bluuebunny/crossref_metadata_2025 huggingface dataset:
A Cryptic Invader of the Genus Persicaria (Polygonaceae) in La Palma and Gran Canaria (Spain, Canary Islands)
Authors: Verloove Filip , Rainer Otto , Janssens Steven , Kim Sang-Tae
Published: October 2021

A cryptic invader of the genus Persicaria is recently increasing in the damper, northern parts of La Palma and Gran Canaria in the Canary Islands (Spain) and locally behaves as an invasive species. Examination of historical herbarium specimens showed this species to be present in Gran Canaria since the 1960’s and the same probably applies to La Palma. Up to now, this species had been assigned to the Old World weed P. maculosa. However, morphologically these plants clearly correspond with P. hydropiperoides, a common and widespread weed native to the New World, and morphologically similar indeed to P. maculosa. Diagnostic features for these two species, as well as for another similar species (P. decipiens, originally described from the Canary Islands), are compared, thoroughly discussed and copiously illustrated. The current distribution, ecology and naturalization status of P. hydropiperoides in the Canary Islands are also assessed. The variability of P. hydropiperoides is discussed, more precisely the taxonomic position of a southern ‘race’ of it that is sometimes referred to as a distinct species, P. persicarioides. In addition to our morphology-based study, a molecular phylogenetic analysis has been conducted on the nuclear ITS region and the plastid DNA region trnL-F.
The Validity and Reliability of the Chula COVID-19 Psychosocial Home Isolation Evaluation Tool (CCPHIET)
Authors: Thisayakorn Paul , Thipakorn Yanin , Suwanpimolkul Gompol , Taechawiwat Tippamas , Prasartpornsirichoke Jirada , Suraphaphairoj Chumpol , Sirinimnuamkul Napat
Published: October 2021

Background: The cumulative number of patients during the COVID-19 pandemic led to a significant shortage of hospital beds. Many patients may not require hospitalization and can be clinically observed in home settings. However, some psychosocial factors are correlated with unsuccessful home isolation (HI), which might negatively affect the transmission control in the community. Therefore, we developed a new psychosocial screening tool (CCPHIET) for assessing HI suitability and examined its validity and reliability.Methods: This cross-sectional descriptive study included COVID-19 patients who were deemed to be medically safe for 14 days of HI. The CCPHIET is comprised of 8 clinical domains pertinent to HI behavioral compliance and risk. We explored its statistical validity and reliability and discussed the potential utility of this tool. Results: A total of 65 COVID-19 patients participated in this study. Most patients (58.5%) were evaluated as good candidates for HI. The CCPHIET has an acceptable content validity (IOC index > 0.5), moderate internal consistency (Cronbach’s alpha = 0.611) and substantial to excellent inter-rater reliability (Intraclass correlation coefficient = 0.944, Cohen’s kappa= 0.627).Conclusions: To compromise between strict and costly absolute institutional quarantine and the potentially unsuccessful absolute HI, the CCPHIET may help to identify good candidates for HI in mild and asymptomatic COVID-19 patients. This psychosocial information would support the physicians in matching each patient to the most suitable setting. Therefore, safe medical care is provided, unnecessary use of medical resources is spared, and local transmission is contained.
Magnetic Resonance Imaging in Animal Models of Alzheimer’s Disease Amyloidosis
Authors: Ni Ruiqing
Published: October 2021

Amyloid-beta plays an important role in the pathogenesis of Alzheimer’s disease. Aberrant amyloid-beta and tau accumulation induce neuroinflammation, cerebrovascular alterations, synaptic deficits, functional deficits, and neurodegeneration, leading to cognitive impairment. Animal models recapitulating the amyloid-beta pathology such as transgenic, knock-in mouse and rat models have facilitated the understanding of disease mechanisms and development of therapeutics targeting at amyloid-beta. There is a rapid advance in high-field MR in small animals. Versatile high-field magnetic resonance imaging (MRI) sequences such as diffusion tensor imaging, arterial spin labelling, resting-state functional MRI, anatomical MRI, MR spectroscopy as well as contrast agents have been developed for the applications in animal models. These tools have enabled high-resolution in vivo structural, functional, and molecular readouts with a whole brain field-of-view. MRI have been utilized to visualize non-invasively the amyloid-beta deposits, synaptic deficits, regional brain atrophy, impairment in white matter integrity, functional connectivity, cerebrovascular and glymphatic system in animal models of amyloidosis. Many of the readouts are translational in clinical MRI in the brain of patients with Alzheimer’s disease. In this review, we summarize the recent advance of using MRI for visualizing the pathophysiology in amyloidosis animal model. We discuss the outstanding challenges in brain imaging using MRI in small animal and propose future outlook in visualizing amyloid-beta-related alterations in brain of animal models.
Por que partem eles (agora)? O regresso à eterna pergunta
Authors: Oliveira Nelson
Published: October 2021

Na sequência da integração europeia, os fluxos migratórios portugueses foram diminuindo, de tal forma que, na viragem do século, acreditou-se que Portugal tinha passado de “país de emigrantes” para “país de imigrantes”. Com efeito, nas últimas décadas do século XX, Portugal atraiu inclusive cidadãos do país que, tradicionalmente, recebeu as mais significativas levas de expatriados portugueses (o Brasil) e, no contexto global, passou a integrar o conjunto de países atrativos para os migrantes económicos. Não obstante, a recente crise económica que pautou os primeiros anos do século XXI veio pôr a descoberto que essa realidade não estava solidificada, pelo menos não tanto como alguns cientistas sociais defenderam. Isto porque novos fluxos migratórios emergiram no território nacional, particularmente visíveis em áreas de baixa densidade, como é o caso da maior parte do distrito da Guarda. Neste trabalho, tendo como pano de fundo a região da Guarda, procuram-se equacionar “as molas impulsionadoras” que estão, novamente, a impelir estes portugueses a procurarem melhores condições de vida longe do país, na tentativa de perceber até que ponto estes novos fluxos migratórios têm uma génese comum aos que os precederam ou se, pelo contrário, têm configurações particulares que os individualizam no panorama migratório português.
Como a redução de algumas doenças cardiovasculares pode afetar a expectativa de vida da população brasileira?
Authors: H. O. Araujo Raphael , R. Barboni André , R. P. Silva Danilo , N. Q. Gomes Thayse , A. C. Sampaio Ricardo , Miranda J. Jaime , J. S. Silva Roberto
Published: October 2021

O presente estudo objetiva analisar o impacto das doenças cardiovasculares (DCV) na expectativa de vida (EV) da população brasileira e identificar como a EV seria afetada pela redução hipotética de 5% a 30% e pela eliminação da mortalidade por essas doenças. Trata-se de um estudo de simulação que utiliza dados transversais a nível nacional. A análise foi realizada por meio do modelo de tábuas de vida de múltiplo decremento, considerando reduções na mortalidade por DCV de 5% a 30%, assim como a sua eliminação. Os ganhos potenciais estimados na EV, em anos e porcentagem, por meio da eliminação das doenças isquêmica, hipertensiva e cerebrovascular foram de, respectivamente, para homens e mulheres, 1,44 (2%) e 1,31 (1,7%), 0,51 (0,7%) e 0,75 (1%), 1,28 (1,8%) e 1,62 (2,1%). Os maiores ganhos ocorrem entre os residentes na região Nordeste. Além disso, para a população em geral, os ganhos estimados em EV a partir de uma redução de 5% na mortalidade por DCV, em homens e mulheres, foram de 0,07 (0,1%) e 0,06 (0,08%), para doença isquêmica, 0,02 (0,03%) e 0,04 (0,05%), para doença hipertensiva, e 0,06 (0,08%) e 0,07 (0,09%), para doença cerebrovascular. Já uma redução hipotética de 30% na mortalidade por DCV foi acompanhada de ganhos na EV, para homens e mulheres, de 0,41 (0,6%) e 0,37 (0,5%), para doença isquêmica, 0,15 (0,2%) e 0,22 (0,3%), para doença hipertensiva, e 0,36 (0,5%) e 0,45 (0,6%), para doença cerebrovascular. Assim, mais investimentos e esforços orientados para a prevenção de DCV aumentariam a EV no Brasil, principalmente nas regiões menos desenvolvidas.
The Age of Popular Protests
Authors: ŞÖHRET Mesut
Published: October 2021

Purpose: The purpose of this research is to examine the difference between the global protests, which have increased unexpectedly in the last decade, from the global protests in the past. In this way, it is to show the main points between the global protests and to reveal how the mass demonstrations taking place around the world have changed numerically and regionally.

Design/Methodology: In the research, qualitative and quantitative research methods were used and the global protests that took place around the world, especially the developments that took place in the last ten years, were supported by graphics and maps. This study is a research article and literature review technique was used.

Findings: While every mass protest over the past decade has its own context, these global mass protests are based on common grievances such as economic hardship, ineffective governance, political crisis, ethnic and religious discrimination, and corruption. The interesting thing is that while our world is witnessing new technological inventions and discoveries every day, this dissatisfaction is increasing. At this point, not only the number of countries where these mass demonstrations took place has increased significantly in the last ten years, but also the number of participants in these demonstrations is increasing day by day. In addition, mass demonstrations are increasing not only in underdeveloped countries but also in developed and developing countries.

Limitations: The study examines the developments of the global protests that occurred around the world in the 10-year period between 2009-2019. In addition, it tries to examine the similarities between the protests from a global perspective by aiming to explain the global protests that took place in general.

Originality/Value: The originality of the research is that it examines the development of global protests, especially taking into account the last ten years, and tries to explain the difference between these protests and global protests in the past. In addition, the study tries to support the arguments it defends with graphics and maps obtained from statistical data.
ELECTRONIC ECONOMICS, ARTIFICIAL INTELLIGENCE AND ECONOMIC THEORY
Authors: Kuregyan S.
Published: October 2021

The article is devoted to the study of electronic economy and artificial intelligence from the point of view of their influence on economic theory. Economic theory is still a science that studies the world of things and the economic relations between people and their economic behavior. At the same time, special importance is attached to the effective use of limited material resources in order to create more wealth. All this is becoming unattainable in the age of information technology, the digital economy, which strengthen the intangible forms of capital and its impact on human life. Therefore, the task is to show how the electronic economy can affect economic science, and how economic science can contribute to the development of this economy.
MARKETING TECHNOLOGIES FOR SEGMENTATION AND REBRANDING
Authors: Drozdovich L.
Published: October 2021

The article discusses the main trends in the development of modern marketing based on
the integrated approach, identifies the causes and factors of the transition to a new marketing paradigm. Some technologies and tools for segmenting markets and their levels, as well as tools for studying needs and selecting target segments in the context of digitalization, are considered. The stages and their contents of rebranding are determined on the basis of the formation of an anti-crisis marketing program.
A Hybrid Model for Simulating Fracturing Fluid Flowback in Tight Sandstone Gas Wells considering a Three-Dimensional Discrete Fracture
Authors: Wang Suran , Bai Yuhu , Xu Bingxiang , Li Yanzun , Chen Ling , Dong Zhiqiang , Li Wenlan , Zheng Xiaowen , Wang Xudong
Published: October 2021

Two-phase (gas+water) flow is quite common in tight sandstone gas reservoirs during flowback and early-time production periods. However, many analytical models are restricted to single-phase flow problems and three-dimensional fracture characteristics are seldom considered. Numerical simulations are good choices for this problem, but it is time consuming in gridding and simulating. This paper presents a comprehensive hybrid model to characterize two-phase flow behaviour and predict the production performance of a fractured tight gas well with a three-dimensional discrete fracture. In this approach, the hydraulic fracture is discretized into several panels and the transient flow equation is solved by the finite difference method numerically. A three-dimensional volumetric source function and superposition principle are deployed to capture the flow behaviour in the reservoir analytically. The transient responses are obtained by coupling the flow in the reservoir and three-dimensional discrete fracture dynamically. The accuracy and practicability of the proposed model are validated by the numerical simulation result. The results indicate that the proposed model is highly efficient and precise in simulating the gas/water two-phase flow and evaluating the early-time production performance of fractured tight sandstone gas wells considering a three-dimensional discrete fracture. The results also show that the gas production rate will be overestimated without considering the two-phase flow in the hydraulic fracture. In addition, the influences of fracture permeability, fracture half-length, and matrix permeability on production performance are significant. The gas production rate will be higher with larger fracture permeability at the early production period, but the production curves will merge after fracturing fluid flows back. A larger fracture half-length and matrix permeability can enhance the gas production rate.
Innovative Method to Optimize Down Hole Control Valves by Well Modeling
Authors: Barghouti Akram R. , Javed M. Imran , Al-Shuwaier Saud A
Published: October 2021

The revolution of smart well completions has been significantly enhancing the oil & gas industry in the recent years, The completions allow for higher PIs, better sweep, longer well life, longer reservoir contact and better water management. These effects came into play and needed once O&G industry moved to drilling multi-lateral wells.

This paper represents a tri-lateral well that was drilled with high reservoir contact. The production optimization was completed to evaluate the contribution of each lateral and decide on the future production strategy for the well. This evaluation also allowed to test the functionality of the Down Hole Flow Control Valves (DHFCVs). Further, determining this functionality allowed identifying cross flow between the ICVs and the laterals. The optimization included multi-stage testing of each lateral to ascertain the high oil & water contributors. The water contribution was recorded across each lateral to optimize the water production and enhance the well productivity. The productivity index was calculated using IPR modeling utilizing Pipe-Sim software based on the commingled multi-rate tests. To further plan the way forward on the well production, a flowchart was established during the optimization operation to guide through the optimization process, identify each lateral water contribution, and production strategy after the operation.

This optimization has resulted in a significant cost avoidance, avoiding coil tubing horizontal logging intervention operations in all the three laterals. The details of the testing stages scenarios and the recommendations of the production strategies will be shared in this paper.
Modelling and Upscaling Unstable Miscible Displacement Processes: Characterisation of Physical Instabilities
Authors: Ogbeiwi Precious , Stephen Karl
Published: October 2021

The compositional simulations are required to model CO2 flooding are computationally expensive particularly for fine-gridded models that have high resolutions, and many components. Upscaling procedures can be used in the subsurface flow models to reduce the high computation requirements of the fine grid simulations and accurately model miscible CO2 flooding. However, the effects of physical instabilities are often not well represented and captured by the upscaling procedures. This paper presents an approach for upscaling of miscible displacements is presented which adequately represents physical instabilities such as viscous and heterogeneity induced fingering on coarser grids using pseudoisation techniques. The approach was applied to compositional numerical simulations of two-dimensional reservoir models with a focus on CO2 injection. Our approach is based on the pseudoisation of relative permeability and the application of transport coefficients to upscale viscous fingering and heterogeneity-induced channelling in a multi-contact miscible CO2 injection. Pseudo-relative permeability curves were computed using a pseudoisation technique and applied in combination with transport coefficients to upscale the behaviour of fine-scale miscible CO2 flood simulations to coarser scales. The accuracy of the results of the pseudoisation procedures were assessed by applying statistical analysis to compare them to the results of the fine grid simulations. It is observed from the results that the coarse models provide accurate predictions of the miscible displacement process and that the fingering regimes are adequately captured in the coarse models. The study presents a framework that can be employed to represent the dynamics of physical instabilities associated with miscible CO2 displacements in upscaled coarser grid reservoir models.
Comparative Evaluation of Gas-Condensate Enhanced Recovery Methods for Deep Ukrainian Reservoirs: Synthetic Case Study
Authors: Burachok Oleksandr , Kondrat Oleksandr , Matkivskyi Serhii , Pershyn Dmytro
Published: October 2021

Low value of final condensate recoveries achieved under natural depletion require implementation of enhanced gas recovery (EGR) methods to be implemented for the efficient development of gas-condensate reservoirs. The study was performed using synthetic numerical 9-component compositional simulation model that approximated the typical conditions of deep gas-condensate reservoirs of Dnieper-Donetsk Basin in Easter Ukraine. Injection of water, methane, nitrogen, carbon dioxide, mixture of methane and nitrogen, mixture of methane, ethane and propane at different concentrations were evaluated at 50% and 100% voidage replacement for reservoir fluids with 100 g/m3, 300 g/m3 and 500g/m3 potential condensate yield. Condensate recovery studied at different stages after primary depletion, when reservoir pressure reached 25, 50, 75% from dew point and at pressure of maximum liquid dropout.

Results comparison was done based on the two criteria: technical efficiency – incremental condensate recovery towards the base depletion cases and economic efficiency – cumulative NPV. Status of initial depletion as well as voidage replacement have a direct impact on breakthrough time and negative economic indicators. Despite providing the highest incremental condensate recovery by injecting CO2 at 100% voidage, it has a strong negative economic effect. Based on incremental condensate recovery EGR methods are ranked as following for all condensate potential yields and levels of primary depletion: CO2 100%; solvent gas mixture of C1 90%, C2 5%, C3 5%; solvent gas mixture C1 98%, C2 1%, C3 1%; C1 100%; mixture of C1 50% and N2 50%; N2 100%; water. Economically, the highest efficiency was shown for C1 100% injection, due to the fact, that produced re-cycled gas has a sales value as well. For the maximum incremental recovery it is advisable to start the injection as early as possible, while highest economic increments received for the cases of delayed injection, particularly when the reservoir pressure is equal to the pressure of maximum liquid condensation.

The results of study can be used a guidance for rapid screening of applicable EGR method for gas-condensate fields depending on depletion stage and potential condensate yield.
Offset Data Analysis and Seam Less Execution Through Real Time Monitoring Results in Step Change in Drilling Performance
Authors: Yadav Singh Anurag , Chohan Imran Muhammad
Published: October 2021

In oil and gas drilling, consistency of performance delivery heavily depends upon rig capability and its ability to maintain performance assurance through its execution cycle. It's not an uncommon occurrence that a rig is found with an underperforming top drive, one such scenario was observed in an in-fill oil well drilling project. This project was essentially drilling horizontal wells with bottom hole assemblies which had primary drive mechanism as a top drive. The rig in question was struggling to provide not only the requisite RPM but also not been able to deliver consistent torque needed to drill the well. This study analyzes how severe rig limitations were overcome through an optimization plan in which most optimal BHA was designed and drilling practices were customized for safe and successful execution of wells.

In order to understand root cause of the challenge, an offset well analysis was conducted, it identified that high torque was mostly generated while drilling through inter-bedded formations which typically caused top drive to stall. In addition, multiple tool failures were encountered due to the high stick slip which rig couldn't mitigate due to the low RPM yield of the top drive. To manage the rpm and torque limitations, a motorized RSS BHA was designed as a solution. Further, based on micro-stall events of motor only BHA's across the inter-bedded formations in the field, a stick slip management tool was placed below the motor so that a potential twist-off and/or motor damages can be avoided. Also, different bottom hole assembly's drilling dynamics response were analyzed to come up with optimal stabilization and connection practices to avoid back reaming while trip outs.

This paper would showcase actual results which highlight improvements achieved in stagnant drilling performance of the project. The analysis would demonstrate how multiple wells were drilled in one run following the risk assessment developed from the optimization study and subsequent real time monitoring of mitigating actions while execution.

The comprehensive bottoms-up drilling optimization approach helped save 4 planned days for each well, this really paves way to pursue applied-engineering solutions to achieve step change in drilling performances, especially on rigs which are severely limited either due to capacity or malperformance issues. The bottoms up approach taken to understand the drilling challenges followed by a methodical approach to address each of the challenges demonstrate importance of effective pre-job planning. Learnings from this study can be adopted as a template to mitigate similar drilling challenges.
Restoring Erroneous or Missing Rates in Interfering Wells Using Multiwell Deconvolution
Authors: Razminia Kambiz , Gringarten Alain C.
Published: October 2021

Objectives/Scope

Single well deconvolution (von Schroeter et al., 2001) has been added to the well test interpretation toolbox nearly twenty years ago. In recent years, the single well deconvolution algorithm has been extended to multiple interfering wells (Cumming et al., 2013), and further improved with the additions of constraints to account for existing a-priory knowledge on the reservoir (constrained multiwell deconvolution, Cumming et al., 2019).

The main objective of multiwell deconvolution is to identify the signatures of all wells involved and the interference signals between wells, from which information can be extracted about the reservoir that may not be obtainable otherwise, e.g. heterogeneities, boundaries and compartmentalization. The single well deconvolution algorithm has also been shown to be capable of restoring erroneous or missing rates (Gringarten, 2010).

As shown in this paper, the same is true with multiwell deconvolution, which is able to restore erroneous or missing rates in all the wells involved.

Methods, Procedures, Process

Starting with arbitrary initial guesses for the missing rates in the various wells involved, we use multiwell deconvolution to estimate these missing flow rates or correct for erroneous ones.

Two methods are presented: (1) we use unconstrained multiwell deconvolution as a first step to estimate the missing/erroneous rates, then use constrained multiwell deconvolution with these rates to estimate deconvolved derivatives; and (2) we restore/correct the flow rates and derive deconvolved derivatives simultaneously using constrained multiwell deconvolution. We show that the first approach is more accurate than the second one. In both approaches, we only obtain rates that are proportional to the true flow rates. To obtain the true flow rates, we need to know either one of the actual flow rates in each well, or the corresponding permeabilities.

Results, Observations, Conclusions

We prove the ability of multiwell deconvolution to estimate rates on synthetic oil reservoirs and gas reservoirs with moderate average reservoir pressure depletion, that include non-interfering wells. We then apply to oil and gas field examples and compare restored vs. actually measured rates. In all cases, the agreement is very good.

Novel/Additive Information

Using only measured pressure data, constrained multiwell deconvolution can be used to restore unknown flow rates and/or correct for erroneous rates, in addition to estimating deconvolved derivatives of all wells. This is particularly useful in the case of allocated rates or when rates are missing in some of the interfering wells.
Inertial Effect on Spontaneous Oil-Water Imbibition by Molecular Kinetic Theory
Authors: Tian Weibing Tian , Wu Keliu , Chen Zhangxin , Gao Yanling , Gao Yin , Li Jing
Published: October 2021

Imbibition is one of the most common physical phenomena in nature, and it plays an important role in enhanced oil recovery, hydrology, and environmental engineering. For the tight reservoirs, the imbibition method has an obvious advantage in fracturing, shut-in, and huff-puff development. Although the current imbibition studies focus on oil recovery, and the inertial effect in imbibition is neglected and its mechanism is also unclear.

In this paper, the inertial effect on spontaneous oil-water imbibition at micron-scale is studied by molecular kinetic theory (MKT). The frictional coefficient in the model is a fitted parameter to match the experimental data during the total imbibition process. Then, the simulation of the initial imbibition stage is conducted and the inertial effect on imbibition is identified by the difference between the model considering the inertial effect (CI) and the model neglecting the inertial effect (NI), or by the proportion of inertial force to the total resistance.

Results show that (i) with an increase in the water phase viscosity, the inertial effect time shortens, maximum imbibition height and rate decrease, and thus the inertial effect on imbibition weakens; (ii) with an increase in the oil phase viscosity, the inertial effect time changes little, the maximum imbibition height and rate decrease slightly, namely, the inertial effect depends slightly on the oil phase. (iii) with an increase in the capillary wettability (hydrophilicity), the inertial effect time shortens, the maximum imbibition rate first increases and then decreases, and the inertial effect on imbibition weakens.

This work sheds light on the inertial effect on oil-water imbibition by MKT, considering the effects of dynamic contact angle, water phase viscosity, oil phase viscosity, and wettabilities, which is helpful to understand the role of inertia in the oil-water or oil-fracturing fluid imbibition process.
Numerical Simulations of Surfactant Flooding in Carbonate Reservoirs: The Impact of Geological Heterogeneities Across Scales
Authors: Pola Jackson , Geiger Sebastian , Mackay Eric , Maier Christine , Al-Rudaini Ali
Published: October 2021

We demonstrate how geological heterogeneity impacts the effectiveness of surfactant-based enhanced oil recovery (EOR) at larger (inter-well and sector) scales when upscaling small (core) scale heterogeneity and physicochemical processes. We used two experimental datasets of surfactant-based EOR where spontaneous imbibition and viscous displacement, respectively dominate recovery. We built 3D core-scale simulation models to match the data and parameterize surfactant models. The results were deployed in high-resolution models that preserve the complexity and heterogeneity of carbonate formations in the inter-well and sector scale. These larger-scale models were based on two outcrop analogues from France and Morroco, respectively, which capture the reservoir architectures inherent to the productive carbonate reservoir systems in the Middle East. We then assessed and quantified the error in production forecast that arises due to upscaling, upgridding, and simplification of geological heterogeneity.

Simulation results showed a broad range of recovery predictions. The variability arises from the choice of surfactant model parameterization (i.e., spontaneous imbibition vs viscous displacement) and the way the heterogeneity in the inter-well and sector models was upscaled and simplified. We found that the parameterization of surfactant models has a significant impact on recovery predictions. Oil recovery at the larger scale was observed to be higher when using the parametrization derived from viscous displacement experiments compared to parameterization from spontaneous imbibition experiments. This observation clearly demonstrated how core-scale processes impact recovery predictions at the larger scales. Also, the variability in recovery prediction due to the choice of surfactant model was as large as the variability arising from upscaling and upgridding. Upscaled and upgridded models overestimated recovery because of the simplified geology. Grid coarsening exacerbated this effect because of the increased numerical dispersion. These results emphasize the need to use correctly configured surfactant models, appropriate grid resolution that minimizes numerical dispersion, and properly upscaled reservoir models to accurately forecast surfactant floods. Our findings present new insights into how the uncertainty in production forecasts during surfactant flooding depends on the way surfactant models are parameterized, how the reservoir geology is upscaled, and how numerical dispersion is impacted by grid coarsening.
Experimental Investigation of Oil/Water Emulsion Rheology in Electric Submersible Pump and its Effect on the Pump Head Performance
Authors: Ridlah Muhammad Rasyid , Zhu Haiwen , Zhang Hong-Quan
Published: October 2021

The presence of formation water throughout the oil well production lifetime is inevitable and consequently forming the dispersion or the emulsion due to the immiscibility of those two phases and the strong shear force acting in a rotating ESP. The formation of stable emulsion close to the inversion point will significantly increase the effective viscosity of an emulsion. This paper will present an experimental investigation of emulsion rheology inside the ESP and its effect on ESP performance under various oil viscosities and different water cuts (WC).

Multi stages radial type ESP were assembled into a viscous flow loop which was initially developed by Zhang (2017). Emulsions at each WC formed from different oil viscosities, similar oil density, and surface tension. Multistage ESP was used to circulate oil/water emulsions in a close flow loop. Mass flowmeter measures both mass flow rate and fluid density, and the effective emulsion viscosity derived from an in-line pipe viscometer (PV) which locates downstream of the ESP discharge. The pressure transmitter is occupied in each pump stage to measure the pressure increment. The experiment results present in terms of pump boosting pressure at each water cut and the flow rate delivered by the pump.

A Single-phase oil experiment was run at a different temperature to validate the accuracy of the PV. The data discrepancy of PV's viscosity and rotational viscometer is ±6%. The experiment results captured the emulsion's effective viscosity trend as a function of WC. A significant increase of effective viscosity close to the inversion point was observed, and it occurs due to a higher number of water droplets and hydrogen bonds which lead to an increase in hydrodynamic forces thus generating a tight emulsion. The experiment results reveal that a higher oil viscosity 70 cp reaches an inversion point at 30% - 35% WC. Meanwhile, for lower oil viscosity 45 cp reaches the inversion point at 35% - 40% WC since the turbulence increases with the decrease of oil viscosity. The increasing of effective viscosity in the water-oil emulsion induces higher pressure loss in the pump due to high friction loss, and it deteriorates the pump head. Nevertheless, as the WC increases further, the pump head will advance close to the single-phase water performance since the water turns as the continuous phase. Eventually, we can observe a prudent relationship in the pump performance in the change of emulsions effective viscosity as a function of WC. The inversion point phenomena occur at a different range of WC for different oil viscosity. Therefore, it is vital to set the possible range of operational conditions away from the inversion point. A better understanding of these aforementioned issues will lead to an accurate ESP design for optimum well performance.
Cyclic Production Scheme for High WC and Low-Pressure Wells for Reservoir Management
Authors: Al-Subaiei Dalal , Jamal Mariam , Barki Jassim , Al-Azmi Ibrahim , Al-Husaini Mohammad
Published: October 2021

Lower Burgan (LB) is one of the most mature reservoirs in north Kuwait divided in to 3 layers, first layer under partial depletion drive and suffer from low reservoir pressure, the second layer under edge-partial water drive and the last layer under active water drive. Increasing trend of water production and high GOR has become a big challenge to control the reservoir production, several of studies done to evaluate the best strategy to enhance the reservoir performance.

A comprehensive review of the performance of the wells was conducted to diagnose the specific reason and necessary remedial measures to be adopted. The review included the assessment of the results of the material balance and numerical simulation studies, depletion strategies, wettability/ relative permeability footprints; proximity to the OWC; past completion practices, well integrity and the time lapse PNC/PLT/ Well testing data. Workflows were developed for the sublayers within the hydraulic unit for systematic water cut diagnostics and preventive steps. Identification of suitable technology to address water cut and GOR management was also done.

The typical trend of water cut and GOR performance with time and the depletion strategy was established to add value to the ongoing production activities and well allowable for each hydraulic unit. Rate sensitive performance was analyzed for the integration into the production plans. Cyclic production is identified as one of the new ways to reduce the water production and maintain the production for the wells producing below the bubble point. The concept was tried at high water cut wells successfully to revive the well from about 100% to 87% water cut with a closure cycle for 3 month and sustaining the production for high GOR wells with good ESP performance. In addition, suitable candidates have been identified for Coning Control Completions to weaken the water encroachment into the downhole wellbore. The overall water cut for the reservoir has been stabilized during last one year, thus helping the water handling constraints at the gathering facility.

This paper will discuss the successful approach to control coning and water encroachment for active Bottom and Edge-Water drive layer and how this approached helped to sustain the production on high GOR wells running below bubble point with necessary diagnostics and remedial measures.
Integrated Brownfield Opportunity Identification Using the Efficiency Factor Approach
Authors: Julier Russell , Smalley Craig , Van der Molen Karen , Roeterink Rene
Published: October 2021

The long-term prosperity of oil and gas companies requires a constant influx of new volumes of producible oil and gas that can be developed to replace existing production. Without such activity it is inevitable that production will eventually fall as the resource base is gradually consumed

The attractiveness of achieving more barrels from existing discovered fields has always been strong as it has long been recognized that such opportunities can be economically attractive and rapidly brought to fruition. It is also recognized however that such opportunities may be more complex relying both upon excellent subsurface understanding and successful brownfield project execution. It is therefore not surprising that in many cases actual recovery factors (produced volume/initial in-place volume) in oil and gas fields can be significantly less than what should be technically achievable.

Identification of economically robust brownfield opportunities remains an industry challenge. In this paper we address this challenge by reporting a new workflow for brownfield opportunity identification leading to recovery factor improvement.

Shell's Recovery Factor Improvement (RFI) Workflow was developed to address these issues and builds upon the existing best practice workflows to better explore and define the activities that would be required to achieve top quartile recovery factor performance.

The workflow combines elements of various existing published approaches: (1) Shell's TQ-EUR Tool is an internal database that allows current and forecast recovery factor to be compared with that of analogue reservoirs using a reservoir complexity factor and key reservoir performance parameters as comparison criteria across the Shell portfolio. (2) An efficiency factor-based analysis of recovery factor; (3) a structured workshop to elicit new recovery factor improvement activities by addressing each individual efficiency factor in turn; (4) Consistent reporting of results.

The combination of these approaches creates a powerful workflow to improve brownfield field opportunity identification and maturation.

The RFI Workflow is intended to provide asset teams with a practicable and repeatable process that can be completed without specialist technical support or software to enable the identification of robust new opportunities.

Experience with using the new workflow has demonstrated that it is able to bring new understanding to asset teams, consistently identify new opportunities and highlight common portfolio-wide opportunity types that would benefit from further central technology development funding.
History to Prediction Transition Calibration of Reservoir Simulation Model Ensemble
Authors: Ludvigsen Bjørn Egil , Sharma Mohan
Published: October 2021

Well performance calibration after history matching a reservoir simulation model ensures that the wells give realistic rates during the prediction phase. The calibration involves adjusting well model parameters to match observed production rates at specified backpressure(s). This process is usually very time consuming such that the traditional approaches using one reservoir model with hundreds of high productivity wells would take months to calibrate. The application of uncertainty-centric workflows for reservoir modeling and history matching results in many acceptable matches for phase rates and flowing bottom-hole pressure (BHP). This makes well calibration even more challenging for an ensemble of large number of simulation models, as the existing approaches are not scalable.

It is known that Productivity Index (PI) integrates reservoir and well performance where most of the pressure drop happens in one to two grid blocks around well depending upon the model resolution. A workflow has been setup to fix transition by calibrating PI for each well in a history matched simulation model. Simulation PI can be modified by changing permeability-thickness (Kh), skin, or by applying PI multiplier as a correction. For a history matched ensemble with a range in water-cut and gas-oil ratio, the proposed workflow involves running flowing gradient calculations for a well corresponding to observed THP and simulated rates for different phases to calculate target BHP. A PI Multiplier is then calculated for that well and model that would shift simulation BHP to target BHP as local update to reduce the extent of jump. An ensemble of history matched models with a range in water-cut and gas-oil ratio have a variation in required BHPs unique to each case. With the well calibration performed correctly, the jump observed in rates while switching from history to prediction can be eliminated or significantly reduced. The prediction thus results in reliable rates if wells are run on pressure control and reliable plateau if the wells are run on group control. This reduces the risk of under/over-predicting ultimate hydrocarbon recovery from field and the project's cashflow. Also, this allows running sensitivities to backpressure, tubing design, and other equipment constraints to optimize reservoir performance and facilities design. The proposed workflow, which dynamically couple reservoir simulation and well performance modeling, takes a few seconds to run for a well, making it fit-for-purpose for a large ensemble of simulation models with a large number of wells.
Evaluation of Machine Learning Methods for Prediction of Multiphase Production Rates
Authors: Gryzlov Anton , Mironova Liliya , Safonov Sergey , Arsalan Muhammad
Published: October 2021

Multiphase flow metering is an important tool for production monitoring and optimization. Although there are many technologies available on the market, the existing multiphase meters are only accurate to a certain extend and generally are expensive to purchase and maintain.

Virtual flow metering (VFM) is a low-cost alternative to conventional production monitoring tools, which relies on mathematical modelling rather than the use of hardware instrumentation. Supported by the availability of the data from different sensors and production history, the development of different virtual flow metering systems has become a focal point for many companies.

This paper discusses the importance of flow modelling for virtual flow metering. In addition, main data-driven algorithms are introduced for the analysis of several dynamic production data sets. Artificial Neural Networks (ANN) together with advanced machine learning methods such as GRU and XGBoost have been considered as possible candidates for virtual flow metering. The obtained results indicate that the machine learning algorithms estimate oil, gas and water rates with acceptable accuracy. The feasibility of the data-driven virtual metering approach for continuous production monitoring purposes has been demonstrated via a series of simulation-based cases. Amongst the used algorithms the deep learning methods provided the most accurate results combined with reasonable time for model training.
Successful Application of Honey-Bee Optimization Technique in Reservoir Engineering Assisted History Matching: Case Study
Authors: Shams Mohamed
Published: October 2021

This paper provides the field application of the bee colony optimization algorithm in assisting the history match of a real reservoir simulation model. Bee colony optimization algorithm is an optimization technique inspired by the natural optimization behavior shown by honeybees during searching for food. The way that honeybees search for food sources in the vicinity of their nest inspired computer science researchers to utilize and apply same principles to create optimization models and techniques.

In this work the bee colony optimization mechanism is used as the optimization algorithm in the assisted the history matching workflow applied to a reservoir simulation model of WD-X field producing since 2004. The resultant history matched model is compared with with those obtained using one the most widely applied commercial AHM software tool.

The results of this work indicate that using the bee colony algorithm as the optimization technique in the assisted history matching workflow provides noticeable enhancement in terms of match quality and time required to achieve a reasonable match.
A Geometry-Based Deep Learning Feature Extraction Scheme for Airfoils
Authors: Xiang Yu , Hu Liwei , Zhang Jun , Wang Wenyong
Published: October 2021

The perception of geometry-features of airfoils is the basis in aerodynamic area for performance prediction, parameterization, aircraft inverse design, etc. There are three approaches to percept the geometric shape of an airfoil, namely manual design of airfoil geometry parameter, polynomial definition and deep learning. The first two methods can directly extract geometry-features of airfoils or polynomial equations of airfoil curves, but the number of features extracted is limited. While deep learning algorithms can extract a large number of potential features (called latent features), however, the features extracted by deep learning are lacking of explicit geometrical meaning. Motivated by the advantages of polynomial definition and deep learning, we propose a geometry-based deep learning feature extraction scheme (named Bézier-based feature extraction, BFE) for airfoils, which consists of two parts: manifold metric feature extraction and geometry-feature fusion encoder (GF encoder). Manifold metric feature extraction, with the help of the Bézier curve, captures features from tangent space of airfoil curves, and GF encoder combines airfoil coordinate data and manifold metrics together to form a novel feature representation. A public UIUC airfoil dataset is used to verify the proposed BFE. Compared with classic Auto-Encoder, the mean square error (MSE) of BFE is reduced by 17.97% ~29.14%.