bluuebunny/crossref_metadata_2025_split huggingface dataset:
Морфологічна мінливість популяції Carabus hungaricus scythus (Coleoptera, Carabidae) в умовах острова Хортиця (Запорізька область)
Authors: Brygadyrenko V. V. , Fedorchenko D. О. 
Published: March 2015

Досліджено закономірності морфологічної мінливості популяції занесеного до Червоної книги України угорського туруна (Carabus (Pachystus) hungaricus scythus Motschulsky, 1847) в умовах національного заповідника «Хортиця». Встановлено, що для популяції в цілому характерне збереження близького до нормального розподілу за основними промірами тіла. Максимальну морфологічну мінливість зареєстровано для самців, вони менші у середньому на 5,9 % за характеристиками тулуба і на 3,4 % – за розмірами кінцівок. Підкреслено, що через генетичну та просторову ізоляцію досліджена популяція потребує моніторингу
Видатні діячі гідробіологічної науки
Authors: Fedonenko O. V. , Sharamok T. S. 
Published: March 2015

Розглянуто історію кафедри іхтіології, гідробіології та екології Дніпропетровського національного університету. Наведено біографію засновника кафедри – Д. О. Свіренка та його послідовників – Г. Б. Мельникова, І. П. Лубянова, С. П. Федія та інших. Вказано основні напрямки роботи кафедри іхтіології, гідробіології та екології на теперішній час.
Роль земноводних і плазунів у створенні екологічного буферу проти техногенного забруднення
Authors: Bulakhov V. L. , Gasso V. Y. 
Published: March 2015

Показано, що рийна активність часничниці звичайної Pelobates fuscus (Laurenti, 1768) в умовах забруднення ґрунтів важкими металами здатна позитивно впливати на вміст металів у ґрунті. Трофометаболічна активність (виділення екскрецій) земноводних (P. fuscus) і плазунів (ящірки прудкої, Lacerta agilis Linnaeus, 1758) зменшує вміст важких металів у ґрунті.
Равновесное состояние сообщества гидробионтов
Authors: Tereshchenko V. G. 
Published: March 2015

Проанализирована многолетняя динамика разнообразия рыбного населения около 70 крупных озер и водохранилищ России и стран СНГ. Предложен метод поиска равновесного состояния водных сообществ. Установлено, что индекс доминирования рыбного населения в стабильном состоянии чаще равен 0,3. Выявлены факторы, определяющие разнообразие рыбного населения озер и водохранилищ.
Examining life quality in Hajdúszoboszló Tourist Area, with a special focus on health conditions
Authors: Margit Csipkés 
Published: March 2015

The present study discusses the partial results of a more comprehensive research and its front line goal is to identify the factors which affect the quality of life. It also attempts to explore the interrelationship of health tourism and the quality of life. Our study merely focuses on the analysis and the introduction of factors that determine health condition.
Good health in itself is not enough, qualitative life requires physical-psychological well-being as well. Years lost from lives due to poor health and early death result not only in human but economic losses as well; so it is highly recommended to dedicate time, money and energy to its investigation.
Preparation of a dynamic simulation model to support decision making in a sensitive rural area
Authors: Varga Mónika , Balogh Sándor , Csukás Béla 
Published: March 2015

This paper focuses on the demonstration of a conceptual framework and a dynamic simulation based tool, through the example of southern catchment basin of Lake Balaton. The objective is to support the sustainable and reasonable environmental management by model based investigation of various scenarios.
In the developed hydrological model, the coherence is given by the compartmentalized dynamic network of water flows and water bodies. The completeness is solved by the complete and disjoint covering of the whole area by modeled patches, corresponding to the CORINE land cover database of natural and human built environment. The complexity of the large scale and long term processes is managed by evaluating detailed models only for one representative patch from each class, while the calculation of the similar patches is solved by simple multiplication rules. According to the first experiences, the developed framework is able to integrate the field experts’ knowledge (data, relations, empirical knowledge, etc.) for the prediction of land use effects besides different climatic scenarios. It is noted, that continuous extension and refinement of the model and of the involved data is necessary, especially through more realistic case studies.
Determination of Invasion Diameter and True Resistivity from the Induction-SFL-Rxo Combination
Authors: Mohammed Akram F. 
Published: March 2015

Abstract
Deep Induction-log readings are often influenced by drilling fluids. If invasion by mud filtrate is deep and Rt/Rxo is small, the Induction log gives values that are higher than the true resistivity. Some water-bearing intervals that are severely invaded could confuse the log analyst by appearing as oil-bearing during interpretation for water saturation.
This paper describes a method that allows the analyst to compute invasion diameter (di) and true formation resistivity (Rt) from the measurements made with the Induction-Spherically Focused (ISF)4 -Rxo combination tool. The ISF log has proven to be a most useful logging tool under conditions of Rxo &gt; Rt, Rmf &gt; Rw, and shallow invasion. The method covers mainly the conditions when Rxo is greater than Rt. When Rxo is less than Rt the Induction log becomes less accurate for Rt evaluation. An accurate invasion correction chart has been constructed to determine values of di, Rxo/Rt, and Rt. Without this correction a serious error could result in the calculation of water saturation (Sw), especially in a deeply invaded formation and with Rxo &gt;&gt; Rt.
Keeping up With Technological Advances - An Innovative Approach to Validate Production Test Data
Authors: Khan M.N. , Menchaca T. Felix 
Published: March 2015

Abstract
The technological advances in oil and gas industry are enabling the operating companies to monitor their hydrocarbon reservoirs closely. Today reservoir surveillance engineers are able to acquire more well/reservoir performance data than in the past.
Multi-Phase Flow Metering is an expedient addition in production testing domain. As per the recent statistics, globally, approximately 4000 Multi-Phase Flow Meters (MPFM) installations are providing reliable measurements under different applications. As with any new technology the philosophy behind MPFM measurements is blurry for many users, who find difficulty establishing and implementing the appropriate data validation workflows on the MPFM data. The conventional production test data validation approach can be applied to the MPFM measurements up to a certain extent, but in order to find the source of discrepancies in MPFM data, additional processes are required to be included in the workflow.
The production history of the majority of hydrocarbon reservoirs in the world was built on conventional test separator flow rate data. Introducing a new measurement technology with different set of accuracies and different working principles has been a challenge for the production data users. To standardize the data validation process, a systematic approach can be implemented to validate the production testing data from different sources, which not only will help the end users to gain confidence in MPFM flow measurements but also will assist identifying the sources of discrepancy in MPFM measurements during day to day operations.
This paper will explain the stepwise data validation approach that can benefit different production test data users in oil and gas industry.
In-Situ Generation of CO2 to Eliminate the Problem of Gravity Override in EOR of Carbonate Reservoirs
Authors: Abdelgawad K.Z. , Mahmoud M.A. 
Published: March 2015

Abstract
Carbon dioxide (CO2) injection into hydrocarbon reservoir is reported by many researchers to be one of the best enhanced oil recovery techniques. CO2 for enhanced oil recovery has favorable characteristics such as miscibility between CO2 and oil under most reservoir conditions, intermediate component extraction and heavy oil viscosity reduction which is named CO2 flooding process. As a result of viscous fingering and gravity override, sweep efficiency decreases and significant amounts of oil are left behind during CO2 flooding. Foaming was used to increase the injected CO2 viscosity but a lot of problems were encountered with the foaming agents such as stability and thermal stability, etc.
In this paper we will introduce a new method of generating CO2 in-situ in carbonate reservoirs during enhanced oil recovery processes. The generation process includes the injection of low pH HEDTA or EDTA chelating agents followed by sea water, high pH chelating agents, or low salinity water. First the low pH chelating agent will react with the carbonate rock and produce CO2 that will diffuse to the oil and increases the oil mobility and in turn more oil will be produced. The chelating agents used are H2Na2EDTA (pH = 4.5), H3HEDTA (pH = 2.5), and H2NaHEDTA (pH = 4). The acid part which contains the hydrogen ions will attack the carbonate rock and produce CO2 that will increase the oil recovery, and then the high pH chelating agent or even sea water can be used to displace the low pH chelating agent and CO2.
The experimental results showed that about 90% of the oil in place was recovered from the carbonate cores without using of surfactants or any other additives. The new method will eliminate the problem of gravity override which is the main problem of CO2 EOR. The chelating agent can be placed in the whole reservoir by introducing a low reactive form of these chemicals or by encapsulating these chemicals to start reacting with the reservoir after the placement is complete. The reaction of the encapsulated chemicals can be triggered by temperature or any other triggering mechanism.
Use of Technology to Enhance Sustained Gas Production in Saudi Arabian Carbonate Reservoirs — Key Enablers
Authors: Rahim Zillur , Al-Anazi Hamoud , Al-Kanaan Adnan , Kayumov Rifat 
Published: March 2015

Abstract
With the increase in gas demand and the need to supply additional energy to the Kingdom, Saudi Arabia is now focusing its drilling and production activities toward exploiting tight carbonate formations. The required key technology to make such reservoirs commercial is the multistage fracturing (MSF). Several drilling, completion, and stimulation techniques are being used to effectively produce the reservoirs. Using well performance as the primary determining factor, a systematic study and evaluation has been conducted for 12 vertical and 11 horizontal wells to assess effectiveness of performed stimulation treatments on the massive carbonate formation. The variants analyzed to determine impact on production include lateral length, hole direction, number of stimulation stages per well, treating fluids and their volumes, pumping rates and pressures, and some others.
The results of these analyses demonstrate that drilling horizontal wells in the direction of minimum in-situ stress (σmin) made a positive impact by achieving satisfactory post-treatment gas rates. Trends also highlight improved well performance with the increase in stimulation stage count and maintaining a positive seal with the adjacent stages in MSF completions. The influence of different fluid types and their volume on post-fracturing productivity was analyzed, and some particular recommendations regarding optimum fluid types and volumes provided. Also, post-fracturing productivity was assessed to detect optimum treatment pump rates and pressures. Some important conclusions were made regarding targeted etched fracture half-length and width. Finally, analysis showed potential benefits from implementation of specific proppant fracturing technologies, such as channel fracturing for carbonate reservoirs to keep the fracture opened at high applied drawdown pressures during production. The analyses identified the key post-fracturing production drivers in the gas reservoirs and ways to improve production of future wells drilled in various formations under similar conditions.
Far Mobility Evaluation Using Minifrac Analysis in a Deep Sandstone Formation: Case Histories
Authors: Rahim Zillur , Al-Anazi Hamoud , Waspada Dwi , Al-Kannan Adnan , Pacheco Eduardo 
Published: March 2015

Abstract
Hydraulic fracturing treatment is one of the major contributors to increase oil and gas production. In most areas, fracturing has remarkable impacts on gas potential and sustainability. Proper design and implementation of fracturing technology and calibration of fracturing parameters provide significant technical and economic advantages. The minifrac treatment conducted before the main hydraulic fracturing, is a tool often used to conduct some essential evaluations of the treatment properties and optimizes the design before the main treatment. Minifrac treatments are also used to understand the reservoir parameters such as well transmissibility that allow making final modifications to the actual fracture design.
The minifrac operation is part of the hydraulic fracturing process that consists of creating and propagating a small fracture using the same fluid that would be used in the main fracturing treatment to observe and measure pressure behavior and calculate hydraulic fracture parameters such as the instantaneous shut-in pressure (ISIP), fracture closure pressure, critical fracture initiation rate, fluid loss coefficient, and the rate and pressure necessary to extend and propagate the induced fracture. Minifracs are also widely used to assess formation properties, such as reservoir permeability and leakoff characteristics. These properties are important for characterizing the reservoir, conducting approximate assessments to evaluate well potential, and optimizing the main fracture treatment design.
This paper describes how minifrac data is used to compute the Nolte G time function (NGTF) and assess fracture pressure decline behavior and evaluate closure pressure and reservoir permeability. The calculated permeability from the minifrac is then compared to the well test pressure data analyses results. Calibration is performed to match the results with well test analyses, which is considered to provide the most precise information about the reservoir. Once a good match is obtained, the process is extended to subsequent wells that allow computing reservoir permeability values using minifrac only, thereby optimizing hydraulic fracture design and predicting production performance.
Evaluation and Assessment of Uncertainity in Electrical Properties for Arabian Carbonate Reservoir
Authors: Okasha T. M. 
Published: March 2015

Abstract
Electrical logging is the most widely used method for identifying hydrocarbon intervals in a wellbore. Standard methods relating oil saturations in clay-free reservoirs to electrical resistivities are based on the Archie equation. Accurate determination of Archie's parameters (saturation exponent, n, and cementation exponent, m) is essential for better estimation of water saturation and log calibration especially for heterogeneous carbonates reservoirs.
In this study, sixty (60) plugs recovered from different wells across an Arabian carbonate reservoir were used to evaluate Archie's parameters. Experimental measurements using state of the art equipment were done by five core analysis service companies. The test results were reviewed for consistency and measurement accuracy. Quality control and statistical analysis of electrical parameters (n and m values) and capillary pressure data addressed uncertainties and errors in measurements. Despite some differences in procedures and experimental conditions, the mean petrophysical values, standard deviations, and ranges of n and m values are consistent.
The range of the saturation exponents and statistical variations of formation factors between wells, indicate that additional petrophysical refinement based on petrophysical rock type may be needed. To assist the rock typing work flow, additional tests for these samples and for any future electrical property samples, the following tests are recommended: NMR T2 and T1 measurements for pore size distributionDual energy x-ray CT scans with maximum sample coveragePlug sample mercury Injection capillary pressure determinations
Experimental Investigation of the Influence of Nanoparticles Adsorption and Transport on Wettability Alteration for Oil Wet Berea Sandstone
Authors: Li Shidong , Torsæter Ole 
Published: March 2015

Abstract
Wettability alteration has been proposed as an important Enhanced Oil Recovery (EOR) mechanism for nanoparticles suspension. For better understanding nanoparticles adsorption behavior inside core and its effect on wettability, a series of wettability measurement experiments for oil wet Berea sandstone were conducted, where the core plugs were treated by different concentration and type of nanoparticles suspensions. Nanoparticles transport experiments also were performed for core plugs with injection of varying concentration and type of nanoparticles suspensions. Pressure drop across the core plug during injection was recorded to evaluate nanoparticles adsorption and retention inside core, as well as desorption during brine post-flush. Both hydrophilic silica nano-structure particles and hydrophilic silica colloidal nanoparticles were utilized in above two experiments. Contact angle between oil and nanofluids measurements also were performed to investigate the effect of nanoparticles on wettability.
The results of wettability alteration experiments indicated that hydrophilic nanoparticles have ability of making oil wet Berea sandstone to be more water wet, and the higher concentration the more water wet will be. Different types of nanoparticles have different effect on the wettability alteration process. The results from contact angle measurements were consistent with wettability index measurements. For nanoparticles transport experiments, the results showed that the nanoparticles undergo both adsorption and desorption during injection. Pressure drop curves showed that absorption and retention of nano-structure particles inside core was significant, while colloidal nanoparticles did not adsorb much. Permeability impairment was observed during nano-structure particles fluid injection, but on the contrary colloidal nanoparticles dispersion injection made core more permeable.
Innovative Rotatable Friction Reduction Tool Applies Extra Force to Deploy Longest 7 in. Liner in Saudi Arabia
Authors: Okot Mike , Dubais Jamal , Al-Hajji Ali , Chima Jude , Deschamps Benoit , Elrefaei Ihab 
Published: March 2015

Abstract
Offshore fields in Saudi Arabia are being developed based on optimum use of onshore drilling rigs. Rather than developing the field completely from offshore platforms, it is developed partially from man-made, interconnected drilling islands. Extended reach wells (ERWs) are necessary for optimum surface location use and maximum reservoir contact.
As the wells increase the step-out, challenges arise not only during the drilling phase but also while running liners to target depth (TD). Wellbore geometry, hole instability issues and torque and drag forces, restrict the ability to deploy the liner to planned depths, setting technical limits to the oil and gas production potential.
The main challenge of running liners through extended lateral sections is the lack of hookload to push the liner to TD, and the ability to rotate the drill pipe without rotating the liner. As more extended reach deployment becomes common practice, it is necessary to implement new running liner practices and tools that rotate the drill pipe above the liner, to break the frictional drag and make more surface weight available, to deploy the liners or completions to TD.
This paper outlines the problem faced when deploying 7 in. liners in ERWs through 8½ in. hole lateral sections, and the solution using an innovative rotatable friction reduction tool, which allows the rotation of the drill pipe without transmitting torque to the liner. A case study is presented showing the main challenges, pre-job engineering calculations, field implementation, final results and lessons learned. Ultimately, the new rotatable friction reduction tool was a key component in the deployment of the longest 7 in. liner run in Saudi Arabia so far.
Setting a New Milestone in Carbonate Matrix Stimulation with Coiled Tubing
Authors: Al-Hajri Nasser M. , Al-Ghamdi Abdullah A. , Al-Subaie Fehead M. , Mujaljil Salih , Al-BenSaad Zakareya R , Srivastava Abhiroop , Ahmed Danish , Aiman Kneina Mohammed , Molero Nestor , Barkat Souhaibe 
Published: March 2015

Abstract
Horizontal carbonate reservoir stimulation has attracted considerable attention in the past decade as one of the major areas for development in matrix stimulation engineering. Modern technologies have enabled technically suitable interventions in extended and even mega-reach wells. In the Middle East especially, carbonate field development strategies have used mega-reach wells as the main technique in achieving the highest possible reservoir contact. In such a case, coiled tubing (CT) intervention becomes a necessity.
With carbonate acidizing, since more than 50% of the matrix is soluble in acid, the objective is to bypass the damage and increase the productivity by creating new highly conductive channels called wormholes. The success of a treatment is a function of fluid penetration, acid reactivity, injection rate and diversion. To increase the success of the treatments, improvements have been made recently in injection rate and diversion using the latest technologies in CT intervention. The introduction of CT provides significant advantages in stimulation execution, yet imposes some challenges. Real-time downhole measurements using fiber optic telemetry have been used frequently to improve chemical diversion and fluid placement. However, pumping rates have been significantly limited to a maximum of 2.0 bbl/min when this technology is deployed.
Extensive engineering work was invested in solving this challenge. The main objective was to obtain the optimum diversion using downhole “point” and distributed measurements without sacrificing the high injection rates. In response to this need, modifications to the existing downhole measurement system were introduced enabling pumping of rates beyond 5.0 bbl/min. The key focus of the redesign was the repackaging of the downhole tools as well as the telemetry link to surface, resulting in expansion of the operating envelope of the technology.
Yard testing has been completed, and results have been encouraging. The solution has been piloted in the field, and a field case study showed remarkable injectivity improvement.