bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Surface and Downhole Microseismic Monitoring Coupled with Hydraulic Fracture Modeling in the Woodford Shale
Authors: Neuhaus Carl W. , Miskimins Jennifer L.
Published: June 2012

The work presented in this paper analyzes surface and downhole microseismic data for a horizontal well in the Woodford Shale in Oklahoma and compares those results with calibrated hydraulic fracture modeling. Hydraulic fracture models were created for each of five stages with a three-dimensional modeling software, incorporating available petrophysical data in order to match the recorded treatment pressure and the fracture geometry obtained from the microseismic data. Further analysis investigated the congruency of the downhole and the surface microseismic data, what differences they produced in a match if used exclusively, the influence of the number of events on the fracture geometry obtained from the microseismic data, the error of event location, the degree of complexity of the created fracture network, and the relationship between the magnitude of events and the time and location of their occurrence.

The fracture models produced good matches for both pressure and fracture geometry but showed problems matching the fracture height due to cross-stage fracturing into parts of the reservoir that were already stimulated in a previous stage. Surface and downhole microseismic data overlapped in certain regions and picked up on different occurrences in others, giving a more complete picture of microseismic activity and fracture growth if used together. However, they deviated in terms of vertical event location with surface data showing more upward growth and downhole data showing more downward growth. In general, the downhole microseismic data showed that the stimulation treatment was successful in creating a fairly complex hydraulic fracture network for all stages, with microseismic recordings making flow paths visible governed by both paleo and present day stresses. Plots showing the speed of event generation, the cumulative seismic moment, and the event magnitude versus the event-to-receiver-distance identified interaction with pre-existing fault structures during Stages III and V.
Determination of the In-Situ Polymer Viscosity from Fall-Off Tests
Authors: Laoroongroj Ajana , Zechner Markus , Clemens Torsten , Gringarten Alain
Published: June 2012

Laboratory experiments and simulations showed that for an Austrian oil reservoir, oil recovery can be significantly increased using polymers. One of the key design parameters for optimizing displacement efficiency while minimizing costs is the in-situ viscosity of the polymer solutions.

Whereas the viscosity of polymer solutions can be measured at surface, the viscosity in the reservoir is difficult to estimate due to degradation of the polymers during the injection process. In addition, polymers exhibit non-Newtonian behaviours resulting in different viscosities of the polymer solutions depending on the shear rate in the reservoir.

For the Austrian reservoir, water injection fall off tests were available. A simulation model was calibrated with these tests, and used to simulate injections of polymer solutions followed by fall offs. Simulation results indicate that water injection and fall off tests followed by a series of polymer injection and fall off tests can be interpreted to determine the in-situ viscosity of polymer solutions and the radius of the polymer front with reasonable accuracy, even in the case of non-Newtonian shear-thinning behaviour.

Being able to determine the in-situ viscosity allows modifying the injection programme (changing pumps, modifying perforations) if the degradation of the polymer viscosity is found to be significant, and adjusting the polymer concentration to improve stability and efficiency of the displacement process.
Multi-phase Well Testing to Calibrate Relative Permeability Measurements for Reservoir Simulation
Authors: Green Alistair J. , Gringarten Alain C. , Whittle Tim M.
Published: June 2012

Special core analysis (SCAL) is the standard method for estimating relative permeabilities. These, however, must be upscaled for reservoir simulation and the upscaling process creates uncertainties that are propagated to field performance forecasts. This paper describes a six-stage well testing procedure to calibrate relative permeabilities for reservoir simulation and to reduce uncertainties in relative permeability end points and curvature.

The well test includes: (1) single phase oil production; (2) buildup; (3) single phase water injection; (4) falloff; (5) two-phase oil and water production; and (6) a final buildup. The final buildup is initiated at minimum well productivity. Transient pressure analyses of the first buildup (2) and the falloff (4) provide the single phase mobility for each fluid at respective saturation end points. These yield an estimate for endpoint water relative permeability. Analysis of the second buildup yields an estimate of the minimum mobility. Uncertainty in oil and water relative permeability curvature is reduced using all three mobility estimates, while uncertainty in end point saturations can be reduced, for example, by comparing resistivity logs before and after water injection.

The procedure is demonstrated by simulating a newly drilled well in a homogeneous oil reservoir. Relative permeability is shown to significantly impact water breakthrough and oil production in an oil field developed by water flood. Sensitivities to reservoir heterogeneity, water cut during the flow back period, numerical dispersion, and capillary pressure have also been explored.

Information provided by the proposed test and interpretation procedure allows improved field development decisions early in field life.
Chalk Reservoir Management Through Rock Physics Diagnostics - Field Examples from the Danish North Sea
Authors: Gommesen Lars , Hansen Hans Peder
Published: June 2012

This paper illustrates the value of an integrated approach to management of chalk reservoirs and aims to provide the reader with 3D and 4D seismic examples that takes offset in the key parameters controlling elastic behaviour of chalk without discussing theories or models in depth, and only include well logs or laboratory derived models to support the examples.

The examples of this paper show how quantitative geophysical analysis through integration with well-established reservoir engineering and geoscience processes has impacted reservoir management and field development significantly. The diagnostics have led to optimized drilling and near field appraisal, maturation of wells, identification of remaining potential and insight to water flooding dynamics.

The paper concludes that an integrated approach to field development and reservoir management includes quantitative geophysical interpretation and that rock physics is an excellent enabler for integration between geoscience and petroleum engineering.
Characterization of Direct Fractures Using Real Time Offshore Detection of Deuterium Oxide Tracer
Authors: Poulsen Allan K. , Lafond Kim Bousquet , Voigt Niels V. , Lundgaard Thomas , Pedersen Lars Malcolm
Published: June 2012

Induced or natural fractures in waterflooded reservoirs can have a negative impact on oil recovery. Direct connections between injectors and producers allow otherwise recoverable oil to be bypassed by the injected water, reducing the sweep efficiency and the pressure support to the reservoir. Knowledge about the number of connections, their location and size is essential to properly design a reliable conformance treatment. The Danish Technological Institute has together with Maersk Oil developed a deuterium based tracer technology which can provide information about high conductivity fractures in tight reservoirs. The method has been proven on several studies in the North Sea and allows quick and direct analysis offshore. Immediate actions based on real time results offshore can be taken and minimum response time is needed for planning further operations.

The tracer used is deuterium oxide which is safe to handle and brings no environmental issues, as it is already naturally present in water. It is completely miscible with water and does not dissolve in the oil phase. The returns are analyzed directly from the produced water stream after separation using a mass spectrometer. This portable equipment allows a quick and reliable analysis with minimal sample preparation.

The concentration of tracer is analyzed to give information such has breakthrough time, concentration profile and volume of tracer returned. This data is then used to determine the number of fractures, their conductivity and their relative position in the wellbore using an injector-fracture-producer model.
Non-Darcy Flow Numerical Simulation for Low-Permeability Reservoirs
Authors: Xu Jianchun , Jiang Ruizhong , Xie Lisha , Wang Ruiheng , Shan Lijun , Li Linkai
Published: June 2012

With further progress of oilfields' development all over the world, more and more low permeability reservoirs are being put in production. However, fluid flow in low permeability porous media no longer obeys Darcy's law and instead conforms to the one of low-velocity non-Darcy seepage. Most commercial numerical simulation software may cause inaccuracy in simulating development performance of low permeability reservoirs. So the non-Darcy flow numerical simulation software has been developed.

In this paper, non-Darcy flow mathematical model was presented. Then, on the basis of practical field and laboratory experiment data, an ideal model of five-spot well pattern was established. Under the same reservoir condition, the non-Darcy simulation, Darcy simulation and quasi-linear simulation were conducted. At last, the simulation results of pressure gradient distribution, accumulative oil production and remaining oil distribution for Darcy flow, quasi-linear flow and non-Darcy flow were given. Research shows that flow of most regions in low permeability reservoir belongs to the curve segment which indicate the rationality of the non-Darcy software; compared with the results of Darcy flow, when considering non-Darcy flow, the accumulative oil production is lower, and the quasi-linear flow is the lowest, so Darcy flow model overstates the reservoir flow capability, and quasi-linear flow model overstates the reservoir flow resistance; analysis of remaining oil saturation indicates that for non-Darcy flow model simulation and quasi-linear flow model simulation, different flow regions exist including dead oil region and flow region which makes the flow patterns more complex in low permeability reservoir.
Assisted Seismic History Matching of the Nelson Field: Managing Large Numbers of Unknowns by Divide and Conquer
Authors: Stephen Karl D. , Kazemi Alireza , Sedighi Farzaneh
Published: June 2012

Automatic history matching may be used to condition reservoir simulation models by including time-lapse seismic data. Stochastic optimization algorithms are used to ensure a good search of the parameter space to ensure proper determination of the best models. These approaches can require many thousands of simulations for large dimensional problems. Divide and conquer is an assisted history matching approach that enables deconvolution of the parameters so that they can be searched more efficiently and also leads to better uncertainty analysis.

We present an application of this approach on the Nelson field. Nine years of production history data are used along with baseline and monitor surveys. Localised variations were made to permeability and net:gross. The reservoir was divided into separate parameter regions by combining experimental design and proxy model analysis. The former enabled insignificant parameters to be discarded while the latter showed that each region could be treated as a separate history matching sub-problem. Each sub-problem was then solved simultaneously using an adapted stochastic genetic algorithm.

The results showed that a forty-two dimensional problem could be reduced to a combination of three 9D problems and a 3D problem due to the spatial deconvolution of parameters and misfits. An improved match was obtained for the production and seismic data. Compared to a full stochastic search of the parameter space, the number of models was several orders of magnitude smaller. Further, improved uncertainly analysis was made possible resulting in better understanding of the future behaviour of the reservoir.

An improved match to reservoir models leads to better confidence in their prediction and thus they can be used more effectively in reservoir management. The method presented here to improve the match retains the benefits of stochastic searching without the penalty of requiring an impractical number of simulations.
Reducing Surface Tension To Improve Clean Up Efficiency Of Hydraulically Fractured Wells: Does It Really Work?
Authors: Ghahri Panteha , Ramli Muhamad Shwaz , Jamiolahmady Mahmoud
Published: June 2012

The main purpose of applying surfactants for hydraulically fractured wells is to reduce fracturing fluid surface tension during the leak-off process and hence improve its cleanup efficiency. Significant research has been devoted to developing such chemicals that can effectively reduce capillary forces between fracture fluid and resident rock and fluids. However, in a recent numerical study (SPE-14414), we have shown that, for some cases, reducing surface tension tends to decrease the cleanup efficiency.

Following our previous study, we have conducted a comprehensive sensitivity study to identify conditions in which reduction of surface tension improves cleanup efficiency. During this exercise, the impacts of matrix permeability (km), fracture permeability (kf) and fracture fluid injection volume were investigated. Over 200 simulation runs were performed covering a wide range of variation of of these pertinent parameters for a single fractured well model.

The results indicate that at the early stage of production the cleanup efficiency is relatively poor and almost independent of IFT, km and kf. At late stages of production and when kf is low, reducing surface tension decreases the cleanup efficiency. For high kf values, on the other hand, cleanup efficiency improves with such a reduction. For the cases with km values greater than 0.001, cleanup efficiency is more effective if IFT increases. Furthermore, as km decreases, the damage due to fracture fluid blockage becomes more severe. It is interesting to note that when km is less than 0.0001, cleanup efficiency always decreases with increasing surface tension, for all different kf values. The amount of gas production loss for such cases is relatively high, indicating the severity of fracture fluid damage for very tight gas reservoirs. Increasing the fracture fluid injection volume did not significantly change the above trend.

The results presented here aim to help the industry in properly evaluating the added value of using surfactant to improve the cleanup process of the hydraulically fractured wells.
Affecting Parameters in Density Driven Convection Mixing in CO2 Storage in Brine
Authors: Soroush Mansour , Wessel-Berg Dag , Torsaeter Ole , Taheri Amir , Kleppe Jon
Published: June 2012

After injecting CO2 into subsurface brine for storage, it will be trapped in the reservoir through various mechanisms. In the beginning, the geological trapping mechanism dominates and the CO2 plume is moving upward below a cap rock. Then brine will imbibe the formation and some parts of the CO2 will be trapped in the pore paces. Later on injected CO2 will dissolve in the brine and increases its density. As a result, the heavier brine will move into deeper parts of the reservoir and density driven convection mixing will occur. This is known as the solubility trapping mechanism.

Here in this study, density driven phenomena in CO2 storage in brine and the influencing parameters are the prime targets. We find particularly interesting results for this through Hele-Shaw cell experiments and numerical simulations. Hele-Shaw flow is defined to occur between two parallel flat plates separated by a small gap. In each experiment the cell is filled with fresh water and a shim prevents it to leak. Then liquid with higher density is placed on top. Several tests including water of varying salinity at the top of the cell have been conducted, and the results are interpreted separately and compared with the base experiment.

More extensive studies and sensitivity analysis is done based on a simulation model constructed on the reservoir properties of a brine formation, with wide range of affecting parameters, including density differences, permeability variations and the effect of diffusion coefficients. It has been also attempted to investigate the effect of anisotropy and heterogeneity on the CO2 state after injection.
Experimental and Simulation Studies of Density-Driven-Convection Mixing in a Hele-Shaw Geometry with Application for CO2 Sequestration in Brine Aquifers
Authors: Taheri Amir , Torsæter Ole , Wessel-Berg Dag , Soroush Mansour
Published: June 2012

CO2 sequestration in deep formations is being actively considered for the reduction of greenhouse gas emissions. Saline aquifers are considered as one of the most favorable options for this purpose. It has been observed that dissolution of CO2 into brine causes increased density of the mixture. If the corresponding Rayleigh number of the porous medium is high enough to initiate convection flows, density-driven-convection happens and the rate of dissolution increases. Early time dissolution of CO2 in brine is mainly dominated by molecular diffusion while it will be accelerated by density-driven-convection. More contribution of dissolution mechanism for trapping of CO2 decreases the risk of leakage.

Density-driven-convection mechanism was investigated in a Hele-Shaw cell with colored-brine and fresh-water instead of CO2-diffusive layer and brine. A convective instability is created by colored-brine diffusing onto the surface of a fresh-water layer. For this configuration, density-driven-convection flow enhances the mass transfer rate of high density fluid into the low density one. The analysis is also done numerically with Eclipse reservoir simulation software. With this analysis, the effects of density-driven-convection on accelerating the rate of dissolution are investigated. Although the horizontal wavelength of the initial instability is small, an increase in the horizontal wavelength of the convective flow with time and depth is observed as the resulting two-dimensional convection develops. Effects of density of fluids and also dip of the systems on convection flows are studied here. Also the changes in geometry of the convection streams with depth and time are investigated. The results have important implications in dissolution trapping of CO2 in brine aquifers.
The Volund Field: Developing A Unique Sand Injection Complex In Offshore Norway
Authors: Townsley Ann , Schwab Anne M. , Jameson Eric W.
Published: June 2012

The Volund Field lies in the Norwegian sector of the North Sea (Block 24/9). It is successfully producing from a large-scale hydrocarbon-bearing sandstone injection complex in the Early Eocene section. The complex was identified from the seismic, which exhibits a Class 3 bright negative amplitude AVO anomaly. The first exploration well was drilled in 2004 on the Hamsun Prospect, and development drilling was completed in 2010. Volund Field is currently producing oil from four horizontal branches, with one water injector well.

Volund Field is unique in that the entire field is composed of a large-scale sandstone injection complex. The reservoir consists of a deeper central unit of stacked sandstone sills, which are surrounded by shallower, steeper dipping injected sandstone dykes (>20°, often called ‘wings’). The injected sands are an excellent reservoir with consistently high porosity and permeability. Based on seismic, many of the steeply dipping injectites were expected to have good connectivity from the water leg through the oil leg and into the gas cap. However, pre-production the extent of aquifer support and efficiency of water sweep were unclear.

Geobodies were extracted from the seismic, based on the AVO anomaly exhibited by the hydrocarbon-filled injectite sands at Volund, and used to capture the geometry of the injectite within a reservoir geomodel. By populating these core bodies and surrounding "halos" with sands of varying properties, a series of realizations were built. Simulation modeling was employed to complete a dynamic uncertainty study and understand the potential effects of connectivity on aquifer and injection support. The four horizontal branches have now been successfully drilled using the seismic to give ~5500m of well control. Production began in April 2010 and has demonstrated that although the reservoir does benefit from aquifer support, water injection is required to maintain pressures at current production rates.

This Volund Field case study is an excellent, unique example of an economic producing sandstone injection complex.
Real Time Advanced Surface Flow Analysis for Detection of Open Fractures
Authors: Al-Adwani Talal , Singh Sunil , Khan Badruzzaman , Dashti Jalal , Ferroni Gionata , Martocchia Alberto , Estarabadi Javad
Published: June 2012

This paper presents a methodology which allows performing a real time characterization of the conductive natural fractures permeability intercepted by the bit while drilling. Such fractures are detected by monitoring continuously flowing from the wellbore into surrounding formations and the mud losses at the rig-site using flow-meters measuring both the ingoing and the outgoing mud flow.

Moreover, when drilling naturally fractured reservoirs, mud loss data provide one of the most effective means to assess the existence of conductive fractures intercepting the wellbore and therefore to identify potentially producing intervals.

The patterns in the variations of these volumes are analyzed to identify open fractures. The advanced Flowmeter has increased the resolution of the mud flow measurements. It has enabled the authors to assess the flow quantitatively and relate mud flow anomalies with the presence of open fractures down hole in the trial exploratory well.

The mud flow anomalies were validated with surface drilling parameters and gas indications. It was observed that the open fractures were associated with increase in torque and gas indication. The mud flow anomalies also provide crucial information for early kick or losses detection in high pressure gas wells because a better accuracy and a quicker response in detecting kicks and losses can be achieved by monitoring the changes of the mud flow rate by using flow meters measuring the inflow and the outflow mud rate, respectively.

Method and Theory The most commonly used techniques to detect the mud losses consist in monitoring the level of the mud pits with acoustic, floating sensors and/or using paddles set inside the flow line that measure the return mud flow rate with a small degree of accuracy. The traditional Flowmeter provides a simple qualitative fluctuation in mud flow. In contrast this advanced Flowmeter works on the principle of converting mudflow out in to an analog signal which represents the volume of mud.
Evaluation of the association between AT1R1166C polymorphism and the incidence of cad and CAC score in the Iranian population
Authors: Mohammadpour Hooshang , Nazemi Saeed , Foroughi Maryam , Ghorbani Maryam , Shamsara Jamal , Behravan Javad
Published: June 2012

Most of the physiological effects of Ag II are mediated by the angiotensin II
type 1 receptor. Polymorphisms of the AT1R gene can affect the function of
this receptor and subsequent atherogenic activity. In this study we
investigated the correlation between AT1R A1166C polymorphism and coronary
artery calcification (CAC), a marker of the coronary artery burden. Fifty CAD
patients and fifty healthy individuals fulfilled the inclusion and exclusion
criteria entered this study. CAC was determined in the left main coronary
artery (LMCA), left coronary artery (LCA), right coronary artery (RCA) and CX
by CT-angiography and a blood sample was taken at this time. DNA extracted
from whole blood leukocytes was analyzed by the polymerase chain reaction -
restriction fragment-length polymorphism (PCR-RFLP) assay. There were no
significant differences in genotype and allele frequencies between the CAD
and control groups. The mean calcium score was compared in genotypes and
alleles and no significant difference was seen. In addition, the frequency of
genotypes and alleles was not significantly different in the calcium score
groups (low<100, medium= 100-400, high >400). An analysis was performed
separately in males and females and no significant correlation was found.
According to our results, no association was found between AT1R1166C
polymorphism and the incidence of CAD and CAC score in our study population.
Correlations between vascular endothelial growth factor expression, microvascular density in tumor tissues and TNM staging in breast cancer
Authors: Comşa Şerban , Cоmpean Maria , Ceauşu Raluca , Suciu Cristian , Raica Marius
Published: June 2012

Breast cancer is the most frequent malignancy in women worldwide. In spite of
its questionable reliability, the TNM (Tumor, Node, Metastasis) staging
system is widely used for the prognosis of this disease. On the other hand,
angiogenesis is considered to have an essential role in the evolution of
breast cancer and the Vascular Endothelial Growth Factor (VEGF) has proven to
be the key regulator of this process. Quantitation of VEGF and the tumor
vasculature might play an important role in predicting tumor behavior and
patient management. The aim of our study was to evaluate the potential
correlation between the VEGF expression, microvessel density (MVD) in the
tumor tissues and TNM staging in breast cancer. We included 34 patients with
breast cancer who had undergone surgical treatment and evaluated each case
clinically, histopathologically and by immunohistochemistry for VEGF and CD31
expression in the tumor tissues. VEGF expression was evaluated by calculating
the average percentage of cytoplasmic positive cells from 3 high power
fields. MVD was expressed as the average number of the CD31+ microvessels
from 3 high power fields. Expression of VEGF was significantly associated
with the number of lymph nodes with metastasis, the number of cells in
mitosis, the presence of necrosis and the T-stage (inverse correlation). MVD
correlated very well with the histological grading, the number of cells in
mitosis, the presence of inflammation and the presence of necrosis. No
correlation could be established between VEGF expression and MVD. Although
their relationship with TNM staging remains unclear, VEGF expression and MVD
proved to be important indicators of the malignant status in breast cancer,
confirming the major involvement of angiogenesis in this type of cancer. Both
of them are valuable prognostic factors in breast cancer, but the pattern of
their relationship needs further analysis of the VEGF receptors in order to
be described.
Estradiol and GH cells: Immunohistomorphometric study in an animal model of andropause
Authors: Milosevic Verica , Trifunovic Svetlana , Filipovic B. , Sosic-Jurjevic Branka , Pantelic Jasmina , Percinic-Popovska Florina , Ajdzanovic V.
Published: June 2012

Andropause, the culminating phase of ageing in males is characterized by the
decline of the growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis
that is responsible for somatic development. Estrogens on the other hand,
assume a relevant somatic role, as well as the one in the pituitary. They are
particularly interesting because of their therapeutic uses in certain common
ageing-associated diseases. The aim of the present study was to examine the
effects of subcutaneous treatment with estradiol, dipropionate on the
immunohistomorphometric features of GH cells, in an animal model of the
andropause. Sixteen-month-old Wistar rats were divided into sham-operated
(SO), orchidectomized (Orx) and estradiol dipropionate-treated
orchidectomized (Orx+Edp) groups. Estradiol dipropionate (0.625 mg/kg/day)
was administered subcutaneously for three weeks while the SO and Orx groups
received the vehicle alone. GH cells were identified by the
peroxidase-antiperoxidase (PAP) immunohistochemical procedure. In the Orx+Edp
group, GH cell volumes as well as the relative volume densities were
significantly (p<0.05) decreased, by 27.4% and by 61.1%, respectively, in
comparison with the same parameters of SO animals. Compared to the Orx
animals, the cell volumes and relative volume densities of GH cells in
Orx+Edp group were also significantly (p<0.05) decreased, by 23.2% and by
64.1%, respectively. It can be concluded that chronic estradiol dipropionate
application in an animal in the andropause results in the suppression of
immunohistochemical and morphometric parameters of pituitary GH cells.
Bioactivity of Centaurea persica boiss. (Asteraceae)
Authors: Sarker Satyajit , Nahar Lutfun , Gujja Srikanth , Begum Shazi , Celik Sezgin
Published: June 2012

The free-radical-scavenging property, antibacterial activity and brine shrimp
toxicity of petroleum ether (PE), dichloromethane (DCM) and methanol (MeOH)
extracts of Centaurea persica, a Turkish medicinal plant, were assessed using
the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, the resazurin microtiter
plate based assay, and the brine shrimp lethality assay, respectively.
Additionally, the disc diffusion assay was also used to assess antibacterial
activity. Only the MeOH extract of C. persica exhibited a significant
free-radical-scavenging property in the DPPH assay, with an RC50 value of
0.025 mg/mL. However, in the TLC-based qualitative assay, petroleum ether and
DCM extracts showed an extremely low level of free-radical-scavenging
property. Among the solid-phase extraction fractions of the MeOH extract, the
fractions eluted with 60% and 80% MeOH in water exhibited the highest level
of free-radicalscavenging activity (RC50 = 0.010 and 0.015 mg/mL,
respectively). While DCM extract showed reasonable antibacterial activity
against five out of the nine test strains both in the disc diffusion assay
and in the resazurin assay, the MeOH extract was highly active against both
Escherichia coli and ampicillin-resistant E. coli strains. Among the
solid-phase extraction fractions of the MeOH extract, fractions eluted with
80% MeOH in water and 100% MeOH displayed significant antibacterial potencies
against both E. coli species. None of the extracts showed any significant
toxicity towards brine shrimps (LD50 = >1.00 mg/mL).
Chloroplast pigments in post-fire-grown cryptophytes on Vidlic mountain (southeastern Serbia)
Authors: Markovic Marija , Pavlovic Dragana , Tosic Svetlana , Stankov-Jovanovic Vesna , Krstic N.S. , Stamenkovic S.M. , Mitrovic Tatjana , Markovic V.Lj.
Published: June 2012

In this study the content of chloroplast pigments (chlorophyll a, b, a+b, and
carotenoids) in the leaves of Geranium macrorrhizum L., Doronicum columnae
Ten., Aegopodium podagraria L. and Tussilago farfara L. from a beech forest
that had undergone fire on Vidlic Mountain was determined. The same species
of plants from a place that had not been exposed to fire were taken as
controls. Chloroplast pigments were determined from acetone extracts of these
plants spectrophotometrically. In the first year after the fire the content
of chlorophyll a, b and a+b in Geranium macrorrhizum L. and Doronicum
columnae Ten. was greater than in the plants not exposed to fire. The results
were the opposite for Aegopodium podagraria L. and Tussilago farfara L. These
differences can be attributed to the different physiology of the plants and
consequently their different adaptation patterns. The carotenoid content was
higher in the plant species at the fire site than in the area not exposed to
fire.
Weed management in tropical turfgrass areas: A review
Authors: Uddin Kamal , Juraimi Shukor , Ismail Razi
Published: June 2012

Cultural practices promoting vigorous, environmentally friendly dense turf
are discussed. These are the most important and least recognized means of
preventing weed establishment and encroachment which includes appropriate
propagation material selection, sanitation and cultivation, adjustment of
planting time, manual weed control (hand pulling, hoeing and rouging),
turfgrass selection to better compete with weed populations, applying
physiological stresses, fertilizer management, moisture management, mowing,
and irrigation with salt water. Cultural management of weed is important
because it reduces dependence on synthetic pesticides. A healthy turfgrass
stand has been reported to be the best defense against weed colonization, and
can be accomplished by proper mowing, watering, and fertilization. Mowing
height is the clearest and best-documented cultural factor and a lower mowing
height is always associated with more weeds in the turfgrass. Split
application of fertilizer at intervals throughout the growing period is
recommended for warm season turfgrasses. The application of fertilizer during
dormant periods or periods of low growth may encourage weed growth. Hand
pulling and hoeing effectively control annual and biennial seedling weeds for
small areas. Irrigation by saltwater has been one method used recently to
effectively control grassy broadleaved and sedge weeds in salt-tolerant
turfgrass species. Cultural weed management practices in turf might provide a
first defense: however, relying only on cultural control measures may not be
a good idea. An integrated approach of combining cultural practices and
chemicals can complement each other and give flexibility to decision making.
Research is needed on optimizing the choices of herbicide and/or cultural
practices as part of an integrated management system for turfgrass.
Community-level response to different human disturbances and land use of small mammals in two marshland habitat patches in Hungary
Authors: Horváth G.F. , Horváth Barbara , Sali Nikolett , Herczeg R.
Published: June 2012

Marshlands are important ecosystems that provide valuable habitats for
wildlife communities. We investigated the small mammal community-level
response to different human disturbances and land use in the Kis-Balaton
Landscape Protection Area, which is an endangered marshland ecosystem of
Hungary. Land use, conservation management and other human disturbances
(burning, mowing) together with unfavorable weather conditions have caused
the degradation of the original homogeneous sedgy marshland on both sampled
areas. We measured the species turnover between the different periods
separated by the habitat changes. Our results suggest that populations of the
habitat-specialist species of marshland areas (e.g. endangered Hungarian
subspecies of root vole) are sensitive to the negative effects of environment
and human disturbances. The combined effect of human disturbances and the
stochastic processes of the environment can cause the disappearance and
substitution of character species stabilizing the communities, which in turn
leads to the modification of species composition and structure of small
mammal assemblages.
Application of grain baits to control common vole Microtus arvalis (Pallas, 1778) in alfalfa crops, Serbia
Authors: Jokic G. , Vuksa Marina , Elezovic I. , Djedovic Suzana , Kataranovski D.
Published: June 2012

In order to compare the efficacies of conventional (cholecalciferol and
bromadiolone) and new (sodium selenite) rodenticides, applied in the grain
bait formulation on the whole-grain of wheat (Triticum aestivum) and
triticale (Triticasecale) in alfalfa crops, experiments were conducted at two
sites near Belgrade, Serbia, in the spring of 2009, using a standard EPPO
method. The presence of rodent populations, their spatial distribution and
density indices were evaluated by pretreatment census and rodenticide
efficacy by counting active holes, 14 and 28 days after treatment. The
average Microtus arvalis numbers of 158/ha and 184/ha were found to cause
7.4% and 9.6% alfalfa green biomass yield decreases, respectively.
Twenty-eight days after treatment, the average efficacy of grain bait
formulation (on wheat and triticale grains) of sodium selenite and
cholecalciferol was 81%, while bromadiolone which had a higher efficiency,
85%, in the control of the common vole in alfalfa crops. The analysis of
variance (ANOVA) showed that the origin of active substances, bases and
associated interactions a.s x based on the efficacy-investigated grain baits
did not have a statistically significant impact on the expression efficiency
of the tested baits. Triticale grains can be used as carriers of active
substances, sodium selenite, cholecalciferol or bromadiolone in preparation
baits. Control of M. arvalis with the new rodenticide, sodium selenite, gave
efficacy results about equal to that of cholecalciferol and bromadiolone and,
therefore, provided a possible alternative rodenticide for vole control in
alfalfa.
Female reproductive characteristics of the Horvath’s rock lizard (Iberolacerta horvathi) from Slovenia
Authors: Ljubisavljevic Katarina , Glasnovic P. , Kalan Katja , Krystufek B.
Published: June 2012

In this paper, we present data on the female reproductive traits of the
Horvath?s rock lizard from Slovenia. The clutch, egg and hatchling
characteristics were investigated based on clutches laid in laboratory
conditions by pregnant females collected from a natural population. A female
lays one clutch of eggs annually with an average number of three (range 1-5)
eggs. We found a significant positive correlation between female size and egg
width and volume. The mean egg length and volume in a clutch decreased
significantly with clutch size independently of female size. The incubation
period averaged 44 days. Significant positive correlations were found between
the hatchling total length and mass, and egg mass. There was a significant
negative relationship between the egg mass and incubation duration. The
life-history strategy of the Horvath?s rock lizard appeared to be shaped by
several factors, such as the constraints of a high-altitude environment,
flattened body morphology and possibly phylogenetic background.
Updated checklist of the Eurytomidae (Hymenoptera, Chalcidoidea) species of Turkey
Authors: Çam H.
Published: June 2012

A checklist of Eurytomidae species known in Turkey is presented for the first
time in the present paper, including their distributions in Turkey. A total
of 88 species in 8 genera belonging to 2 subfamilies (Eurytominae, Rileyinae)
are determined. Sycophila mellea Curtis, 1831 is presented as a new record
for Turkish fauna.
The aphid fauna of Turkey: An updated checklist
Authors: Görür G. , Akyildirim H. , Olcabey G. , Akyurek B.
Published: June 2012

This study provides a comprehensive list of Turkey aphid fauna (Hemiptera:
Aphididea). A total of 466 species and 12 subspecies belonging to 141 genera
and 13 tribes, are listed. The list includes all records from 1903 to 2011.
The family of Aphididae comprise the highest number of species (457),
followed by Adelgidae (6) and Phylloxeridae (3), respectively. Inside
Aphididae, the tribe of Macrosiphini is the richest group with 197 species,
whereas the tribe of Cinarini has only one species. The number of aphid
species actually reported for Turkey is lower than recorded for neighboring
countries, suggesting that further faunistic studies needs to improve
informations on this topic.
Chthonius (Chthonius) makirina (Chthoniidae, Pseudoscorpiones), a new species from Croatia
Authors: Curcic B.P.M. , Dimitrijevic R.N. , Radja T. , Milincic M.
Published: June 2012

The pseudoscorpion sample discovered under a stone in Dalmatia (Croatia) was
studied. A new species is described herein: Chthonius (Chthonius) makirina n.
sp. This taxon is considered endemic to Dalmatia and the Balkan Peninsula.
Along these lines, the diagnostic characters of the analyzed species are
thoroughly described and figured. Taxonomic interrelationship and geographic
distribution are briefly discussed.
Analysis of the bacterial vaginosis predictive significance in the diagnosis of inflammatory processes in female pelvic minor
Authors: Loncar D.
Published: June 2012

Pelvic inflammatory disease (PID) has an incidence of 100-200/100,000. The
aim of this study was to determine whether there is a correlation between the
serum proinflammatory cytokines IL-1? and IFN-? and the presence of bacterial
vaginosis (BV) or chlamydia infections (Chl) in women with symptoms of
inflammatory processes in the pelvic minor. The study included fifty patients
diagnosed with PID and an average age of 32 years. The results of this study
revealed that the number of women with BV and PID presented increased IL-1?
levels in the serum, whereas in women with chlamydial infections and PID
serum the level of IFN-? was increased. The study shows that in patients with
PID, in whom there was no diagnosis of BV and infection with Chlamydia
trachomatis, the levels of IL-1? and IFN-? were increased. The conclusion of
this research points to the importance of monitoring levels of cytokines in
patients with homeostasis of vaginal flora disorders in the prevention of
PID.
First record of Aeolothrips gloriosus Bagnall (Thysanoptera: Aeolothripidae) in Slovenia
Authors: Trdan S. , Vidrih M. , Vierbergen G.
Published: June 2012

In May 2011, females of Aeolothrips gloriosus were found in the blossoms of
olive trees in olive plantations at Dekani and Skocjan. This is the first
record of the species in Slovenia, and its occurrence may be of economic
importance because the larvae can be efficient predators of plant pests. In
this paper the detection, morphology, distribution and hosts of A. gloriosus
are presented.
Neoteny of the European plane tree
Authors: Ocokoljic Mirjana , Sijacic-Nikolic Mirjana , Vilotic Dragica , Vujicic D.
Published: June 2012

The neoteny of 64-day-old European plane tree autovegetative progeny is
described, starting from the fact that sexual maturity in the juvenile stage
of tree development is a rare and significant process by which the period of
synthesis of new lower taxonomic units is shortened. The observed formation
of European plane tree reproductive organs has been classified as induced
neoteny. Compared to the inflorescences of mature European plane trees, the
number of precocious inflorescences was lower, flower structure was simpler,
and the diameters of inflorescences were the same. As neoteny is a genetic
and physiological marker for the tree genotype and the species, and as it is
classified as an example of parallelinherited variability explained by
changed interactions of trophic, hormonal and genetic systems, this analysis
of neoteny can be a contribution to its further scientific study and its
practical utilization at a larger scale.
Pollinator diversity (Hymenoptera and Diptera) in semi-natural habitats in Serbia during summer
Authors: Mudri-Stojnic Sonja , Andric Andrijana , Józan Z. , Vujic A.
Published: June 2012

The aim of this study was to assess species diversity and population
abundance of the two main orders of pollinating insects, Hymenoptera and
Diptera. The survey was conducted in 16 grassland fragments within
agro-ecosystems in Vojvodina, as well as in surrounding fields with
mass-flowering crops. Pollinators were identified and the Shannon-Wiener
Diversity Index was used to measure their diversity. Five families, 7
subfamilies, 26 genera and 63 species of insects were recorded. All four big
pollinator groups investigated were recorded; hoverflies were the most
abundant with 32% of the total number of individuals, followed by wild bees -
29%, honeybees - 23% and bumblebees with 16%.
Climate change impact on wetland forest plants of SNR Zasavica
Authors: Cavlovic Dragana , Obratov-Petkovic Dragica , Ocokoljic Mirjana , Djurdjevic Vladimir
Published: June 2012

Wetlands are among the most vulnerable habitats on the planet. Very complex
forest ecosystems are also parts of wetlands. Research and analysis of forest
vegetation elements, leads to a conclusion about ecological conditions of
wetlands. The aim of the paper is detail forest vegetation study, and
analyzing the impact of climate changes on wetland forest vegetations of the
strict protection area at the SNR Zasavica Ramsar site. Field research was
carried out by using Braun-Blanquet?s Zurich-Montpelier school method.
Phytogeographical elements and life forms of plants were determined
subsequently, in order to get indicator values of wetland plants. Coupled
Regional Climate Model (CRCM), EBU-POM was used for the climate simulations.
Exact climatic variables for the site were determined by downscaling method.
Climatic variables reference values were taken for the period of 1961-1990,
and climate change simulations for the period 2071-2100 (A1B and A2).
Indicator values of forest plants taken into consideration were humidity and
temperature; therefore, ecological optimums were determined in scales of
humidity and temperature. Regional Climate Model shows that there will be a
long and intensive dry period in the future, with high temperatures from
April till October. Continental winter will be more humid, with higher
precipitation, especially in February. Based on the analysis of results it
was concluded that wetlands are transitional habitats, also very variable and
therefore vulnerable to changes. The changes may lead to the extinction of
some plant species.
Bark stripping damage by red deer (Cervus elaphus L.) in the fenced rearing centre “Lomnicka Reka“
Authors: Gacic Dragan , Danilovic Milorad , Zubic Goran , Cirovic Predrag
Published: June 2012

Bark stripping damage is a serious problem in some forest hunting grounds in
Serbia. This study aimed at assessing the incidence and intensity of bark
stripping by red deer in the fenced rearing centre ?Lomnicka Reka? (Mt.
Veliki Jastrebac, central Serbia). The data were collected by detailed
surveying of the entire rearing centre over spring and autumn 2008, 2009 and
2010. Our results show that, in spring and summer, it is exclusively
broadleaf tree species that are bark stripped by red deer, mainly beech
(86.3% or 536 trees) and hornbeam (10.1% or 63 trees). The incidence and
intensity of bark stripping were the highest in the diameter class of 20-39.9
cm. Damaged trees were identified in all parts of the rearing centre, at all
aspects and at different slopes. Beech bark was stripped over the period
May-August, with the focus in June or July.
Effect of bending pattern on finger joint bending strength
Authors: Dzincic Igor , Palija Tanja , Pavlovic Dragan
Published: June 2012

Limited information is available on end gluing hardwoods in contrast to
softwoods, which have been extensively investigated. The objective of this
study was to examine the influence of bending patern on bending strength of
finger jointed beech wood. In structural uses finger jointing is finally the
major method to end joint timber for the production of glue-laminated
elements. There are no bending strength experimental results for
finger-jointed hardwoods for investigations conducted in Serbia. Two finger
jointed profiles were studied in accordance with DIN68140. The finger joints
were made by side and by face of beam. Length jointed samples were loaded at
the side and in the face. The obtained results led to the conclusion that the
direction of load, gluing surface and the position of joint influence on the
strength of continued longitudinal beams.