphase flow model, the inversion approaches estimate well rates, back flow allocation, productivity index and reservoir pressure response specific to a given measurement domain by numerically reproducing the available measurements. The model and estimation techniques are evaluated with field data obtained from multiple wells located in a producing field. Many estimation simulations are performed using various sampling rates of the ESP AutographPC software. The satisfactory predictive accuracy of the physics-based data driven model makes the determination of multiphase flow and reservoir parameters computationally inexpensive, adaptive to operational changes, and suitable for online real-time system implementation.
Costs and Health-Related Quality of Life in Relation to Caries
Authors: Kastenbom Lisa , Falsen Alexandra , Larsson Pernilla , Sunnegårdh-Grönberg Karin , Davidson Thomas 
Published: July 2019

Abstract
Background

Dental caries remains a common and expensive disease for both society and affected individuals. Furthermore, caries often affect individuals’ health-related quality of life (HRQoL). Health economic evaluations are needed to understand how to efficiently distribute dental care resources. This study aims to evaluate treatment costs and QALY weights for caries active and inactive adult individuals, and to test whether the generic instrument EQ-5D-5L can distinguish differences in this population.

Methods

A total of 1200 randomly selected individuals from dental clinics in Västerbotten County, Sweden, were invited to participate. Of these, 79 caries active and 179 caries inactive patients agreed to participate (response rate of 21.7%). Inclusion criteria were participants between 20-65 years old and same caries risk group categorization in two consecutive check-ups between 2014 and 2017.

Results

Treatment costs showed to be twice as high in the caries active group compared to the caries inactive group and were three times higher in the caries active age group 20-29 compared to the caries inactive age group 20-29. Differences between the groups was found for number of intact teeth according to age groups. In the EQ-5D-5L instrument, more problems relating to the dimension anxiety/depression was seen in the caries active group. QALY weights showed tendencies (non-significant) to be lower in the caries active group.

Conclusions

These findings highlight the need for efficient treatments and prevention strategies as well as adequate money allocation within dentistry. However, further research is needed to assess appropriate instruments for health economic evaluations.
A comparison between the Disposcope endoscope and fiberoptic bronchoscope for nasotracheal intubation-A randomized controlled trial
Authors: Yu Junma , Hu Rui , Wu Lining , Sun Peng , Zhang Zhi 
Published: July 2019

Abstract
Background: Nasotracheal intubation (NTI) is frequently performed in oral and maxillofacial surgeries. This study evaluated whether NTI is easier when guided by Disposcope endoscopy or fibreoptic bronchoscopy.
Methods: Sixty patients (30 per group) requiring NTI were randomly assigned to undergo fibreoptic bronchoscopy-guided (fibreoptic group) or Disposcope endoscope-guided (Disposcope group) NTI. Then, the NTI time, which was deﬁned as the time from when the fibreoptic bronchoscope or aseptic suction catheter was inserted into the nasal cavity to the time at which the tracheal tube was correctly inserted through the glottis, was recorded. Epistaxis was recorded using direct laryngoscopy ﬁve minutes after completing NTI and was scored as one of four grades according to the following modiﬁed criteria: no epistaxis, mild epistaxis, moderate epistaxis, and severe epistaxis.
Results: The time to complete NTI was significantly longer in the fibreoptic group than that in the Disposcope group (38.4 sec vs 24.1 sec; mean difference, 14.2 sec; 95% confidence interval (CI), 10.4 to 18.1). In addition, mild epistaxis was observed in 8 patients in the fibreoptic group and in 7 patients in the Disposcope group (26.7% vs 23.3%, respectively; relative risk, 1.2; 95% CI, 0.4 to 3.9). No moderate or severe epistaxis occurred in either group. Furthermore, no obvious nasal pain was reported at any time point after extubation in the two groups (P = 0.74).
Conclusion: NTI can be completed successfully using either fibreoptic bronchoscopy or a Disposcope endoscope as a guide without any severe complications. However, compared to fibreoptic bronchoscopy, the Disposcope endoscope requires less execution time (the NTI time).
Determinants and Seasonality of Major Structural Birth Defects Among Newborns Delivered at Primary and Referral Hospital of East and West Gojjam Zones, North West Ethiopia 2017- 2018: Case- Control Study
Authors: Tsehay Binalfew , Shitie Desalegn , Lake Akilog , Abebaw Erimiyas , Taye Amisalu , Essa Enatinesh 
Published: July 2019

Abstract
Objective: Although infant mortality because of birth defect has increased in both developed and developing countries, had not got attention like other health issues at national, regional, or local levels. Documenting the risk factors that influence the occurrence of birth defects and its seasonality will help to inform the community and to develop preventive strategies for the country.
Results: Factors associated with higher likelihood of a major structural birth defects included maternal age; neonates born from women living in urban; and in Dega; history of fever during pregnancy; intake of herbal medicine; and drinking alcohol. Counselling for pregnancy preparation and folic acid supplementation was found protective for the likelihood of birth defect.
Key words: Birth defect, maternal illness, maternal medication use, environmental exposure
Comparative transcriptome analysis revealed the conversions of stamens into pistil-like structures in Aegilops crassa cytoplasmic male sterile wheat (Triticum aestivum)
Authors: Liu Qi , Liu Zi han , Li Wei , Song Xi Yue 
Published: July 2019

Abstract
Background: Aegilops crassa cytoplasm is an essential material for investigating the cytoplasm of cytoplasmic male sterility (CMS). Moreover, the stamens of C303A exhibit a high degree of pistillody, turning almost white. However, the underlying molecular mechanism of C303A pistillody remains unclear. Therefore, to gain a better understanding of C303A, the phenotypic and cytological features of C303A were observed to identify the key stage that the homeotic transformation of stamens into pistil-like structures, transcriptome profiles were determined by Illumina RNA sequencing technology (RNA-Seq) of stamen.
Results: Through morphological observation, for CMS wheat with Aegilops crassa cytoplasm (CMS-C) line C303A, the pistil of which developed normally, but stamens were ultimately aborted and the stamens released no pollen when mature. According to the results of the paraffin section, stamens began to transform into pistils or pistil-like structures at binucleate stage (BNS). Therefore, the stamens of line C303A and its maintainer 303B at BNS were collected for transcriptome sequencing. A total of 20,444 wheat genes were detected as being differentially expressed between C303A and 303B stamens, included 10,283 up-regulated and 10,161 down-regulated genes. Gene Ontology Enrichment Analyses showed that most differentially expressed genes (DEGs) distributed on the metabolic process, cell, cellular process, catalytic activity and cell part. From KEGG, we knew that DEGs were mainly enriched to energy metabolism. We also found several essential genes that may contribute to pistillody in C303A. Based on the above analysis, we believe that due to the confusion of energy metabolism and reactive oxygen metabolism, thereby inducing the pistillody and eventually lead to the abortion of C303A.
Conclusion:This study unravels the complex transcriptome profiles in C303A stamen, highlighting the energy metabolism and class B MADS-box genes related to pistillody. This work should lay the foundations of future studies in the mechanical response to wheat stamen and pollen development in CMS.
Accuracy and efficacy of diagnosis via integrated with metabolomics in patients with PCOS: study protocol for a randomized controlled trial
Authors: Ni Cheng-Ming , Huang Wen-Long , Jiang Yan-min , Xu Juan , Duan Ru , Zhu Yun-Long , Zhu Xu-Ping , Fan Xue-Mei , Luo Guo-An , Wang Yi-ming , Li Yan-Yu , He Qing , Xu Lan 
Published: July 2019

Abstract
Background
Polycystic ovary syndrome (PCOS) is defined as a complex endocrine syndrome and the mechanisms underlying its various clinical signs and symptoms are still poorly understood, brings huge difficulties for clinical diagnosis and treatment. General agreement based on several clinical guideline[1, 2] suggest that it is critical to precisely diagnose the phenotypes of PCOS and give them an individual therapy. However, the criteria for different phenotypes remains unclear, mostly based on symptoms, physical examination and laboratory evaluation. The aim of this study is to compare the accuracy and preciseness of metabolomics markers with common clinical characteristics to find a more effective way to diagnose and treat these two subgroups (based on our basic study[3]) of PCOS patients. What’s more, the effects of different interventions according to two subgroups will also be observed.
Methods/design
This is a prospective, multicenter, analyst-blinded and randomized controlled trial. One healthy control group and two parallel experiment arms will be proposed in this study: (1) people without PCOS (health control group); (2) PCOS patients diagnosed mainly based on clinical indexes (group one); (3) PCOS patients diagnosed mainly based on metabolomics indexes (group two). A total of 276 eligible people will be recruited, which includes 60 healthy people and 216 PCOS patients, which will be randomly assigned to different diagnosis groups in a 1:1 ratio. Patients in two different diagnosis groups will be divided into two different subgroups according to their clinical characteristics (group one based on clinical indexes, group two based on metabolomics indexes) and receive a 6-month corresponding treatment. The primary outcome for experiment groups will be the condition of PCOS. All data will be analyzed periodically.
This trial will help us to clarify the value of metabolomics integrated with clinical characteristics in diagnosis and treatment of two PCOS subgroups. It will also highlight any differences in the accuracy and efficacy of these two techniques and it may provide a new specific direction of integrated method for the PCOS therapy.
Discussion
The purpose of this trial is to determine whether integrated metabolomics indexes is more accuracy and effective than clinical characteristics in diagnose the phenotypes of reproductive females with PCOS. This trial will, therefore, contribute to providing a solid foundation for clinical precise diagnosis of two PCOS subgroups, as well as future research in PCOS individual therapy.