bluuebunny/crossref_metadata_2025 huggingface dataset:
Los señores mayas y la recreación de episodios míticos en los programas escultóricos integrados en la arquitectura
Authors: Salazar Lama Daniel
Published: December 2016

La progresiva incorporación de la figura real a los programas escultóricos integrados en la arquitectura en espacios públicos muestra la recurrente adopción de ciertas características conductuales de los dioses por parte de los gobernantes, quienes recrean ocasionalmente episodios míticos/cosmogónicos. Los casos de estudio de esta investigación, el friso de Balamkú (Campeche) y los relieves de la Gran Acrópolis Central en El Mirador (Petén, Guatemala), arrojan importante información sobre los recursos utilizados en la configuración de este tipo de escenas. Los resultados indican que, en ausencia de textos, recursos como el uso de un código visual de alto contenido simbólico y la adecuada construcción de la imagen son capaces de transmitir mensajes con sólidos trasfondos ideológicos que responden a las funciones sociales de los gobernantes.
Pedagogy, Pleasure and the Art of Poking Fun: Anti-colonial humour in Australian Indigenous studies
Authors: Jones Garry , Mcgloin Colleen
Published: December 2016

Australia's colonial history is fraught with ongoing social injustice and can be difficult to teach. The inclusion of humour on Australian Indigenous studies courses presents both challenges and opportunities for educators in the field. Students’ reactions to the inclusion of humour are often varied and care must be taken to ensure that Indigenous histories are taught with a view to balancing pleasure in learning while maintaining a focus on content. This paper elucidates the inclusion of humour in an undergraduate course where the student cohort is primarily non-Indigenous. Drawing from a range of critical works on humour, and on the teaching experience of the authors, the paper constitutes a work in progress that seeks to contribute to a sparse body of work dealing with Australian Indigenous humour in pedagogical contexts. The paper reflects on the course in question through an examination of texts used to teach students about the effectiveness of humour and its uses and applications in teaching Australian Indigenous studies.
“I'M Just as Indian Standing before you with no Feathers Popping Out of my Head”: Critiquing Indigenous performativity in the YouTube performances of the 1491s
Authors: Berglund Jeff
Published: December 2016

This article analyzes two YouTube videos by the 1491s, a Native American sketch comedy troupe. By using the interpretive framework of social media and film studies, which considers the role of viewership and fan participation in shaping reception, this article argues that the 1491s challenge Indigenous people to resist becoming complicit in the processes of simulation through an assertion of “visual sovereignty”. Additional analysis examines a representative range of viewers’ responses to the videos to flesh out how the 1491s’ work is understood and valued by various viewers, many of whom take the opportunity to self-identify as Native American. Taken together with additional insights provided by the performers themselves, this article assesses how comedy is used to draw attention to the ironic situation of Native people “redfacing,” of fabricating false and stereotypical identities, to appeal to non-Native peoples, particularly consumers, but also to enact critiques.
Change Point Estimation in Panel Data without Boundary Issue
Authors: Peštová Barbora , Pešta Michal
Published: December 2016

Panel data of our interest consist of a moderate number of panels, while the panels contain a small number of observations. An estimator of common breaks in panel means without a boundary issue for this kind of scenario is proposed. In particular, the novel estimator is able to detect a common break point even when the change happens immediately after the first time point or just before the last observation period. Another advantage of the elaborated change point estimator is that it results in the last observation in situations with no structural breaks. The consistency of the change point estimator in panel data is established. The results are illustrated through a simulation study. As a by-product of the developed estimation technique, a theoretical utilization for correlation structure estimation, hypothesis testing, and bootstrapping in panel data is demonstrated. A practical application to non-life insurance is presented as well.
Environmental Tipping Points for Sperm Motility, Fertilization, and Embryonic Development in the Crown-of-Thorns Starfish, Acanthaster cf. solaris
Authors: Caballes Ciemon Frank , Pratchett Morgan S. , Raymundo Maia L. , Rivera-Posada Jairo A.
Published: December 2016

For broadcast spawning invertebrates such as the crown-of-thorns starfish, early life history stages (from spawning to settlement) may be exposed to a wide range of environmental conditions, and could have a major bearing on reproductive success and population replenishment. Arrested development in response to multiple environmental stressors at the earliest stages can be used to define lower and upper limits for normal development. Here, we compared sperm swimming speeds and proportion of motile sperm and rates of fertilization and early development under a range of environmental variables (temperature: 20-36°C, salinity: 20-34 psu, and pH: 7.6-8.2) to identify environmental tipping points and thresholds for reproductive success. We also tested the effects of water-soluble compounds derived from eggs on sperm activity. Our results demonstrate that gametes, fertilization, and early development are robust to a wide range of temperature, salinity, and pH levels that are outside the range found at the geographical limits of adult distribution and can tolerate environmental conditions that exceed expected anomalies as a result of climate change. Water-soluble compounds associated with eggs also enhance sperm activity, particularly in environmental conditions where sperm motility is initially limited. These findings suggest that fertilization and embryonic development of crown-of-thorns starfish are tolerant to a wide range of environmental conditions, though environmental constraints on recruitment success may occur at later ontogenic stages.
Examining the Spatio-temporal Dynamics of PM2.5 in Saudi Arabia Using Satellite-derived Data: A Cluster Study
Authors: Aina Yusuf , Adam Elhadi , Ahmed Fethi
Published: December 2016

The study of the concentrations and effects of fine particulate matter in urban areas have been of great interest to researchers in recent times. This is due to the acknowledgment of the far-reaching impacts of fine particulate matter on public health. Remote sensing data have been used to monitor the trend of concentrations of particulate matter by deriving aerosol optical depth (AOD) from satellite images. The Center for International Earth Science Information Network (CIESIN) has released the second version of its global PM2.5 data with improvement in spatial resolution. This paper revisits the study of spatial and temporal variations in particulate matter in Saudi Arabia by exploring the cluster analysis of the new data. Cluster analysis of the PM2.5 values of Saudi cities is performed by using Anselin local Moran’s I statistic. Also, the analysis is carried out at the regional level by using self-organizing map (SOM). The results show an increasing trend in the concentrations of particulate matter in Saudi Arabia, especially in some selected urban areas. The eastern and south-western parts of the Kingdom have significantly clustering high values. Some of the PM2.5 values have passed the threshold indicated by the World Health Organization (WHO) standard and targets posing health risks to Saudi urban population.
Germination of Bouteloua dactyloides and Cynodon dactylon in a Multi-Polluted Soil
Authors: Delgado-Caballero María Del Rosario , Alarcón-Herrera María Teresa , Valles-Aragón María Cecilia , Melgoza-Castillo Alicia , Leyva-Chávez Arwell , Ojeda-Barrios Damaris Lepoldina
Published: December 2016

Mining wastes generate a high environmental impact, and population exposure to metals and metalloids. Phytoremediation is a technology that uses plants to remediate polluted sites, one of its limitations is seed germination in soil with high content of metals and metalloids. B. dactyloides is a native specie from semiarid regions, while C. dactylon is an introduced specie, both are tolerant to drought and low temperatures. Owing, the objective of this research was to evaluate the germination of both species, exposed to a multi-polluted soil with As, Cd, Pb and Zn of a mining site, pondering different pH conditions (from 5.0 to 9.0). The study considered 4 repetitions by type of seed and soil pH. B. dactyloides showed higher germination percentage (83%) with pH 7.8; while the greater germination of C. dactylon was 34 % at pH 6.0. In the soil at pH 5, the germination in both species was not reached, owing that metals are more bioavailable in an acid environment. C. dactylon is less tolerant to As, Cd, Pb and Zn, so it is considered not effective for phytoremediation process. B. dactyloides has a high phytoremediation potential for multi-polluted sites, but further experiments are needed.
Kriging with Unknown Variance Components for Regional Ionospheric Reconstruction
Authors: Huang Ling , Zhang Hongping , Xu Peiliang , Geng Jianghui , Wang Cheng , Liu Jingnan
Published: December 2016

Ionospheric delay has been a critical issue that limits the accuracy of GNSS precise positioning and navigation for single-frequency users, especially in mid- and low-latitude regions where irregularity of ionosphere is often significant. Kriging spatial interpolation techniques have been recently introduced to model the spatial correlation and variability of ionosphere, which intrinsically assume that the ionosphere field is stochastically stationary but does not take the random observational errors into account. In this paper, by treating the spatial statistical information on ionosphere as prior knowledge and based on TEC semivariogram analysis, we use Kriging techniques to spatially interpolate TEC values. By assuming that the stochastic models of both the ionospheric signals and measurement errors are only known up to some unknown factors, we propose a new Kriging spatial interpolation method with unknown variance components for both the signals of ionosphere and TEC measurements. Variance component estimation has been integrated with Kriging to reconstruct regional ionospherical delay. The method has been applied to data from the Crustal Movement Observation Network of China (CMONOC) and compared with the ordinary Kriging and polynomial interpolations with spherical cap harmonic functions, polynomial functions and low-degree spherical harmonic functions. The results have shown that the interpolation accuracy of the new proposed method is better than the ordinary Kriging and polynomial interpolation by about 1.2 TECU and 0.7 TECU, respectively. The root mean squared error of the proposed new Kriging with variance components is within 1.5 TECU and is smaller than those from other methods under comparison by about 1 TECU. When compared with ionospheric grid points, the mean squared error of the proposed method is within 6 TECU and smaller than Kriging, indicating that the proposed method can produce more accurate ionospheric delays and better estimation accuracy.
Miokinezyterapia jako forma rehabilitacji w ortopedii szczękowej
Authors: Gębska Magdalena , Wojciechowska Alina , Weber‑Nowakowska Katarzyna , Mikołajczyk Anna , Żyżniewska‑Banaszak Ewelina
Published: December 2016

W okresie wczesnego dzieciństwa narząd żucia może być podatny na działanie szkodliwych czynników zewnątrz‑ i wewnątrzpochodnych. Nieleczone odchylenia czynnościowo‑morfologiczne z tego okresu sprzyjają pojawieniu się zaburzeń w późnym dzieciństwie. Miokinezyterapia to zespół ćwiczeń, które obejmują mięśnie mimiczne i narząd żucia oraz mają na celu leczenie lub zapo‑ bieganie wystąpieniu wad zgryzu.
Badania składu ilościowego i jakościowego grzybów zasiedlających nasiona słonecznika (Helianthus annus L.)
Authors: Janda Katarzyna , Wolska Jolanta , Dębia Kamila
Published: December 2016

Wstęp: Celem pracy była ocena składu ilościowego i jakościowego grzybów zasiedlających nasiona słonecznika na podłożu RBCA, YpSs i DG18 w temperaturze 25, 37, 45°C.Materiał: Materiał badawczy stanowiło 20 próbek nasion słonecznika (niesolonych i nieprażonych). Najwięcej wyizolowano gatunków kserofilnych na pożywce DG18 w 25°C (33), w dalszej kolejności gatunków mezofilnych na RBCA w 25°C (29) oraz mezofilnych (22) i termofilnych (10) na pożywce YpSs (odpowiednio w 37°C i 45°C). Grzybem izolowanym ze wszystkich próbek był Eurotium herbariorum. Łącznie wyizolowano 287 szczepów należących do 52 gatunków.Wnioski: Przeprowadzone badania wzbogaciły mykocenozę nasion słonecznika o nowe gatunki, dotychczas nieizolowane z nasion tego gatunku
Medycyna i polityka w życiorysach Kazimierza Noiszewskiego, Józefa Piłsudskiego, Bolesława Wieniawy‑Długoszowskiego oraz Felicjana Sławoja Składkowskiego
Authors: Polak Agnieszka , Rejdak Robert , Czepita Damian , Rękas Marek , Wróbel Andrzej
Published: December 2016

W konsekwencji zmian ekonomicznych, jakie dokonały się podczas XIX w., ukształtowała się grupa polskiej inteligencji pracującej, m.in. lekarzy. Studia podejmowała młodzież pochodzenia mieszczańskiego, a w II połowie XIX w. wzrosła liczba studentów wywodzących się z rodzin ziemiańsko­‍‑szlacheckich. Polacy koń- czyli uczelnie wyższe poza granicami ziem polskich, spolonizowane po 1867 r. Uniwersytety w Krakowie i Lwowie. Artykuł przedstawia fragmenty biografii czterech Polaków: Kazimierza Noiszewskiego, Józefa Piłsudskiego i Bolesława Wieniawy­‍‑Długoszowskiego, Felicjana Sławoja Składkowskiego, którzy po 1864 r. podjęli studia medyczne. Kazimierz Noiszewski, dziecko emigrantów politycznych, żył i pracował w Rosji, aktywnie wspierał działalność Polonii oraz rozwój polskiej nauki medycznej. Józefowi Piłsudskiemu i Felicjanowi Sławojowi Składkowskiemu studia medyczne otworzyły drogę do konspiracyjnej i politycznej działalności. Bolesław Wieniawa­‍‑Długoszowski, postać o wszechstronnych zainteresowaniach, po ukończeniu studiów medycznych na Uniwersytecie Lwowskim i krótkim pobycie w Paryżu zaangażował się w walkę o wyzwolenie Ojczyzny.
Retrospektywna analiza zakażeń u pacjentów po przeszczepieniu nerki
Authors: Czarnota‑Chlewicka Joanna
Published: December 2016

Wstęp: Transplantacja nerki jest najlepszym sposobem leczenia schyłkowej niewydolności tego narządu i najczęściej wykonywanym zabiegiem spośród wszystkich transplantacji narządów unaczynionych. Rozwój immunologii transplantacyjnej oraz udoskonalanie schematów leczenia immunosupresyjnego powodują zmniejszenie liczby epizodów ostrego odrzucania i pozwalają na wieloletnie funkcjonowanie przeszczepionego organu. Jednak konieczność osłabiania systemu odpornościowego poprzez przyjmowanie leków immunosupresyjnych w celu zapobiegania odrzucania przeszczepu przyczynia się do pogorszenia możliwości organizmu w walce z infekcjami. Pacjenci po przeszczepieniu nerki są w grupie szczególnego ryzyka zakażeń bakteryjnych, wirusowych i grzybiczych, które stanowią istotny problem terapeutyczny.Celem pracy była retrospektywna analiza zakażeń u pacjentów po przeszczepieniu nerki i ustalenie czynników etiologicznych oraz postaci klinicznych zakażeń, a także ustalenie czynników ryzyka zakażenia u biorców nerki.Materiał i metody: Badaniami objęto 147 pacjentów hospitalizowanych na Oddziale Nefrologii i Transplantacji Nerek w Samodzielnym Publicznym Wojewódzkim Szpitalu Zespolonym w Szczecinie w okresie 1.01.2007–31.12.2008 r. Dane do badań zostały uzyskane z dokumentacji medycznej – protokołów przeszczepiania nerki, historii choroby oraz wyników badań mikrobiologicznych i serologicznych.Wnioski: 1. Podwyższone ryzyko wystąpienia zakażenia występowało w przypadku niskiej zgodności w układzie zgodności tkankowej HLA, długiego czasu niedokrwienia oraz u biorców, u których była konieczność stosowania większych dawek glikokortykosteroidów. 2. Szybkie rozpoznanie zakażenia i wczesne wdrożenie odpowiedniej terapii wydaje się mieć fundamentalne znaczenie dla skuteczności leczenia oraz profilaktyki dalszych powikłań infekcyjnych u pacjentów po przeszczepie nerki.
Wpływ terapii uzdrowiskowej na obniżenie natężenia odczuwania bólu u pacjentów z chorobą zwyrodnieniową stawów i kręgosłupa
Authors: Kuciel-Lewandowska Jadwiga , Paprocka‑Borowicz Małgorzata
Published: December 2016

Wstęp: Chorobie zwyrodnieniowej stawów i kręgosłupa towarzyszy przewlekły ból, będący głównym objawem chorobowym. Zadaniem medycyny uzdrowiskowej jest kompleksowa terapia w zakresie schorzeń narządu ruchu i innych układów oraz walka z bólem.Celem pracy była ocena wpływu terapii uzdrowiskowej na poziom odczuwania bólu u pacjentów z chorobą zwyrodnieniową stawów i kręgosłupa.Materiał i metody: Obserwacją objęto 120 osób z chorobą zwyrodnieniową stawów i kręgosłupa leczonych w uzdrowisku. W badaniu uwzględniono kompleksową terapię prowadzoną w czasie 21‑dniowych turnusów w uzdrowisku Przerzeczyn‑Zdrój z zastosowaniem wybranych zabiegów fizykalnych, kinezyterapii oraz naturalnych surowców leczniczych: borowiny i wody leczniczej radonowo‑siarczkowej. Ponadto prowadzono poradnictwo psychologiczne oraz edukację zdrowotną. W badaniu uwzględniono również obserwację 21‑osobowej grupy kontrolnej. Pacjenci z grupy kontrolnej nie korzystali z balneoterapii oraz opieki psychologicznej i edukacji. Zastosowano standardową wizualno‑analogową skalę oceny bólu (VAS) oraz niestandardową ankietę oceny bólu skonstruowaną na potrzeby badania. Ocenę bólu za pomocą VAS, a także ankiety oceny bólu w grupie badanej i grupie kontrolnej wykonywano przed terapią oraz po jej zakończeniu. Otrzymane wyniki opracowano statystycznie za pomocą programu Statistica PL. W ocenie uzyskanych wyników zastosowano test znaków i test Wilcoxona oraz statystyki opisowe.Wyniki: W wyniku terapii uzdrowiskowej oraz terapii prowadzonej ambulatoryjnie uzyskano poprawę w zakresie obniżenia natężenia bólu.Wnioski: 1. Leczenie uzdrowiskowe oraz leczenie prowadzone ambulatoryjnie wpływają na obniżenie poziomu bólu u pacjentów z chorobą zwyrodnieniową stawów i kręgosłupa. 2. Większą skuteczność w zakresie obniżenia poziomu bólu stwierdzono w przypadku terapii prowadzonej w uzdrowisku.
Laboratory Analysis of Several Solvent Systems to Dissolve Wellbore Organic Deposits
Authors: Al-Hajri Nasser M. , Taq Ali A. , AlAjmi Mohammed D. , Al-Ghamdi Abdullah A.
Published: December 2016

This paper will present a laboratory experimental work to examine the performance of a plurality of a solvent systems to dissolve wellbore organic deposits. Wellbore organic deposition has adverse effects on a petroleum well production or injection capability. The case study of the paper is a water injector, completed near a tar mat formation to provide pressure maintenance. The injector was identified with a wellbore obstruction. Samples from the obstructing material were analyzed in the laboratory using solvent extraction and infared spectroscopy. The downhole sample was found to be comprising 25 wt. % asphaltene and 75 wt. % maltene. The maltene was present in the form of saturates representing 32 wt. % of the sample and aromatics and resins representing 43 wt. % of the sample.

The wellbore sample was subjected to a range of solubility tests at a selected downhole temperature. The tests were conducted at static conditions; without agitation. Several solvent systems were evaluated as follows:

Xylene in diesel was used with 5 vol % mutual solvent. This system was examined at different xylene concentrations ranging from 10 to 30 vol %. A solvent system containing n-methylpyrrolidone, diesel, surfactant, and an aromatic solvent. A solvent system containing a chemical solvent, mutual solvent and diesel. This system was examined at different chemical solvent concentrations ranging from 10 to 30 vol %. An emulsified solvent system comprising n-methylpyrrolidone, fresh water, emulsifier, and an aromatic solvent

All solubility tests were monitored as a function of the soaking time required to dissolve the organic deposits.

The results of this lab work showed that several solvent systems are able to dissolve the wellbore organic deposits at varying solubility performances. Factors such as chemical handling and cost were considered to select the proper solvent treatment system for field application.
Origin of Cement, Diagenesis and its Role in Fluid distribution in Shallow Heavy Oil Unconventional Reservoir in Kuwait
Authors: Choudhary Pradeep Kumar , Al-Rashdan Saad , Ferdous Hasan , Saikia Pabitra , Ahmed Khalid , Ahmad Fatma
Published: December 2016

A shallow unconventional heavy oil reservoir in Kuwait is primarily an unconsolidated sandstone reservoir with intervening cemented siltstone and sandstone, and thin shale layers. The process and relative timing of cementation in the reservoir played a key role in fluid distribution as the pore-filling cements originated prior to oil migration. Moreover, oil migration into the cemented zones was prevented by the presence of cement.

This paper presents a study based on over 100 logs and 10 conventional cores in north of the reservoir. Detailed core analysis including petrography, XRD and SEM studies were considered understand the origin of cement, diagenesis and role in fluid distribution.

In terms of origin and diagenesis, three types of cements were identified namely Calcite, Dolomite, and Argillaceous. Calcite and Dolomitic cements are admixture of calcium carbonate and calcium-magnesium carbonate with argillaceous components. Argillaceous cement is dominated by illite-montmorillonite and palygorskite with minor amount of kaolinite and chlorite. Argillaceous one primarily originated from feldspar, calcite from meteoric water rich in dissolved calcium (gypsum) and Dolomite as replacement of precursor calcite.

Cement plays different roles in fluid distribution. Argillaceous cements cause pore-throat blockage due to presence of illite and palygorskite that form filamentous-fibrous aggregates. Cemented layers act as baffles in between oil layers capable of producing significant amount of trapped water in low pressure regime as they have significant amount of porosity and permeability. Finally cement layers hold water due to high capillary pressure and act as "water above oil" behaving as thief zone during thermal steam operation.

Understanding origin of cement, diagenesis and its role in fluid distribution assist in evaluation of the layered nature of this complex fluid distribution pattern reservoir. Finally, integration of depositional environment, lithofacies, and cement distribution greatly enhance the assessment of lateral extension and characterization of these type of reservoirs.
Integrated Geophysical Reservoir Monitoring for Heavy Oil
Authors: Passalacqua H. , Strack K.
Published: December 2016

Heavy oil (HO) is often produced with Enhanced Oil Recovery (EOR) methods such as steam or water flooding. In addition to flood front movements reservoir seal integrity has become an issue. Seal integrity is best addressed with microseismics and water flood front bets with electromagnetics. We address the fluid imaging problem using electromagnetics and after careful 3D feasibility and noise tests. We selected Controlled Source Electromagnetics (CSEM) in the time domain as the most sensitive method. From the 3D modeling we derived as key requirement that borehole and surface data needed to be integrated by measuring between surface to borehole and also calibrated using conventional logs.

Depending on the resistivity contrasts between the reservoir and the surrounding formation we need to measure electric AND magnetic fields as each of them have different sensitivity. The magnetic field senses more conductive strata, while the electric field will define fluid changes inside the HO reservoir. Furthermore, for shallow reservoir multi-frequency band sensors need to be deployed to get the optimum sensitivity.

Over the last decades we carried out 3D feasibilities for many oil fields and we are presently conducting the FIRST steam flood Pilot in an oil field in Asia. We also design custom data acquisition system for land, marine and borehole. Carrying out a Feasibility for each reservoir is key to control risk and cost. 3D modeling allows to integrate complex nature of the reservoir by constraining the model with existing seismic data. In all hydrocarbon cases it shows the need for full tensor CSEM, surface and borehole measurements to effectively determine the HO/steam flood front.
Pore Scale Representation of Near Wellbore Damage due to Asphaltene Deposition: Effect of Sand Grain Size and the Presence of Clay in Reservoir Rock
Authors: Prakoso Andreas , Punase Abhishek , Hascakir Berna
Published: December 2016

The near wellbore damage due to asphaltenes deposition is one of the major flow assurance issues currently faced by the petroleum industry. This study examines the pore scale flocculation and deposition processes of asphaltenes onto rock matrices. The effect of sand-grain size, clay presence in the reservoir rock, crude oil type, and precipitated asphaltenes type on the depositional behavior of asphaltenes is investigated. The porous media is prepared using sands with two different grain sizes or using sand-clay mixtures. Reservoir rocks were fully saturated with two different oil samples. 8 samples was prepared and they were washed by using either n-pentane or n-heptane, which are known as asphaltene insoluble solvents. In total, 16 experimental samples washed with solvents were subjected to optical microscopy and Scanning Electron Microscopy (SEM) – Energy Dispersive Spectroscopy (EDS) analyses to assess the asphaltene depositional mechanism. For all cases, porosity variations were measured experimentally. Our results suggest that asphaltene-clay interaction can increase the near-wellbore damage due to the strong polar ends in asphaltenes which are attached to clay surfaces and/or asphaltenes that are stuck in clay layers. Porosity of the sand has been found to decrease after the injection of solvents, indicating pore blockage due to asphaltene deposition. While the n-pentane precipitated more asphaltenes than n-heptane, n-heptane asphaltenes occupied more volume and resulted in higher porosity reduction due to higher polarity of n-heptane asphaltenes than n-pentane asphaltenes. Furthermore, the presence of clays and non-uniformity of grain sizes are observed to aggravate formation damage by asphaltenes. The SEM images showed that the interaction of clays with asphaltenes mainly reduces the permeability rather than porosity. The EDS analyses indicate that the impurity content of asphaltenes affect mainly the interaction of asphaltenes and clays.
Unique Cement Design to Mitigate Trapped Annular Pressure TAP Between Two Casing Strings in Steam Injection Wells
Authors: Brown Jeanna , Kenny Neil , Slagmulder Yves
Published: December 2016

Shell has experienced production casing deformation on several infill wells in an existing thermal development project in Canada. A full investigation identified trapped annular pressure (TAP) caused by unreacted water fraction in set cement between casing strings as a potential casing failure mode. A novel and innovative application of an existing technology (a cement blend incorporating hollow-glass microspheres) was developed, tested and implemented as an effective means to provide pressure relief in the cemented casing-casing annulus on steam injection wells.

Thermal cement blends from two suppliers were used in the testing program. The test slurries were cured in a test cylinder until compressive strength development tapered off, and then heated in increments to 320°C while pressure was recorded. Typical thermal blends containing a range of concentrations of hollow-glass microspheres were tested in this manner to establish a slurry design that would prevent the pressure build up from surpassing the temperature de-rated collapse resistance of the casing.

The tests using typical thermal cement blends with no glass bead additive resulted in rapid increase in pressure as the test cell was heated, and exceeded the temperature de-rated collapse value of the production casing string at temperatures much lower than typical steam injection temperatures. Tests performed on blends containing the glass spheres showed consistency and repeatability in results, and pressures were well below the de-rated collapse pressure of the production casing string at the maximum steam injection temperature.

Based on preliminary results, this investigation has concluded that the cement blend containing 10% BWOC hollow-glass microspheres is a viable alternative to conventional thermal blends, capable of providing hydraulic isolation to meet regulatory requirements and industry best practices, with the added benefit of providing a mechanism to mitigate TAP on steam injection wells.
Cost Optimization of a Thermal Recovery Project in Heavy Oil Green Field - Kuwait
Authors: Ortiz-Volcan J. L. , Behbahani F. M. , Akbar M. G.
Published: December 2016

This paper presents a practical approach toward cost optimization of a thermal recovery project in a heavy oil green field in Kuwait. This objective is achieved by understanding total cost breakdown for Capital Expenditure (CAPEX) and Operating Expenditure (OPEX) for all assets (natural and physical) during the economic horizon of the project and the identification of root causes of cost drivers that cause the total cost to increase, potential project delay and poor performance.

Complex cause and cost effect relationships are visualized using causal maps and loss causation models for seven most important group of risks during field life cycle. Uncertainties are addressed by comparison with analog fields undergoing Cyclic Steam Stimulation and Steamflood. One-way sensitivity analyses and stochastic modeling of key cost drivers solve a critical uncertainty, lack of OPEX data during commercial operations. Other application includes assessment of risks affecting total cost per barrel and selection of best strategy for risk mitigation with their costs and benefits.

A work vs. total undiscounted cost breakdown structure showed the 12 most critical cost drivers, where 70% corresponds to OPEX and 30% to CAPEX, fuel for steam flooding being the highest with 55%. A map with 17 elements was analyzed for associated physical assets, 2 causation maps describes 14 causes of total costs for surface and subsurface, including identification of key uncertainties and risks. Seven most significant groups of risks (total 66 risks) were modeled to visualize the impact on cost, people (health & safety) and environment with all mitigation actions ranked by cost benefit.

Understanding causes of high cost per barrel and their relationship with uncertainties and risks for a green heavy oil field, is a formidable tool for multidisciplinary cost optimization as it provides a common language that is understood by all disciplines involved.
An Approach to Mitigate Subsidence in Soft Rocks through Coupling Surface Tiltmeter and Injection/Production Data
Authors: Temizel Cenk , Kirmaci Harun , Inceisci Turgay , Wijaya Zein , Balaji Karthik , Suhag Anuj , Ranjith Rahul , Tran Minh , Al-Otaibi Basel , AlKouh Ahmad , Zhu Ying , Yegin Cengiz
Published: December 2016

Diatomites are high-porosity, low-permeability reservoirs with elastoplastic properties and high geo-mechanical responsiveness. They have a great potential for oil recovery despite these drawbacks. Withdrawal of fluids from the reservoir rock leads to subsidence causing compaction and shear stresses. This disturbed stress distribution results in well failures that causes loss of millions of dollars. Successful maintenance of pressure support through optimum injection/production is key to preventing subsidence to mitigate the risk of well failure and achieve better sweep efficiency for recovery.

There have been different approaches to tackle subsidence and well failures in diatomites, including the use of ‘backpressure method’, coupled with a neural network to optimize injection-production to ‘balance’ the rock in terms of stress-distribution and thus decrease well failure due to shearing. However, using such methods may mask other problems the well is experiencing including several mechanical issues that influence production. Another existing approach, satellite-imaging (InSAR) cannot be used to take real-time actions that is crucial in diatomites.

Surface tiltmeter data is collected to undertsand the relationship between injection/production and resulting surface deformation, which also provides information about well-to-well connectivity. A neural network-based approach is followed to determine the nonlinear relationship between surface subsidence/dilation and injection-production. This is then used to build an objective function that works to minimize the differences between well-to-well subsidence/dilation measured by the tiltmeters, by adjusting injection-production for the wells.

In this paper, a method that harnesses real-time surface tiltmeter data to adjust injection-production distribution in diatomites to decrease well failures is used beyond the existing applications of surface tiltmeter, for instance, in the areas of detection of early steam breach to surface in steam operations and fracture orientation. This method also provides real-time data for robust reservoir management of such reservoirs where satellite imaging is not effective.
Molecular Weight Correlation for Crude Oil in the Fields of Saudi Arabia
Authors: AlMatouq Hana
Published: December 2016

Molecular weight determination of crude oil samples is an important factor in the process of oil production in any oil field. This paper shows an experimental study to develop a correlation that numerically predicts the molecular weight of any crude oil sample with a known density.

The current method used in the laboratory to test the crude oil samples for average molecular weight value is the freezing point depression method, which is implemented in an automated cryometer 1. This method takes a relatively long time to perform. The use of the developed correlation will help in predicting a numerical estimation of the expected average molecular weight value for each tested sample. It will also help as a quality check step on the values we get from the performed experiment. Moreover, if this correlation continues to give accurate results, it can be used as an alternative method to the laboratory test.

The author carefully analyzed experimental data of average molecular weight as well as density to look for a correlation that relates both quantities. The analyzed data was of crude oil samples from thirty different fields in the Saudi Arabian region. This analysis required assuming that density is the only factor affecting the molecular weight value at constant temperature and pressure.

After analyzing all the experimental data generated in the laboratory, we successfully developed a correlation that gives accurate and comparable results within 2% average error to the obtained experimental values. These results were found for samples from several but not all of the Saudi Arabian fields. The study did not include new exploration fields or fields with insufficient data. Furthermore, this study concentrates solely on black oil samples and excludes gas condensate samples.
Wellbore Organic Deposits Dissolution Using An Emulsified Solvent System - Field Treatment
Authors: Al-Hajri Nasser M. , Al-Ajmi Mohammed D. , Al-Ghamdi Abdullah A. , Green Todd A. , Taq Ali A. , Al-Subaie Fehead M.
Published: December 2016

This paper will present a field case study to clean out wellbore organic deposits using a high flash point emulsified solvent system. Wellbore organic deposition was present in a horizontal water injector, Well-X, at 140 feet (ft.). The water injector is a pilot well completed above a tar mat formation to provide reservoir pressure maintenance. The wellbore deposits have restricted wellbore accessibility and caused loss of injection potential. Downhole samples from the obstructing material were collected from the wellbore using a wireline bailer. The samples were analyzed in the laboratory using solvent extraction and infared spectroscopy. The downhole samples were found to be comprised mostly of maltene which was present in the form of saturates, aromatics and resins at varying weight percentages. The organic deposits also contained asphaltene.

The wellbore organic materials underwent extensive solubility testing at a simulated downhole temperature. Several solvent systems were evaluated such as xylene in diesel and aromatic solvent systems. Based on the performance of the dissolution systems in terms of solubility and soaking time an emulsified solvent system comprising n-methylpyrrolidone, fresh water, emulsifier, and an aromatic solvent was chosen for field deployment. Other factors such as chemicals hazards and cost were also considered as part of the treatment fluid selection process.

The treatment fluid deployment was carried out using both the bull heading and coiled tubing (CT) techniques to ensure full exposure of wellbore organic deposits to the emulsified solvent system. The treated deposit solutions were flowed back using zero discharge system and their organic contents were inspected periodically. The field treatment design, job execution, contingencies, and what-if scenarios will all be discussed in this paper.
3D VSP Surveillance of Thermal Heavy Oil Recovery in Kuwait
Authors: Ren Zu Biao , Al-Haqqan Hamad , Ahmad Fatma , Tinnin John , Hamilton Angus
Published: December 2016

Some key challenges in thermal heavy oil recovery include how to monitor steam flood effectiveness and cap-rock integrity. Kuwait Oil Company acquired baseline 3D VSP surveys in January 2016 as geophysical surveillance projects for a steam flood pilot. This paper presents a technical approach of 3D VSP acquisition design, data processing, seismic inversion, quantitative interpretation and its application for the monitoring of steam movement.

Applying pressured steam to a reservoir can lead to damage of overlying cap-rock and could cause energy leakage through fractures. The technique of baseline 3D VSP and future time-lapsed 4D VSP are designed to image steam flood movement within the reservoirs. The possible applications of 3D/4D VSP technology include imaging the steam chamber size of a 30-day steam cycle, reservoir characterization and investigating integrity of the sealing cap shale.

Extensive planning and immaculate execution of the 3D VSP operations resulted in timely completion of survey acquisitions with high quality data. Because of the optimized acquisition parameters, the frequencies attained in these surveys were more than 30% higher than previously achieved in this same area. Extensive modeling enabled innovative customization of the acquisition design, optimized parallel processing, and interpretation techniques have allowed for a time effective acquisition-to-results turnaround that may affect the second cycle of the steam injection program. Resulting analysis on processed data clearly indicate the steam flow shape and direction. These significant results are providing important input for development decisions.

The reduction of the bin size from high fold and tight source / receiver distribution proven to be an effective and high quality method for imaging shallow geological target reservoirs. The resulting high frequencies obtained allowed for better vertical and spatial resolution, which enabled steam chamber size estimation and study of cap-rock integrity.
Estimating and Modeling Fluid Saturations in Viscous-Oil bearing Clastic Reservoirs Lithological Controls on Reservoir Properties and Fluid Contacts
Authors: Jha M. K. , Al-Dohaiem K. , Saikia P. , Al-Ali Y. , Al-Rashdan S. , Shanat F. H. , Ahmed K. , Ahmad F. , Tye R. , Dharanidharan B. , Prasse E. M. , Veedu F. Koyassan
Published: December 2016

Identifying oil-saturated versus water-saturated sands in shallow, unconsolidated, viscous-oil-bearing terrigenous-clastic reservoirs of Kuwait field is challenging. Field appraisal was based upon seismic, core and wireline-log data from 19 wells. Static and dynamic models incorporating all subsurface data were built to estimate oil-in-place and forecast production. Estimating and modeling fluid saturations in reservoir zones was accomplished by integrating core, dielectric-resistivity, Nuclear Magnetic Resonance (NMR) and Wireline Formation Tester (WFT) data. Wells were drilled along a northwest/southeast-trend, thus geologic and reservoir-property variability in east and west parts of the field are uncertain.

Stratigraphy and lithologic properties in these Miocene-age fluvial to shallow-marine strata impart a complex 3–D fluid distribution in the field. Repeated shoreline progradations and retrogradations deposited a stratigraphic succession defined by five facies-associations (i.e., shoal, tidal flat, tidal channel, lagoon, sabkha). Five lithofacies (i.e., shale, shaly sandstone, sandstone, carbonate-cemented sandstone, evaporite) were identified from core, elemental spectroscopy logs, and X-ray diffraction (XRD) data. Facies associations and lithofacies models were built using a combination of multiple-point statistics and sequential-indicator simulation. Lithofacies distribution in the static model was constrained by the facies-association distribution; reservoir-property distribution (e.g., porosity, permeability) was conditioned by lithofacies.

Discrete reservoir zones were defined to separate oil-saturated versus water-saturated sands. The volume and position of oil-bearing sands are controlled by the defined zones and permeability distribution. The oil-filling process in these viscous oil-bearing reservoirs is typically controlled by the pore throat distribution with the migrating oil taking the path of least resistance. Due to the presence of stratigraphic-flow baffles, fluid contacts vary from sand-to-sand vertically and laterally. Log data, core descriptions, ultraviolet photographs, WFT and pressure volume temperature (PVT) data guided the interpretation of lowest known oil and highest known water levels, thus reducing fluid saturation uncertainty in the field.
Geosteering Application in Heavy Oil Environment, Study Case in North Kuwait
Authors: Sitinjak Eri Sarmantua , Hasan Fawwaz , Abbas Faisal Fadel , Choudhary Predeep Kumar
Published: December 2016

The field study is in northern part of Kuwait targeting heavy oil formation, known to be shallow unconventional oil reservoir. It is heterogeneous shallow sandstone reservoir (500ft TVD) with low maturity oil, has low natural pressure, and poorly consolidated. Mud losses known to be the main risk of horizontal drilling in shallow heavy oil environment and the heterogeneous including continuity of the sand are also challenging for geo-steering team in order to place the well in the optimum position. Seismic is not available, however due to high offset well density a good correlation map has been produced. We are using formation tops from offset wells to delineate the continuity of the sand and trend of the structure dipping, we called it as shooting point method, which is assuming the trend of the structure from one offset well to another nearby offset well. The resistivity contrast will be expected to give us around 9 ft depth of detection (DOD) for our Azitrak resistivity tool based on Picasso plot. We made some scenarios for exiting the reservoir and it showed us some early warning 80ft to 180 ft prior to exit the reservoir. We use Autotrak, Azitrak dan Litotrak formation evaluation and density imaging tool to geo-steer and optimally place the wellbore inside 1B sandstone. The expectation of drilling the lateral was below 1000ft MD due to wellbore stability issue. From the correlation of available offset well it is clearly seen, there are two sand bodies in heavy oil target sand. The thickness is around 30-40 ft TVD and the structure was expected to be flat or a little bit dipping down. The well was landed in the middle of 1B, based on correlation of actual landing point log data to the nearest offset wells. Distance to bed boundary (D2B) showed local conductive layer from bottom since drilling the lateral section, which was not the response of base of 1B sand. So it was recommended to go down in stratigraphy in order to place the trajectory at the bottom part of 1B sand. In order to minimize wellbore stability issue along the lateral section, Bakerhughes recommended to maintain consistent faster ROP (80-100ft/hr) and effective hole cleaning. In the middle of lateral section of well B (1750ft MD) the well trajectory was inverted for the optimum production purposes to total depth (2250ft MD). Total lateral length achieved is 1116ft MD which covers 100% of the lateral length. Shooting point method in defining the rough structure trend from one well to another well was effectively applicative in the field, where current structure after drilling the lateral section is almost flat or slightly dipping down same as predicted before.
Well Design, Construction and Completion Considerations in a Thermal Oil Sand Development Project
Authors: Zatka Mirko
Published: December 2016

The sub-surface design of wellbores and associated well completions to be used in thermal oil sand operations must take into account a significant number of criteria and factors to ensure the delivered wells can provide the required long-term operating life and reliability required of them, especially when it comes to operating safety.

These considerations cover a wide range of primarily technical aspects, including the location and layout of the wells at surface and sub-surface; type of service the wellbore will be used for, therefore, the construction materials to be used and their properties; recovery process impact on the wellbore design including the geology and reservoir behaviour; tubing size, perforation and sand control considerations; artificial lift requirements; downhole operation selectivity; produced fluid compositions and conditions, and well operability requirements.

The level of detail that needs to be considered for each of these depends on the stage of project development. As work progresses, the level of detail increases in order to be able to arrive at an appropriate and balanced technical and safety design, as well as associated cost, once the final concept selection is made. The subsequent "Detailed Engineering" phase should be used only to fine-tune any remaining questions or issues that may arise in preparation for final project approval, and to provide the required definition of each element in order to be able to build / purchase / install / operate it. It is not discussed in this paper.