bluuebunny/crossref_metadata_2025 huggingface dataset:
Cash Economy and Its Influence on the Economical Safety of the Country
Authors:   Saratov State University, Oskina E. A.
Published: April 2024

The article analyses cash economy and its influence on the economi‑ cal safety of the country. There are the characteristics of the notion «cash economy» in Russian and foreign literature. Special attention is given to the criminalization of economy and to the safety of Russia.
The Methods of Financial Risk’s Valuing
Authors:   Saratov State University, Vigodchikova I. Y.
Published: April 2024

This paper is devoted to the financial risk’s valuing by mathematics’ methods. Is studied statistic’s methods based at valuing financial indexes fluctuation’s scale. The weighted periods of financial instruments are analyzed. Is suggested the index’s calculation for financial portfolio. Considered the problem of uniform portfolio risk’s minimizing.
Strategic Marketing Approach to Management of Innovation Activity of Industrial Enterprises
Authors:   Saratov State University, Gerchikova E. Z.
Published: April 2024

The basic adaptation mechanisms of industrial enterprises to modern market conditions are identified and analyzed. The main factors that determine competitive advantages of products of manufacturing and technical purposes in the analyzed markets are examined. Method of determining the compliance of product range update policy of manufacturers to dynamically changing market requirements is suggested. The main directions of movement and abilities to manage of material flows of industrial enterprises in expanding of their scope of action are structured.
Peter I and the Creation of the Concept of «Schools Service to the State»
Authors:   Saratov State University, Vasilieva L. E.
Published: April 2024

XVIII century laid the foundations of Russia’s education, which was based on European-ical culture and science, while much ahead in the field of education pat-riarhalnuyu Russia.In the era of Peter the public service wore a centralized structed nature and uniformity throughout the country, so the opening of new schools gradually began to take in the conduct of the state.It was vyzva, but especially acute need for the state in literacy, knowledgeable officials. Training for the new state apparatus was carried out to special schools and academies in Russia and abroad.
Central limit theorem for the number of records in Fα-scheme
Authors: Kolesnik Oleksandr
Published: April 2024

Consider the sequence {Xk, k ≥ 1} of independent identically distributed random variables whose distribution function is continuous. Then events of the type {Xi = Xj} have probability 0 if i ≠ j. Let L(1) = 1. For n ≥ 2, we define random variablesL(n) = inf{k > L(n − 1) : Xk > XL(n-1)}assuming that inf ∅ := +∞. The members of the sequence L = {L(n), n ≥ 1} are called moments of records constructed for {Xk, k ≥ 1}. Consider the sequence of random variables μ = {μ(n), n ≥ 1}, defined by the relationμ(n) = #{k : L(k) ≤ n}, n ≥ 1.It is clear that μ(n) – is the number of records that happened up to the moment n inclusive.In the work [10], the so-called Fα-scheme is considered for the first time, which is built using a given distribution function and a sequence of positive numbers {αk}. It is clear that Fαn(x) is the distribution function for each n ≥ 1. The set of independent random variables {Xn} is called the Fα scheme, if the distribution function of the random variable Xn is Fαn(x). If all αn are equal to each other, then the Fα scheme – is a set independent identically distributed random variables. If not all αn are equal to each other, then the Fα scheme – is a generalization of the classical case.This paper examines the assertions related to the fulfillment of the central limit theorem (CLT) for the number of records in the Fα-scheme of records. The method of finding exact asymptotic expressions for mathematical expectation and variance, which can be used to replace the real characteristics in CLT, is given.A specific example of power-law growth of exponents of the Fα-scheme was considered, and CLT is constructed only in terms of the moment of observation and the power of growth.The article contains 4 theorems with complete proof. Theorem 1 relates the mathematical expectation and variance to the accumulated intensity of the Fα-scheme. Theorem 2 establishes the implementation of CLT in general, and theorem 4 – for a specific case.
The best approximation of analytic in a unit circle functions in the Bergman weight space B_(2,μ)
Authors: Langarshoev Mukhtor R.
Published: April 2024

The paper studies the issues of the best approximation of analytical functions in the Bergman weight space B_(2,μ). In this space, for best approximations of functions analytic in the circle by algebraic complex polynomials we obtain the exact inequalities by means of generalized modules of continuity of higher order derivatives Ω_m (z^r f^((r) ),t),m∈N,r∈Z. For classes of functions analytic in the unit circle defined by the characteristic Ω_m (z^r f^((r) ),t), and the majorant Φ, the exact values of some n-widths are calculated. When proving the main results of this work, we use methods for solving extremal problems in normalized spaces of functions analytic in the circle, N.P. Korneichuk’s method for estimating upper bounds for the best approximations of classes of functions by a subspace of fixed dimension, and a method for estimating from below the n-widths of function classes in various Banach spaces.
Kadına Yönelik Partner Şiddeti Hakkındaki Mitlerin Kabulü Ölçeği’nin Türkçe Geçerlik ve Güvenirlik Çalışması
Authors: Gündüz Tuğçe , Toktay Duran Emine , Yılmaz-karaman İmran Gökçen
Published: April 2024

Kadına yönelik şiddet tüm dünyada güncelliğini koruyan halk sağlığı sorunlarından biridir. Bu sorun için etkili çözüm yollarının geliştirilmesinde en önemli adımlardan biri soruna ilişkin bilimsel bilgi üretilmesidir. Bu bakımdan bu çalışmada Kadına Yönelik Partner Şiddeti Hakkındaki Mitlerin Kabulü (AMIVAW) Ölçeği’nin Türkçe versiyonunu geliştirmek, psikometrik özelliklerini incelemek ve sağlık çalışanlarının şiddet görmüş bir kadın hasta için adli süreç başlatma niyetlerini yordayan değişkenleri saptamak amaçlanmıştır. Bu amaçla yaş ortalaması 39.27 (SS ± 9.52) olan 249 sağlık çalışanına ulaşılmıştır. Katılımcıların %24.7’ini erkekler ve %75.5’ini ise kadınlar oluşturmaktadır. Ayrıca örneklem grubun; %30.9’u doktor, %45.8’i hemşire ve %23.3’ü ise diğer paramedik sağlık çalışanlarından oluşmaktadır. Katılımcılara kadına yönelik partner şiddeti hakkındaki mitlerin kabulü ölçeği, çelişik duygulu cinsiyetçilik ölçeği ve adil dünya inancı ölçeğinden oluşan bir ölçek bataryası sunulmuştur. Sonuçlara göre özgün çalışmayla tutarlı olarak kadına yönelik partner şiddeti hakkındaki mitlerin kabulü ölçeğinin tek faktörlü yapıda olduğu görülmüş ve Cronbach Alfa güvenirlik katsayısı .81 olarak hesaplanmıştır. Ayrıca şiddet görmüş bir kadın hasta için adli süreç başlatma niyetini yordayan değişkenleri saptamak için kurulan regresyon modeli yalnızca partner şiddetine ilişkin mitlere duyulan inancın (β=-.03, t=2.62, p<.05) anlamlı bir yordayıcı olduğunu göstermiştir [F(4-244)= 2.68, p<.05]. Katılımcıların düşmanca (β =.01, t=.03, p>.05) ve çelişik (β =-.01, t=-.03, p>.05) duygulu cinsiyetçilikleri ve adil dünya inançları (β =.02, t=.09, p>.05) şiddete maruz bırakılmış bir kadın hasta için adli süreç başlatma niyetlerini yordamamaktadır. Buna göre katılımcıların partner şiddeti hakkındaki mitlere duydukları inanç arttıkça, şiddet görmüş bir kadın hasta için adli süreç başlatma niyetleri azalmaktadır.
Lymphatic spread from left-sided intrahepatic cholangiocarcinoma: reconsiderations based on the lymphatic drainage from the liver
Authors: Ohtsuka Masayuki , Takayashiki Tsukasa , Takano Shigetsugu , Suzuki Daisuke , Sakai Nozomu , Hosokawa Isamu , Mishima Takashi , Konishi Takanori , Suzuki Kensuke , Nishino Hitoe , Nakada Shinichiro
Published: April 2024

Intrahepatic cholangiocarcinoma (ICC) is known to have a high frequency of lymph node metastasis. Lymph node dissection (LND) is recommended for accurate staging, but the survival benefit of LND remains unclear. Knowledge of the pathways and direction of lymphatic drainage to the regional lymph nodes is essential when considering LND to improve patient survival. The liver has three lymphatic drainage pathways: portal, sublobular, and subcapsular. Of these, the portal lymphatic pathway, which lies along with the portal tracts, is the primary pathway. The efferent portal lymphatic vessels from the left-sided liver, which continue from the portal lymphatic pathway of the liver, communicate with the lymphatic vessels and lymph nodes along the hepatic artery at the hepatoduodenal ligament. In addition, lymphatic flow may also present along the left embryonic (aberrant) hepatic artery in the lesser omentum, based on our experience. This pathway is the previously reported pathway from the left-sided ICC to the lesser curvature of the stomach. However, through this pathway, ICC cells reach lymph nodes along the root of the left gastric artery but not the perigastric lymph nodes along the lesser curvature because of the opposite direction of lymph flow. Although further analyses using a large number of cases are needed to confirm these observations, these two pathways, along the hepatic artery at the hepatoduodenal ligament and the left embryonic (aberrant) hepatic artery in the lesser omentum should be considered when performing LND in the case of ICC in the left-sided liver.
A CONTRIBUIÇÃO DOS AMICUS CURIAE NA AÇÃO DIRETA DE INCONSTITUCIONALIDADE N. 3239-DF SOBRE A TITULAÇÃO DE TERRITÓRIOS QUILOMBOLAS
Authors: Ribeiro de Melo Janykelle , Martins Lemes João Vitor
Published: April 2024

As territorialidades quilombolas são objeto de disputa frequente no judiciário brasileiro, sendo a Ação Direta de Inconstitucionalidade n. 3229-DF, a ação judicial que define os contornos dos direitos territoriais quilombolas a partir da discussão da constitucionalidade do Decreto 4.887/2003, que trata de regulamentar o art. 68 do Ato das Disposições Constitucionais Transitórias. Tendo sido ajuizada em 2004 e julgada entre 2012 e 2018, a ação teve a participação, na condição de amicus curiae, de diversas organizações governamentais e não-governamentais que, a partir de sua expertise e de suas realidades sociojurídicas e político-econômicas, apresentaram argumentos tanto em defesa da constitucionalidade quanto da inconstitucionalidade do decreto em análise. Dessa forma, por meio de pesquisa quali-qualitativa e com uso de análise dos documentos e registros de vídeo das sessões de julgamento da referida ADI, a presente pesquisa objetiva identificar de que forma se se deu a participação dessas organizações e sistematizar quais os argumentos que elas apresentaram, de modo a compreender qual o impacto da participação desses grupos para o julgamento realizado.
Spectral methods for polynomial interpolation and approximation
Authors: Varin Victor Petrovich
Published: April 2024

Classical problem of interpolation and approximation of functions with polynomials is considered here as a special case of spectral representation of functions. We developed this approach earlier for Legendre and Chebyshev orthogonal polynomials. Here we use Newton's fundamental polynomials as basis functions. We demonstrate that the spectral approach has computational advantages over the divided differences method. In a number of problems, Newton and Hermite interpolations are indistinguishable in our approach and computed by the same formulas. Also, computational algorithms that we constructed earlier with the use of orthogonal polynomials are adapted without modifications for use of Newton and Hermite polynomials.
Quality of complete feed wafer supplemented with different plant protein sources for small ruminants
Authors: Bira Gerson Frans , Tefa Azor Yulianus , Kolo Maria Magdalena , Nitbani Cornelis Astridino , Yonathan Lulu Deni , Akoit Agustinus
Published: April 2024

Objective: This study aimed to assess the quality of complete feed wafers with different plant protein sources for a feed of small ruminants.

Methods:The research was conducted in May-September 2022. The research method used a completely randomized design (CRD) with 4 treatments and 4 replications. The method used in this study was Completely Randomized Design (CRD) with 4 treatments, namely R0 = Wafer with an animal protein source (Fish meal) (Control), R1 = Wafers with protein source Sesbania grandiflora, R2 = Wafers with protein source Gliricidia sepium. R3=Wafer with protein source Leucaena leucocephala.The research variables consisted of physical quality (moisture content, wafer density, specific gravity, water absorption) and nutritional quality (dry matter, organic matter, crude protein, crude fat, crude fiber, and nitrogen free extracts). Data analysis according to the Analysis of Variance procedure using SPSS version 21.

Results:The results showed that the use of plant protein sources had no significant effect (P>0.05) on water content and wafer density but had a significant effect (P<0.05) on specific gravity and water absorption capacity. The use of plant protein sources can increase the value of water content, wafer density, and specific gravity and reduce water absorption capacity. Meanwhile, the crude protein (CP) content of the wafer had no significant effect (P>0.05) and produced the same value as using fish meal. Other nutritional variables had a significant effect (P<0.05) such as DM, OM, EE and NFE which increased and CF decreased on the use of plant protein sources in making feed wafers compared to the use of fish meal.

Conclusions: It was concluded that the use of legumes Sesbania grandiflora, Gliricidia sepium, and Leucaena leucocephala as a source of vegetable protein in wafers could replace fish meal. The three types of legumes had the same effect on the physical and nutritional quality of the resulting product.
Proximal Row Carpectomy with and without Capitate Resurfacing
Authors: Hones Keegan M. , Rakauskas Taylor R. , Hao Kevin A. , Densley Sebastian , Kim Jongmin , Wright Thomas W. , Chim Harvey
Published: April 2024

Background:

In wrist salvage, proximal row carpectomy (PRC) has increasingly shown superior outcomes to four-corner fusion (4CF). Furthermore, PRC with resurfacing capitate pyrocarbon implants (PRC + RCPIs) provides a treatment option that may allow patients to avoid 4CF or wrist arthrodesis and help restore natural joint function and distribute loads evenly across the implant, though RCPI has yet to be evaluated on a large scale. We aimed to compare outcomes between PRC and PRC + RCPI for the treatment of scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) wrists.

Methods:

A systematic review and meta-analysis was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed/MEDLINE, Embase, Web of Science, and Cochrane were queried for articles on PRC and PRC + RCPI performed for SLAC and SNAC wrist with minimum 12-month follow-up. Primary outcomes included wrist range of motion (ROM), grip strength, and outcome scores including Disabilities of Arm, Shoulder, and Hand (DASH) and QuickDASH scores, Patient-Rated Wrist and Hand Evaluation (PRWHE), and visual analog scale pain scores.

Results:

Twenty-two studies reporting on 1,804 wrists were included (1,718 PRC alone, 86 PRC + RCPI). PRC + RCPI was associated with greater postoperative radial deviation, but poorer flexion. PRC + RCPI also had significantly lower postoperative QuickDASH (less disability and symptoms) and postoperative PRWHE (lower pain and disability) scores and an improvement in PRWHE compared with PRC. There was no significant difference in grip strength.

Conclusion:

PRC + RCPI demonstrated similar postoperative ROM to PRC alone. While PRC + RCPI was associated with more favorable outcome scores, further research is needed to confirm these findings and assess the incidence and profile of complications related to RCPIs.

Level of Evidence:

Level IV. See Instructions for Authors for a complete description of levels of evidence.
Brownfield Management: Waterflood Surveillance Framework, Streamline Simulation, and Bright Water Polymer Flooding
Authors: Patel Manav Divyeshkumar , Patel Shubham Bhavin , Brajesh Shantnu , S. Hari , Krishna Shanker
Published: April 2024

Mature oil and gas fields typically exhibit declining production rates, necessitating the application of various techniques to alleviate this decline. One such method is waterflooding, a secondary recovery technique involving the injection of water into the reservoir. This process displaces and sweeps oil towards production wells, thereby enhancing recovery rates. However, as these fields mature, challenges become more pronounced. The water cut, representing the ratio of water produced to total fluids, tends to increase over time, posing a significant threat to economic viability. It becomes imperative to implement strategic interventions and advanced technologies for efficient reservoir management, particularly in addressing issues related to aging wells, such as early water breakthrough, and maintaining optimal injection rates.

To tackle these challenges, sophisticated reservoir simulation models are employed to optimize injection patterns, predict reservoir behavior, and enhance overall field performance. Additionally, advanced surveillance technologies are utilized to monitor reservoir dynamics, identify regions with poor sweep efficiency, and adapt water injection strategies accordingly.

This research paper investigates the efficacy of the streamline method in various domains of reservoir management, with a focus on waterflood balancing, rate re-allocation, and improved oil recovery. Through rigorous surveillance analysis using streamline simulation-based workflow, dynamic well pair allocation factors, specific injector efficiency and strategic reallocation of water injection, significant improvements were observed in key producers, validating the adaptability and speed of the streamline method. However, challenges such as thief zones persist, necessitating further exploration. To address this issue of water recycling, bright water polymer was implemented. The bright water solution demonstrated remarkable efficiency in displacing remaining oil and enhancing oil recovery by improving sweep efficiency. This was achieved through a synergistic combination of polymer viscosity and mobility control, resulting in better reservoir sweep and increased oil displacement. Notably it yielded a substantial incremental oil recovery of 1.4 million sm3, accompanied by a significant reduction in water production by 2 million sm3. These findings underscore the effectiveness of the strategies employed, indicating enhanced reservoir performance and optimized oil recovery processes. As efforts continue to refine and expand upon these methodologies, the streamline method emerges as a promising tool for optimizing reservoir management and enhancing oil recovery processes.
Low Molecular Weight Sodium Polyacrylate to Minimize Polymer Retention in Clayey Formations
Authors: Muhammed F. , O’Brien T. , Mohanty K. , Niu F.
Published: April 2024

Clay particles can irreversibly adsorb polymers, limiting the availability of flowing polymers to sweep the reservoir. The adsorption in the near wellbore region can also lead to reduced injectivity. This study investigates the potential of sacrificial agents, specifically sodium polyacrylate, to mitigate polymer retention during polymer flooding. This research aims to determine whether the low molecular weight sodium polyacrylate can minimize polymer retention and enhance the performance of polymer floods in low permeability reservoirs.

Comprehensive experiments were conducted to evaluate the effectiveness of the sacrificial agents. Rheological measurements assessed any potential alteration in the main polymer solution's behavior due to the sacrificial agent's presence. An adsorption study was conducted with clays and crushed rock samples to determine the adsorption of a sacrificial agent and its effect on the adsorption of the polymer. Coreflood experiments were performed to determine the polymer retention and injectivity properties.

The results obtained from the experimental study demonstrated the potential of the low molecular weight polyacrylate polymer as a sacrificial agent in minimizing polymer retention. The sacrificial agent did not alter the polymer rheology. The static adsorption test shows that the pre-adsorption of the sacrificial agent can reduce the polymer adsorption. The adsorption of HPAM polymer in Illite clay was 0.79 mg/gm without the sacrificial agent. It was reduced to 0.44 mg/gm in the presence of the polyacrylate about 56% reduction. The dynamic coreflood tests showed that retention can be reduced significantly by 50% - 70% in the presence of the sacrificial agent. This reduction in retention enabled quicker pressure stabilization, increasing injectivity, and had the added benefit of reducing the residual resistance factor by approximately 47%. The protective layer formed by the sacrificial agent effectively reduced the irreversible adsorption of the main polymer, thereby preserving its integrity and functionality.

This study demonstrated that a small dosage of sodium polyacrylate could reduce the retention of polymers in low-permeability and clay-rich reservoirs. This treatment also increases the injectivity of polymers in clayey sandstone reservoirs. The properties of the liquid Na polyacrylate make it easy to use in the field during waterflood before starting polymer injection. Na polyacrylate can also contribute to scale prevention in and near the wellbore.
Numerical Evaluation of the Carbonate Acid Stimulation Coupling with Co2 Flooding
Authors: Jia Cunqi , Longlong Li , Sepehrnoori Kamy
Published: April 2024

CO2 flooding is emerging as a pivotal technique extensively utilized for carbon capture, utilization, and storage (CCUS) strategies. Acid stimulation is one common technique widely employed to improve well-formation connectivity by creating wormholes. This work is motivated to investigate the gas-fingering behavior induced by the acid stimulation during CO2 flooding. We present an integrated simulation framework to couple the acid stimulation and CO2 flooding processes, in which the two-scale continuum model is used to model the development of wormhole dissolution patterns. Then, sensitivity case simulations are conducted through the EoS-based compositional model to further analyze the CO2 fingering behavior in acid stimulation formations separately under immiscible and miscible conditions. Results demonstrate that for acid stimulation, the typical dissolution patterns and the optimum acid injection rate corresponding to the minimum acid breakthrough volume observed in the laboratory are prevalent in field-scale simulations. For CO2 flooding simulation, the dissolution patterns trigger CO2 fingering (bypassing due to the high conductivity of wormholes) in the stimulated region, and a lateral boundary effect eliminating fingers exerts its influence over the system through transverse mixing. The optimum acid injection rate varies when the focus of interest changes from the minimum acid breakthrough volume to CO2 flooding performance. The best CO2 flooding performance is always observed in uniform dissolution. This work provides technical and theoretical support for the practical application of acid stimulation and CO2 flooding.
Flow Reversibility in Hydrogen Storage in Subsurface Aquifers
Authors: Lan Yuzheng , Lake Larry W.
Published: April 2024

Rising interest in hydrogen as an alternative energy source calls for investigation into how to produce, store and extract hydrogen efficiently from subsurface aquifers. This work studies the storage and extraction of hydrogen underground in aquifers using fractional flow theory. The similarity between injection (to store) and production (to extract) of hydrogen into and from the subsurface is how we define flow reversibility in this work.

First, we identify possible sources of irreversibility from the general fractional flow equations because these express how much of the injected hydrogen can be recovered. Full reversibility means that all the injectant will be recovered. Then, we examine, case by case, how shock formation, trapping hysteresis and gravity impact flow reversibility. Finally, we study how the shape of fractional flow curve and residual saturation hysteresis curve quantitatively affect flow reversibility.

We establish two types of reversibility. Reversibility of the first kind belongs to processes where the forward and reverse displacements are time symmetrical; such processes do not form shocks. Reversibility of the second kind refers to scenarios where key observables measured by an observer are not hysteretic. Hence, this study establishes several points of interest in quantifying hysteresis caused by flow reversal.

For hydrogen storage and extraction, we identify that both gravity and trapping hysteresis contribute to irreversibility of the first kind; gravity does not directly cause irreversibility of the second kind while trapping hysteresis necessarily does. Both kinds of irreversibility are associated with time asymmetry, with the second kind of irreversibility being incapsulated by the first kind of irreversibility.
South Oman Polymer Project: A Decade of Operational Excellence and Comprehensive Reservoir Monitoring and Surveillance
Authors: Al Sawafi M. M. , Aljabri A.
Published: April 2024

The largest polymer flood field in the Middle East has been in operation since 2010, with over 45 polymer patterns and approximately 300 wells. Over the past 13 years, the project has faced various challenges, including ensuring sustained injection uptime, maintaining polymer viscosity stability, and optimizing the polymer pumps uptime, all of which directly impacting the field's polymer oil recovery.

Managing such a complex project necessitates a comprehensive understanding of fluid dynamics. To comprehend the reservoir's behavior, an exhaustive surveillance plan is conducted annually, enabling the team to assess performance and take appropriate actions as needed. A substantial amount of data has been gathered to monitor polymer performance, encompassing surface and subsurface aspects such as wells' production data, polymer and water injection rates, polymer daily consumption, polymer viscosities, back-produced polymer concentration, pressure data and others.

The large amount of data requires periodic analysis. To facilitate this, the team has developed automated tools to visualize polymer flood performance in real-time. These tools incorporate pre-defined sets of algorithms to retrieve surveillance data and present it in easily interpretable charts and tables, allowing the team to concentrate on areas of concern.

Furthermore, well and pattern monitoring is conducted through an approach known as exceptional based surveillance (EBS), which triggers alarms when data deviates from preset operational parameters.

These efforts have resulted in increased recovery from the polymer flood. Surveillance activities have demonstrated the effectiveness of data-driven and focused efforts in improving performance. In conjunction with operational excellence, an increase of around 50% in oil recovery has been achieved over the past few years.

The paper will provide examples of acquired data, analyses performed, and actions taken to enhance oil recovery.
The Investigation into Carbonated Water as Pre-Fracturing Fluid to Improve Shale Oil Recovery by CT Online Scanning and Imbibition Experiments
Authors: Han Xiaobing , Yu Haiyang , Tang Huiting , Shi Jianchao , Huang Tao
Published: April 2024

Carbonated water (CW) imbibition is an effective method for enhanced oil recovery, by combining the advantages of CO2 and water. Nevertheless, there are few reports in existing studies on its performance in shale oil reservoirs. This research is specifically focused on these shale oil reservoirs, investigating the variation in countercurrent imbibition distance (CID) and the imbibition effects of using CW as a pre-fracturing fluid. In this study, CT online scanning experiments were conducted with shale cores to investigate the CID of formation water, CW, and fracturing fluids. Simultaneously, we determined and comparatively analyzed the countercurrent imbibition recovery (CIR) of these fluids. Furthermore, imbibition experiments were conducted using a high-temperature and high-pressure visual apparatus to assess the imbibition recovery of formation water, CW, and fracturing fluids. The findings suggest that CW significantly enhances shale oil recovery, with CID and CIR values reaching 1.75 cm and 6.95%, respectively. Compared to formation water and fracturing fluid, the CID of CW increased by 0.75 cm and 0.25 cm, while the CIR rose by 4.77% and 1.90%, respectively. CW achieved the highest imbibition recovery at 29.22%, exceeding that of fracturing fluids (25.18%) and formation water (10.25%). In this research, the application of CW as a pre-fracturing fluid to enhance shale oil recovery is introduced for the first time. Moreover, it quantifies the CID of CW and fracturing fluids in shale matrices, offering a pioneering strategy for the enhanced coordination of fracturing, shut-in, and production processes in shale oil exploitation.
Adsorption Kinetics of Copolymers and Sulfonated Polymers for Enhanced Oil Recovery
Authors: Silva C. , Beteta A. , McIver K. , Sorbie K. , Johnson G. , Hesampour M.
Published: April 2024

Polymer flooding is one of the most mature enhanced oil recovery (EOR) techniques, where the injection water viscosity is increased through addition of a high molecular weight polymer. In field operations, one of the most critical parameters for successful polymer flooding is the polymer adsorption. During transport, the polymer will irreversibly adsorb onto the reservoir rock, with the exact extent of adsorption depending on reservoir/polymer properties, such as the polymer composition and molecular weight, mineralogy of the reservoir, brine composition, reservoir temperature etc. For each reservoir, there will be an upper limit of adsorption above which sufficient polymer will be removed from solution to make the process uneconomic.

Copolymers of acrylamide (AM) and acrylic acid (AA) have been the most prominent chemicals to be applied, whereas sulfonated polymers containing acrylamide tertiary butyl sulfonic acid (ATBS) have been used for higher temperature and/or salinity conditions. In this work, it is demonstrated that there is a large kinetic component to the adsorption for a range of six polymer species on silica sand. The work was carried out in a field composition brine at a temperature of 31°C. The polymers consisted of AA-AM co-polymers (20-33 % AA) and AM-AA-ATBS ter-polymers (up to 15 mol% ATBS). While an adsorption of ~20 µg/g was measured after 24 hours, this increased continuously over 20-30 days for the AA-AM co-polymers. The same trend was observed for the AM-AA-ATBS terpolymers – with an adsorption at 24 hours of ~15 µg/g increasing over time to 36 ug/g. Two polymer species (33 % AA & 15 % ATBS) were then taken forward to dynamic core flood experiments where a novel shut-in procedure was used to highlight the kinetic behavior. The breakthrough profiles were matched via numerical simulation using a simple isotherm and kinetic constant. These results were then extrapolated to other conditions to highlight the potential for misinterpretation of traditional core flooding approaches. To the authors knowledge, the kinetic adsorption and its impact has not been very extensively discussed in the literature.

The ability to accurately plan polymer flooding projects is essential to fully optimise recovery performance as efficiently as possible, minimise the environmental footprint and reliably predict polymer breakthrough for production chemistry requirements. Thus, a complete understanding of the polymer adsorption and adsorption kinetics is critical for the continued development of polymer EOR.
Review of Ongoing CO2 Enhanced Oil Recovery Operations in Wyoming, USA
Authors: Robertson E. P.
Published: April 2024

This paper presents a summary of oil recovery from each of the nine commercial scale CO2 enhanced oil recovery projects in Wyoming along with a brief discussion of the geology of the fields. The current CO2 supply and pipeline system for the State is discussed along with an estimate of potential future production from CO2 enhanced oil recovery (EOR), if widely employed in Wyoming. CO2 injection, production, and pipeline sales data were obtained from the Wyoming Oil and Gas Conservation Commission and supplemented where possible by production data elsewhere in the public domain; all data used is public. Wyoming has world-class fields that have proven to be excellent targets for CO2 EOR. The process has been used in Wyoming since 1986 and there are nine commercial-scale floods that are currently active in the State. The average incremental oil recovery for Wyoming's ongoing CO2 EOR floods is over 10% of original oil in place and the average total incremental oil recovered for all ongoing CO2 floods is over 15 million barrels per reservoir and over 135 million barrels for the State. Since 2010, over 10% of the state's oil production has been incremental oil from CO2 floods. The State has excess CO2 supply that can be used for EOR, the current pipeline system has excess capacity, and the State has many fields within its four main oil producing basins that appear to be amenable to CO2 EOR.
Hydraulic Fracturing and Flowback in the Heterogeneous Unconventional Formation: Do Water Blocks Still Play a Role?
Authors: He Zexuan , DiCarlo David
Published: April 2024

Understanding the dynamics of water blocks in reservoir formations is crucial for optimizing hydrocarbon production in unconventional reservoirs. This study investigates the impact of heterogeneity on water block behavior through experimental analysis using a composite heterogeneous two-layer core sample. The experimental results reveal that the presence of high permeability layers mitigates the severity of water blocks compared to homogeneous low permeability layers. During hydraulic fracturing, fracturing water primarily invades the high permeability layer, resulting in uneven water saturation distribution across the core sample. Pressure drop analysis during flowback and hydrocarbon production indicates rapid normalization of pressure drop in heterogeneous unconventional formations, contrasting with prolonged normalization in homogeneous formations. These findings underscore the importance of reservoir heterogeneity in minimizing water block impact and optimizing hydrocarbon production. By elucidating the mitigating effect of high permeability layers on water block behavior, this study provides valuable insights for reservoir management strategies in unconventional reservoirs.
Full Field Polymer Flooding Development Concept in Nimr Oil Fields with Horizontal Injectors and Strong Bottom Aquifer
Authors: Karpan V. M. , Bimani A. , Bellman L. , Ketkar S. , Amri I. , Al Sulaimani H. , van Batenburg D. W. , Zaynetdinov T. , Bouwmeester R. , de Almeida P.
Published: April 2024

The Nimr fields comprise a group of medium size mature oil fields in the Southern part of Oman. This study focuses on Nimr-A and Nimr-E fields. The fields have similar reservoir properties and have been in commercial production since 1980 through the depletion. The strong regional bottom aquifer provides pressure support in these fields. The combination of a strong aquifer and relatively high viscosity of Nimr crude (~250-700 cP at reservoir conditions) resulted in the rapid development of water conning, limiting the oil recovery efficiency. Therefore, polymer flooding was selected as the technology to improve recovery. During 2013-2019, a polymer injection trial was executed in the Nimr-E field, whereby three horizontal injectors were used to evaluate the performance of polymer flooding under the reservoir conditions. As a result, the incremental recovery factor due to polymer has reached ~7% of STOIIP. Furthermore, due to the strong bottom aquifer, incremental oil production was observed even during the extended periods of injection shut-in through the "water cone recharging" mechanism. This has led to the proposal of a new polymer flooding concept for oil reservoirs with strong bottom aquifers called Nothing-Alternating-Polymer (NAP). In 2020, a new field trial was started in the Nimr-E field to investigate the performance of the concept under controlled field conditions and identify the optimal NAP design.

This publication presents the conceptual design of an integrated polymer flooding project in two mature Nimr oil fields. Both surface and subsurface considerations were taken into account and discussed here. Despite moving at different project development paces at the earlier stages, the projects were synchronized, and their value drivers were reviewed in line with modern-day requirements. Considerable attention was paid to reducing carbon intensity and water source sustainability. Polymer flooding was selected due to incremental and accelerated oil recovery at reduced carbon intensity. The selection of a sustainable water source was also important, given the high value of water resources in Oman.

Commercial-scale polymer flooding in Nimr A and Nimr E is PDO's most recent polymer flooding project, with value drivers focused on reduced CO2 intensity, water sustainability, and commercial robustness. The proposed multi-field, phased polymer development concept uses ~80 horizontal injectors above the oil-water contact to benefit from the aquifer support. Nimr is a flagship project for polymer flooding, with its results defining the development of polymer flooding in Oman for years to come.
Use of Polymer Flooding to Enhance Oil Recovery from the Largest Oil-Bearing Clastic Reservoir in the South of the Sultanate of Oman
Authors: Al Nabhani H. , Al Riyami O. , Al Sulaimani H. , Karpan V. , Bellmann L.
Published: April 2024

For more than 85 years, Petroleum Development Oman (PDO) has gained significant experience in oil production from different types of reservoirs, of which Gharif is the largest clastic formation in terms of oil reserves. The formation bears mainly medium to heavy oil, making primary and secondary (waterflooding) oil recovery less efficient due to the unfavorable oil-water mobility ratio. This paper demonstrates that polymer flooding is the best technology to improve sweep efficiency and achieve higher oil recovery at acceptable costs and risks. The technology is not new to PDO and has been implemented in the Al-Khlata formation in the Marmul oil field since 2010 (Svec et al., 2021). Gharif reservoir properties are more complex than those of Al-Khlata; therefore, additional laboratory studies were performed. The paper aims to present the results of such studies complemented by the production forecast results obtained from fit-for-purpose modeling approach. The approach was then used to accelerate phased project development in the Rahab field with multiple Gharif reservoirs, each characterized by a different oil viscosity.

The Rahab polymer project aims to develop heavy oil in the Gharif formation through vertical polymer injection patterns. The success of this project will pave the way for future developments in the fields with similar reservoir (Gharif) characteristics.

In order to reduce technical risks for Rahab polymer flooding, the project development was phased with Phase 1 as a trial and Phase 2 as a commercial-scale project. This paper is focused on the technical work done to design a polymer injection project for Phase 1. The objectives of Phasel are to: Expedite polymer injection in this field to monetize the opportunity while collecting more data and building a more robust understanding of Gharif polymer performance.Evaluate the surface facility modular approach against the standalone facility per single field (standard PDO approach). This could minimize the surface facility Capex and provide more operational flexibility.
Multi-Scale Optimization of Three-Million-Ton-Class CCUS Project in the Largest Oilfield in China: Zone Control Technology of Large PV CO2 Flooding
Authors: Wen Xin , Zhao Yang , Zhang Zheng , Peng Zesen , Liu Yueliang , Hu Ting , Rui Zhenhua
Published: April 2024

Large-PV (>1 PV) CO2 flooding is a technology that significantly improves oil recovery for ultra-low-permeability reservoirs. However, connected water-flooded channels formed by high-pressure water injection can lead to serious gas channeling, reducing the performance of large-PV CO2 injection. This article innovatively proposes a zoning control technology based on engineering geological characteristics of implementing million-ton CCUS in Changqing (China's largest oilfield). Multi-scale optimization is performed to achieve efficient and safe storage while maximizing oil recovery.

Taking HX block of Changqing Oilfield as an example, through production performance analysis, the entire area is divided into different levels based on the lifecycle of the well network. Conduct sensitivity analysis and ranking of oil recovery and storage efficiency. Parameter optimization of typical well patterns through CMOST-AI. Based on the comprehensive economic indicators, the collaborative optimization of oil recovery and CO2 storage efficiency is completed, and the channeling control method is further explored through gel plugging and shut-in timing simulation.

According to statistics, over 60% of the well patterns have entered the medium to high water cut. Through multi-scale classification and control, both types of well patterns CO2 flooding increased oil recovery by over 25%, and the ultimate CO2 storage capacity could reach over 3 million tons. The low water cut model was more effective in storing CO2 under the same injection conditions. Through sensitivity analysis, we found that the impact of injection-production parameters on recovery and storage efficiency varied. Gas injection pressure had the greatest impact on recovery and storage efficiency in the medium- to high-water-cut well patterns. While in the low-water-cut well pattern, it was the water slug volume. In addition, the water-to-gas ratio was the main influencing factor. Therefore, precise and case-specific optimization of injection parameters was necessary. In the later stage of the low-water-cut well pattern, gas channeling was severe, and the gradual alternation of water-gas-ratio can suppress this phenomenon. Consequently, appreciable oil recovery can be maintained in the later stages of development to ensure economic benefits.

This article proposes for the first time a multi-scale collaborative, hierarchical classification-controlled large-PV CO2 injection technology that can simultaneously consider recovery efficiency and achieve CO2 million-ton level storage. In short, it is simple and fast to predict the development and storage effects of CO2 flooding in the entire region and provide guidance for the development of ultra-low permeability reservoirs and CCUS engineering.
A Novel On-Chip Oil Swelling Measurement Platform for Gas Injection EOR Processes
Authors: Barikbin Z. , Ahitan S. , Genereux J. , Abedini A. , Ungar F. , Yang T. , Wanat E. , Li Z. , Alboudwarej H. , Burger J.
Published: April 2024

Oil swelling test data is essential to tune the EOS models to simulate gas injection EOR processes and evaluate the reservoir-scale recovery performances. PVT cells are typically used to measure this property; however, it may involve some challenges with runtime, fluid handling, and test operations. Here, a high-pressure high-temperature microfluidic approach is developed to measure the oil swelling in response to gas exposure under step-wise increasing pressure with different injection gas mole fractions. The microfluidic chip consists of a high-throughput gas-in-oil slug generator that produces multiple isolated gas-in-oil compound slugs with known initial volumes of gas and oil phases, each representing a single mixing condition that can be tested for oil swelling measurements. These isolated gas-in-oil compound slugs are generated at a pressure slightly higher than the oil bubble point pressure to ensure that oil remains in single-phase. A high-resolution microscopic camera is utilized to record time-lapse images of the volume at elevated pressures and the swelling factor is measured at the corresponding saturation pressure. Additionally, liquid volume fraction and relative volume are measured at each pressure step. The range of the data can be broadened so that the saturation pressure curve covers both bubble and dew points, representing both oil and retrograde gas condensate phase behaviors of single-phase fluid once reservoir oil and injection gas are fully mixed. The microfluidic swelling test results are also compared with those obtained with the conventional PVT cell, exhibiting a promising agreement between the measured data (i.e., average of ~5% deviation). While the PVT cell method may require several weeks to provide a full oil swelling dataset, the microfluidic approach developed here is notably faster and easier to operate for different types of reservoir oils and injection gases, stemming from small volume of fluid samples required for the testing procedure. The novel microfluidic platform developed here provides a unique opportunity to rapidly measure the large-scale oil swelling data, which has not been historically obtainable using conventional PVT cell. It can also facilitate tailoring and optimizing the injection gas through fast and accurate access to the relevant swelling data, informing the operators to better design gas injection projects. This can make gas injection PVT data accessible by an order of magnitude reduction in time, cost, and sample size requirements - in stark comparison with conventional methods.
A 2D Visualization Study of Polymer-Alternating-Gas Flood for Heterogeneous Reservoirs
Authors: Pang J. , Mohanty K.
Published: April 2024

Miscible gas flooding is an effective enhanced oil recovery method, but its sweep efficiency is low due to gravity segregation and viscous fingering. This issue is worse in reservoirs with a high-level heterogeneity. Water-alternating-gas (WAG) injection is often applied to improve sweep efficiency, but with limited success. Polymer flooding is a proven approach to improve sweep efficiency. This study aims to evaluate the performance of CO2 Polymer-Altering-Gas (CO2-PAG) floods through a series of visualized experiments conducted at the lab scale. Simulations were employed to optimize the injection schedule of CO2-PAG. The experiments included continuous gas (CG), WAG, and PAG injection in 2D heterogeneous sand-packs. To visualize and understand the performance of CO2-PAG, a 2D view cell was used, and a layered heterogeneous sand-pack was constructed. During water flooding, the layer with higher permeability was highly swept and the layer with lower permeability was minimally swept. In PAG flooding, the polymer solution selectively swept the lower portion of the higher permeability layer, while the solvent predominantly swept the upper portion of the higher permeability layer. A small portion of the solvent also entered the upper part of the low permeability region. PAG flooding exhibited a higher swept area (than CG and WAG), leading to increased incremental oil recovery. However, gravity segregation remained a challenge, leaving a significant portion of the lower permeability layer upswept. The simulation results show that the injection schedule with more 5 PAG cycles had the highest incremental oil recovery. The introduction of tapering slug sizes did not significantly impact the performance of PAG. These findings provide valuable insights into optimizing the PAG process for enhanced oil recovery.