bluuebunny/crossref_metadata_2025_split huggingface dataset:
Orobanche lutea Baumg. (Orobanchaceae) in Poland: revised distribution, taxonomy, phytocoenological and host relations
Authors: Piwowarczyk Renata , Krajewski Łukasz 
Published: March 2015

Abstract
The paper presents current distribution of Orobanche lutea Baumg. in Poland based on a critical revision of herbarium and literature data as well as results of field investigations conducted between 1999-2014. Majority of localities are centred around the Silesia-Cracow, Małopolska and Lublin-Lviv Uplands. The greatest density of sites with probably the most abundant populations in Europe is in the central part of Silesia-Cracow Upland, which, by several hundred years, was heavily exploited for calamine mining (rich in zinc, lead and silver). This resulted in the formation of large areas of gangue containing toxic heavy metals. Since limestone, dolomite, marl and postglacial calcareous clay and sands occur there in most places, the soil is often strongly calcareous. Populations of O. lutea contain here many thousands of shoots. The distribution of the species in Poland is mapped. The taxonomy, biology, ecology and threats are also discussed.
Orobanche flava (Orobanchaceae) in Poland: current distribution, taxonomy, hosts and plant communities
Authors: Piwowarczyk Renata 
Published: March 2015

Abstract
Orobanche flava is a species of Central European mountain ranges, mainly the Alps and Carpathian Mts. The paper presents the current distribution of O. flava in Poland based on a critical revision of herbarium and literature data as well as results of field investigations conducted between 1999 and 2014. The distribution of species is centered in southern Poland, mainly in the Carpathian Mts., and, sporadically, in the Sudeten Mts. The distribution of O. flava in Poland is mapped. The taxonomy, biology, and ecology are also discussed.
First white-flowered species of Sertifera (Orchidaceae) discovered in Colombia
Authors: Szlachetko Dariusz L. , Kolanowska Marta , Medina Trejo Ramiro 
Published: March 2015

Abstract
A new species of Sertifera is described and illustrated based on Colombian material. The novelty resembles Sertifera colombiana, but it is characterized by glandular leaf sheaths, larger, white flowers, ovate to oblong-ovate sepals, ligulatelanceolate petals and apically triangular lip. This is the first report of a white-flowered representative of the genus.
Orchidaceae in the Pieniny Mountains (Western Carpathians)
Authors: Frey Ludwik 
Published: March 2015

Abstract
Orchids constitute an important component of the Pieniny Mts. flora. The presence of 35 orchid species has been noted so far in this region. A considerable number of these species are endangered for various reasons. Eight species have been deemed extinct in the area. On the other hand, the orchid flora of the Pieniny Mts. includes species that widen their local ranges and can, thus, be considered expansive as well as new species, recently entered in the list of orchids occurring in the said mountain range (Epipactis microphylla and Epipactis muelleri). It is necessary and important to conduct an inventory of Pieniny orchid resources (the major aim of this study) that would be repeated at certain intervals, in order to know the number of stations and of individuals per population of each species, which would enable taking relevant actions needed to prevent the disappearance of these plants from the Pieniny Mts.
Overview of the Mceliece Cryptosystem and its Security
Authors: Repka Marek , Zajac Pavol 
Published: March 2015

Abstract
McEliece cryptosystem (MECS) is one of the oldest public key cryptosystems, and the oldest PKC that is conjectured to be post-quantum secure. In this paper we survey the current state of the implementation issues and security of MECS, and its variants. In the first part we focus on general decoding problem, structural attacks, and the selection of parameters in general. We summarize the details of MECS based on irreducible binary Goppa codes, and review some of the implementation challenges for this system. Furthermore, we survey various proposals that use alternative codes for MECS, and point out some attacks on modified systems. Finally, we review notable existing implementations on low-resource platforms, and conclude with the topic of side channels in the implementations of MECS
Stability of the Semi-Implicit Discrete Duality Finite Volume Scheme for the Curvature Driven Level Set Equation in 2D
Authors: Handlovičová Angela , Kotorová Dana 
Published: March 2015

Abstract
Stability of the linear semi-implicit discrete duality finite volume (DDFV) numerical scheme for the solution of the regularized curvature driven level set equation is proved. Our scheme is linear, it is efficient regarding computational times. Numerical experiments confirm accuracy of the proposed scheme
An Effective Method to Improve Recovery of Heavy Oil Reservoir with Bottom Water Drive
Authors: Ju Binshan , Dai Shugoa , Fan Tailiang , Wang Xiaodong , Wu Haiqing 
Published: March 2015

Abstract
The coning problem for vertical wells and the ridging problem for horizontal wells are very difficult to solve by normal methods in the process of producing oil from the reservoir with bottom water drive. For heavy oil reservoirs, this difficult problem becomes more complicated for the non-Newtonian properties. An innovative completion method with downhole water sink was presented by dual-completed in oil and water columns with a packer separating the two completions for vertical wells and dual-horizontal wells that the upper well produce the fluid over the oil water contact (OWC) and down well the lower well produce the water below the OWC. The unique technique may restrain the formation of the water coning and ridging by adjusting production rates upper and lower OWC and enlarges the oil draining area, which in turn improve the oil recovery.
In order to evaluate quantatively the production performances by using the new method, numerical simulation technique was employed to find out optimal perforation segment and fittest production rates from the formation of the upper and lower OWC.

Introduction
Water coning has been regarded as the biggest problem during the oil production from a reservoir with bottom water. The phenomenon has been known for at least 100 years. The theory of water coning has been discussed by Smith, C.L.1 62 years ago and some other previous researchers before him. Resumptively, the occurrence of water coning is due to pressure gradients resulting from well production from the pay zone. The pressure gradients result in a water cone to rise toward the bottom of the producing interval. The tendency of the water to cone is offset or partially offset by gravity forces since the water has a higher specific gravity than the oil. A dynamic balance exists between the gravitational forces and the pressure gradients caused by well production. If the pressure gradient exceeds the gravitational force, water coning to the wellbore will occurs.
Mitigating Formation Invasion to Maintain Fracture Conductivity
Authors: Nguyen Philip Duke , Dusterhoft Ronald Glen , Clarkson Brad A. , Edwards William Jason 
Published: March 2015

Abstract
Intrusion or embedment of formation sand and fines from unconsolidated formations into proppant packs is known to diminish effective propped- fracture width, thus impacting fracture conductivity and potential well productivity. The work presented in this study shows that it is necessary to control the invasion of formation particulates into the proppant pack in the fracture to maintain its conductivity, and ultimately, the productivity of the well.
Core face materials of unconsolidated sand were used in examining their impact on fracture conductivity under high gas flow rates and frequent stress cycling. Results of laboratory testing indicates that on-the-fly coating of proppant with surface-modification agents (SMA) can provide an effective means for treating the formation surface in the fracture. The transfer of SMA from the proppant to the formation sand allows the loose, unconsolidated material to be transformed to a cohesive, bounded porous medium. As a result, it was observed that in all proppant types used in this study, the amount of formation material that appeared to be filling pore spaces in the proppant pack was much greater for the uncoated proppants. The coated proppants showed much less formation intrusion and much less formation material filling the porosity in the proppant pack. The effects of non-dDarcy flow are also examined and compared to baseline data. The beta factor of the coated proppant is lower than that of the uncoated proppant under nearly all test conditions.

Introduction
Formation fines are known to cause severe formation damage during production, limiting the potential production of the well. Many factors contribute to the migration or movement of formation fines. Various techniques have been developed in the industry through the years for examining fines-stabilizing solutions to overcome the effects of fines migration. Acidizing has been used to dissolve fines for "unblocking" and enlarging the pore throat in the formation near the wellbore to increase the permeability of the formation. Other chemical treatments, including (1) clay-stabilizing surfactants as part of the completion fluids, or (2) polymers in remedial operations, have been applied to minimize fines migration and enhance the well productivity. These treatments commonly require the treatment fluids to be injected deep into the formation matrix, allowing the surfaces of the fines and pores to be in contact and interact with the treatment fluid. Large volumes of treatment fluid are often required to achieve the desired results. Most such treatment fluids provide only temporary solutions, because they tend to desorb with time and with production of fluids from the well.
Shell's GTL: Its Technology and Design, Its Operation and Products
Authors: Senden Matthijs , Martens Frans , Steenge Wiecher , Klein Nagelvoort Rob 
Published: March 2015

Abstract
This paper reports on the Shell GTL technology and design, its operation and products.
The process is based on the Fischer Tropsch conversion of synthesis gas in multi-tubular reactors over a proprietary catalyst, followed by hydro-conversion and distillation. The synthesis gas is produced by partial oxidation of natural gas with pure oxygen in the Shell Gasification Process. Critical design features and performance of these main process steps are discussed.
A GTL complex is much more than just the sum of its individual process steps. The high level of integration of process and utilities poses many challenges to reliability and efficiency of operation of the complex. Important learning of eleven years of Bintulu operation will be shared. It gives insight in what makes GTL technology safe, efficient and reliable. These lessons have been implemented in the design of the 140,000 bbl/d GTL plant, which Shell is planning to realize together with QP in Qatar.
The Bintulu plant provides valuable experience in producing synthetic GTL products. A concise review will be presented. Understanding of the relationship between plant operation and product slate and – properties has been obtained, completed by experience of subsequent product performance in different applications. When new GTL capacity comes on-stream in the Middle East larger volumes of GTL product will become available to both bulk users and niche markets.

Technology and Design
The Shell's GTL technology consists of three basic stages:The 1st stage is the production of the synthesis gas from the partial oxidation process of natural gas with pure oxygen via the Shell Gasification Process (SGP), in combination with a Steam Methane Reformer (SMR). This combination enables a reliable, energy efficient and cost effective design for syngas production of the right composition.The 2nd stage is the Heavy Paraffin Synthesis (HPS), where the synthesis gas is converted into paraffin molecules. The process is a modern version of the Fischer Tropsch synthesis invented in Germany in the 1920s to produce liquid hydrocarbons from coal derived synthesis gas.The 3rd and final stage comprises of hydroconversion and distillation steps to convert the intermediate HPS product into high quality products.
Recent Advances in Carbonate Stimulation
Authors: Gdanski Rick David 
Published: March 2015

Abstract
Carbonate acidizing continues to be a vital process for improving the production of oil and gas wells. Laboratory studies and field evaluations of carbonate acidizing during the past 30 years have shown a continually improved understanding of the fundamental issues. This paper discusses the current state of the advances in carbonate stimulation. Average reactivity data for several limestones and dolomites are presented and can be used as improved default values for simulators. Wormhole development and structure during matrix acidizing are viewed as symmetry dominated processes controlled by fluid flow that obeys the native permeability contrasts within the matrix. The resulting simplification allows for rational treatment designs for matrix acidizing of carbonates. Zonal coverage of long carbonate sections, whether vertical or horizontal, remains a challenge. However, using the "75–25" rule for horizontal wells, creating a "thief zone" at the bottom or toe of the well, and utilizing the "top decade of permeability" rule can aid in achieving reasonable designs for maximizing productivity. The three fundamental issues of fracture acidizing are addressed: reactivity control, fluid loss control, and conductivity generation. Because synthetic polymers for acid gellants have made reactivity control easy, fluid loss control is usually the most dominant issue to be addressed in fracture acidizing.

Carbonate Reactivity
Several models are available to predict the spending of acid on carbonates. Some calculate the spending during fracture acidizing while some calculate the spending during matrix acidizing and wormhole generation. The earliest spending tests were simple spending time experiments in open beakers. However, it soon became clear that this was an inadequate procedure because mass transport definitely plays a role. Experiments conducted on quarried limestone and dolomite during the 1970s gave our first estimates of the temperature dependence of the reactivity of HCl on carbonates. These experiments suggested that limestones had incredibly high reactivity with acid such that one could assume a mass transport limited process.
Intensive Data Gathering Through a Waterflood Pilot for Redevelopment of a Giant Fractured Carbonate Field, Oman
Authors: Al-Habsi Mohammed , Stoffels Peter 
Published: March 2015

Abstract
Due to their strong sub-surface heterogeneity many Middle Eastern fractured carbonate reservoirs are characterized by significant and wide range of uncertainties. This paper presents a case study of one of the largest and oldest oil fields in Oman. Despite over 35 years of production through various drive mechanisms, there remains an opportunity to realize significant additional value in the field.
This paper presents the biggest data acquisition program anywhere in Oman that is ongoing in a giant fractured carbonate field to support the planned water flood project there.
A total of 28 wells have been drilled on four inverted 5-spot patterns, each containing a central water injection well, four equidistant producers and two dedicated observation wells. Each well is deviated with an S-shaped hole, so that they arch away from the linear pad on surface and end up vertically in the reservoir building a square with the injector in the middle. All the patterns have been drilled, completed and been put on production. Initial surveillance activities have been already executed and analyzed.
The primary aim of the project is to gather data about the water flood behavior in different reservoir layers in the field by running reservoir analysis logs in the wells, measuring production data and injecting tracers to track the oil and water movements. The plan is to carry out up to 25 logs (EMI, PLT, PNN, Induction) and pressure surveys (BHP, PBU, PFO) per month, in addition to coring the central water injectors. The first pad "Phase1-1" started in September 2004, the second pad "Phase1-3" in March 2005, whereas the other two pads "Phase1-2 and Phase 2-3U" came on stream in August 2005.
Towards the end of 2006 the decision based on the pilot data results will be made on whether to extend the waterflood across the whole field. The alternative would be to rely on Gas/Oil Gravity Drainage, which is a lower investment option than water flood, but ultimately would achieve a lower recovery as well. Also combinations of both development options and/or an EOR development have to be evaluated.
This paper will highlight the water flood pilot set-up and the early results from this intensive data gathering and analysis for a water flood project.
Regional Structural Analysis and Kinematic Framework of the Euphrates Graben, East Syria
Authors: Koopman Anton 
Published: March 2015

Abstract
The Euphrates Graben in East Syria is a "hidden" intra-cratonic rift-basin of some 120 km wide, formed by crustal extension in the Middle to Late Cretaceous. Pre-rift clastic reservoirs, differentially subsided along a complex pattern of faults, are charged from syn-rift source rocks and covered by a thick late syn-rift to post-rift seal. An early syn-rift waste rock unit exerts a decisive control on trap size in large part of the basin. Static and dynamic field models, as well as positioning of wells have proven to be critically dependent on definition of faults, and characteristics of fault geometries. Structural geological data from a variety of seismic attribute images were compiled and synthesised into a consistent and geomechanically viable regional structural framework of the basin and its fields, in order to contribute to better definition of its hydrocarbon volumes, to enhance hydrocarbon recovery, and to improve subsurface targeting of wells. The fault pattern of the rift basin is organised according to a number of highly interlocking but laterally persistent trends, most of which are inherited from already existing anisotropies in structural basement and its pre-rift overburden. A diffusely distributed and limited component of northerly trending left-lateral shear appears to be a major contributor to structural complexities within the basin. Relatively simple interpretation concepts of composite faulting, consistent with the regional framework and underpinned by experimental models and outcrop analogues, have contributed to a better understanding of the basin and its fields.

Introduction
The Euphrates Graben is a "hidden" intra-cratonic basin of some 120 km wide, which was formed by a SSW – NNE oriented crustal extension event during Middle to Late Cretaceous time (Lovelock, 1984; de Ruiter et al., 1995; Litak et al., 1998). The rifting and its associated structural relief followed a Base Upper Cretaceous Unconformity (BKU, Figures 1 and 2) of regional extent. Pre-rift clastic RESERVOIRS of the Mulussa F and Rutbah Formations (Figure 2), differentially truncated at this BKU and a more local rift-basin unconformity (RBU), subside along a complex pattern of highly interlocking faults according to different trends.
Fracture Network Modeling and Dual-Permeability Simulation of Carbonate Reservoirs
Authors: DeGraff James Michael , Meurer M. Ellen , Landis Lester Henry , Lyons Stephen Lincoln 
Published: March 2015

Abstract
Fractured and fracture-enhanced reservoirs are becoming increasingly important as the world's remaining hydrocarbon assets are developed. New modeling and simulation techniques must be developed to guide business decisions, improve economic forecasts, and maximize productivity. To address this need, a fractured reservoir modeling and simulation workflow was developed to integrate evolving technology for fracture characterization, geologic modeling, and flow simulation. The workflow is based on: common-scale geologic and simulation models;fine-scale element models to compute effective matrix permeability;analysis of fracture data from core, image logs, and outcrop; andintegration of field performance, structure, stratigraphy, and lithology.
Directional equivalent fracture permeability, porosity, and matrix block dimensions are estimated using discrete fracture network (DFN) and 3D geologic models, while effective matrix permeability is derived using proprietary technology (patent pending). Fracture analysis consists of identifying structural and stratigraphic controls on fracture data from available sources, and then using this knowledge to derive a set of rules to populate a DFN model. Dual-porosity/permeability reservoir simulation models are built in EMP Power™ Pusing similar grid geometry and cell size, effective matrix properties, and DFN-generated fracture properties. Simulation results show a better history match with less iteration than previous models when compared with multiphase production history. In our test cases, dual-porosity/ permeability models more accurately capture the impact of fractures on fluid flow than do single-medium models. Our study also demonstrates an effective and efficient process for dual-porosity/permeability modeling and simulation of fractured reservoirs.

Fractured Reservoir Modeling and Simulation Workflow
The integrated workflow discussed here addresses fractured reservoir characterization and fluid-flow simulation, using ExxonMobil proprietary and vendor software tools. It generates effective matrix properties, directional fracture permeabilities, and equivalent matrix block dimensions that are used to build dual-porosity/dual-permeability reservoir simulation models. The workflow is as follows.
Rheological Indicators for Environmental Stress Cracking Resistance of Polyethylene
Authors: Sardashti P. , Tzoganakis C. , Zatloukal M. , Polak M. A. , Penlidis A. 
Published: March 2015

Abstract
Most studies on environmental stress cracking resistance (ESCR) of polymers have focused on performing mechanical tests in the solid state. In this work, investigations in the melt state were carried out, to identify potential melt indicators for a relative measure of ESCR. A normalized characteristic relaxation time (λN), obtained from dynamic shear experiments, was established as a valid measure of ESCR of linear low density polyethylene, where a large content of short chain branches is present. In addition, the melt strain hardening coefficient (MSHC), obtained from extensional rheological methodologies, was found to be another potential and reliable indicator of ESCR. An inverse correlation between MSHC and ESCR was observed, indicating an inverse relationship between ESCR and chain extensibility in the melt. Furthermore, a new factor called “melt hardening stiffness (mHS)” was developed from the slope of a stress vs. Hencky strain obtained from a Sentmanat extensional rheometer. mHS was found to be another promising indicator of ESCR obtained from rheological studies conducted in this work.