bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Cluster Well Drilling Technology in Sulige Gas Field
Authors: Zhou Zongqiang , Cui Longlian , Li Jianmin , Zhang Fucheng , Wu Xuesheng , Wang Haige , Ju Mancheng , Ouyang Yong
Published: July 2012

Advantages of cluster well are that the technology can save land resources, reduce development costs. Sulige gas field is a typical low porosity, low permeability and low abundance. The advantages can meet the requirement of developing and constructing a "scientific, harmonious and environmental friendly" Sulige gas field. There are some difficulties in cluster wells drilling operation in Sulige gas field as following: strong abrasive formation, difficult in trajectory control, low ROP and high drilling costs.

To address these difficulties and promote the application of cluster well, the following researches were carried out: (1) Optimization the numbers of wells under different cluster well network conditions. Combined average horizontal displacement, anti-collision, trajectory control and integrated the cost, the number of wells were calculated, analyzed and optimized. (2) Optimization casing profile. Casing section was optimized into the current "straight - slow bulid - hold-slow drop"; (3) Optimization the well trajectory control mode. A practical and efficient directional well trajectory control technology were explored, and BHAs were developed; (4) Individual design PDC bits. " Spiral knife-wing, short outside the parabolic shape of the crown, double cutting structure, spiral gage" structure of the PDC bits were designed for Sulige formation.

Through innovative research and field integration applications, cluster well drilling supporting package technology have primarily matured in Sulige gas field. The drilling cycle of cluster well was reduced by 35%, with 17.4d drilling cycle in 2011; the ROP was improved by 106.1%, with 14.9m/h ROP in 2011. By the end of 2011, total 468 cluster well grops have been completed and 750 hectares land were conserved. Through the application of cluster well drilling in Sulige field, the development costs were reduced significantly. Cluster well technology has become one of the major development models in Sulige gas field.
Research and Application of BH-ATH (Anti-Three High) Drilling Fluid System
Authors: Minli Zhang , Zengyan Tian , Shaoying Xu , Dianbin Dong , Da Yin , Fengjiang Zuo , Changshu Wang , Li Yin , Liang Ren
Published: July 2012

Traditional anti-high temperature, anti-high pressure, anti-high gypsum salt drilling fluid has many technical problems such as difficult rheology control, low solid content capacity, poor pollution resistance ability and large dosage of various additives. As a result, a new "anti-three high" drilling fluid has been developed together with the key additives including complex organic salt (BZ-WYJ-I, II, III), filtration reducer with gypsum salt resistance and high temperature resistance ability(BZ-Redu-I,II,III), anti-gypsum salt viscosifier(BZ-VIS), inhibitive anti-caving agent(BZ-YFT) and inhibitive lubricant(BZ-YRH). The formula of the system is not complicated and easy for treatment. Besides, the system has the features of strong inhibition, 220°C temperature resistance, maximum density up to 2.6g/cm3, saturated gypsum salt resistance and gypsum insolubilization. It has been applied in 23 wells in Tarim oilfield, HuaBei oilfield in China, Madura block in Indonesia, Halfaya block in Iraq with the maximum density of the application wells up to 2.41g/cm3 and the highest temperature up to 206°C. The site application effect is remarkable since the technical problems such as caving, tight hole, gypsum salt pollution, thermal stability in high temperature have been effectively solved without incidents or discharge.
Clean Sand Consolidation Technology Research and Application
Authors: Zhiyong He , Guijun Wang , Susu Cao , Wei Dang , Fengxiang Zhou , Qingjiang Gu
Published: July 2012

With indepth development of each oil field, the demand for well types with special structures takes a trend of gradual rise. This kind of wells are generally complicated in well conditions, thus the requirements for tool performance are high, and the application scope of corresponding support measures shall be expanded. Besides, risks could increase if mechanic sand control technology is adopted and the solution in later stage will be difficult. The new type clean sand consolidation technology has solved the problems which may occur when with traditional sand consolidation technology and products, such as uneven cementation in sand consolidation, severe damage to formation porosity and permeability, low consolidation strength, etc. This paper describes the principle of clean sand consolidation technology and lab study of auxiliary fluid system, especially the principle of pore increasing before consolidation; while also discussing application scope and application prospect of the clean sand consolidation technology by presenting Well NP23-x2219 as an example.

So far, the clean sand consolidation technology has been successfully applied for 18 wells in domestic oil fields. The operation success rate is 100% and the effective rate reaches 94.4%.

The technology not only meets the demand of sand consolidation for initial sand consolidation for oil wells and water wells, but also has an excellent effect on tackling the problems concerning large production pressure difference, heavy oil, sand sticking or burying oil layer with fine siltstones in middle or later stage, which is applicable for multilayer sand control in long well section.

The clean sand consolidation technology employs the philosophy of safety and environmental protection, with extremely small damage to the formation, surface equipment and personnel, which has explored a new thought for development of chemical sand control technology in future.
Complication Circumstance Directional and Horizontal Wells Drilling Technology in Iran
Authors: Chao-hui Fu , Hu Zhao , Zhi-sen Yun , Yu-qiang Tang
Published: July 2012

Directional drilling technology has been applied widely since the last century. Directional tools and directional drilling technology shall be applicable to the different circumstances.Thus it is necessary to improve directional tools and directional drilling technology according to operation experiences.

In Iran, 146 directional and horizontal wells onshore and 16 directional wells offshore have been drilled by DDDC since 1997. Directional well technology have been applied under different circumstances such as in high weight and saturated salt water drilling fluid system, in the conditions of loss with low flow rate or in 26" or 4 1/8" unconventional hole size.

After contant improving directional drilling technology and tools, drilling hours of the directional drilling tools have been increased from 20 hrs to more than 120 hrs, and the maximum have reached 300 hrs in some wells, the directional tools can keep working in the loss condition, and the unconventional hole of directional wells are completed successful. Improving directional tools and technologY according to the different operation circumstances can lead to increased efficiency of drilling.

This paper presents some practical examples of how to improve directional drilling technology and tools under complicated circumstances, which can contribute to great improvements of directional well service performance.
Solving Slow Drilling/Hole Deviation Issues: Modeling Effort Increases ROP by 250% Saving Operator 14-Days Rig Time, Turfan Basin China
Authors: Tao Dong Zhen , Long Jing Zhang , Zhi Lai Bi , Nan Wenza , Zhang Xiao Long , Kang Tom , Downie Simon , Ke Colin , Jun Jim Zhao , Yong Mike Zhang , Liu Xiao Jun
Published: July 2012

The operator must reduce deviation tendencies in the 8-1/2" vertical hole section drilling the difficult J2x formation to efficiently develop gas reserves in Turfan basin, China. The challenge is to maintain near perfect perpendicular hole trajectory from 2400-3500m while drilling interbedded sandy claystone and coal layers. In the worst case scenario, the operator is forced to make several costly correction runs before starting the horizontal production hole. To solve the problems, engineers experimented with pendulum and steerable motor BHAs to maintain wellbore vertically with limited success.

Most recently, Kekeya wells Ke28 and Ke33 required 6-5 bits/trips respectively to complete the 8-1/2" hole section at unacceptably low average ROPs of 1.6 m/hr and 2.4 m/hr. The operator required a PDC/deviation control tool to maintain verticality and increase ROP. To accomplish the objective, the drilling team utilized a rock strength program and a bit/BHA modeling system to investigate several different cutting structures to determine the best blade count and cutter placement configuration. Based on the study, a six-bladed 8-1/2" PDC bit was identified as the best candidate to accomplish the objectives. To mitigate deviation tendencies, a reliable automatic vertical drilling system (VDS) was selected. The reliable VDS tool does not require a MWD logging sub and can be deployed during normal drilling operations including backreaming and shoe drillout.

The new-style 8-1/2" PDC bit was run in combination with VDS on new well Ke282 with outstanding results. The bit/VDS bottom hole assembly drilled the entire 740m section at 7.1 m/hr through the difficult J2x formation in a single run setting a new field benchmark. The optimized PDC bit increased ROP by 250% while reducing trips/bit consumption by 82%. The performance improvement saved the operator more than 14 days of rig time for a total cost savings of $93,000 USD.
Pre-Drill WBS Evaluation: Plane of Weakness and Well Design - A Case Study in the South of Mexico
Authors: Tellez Carlos Perez , Cabrera Jose R. , Balasejus Detlef
Published: July 2012

Borehole instability mechanisms have been studied in oilwell drilling for many years. Rock behavior has been important because drilling complexity and risk increase accordingly, leading to the need of more complete risk assessments in well design. A new need for risk assessment arises in South Mexico where Pemex and Schlumberger have encountered very challenging areas: a depositional HPHT environment with salt presence, faulted formations, and depleted reservoirs resulting in high-risk wellbores.

In strong dipping formations, wellbore instability occurred as a result of planes of weakness. Several events that resulted in stuck pipe due to packing off, losing wellbore sections and downhole tools translated into severe financial impact. Planes of weakness are directly related to the well's trajectory. Developing a method was needed to predict the attack angle - during the design phase. An erroneous appreciation of the instability mechanism could lead to wrong actions, like increasing the mud density without additional considerations, making problems worse.

Using surface seismic readings and attributes resulted in successfully predicting wellbore instability caused by planes of weakness. The signal-to-noise ratio of a seismic survey was enhanced. Attributes were applied to get an improved structural continuity with reliable dip/azimuth results. An innovative methodology to calculate the attack angle from dip/azimuth from seismic and associated risks of wellbore instability was developed. Three wells drilled in a complex structure affected by a compressive salt environment were evaluated and compared to well logs, getting a good fit.

A complete risk assessment includes the calculation of the attack angle, fault mapping, and rock strength. Knowing these allows for a more complete trajectory planning while predicting wellbore instability. Thus, the output provides a valuable tool to predict failure caused by planes of weakness in the design phase, allowing trajectory modification and operational prevention/mitigation measures to avoid catastrophic stuck pipe incidents and achieve a hazard-free well construction.
Innovative Application of Underbalanced Drilling Technology for Deep Drilling in Wuxia Area of Junggar Basin
Authors: Wei Zhang , Xinjun Mao , Hong Yang , Guobin Wang , Yuezhi Wang , Biao Ruan
Published: July 2012

The rock in deep strata of Wuxia area in Junggar Basin is abrasive and with low drillability. Part of the formation sections with abundant fractures, which leads to mud lose frequently. The exploration progress has been slowed down by low drilling speed and accidents. The exploration department of Xinjiang Oilfield Company preferred underbalanced drilling technology on well F8 and A1 on the basis of feasibility analysis of UBD technology in Permian strata. The applications reduced lose circulation effectively and promote the rate of penetration considerably.

Well F8 and A1 used foam and nitrogen as underbalanced drilling circulation medium respectively. The wellbore sizes are 215.9 mm. The rate of penetration in underbalanced drilling sections are quintuple than conventional rotary drilling. It saved more than 20 days in the overall drilling time. The conversions between foam/nitrogen with mud were successfully once only. There was no losing circulation during underbalanced drilling progress.

The successful application of underbalanced drilling technology in deep strata of Wuxia area solved the deep drilling speed improved problems entirely. It reduced mud lose and promote drilling speed. The drilling overall time and exploration cost has also been decreased greatly. The innovation application provides a new method for deep drilling speed improved in this area.

In the passed drilling, the ROP of advanced cone and PDC bits was nearly 0.65 m/h, and the ROP was no more than 0.92 m/h even with turbodrills and impregnated bits. However, the ROP of underbalanced drilling section has promoted several times than conventional drilling. ROP optimizing was substantial versus direct offset wells that experienced quintuple drilling time through the same formation. With this success, the team has accumulated valuable experience of deep drilling for Junggar Basin.
Experimental Study on the Efficiency of Cuttings Carrying with Supercritical CO2
Authors: Li Gensheng , Haizhu Wang , Zhonghou Shen , Song Xianzhi , Guanwei Tang , Xinjuan Hou
Published: July 2012

Supercritical carbon dioxide (SC-CO2) has the characteristics of high density, low viscosity and high diffusivity, and higher penetration rate can be achieved with SC-CO2. But the law of cuttings carrying is not clear, in order to make clear the influence of pump displacement, well incline, cuttings diameter, wellbore temperature and pressure on cuttings carrying efficiency, the laboratory experiments was carried out to simulate the cuttings carrying with SC-CO2 in annulus. The result shows that the cuttings carrying efficiency decreases when pump displacement decreases and cuttings diameter increases, and it decreases with the increasing of well incline at first, and then increases. Wellbore temperature and pressure have much more influence on cuttings carrying efficiency, and it decreases when the wellbore pressure increases, if keeping the wellbore temperature and pump displacement in constant; and it increases when wellbore temperature increases, if keeping the wellbore pressure and pump displacement in constant. So the wellbore temperature can be adjusted to compensate the cuttings carrying efficiency's changes caused by pressure changes, and the excess annulus velocity should be in consideration to avoid erosion of casing, drilling pipe and other down hole tools.
Successful Implementation of Latest Generation of Double Shoulder Connection Technology in Fast Slimhole Drilling - A Review after Broad Adoption in the Gulf of Thailand
Authors: Plessis Guillaume , Brock Jim , Wood Jeff
Published: July 2012

In 2010, Chevron Thailand successfully conducted a unique comparative field test involving two strings of drill pipe, one featuring a new 3rd generation double shoulder connection (3rd Gen DSC) against another with the previous generation connection (2nd Gen DSC). Both strings were used to drill off the same offshore platform with all parameters being equal besides the drill pipe connection selection. This test was required to gauge a possible solution to the operator's need for higher drilling torque in the challenging fast rotary drilling of the slimhole production interval.

The evaluated 3rd Gen DSC was originally developed and introduced to allow drilling always more challenging wells. It was designed to achieve a set of performances, which exceed the capability of the successful 2nd Gen DSC for torque and hydraulics with an enhanced fatigue resistance. One of the particular design priorities was to allow for fast makeup and breakout through the use of a new feature to drill pipe; a double start thread.

Results of this field trial were gathered in a previous paper that shows actual time saving in running speed, which is of interest to Chevron, initial trend seen in the lower number of connection needing repairs and evaluation of the cost saving for adopting the new technology on all rigs drilling for the operator. Based on this initial set of data, Chevron decided to switch to the 3rd Gen DSC for the 4 in. drill pipe used in slimhole drilling.

This new paper will briefly summarize the result of previously presented material but will focus on the actual field experience with the new technology deployed on three drilling rigs for more than six months now. Special emphasis will be put on evaluating the connection ruggedness through results found in the inspection of the equipment, which was hard to evaluate on the initial short time trial.
BHA Modeling Coupled with High Frequency Downhole Vibration Data Provides Unique Solution to Inconsistent Drilling Performance in South Iraq Oilfield
Authors: Teasdale Paul , Chafai Ridha , Saeed Ahmed , Hussain Muneeb , Perez Daniel , Sun Xueying , Yingguang Li
Published: July 2012

Drilling activity has increased rapidly in Iraq over the last few years. With the lack of reliable downhole data to develop a solid strategy to optimize drilling operations, the drilling performance has been inconsistent with frequent failures of drill stem components. Without the aid of quality downhole data it is very difficult to identify the root cause of these failures, and more importantly, provide a means to identify a solution to improve performance.

This paper showcases a project in South Iraq where modeling of the drilling BHA's using a unique Finite Element Analysis software package identified critical natural frequencies of the drillstring. The integration of high frequency downhole vibration data collected in multiple positions of the string provided the evidence to validate the vibration road map delivered by the BHA analysis.

The objective of the project was to identify the primary vibration mode, evaluate the vibrations severity, cause and source in the 12¼" vertical section and provide recommendations to achieve performance improvement through controlled step changes in bit & BHA design, drilling parameters and operational procedures. The pre-well BHA model analysis identified that the premature bit failure was a direct result of lateral vibrations induced by operating in a critical lateral harmonic zone. This was validated with the downhole vibration data.

A well-established optimization process including expert detailed analysis of the high frequency downhole vibration data provided a clear understanding of the relationship between the pre-well BHA model, the drilling parameters planed and the associated downhole drilling dynamics.

The impact on performance was clear. Implementation of the new recommended drilling parameters derived from the BHA analysis applied to the same bit and BHA used in Well #1 resulted on a 26% increase in drilling performance in well 2.
Evaluation of a New Environmentally Friendly Treatment to Remove Mn3O4 Filter Cake
Authors: Elkatatny S. M. , Al Moajil A. , Nasr-El-Din H. A.
Published: July 2012

Manganese tetraoxide is used as a weighting material in drilling deep wells (> 90 lb/ft3). Removal of the filter cake that contains Mn3O4 is a difficult task. This is mainly because Mn3O4 is a strong oxidizing agent.

Extensive lab work was done to: 1) study the reaction of glycolic acid with Mn3O4 particles (D50 =1 μm) as a function of time at 190°F in a batch reactor, 2) examine the solubility of the filter cake using a modified HP/HT filter press, 3) determine the compatibility and thermal stability of cleaning fluids with α-amylase using an HP/HT visual cell, 4) characterize the filter cake using computer tomography (CT), and 5) assess the retained permeability of limestone and sandstone cores.

The results following the removal of the filter cake showed that 4 wt% glycolic acid (4 g Mn3O4 to 200 ml acid solution) dissolved 75 wt% of Mn3O4 particles at 190°F. Glycolic acid (5 wt%) had a removal efficiency of 85 to 90% of manganese tetraoxide-based filter cake after 20 hrs soaking time. The retained permeability was 100% for the Indiana limestone core and 125% for the Berea sandstone cores. CT results showed that glycolic acid was able to stimulate the cores and no formation damage was observed.
Three-Dimensional Modeling of Casing and Cement Sheath Behavior in Layered, Nonhomogeneous Formations
Authors: Shen Z. , Beck F. E.
Published: July 2012

Shale is identified as one of the main factors strongly impacting the distribution of stress in the casing and cement sheath system. The risk of radial cracking induced by thermal stress should not be overemphasized, and it highly depends on fluid temperature in the wellbore and fluid circulation time. Long-term casing and cement integrity is fundamental to the successful and economical development of high-pressure, high-temperature (HPHT) hydrocarbon reservoirs. Casing failure and cement debonding as a result of extreme downhole conditions have been recorded worldwide. Research on casing and cement sheath failure in the past few years has been conducted assuming either plain strain or axisymmetric strain in a homogeneous formation. It usually underestimates casing deformation and cement sheath failure caused by the effect of a nonhomogeneous formation.

We present a three-dimensional (3D) finite element model consisting of five formation layers to simulate casing and cement sheath mechanical response in interbedded, nonhomogeneous formations. The radial stress of cement sheath is found to be highly variable and affected by the contrast in Young's moduli in the different formation layers. Maximum stress concentration is predicted in the casing-cement sheath confined by sandstone. Application of this research is useful for casing design, as well as evaluation of downhole failures.
Innovative Casing Exit Milling System Optimized Using Drillstring Dynamics Simulation for Efficient Multilateral Completions
Authors: Guidry Christopher W. , Thomas Reena
Published: July 2012

A typical method of creating casing exit windows for multilateral completions includes using tool strings comprised of mills for traversing whipstocks and creating elliptically shaped windows. This paper describes an innovative casing exit milling bottomhole assembly (BHA) and the method by which its design and predicted performance were optimized using inhouse-created drillstring dynamics finite element analysis (FEA) software.

Relatively longer casing exit windows are required to be generated for subsequent passage of contemporary drilling equipment. Sophisticated simulation technology is being used in designing the milling BHAs to create these longer exits. Paramount to generating a long window is maintaining sufficient restraining forces on the bottom-most mill to keep the mill tracking the full ramp length. Preferably, the BHA is designed so that the bottom-most mill can traverse against the entire ramp, and then deviate away from the ramp to avoid undesirable re-entry into the exited wellbore. The challenge is to optimize the milling BHA's endured contact forces so that its fatigue life is increased.

The aforementioned analytical tool helped in designing the milling BHA so that its operational bending stresses were reduced and its fatigue life was increased. Purposefully designed shapes and placements of the BHA's bladed cutting sections provided a favorable distribution of restraining forces, thus enabling an optimal-length casing exit window.

As directional drilling assemblies continue to be made longer and stiffer, there is an increased significance of using simulation tools to design milling BHAs. These newly designed BHAs will continue to be enhanced to maximize window length for improved ingress and egress of rotary steerable drilling BHAs. Extensive analysis, qualification testing, and field trials were performed on these systems. Case histories describing operational results will be shared and discussed during the paper presentation.
Expanding Surfactant Technology to Enable Project Successes
Authors: Jones Tom A. , Quintero Lirio , Toro Carlos , Ullauri Patricia , Guerra Cesar
Published: July 2012

Surfactants systems have been used in oil well drilling and completion fluids for several decades and have been used for numerous applications, including emulsification of brine for invert emulsion fluids, emulsion prevention in completion fluids, wellbore clean-up in spacer trains, flowback enhancement in drill-in fluids, etc.

In recent years, the use of specialized designer surfactant blends to remove formation damage and dramatically improve production in cased hole and open hole completed wells has prompted field personnel to expand the range of target applications of this technology.

The aforementioned specialized surfactant blends have several unique functional characteristics that make them ideal for multiple uses in the field. Generally, these systems solubilize oil, remove oil from surfaces, remove emulsions, water-wet and disperse solids, reduce interfacial tension and mobilize in-situ fluids.

With a full understanding of the mechanistic ways that these surfactant blends function under downhole conditions and when confronted with various operational issues in the field, this technology was successfully used to free stuck pipe, to free blocked completion screens of heavy oil sediments and to prepare a well for water injection.

This paper presents some of the technology associated with specialized designer surfactant blends and the case studies where the technology was applied in the field to enable project successes.
Innovation of Coal Seam Gas Well-Construction Process in Australia: Lessons Learned, Successful Practices, Areas of Improvement
Authors: Bennett Thomas
Published: July 2012

From by-product to multi-billion dollar industry, the Coal Seam Gas (CSG) industry in Australia has recently experienced rapid growth however is still facing many challenges. The Australian CSG industry is approaching a cross-road; the transition from a Domestic Gas business to exporting the CSG resources, requiring a significant scale up of current operations. Well design innovation is one of the necessary levers to maximize the full potential of CSG as a competitive energy resource. This paper focuses on the technical challenges associated with driving continuous improvement in drilling and completion practices as a key success factor for competitive performance.

The growth expected in the CSG industry over the next few years will be rapid. Arrow Energy plans to increase its production from 150 TJ/day in 2012 to 1350 TJ/day in 2018. This will require increases in drilling performance. Much of the early success will likely be obtained from the transfer of benchmark practices, where relevant, from the more mature global oil and gas industry - rather than from true CSG innovation. However, given the lower cost margins and economics of CSG, this knowledge transfer will need to be coupled with innovative application and new approaches.

This paper will discuss the importance of innovation in basis of well design as a lever to drive improvements in CSG in Australia and outline some of the key areas that Arrow Energy is focusing on to achieve this, including:

The need for fit for purpose rigs to meet well design criteria and well safety requirements. Standardization of well designs and equipment aligned to local government regulations and American Petroleum Institute (API) regulations. Vendor alignment and incentivized performance to meet company targets. Problems associated with innovation and difficulties of implementation in short time frames as well as the application of lessons learned from trials. Well design evolution and optimization of gas recovery. The importance of adopting a culture of learning and flexibility to implement changes as design standards progress.
Research and Application of Nanoscale Emulsion Lubricating Material for Drilling Fluid in Daqing Oil Field
Authors: Yang Zhiguang , Liu Yonggui , Zhao Xiaozhu , Song Tao , Yan Jing , Jia Weijun
Published: July 2012

In Daqing Oil Field of China, to solve the problem of low drilling rate, high friction drag, complex accidents(such as pipe sticking) and long non-penetration time, a nanoscale emulsion lubricating material has been developed. Its nanoscale particles can adhere to the wall and the string directionally and then form the dense lubricant film and protective film. It can improve the lubricity, make wall wettability reversal, inhibit the clay swelling, plug the micro-fracture and stabilize the wall.

In the process of application in 60 wells in Daqing Oil Field of China, this material solved the problems of high friction drag in drilling operation, reduced the non-penetration time due to moving drilling tools caused by high friction drag, decreased the pipe-sticking risk and complex accident rate, improved the drilling rate. The average drilling cycle is reduced by three to five days in shallow horizontal wells. It can avoid complex accidents (hole collapse, pipe sticking, etc), ensure the operation successful and increase the drilling rate obviously in deep horizontal wells.

It can improve the lubricity and inhibitive ability of drilling fluid and replace the mineral oil, reduce the circulation time of geologic control, increase the drill-meeting rate of oil sandstone and is favor of discovery of reservoir.

It solved the problem of low drilling rate, high backing pressure and high complex accident rate, decreased environment pollution, ensured the hole stability and can be popularized in unconventional wells, including horizontal wells, directional wells, etc.
A preliminary appraisal of Thurnham dual polarisation radar in the context of hydrological modelling structure
Authors: Zhu D. , Cluckie I. D.
Published: July 2012

The Thurnham radar is a prototype of a potential operational C-Band dual-polarisation weather radar designed specifically for the measurement of rainfall. It is also designed to increase the radar coverage over London when operating as a conventional C-Band radar as a direct consequence of the Lewes floods of October 2000. Dual-polarisation processing is expected to provide improved estimation of rainfall rates, especially at higher intensities, in terms of clutter removal, attenuation correction and rainfall estimation. In this study, three hydrological models with different mathematical structures were selected to evaluate the impact that dual-polarisation technology could have on operational hydrology and recommendations provided on the further development of the dual-polarisation algorithms in the short term. The preliminary appraisal was focused on the Upper Medway Catchment (south of London, UK) using different precipitation inputs, including raingauge measurements, radar rainfall estimates from single-polarised algorithms (cartesian format) and five different dual-polarisation algorithms (polar format). The influence of the different rainfall inputs on the various hydrological models were compared using a extreme flood event to provide an initial evaluation of the performance of the Thurnham radar. Recommendations for applying dual-polarisation radar to real-time flood forecasting are discussed in detail.
Simulation of snow and soil water content as a basis for satellite retrievals
Authors: Sandells M. J. , Flerchinger G. N. , Gurney R. J. , Marks D.
Published: July 2012

It is not yet possible to determine whether global snow mass has changed over time despite collection of passive microwave data for more than thirty years. Physically-based, but computationally fast snow and soil models have been coupled to form the basis of a data assimilation system for retrievals of snow mass and soil moisture from existing and future satellite observations. The model has been evaluated against observations of snow mass and soil temperature and moisture profiles from Reynolds Creek Experimental Watershed, Idaho. Simulation of snow mass was improved early in the season due to more realistic representation of soil heat flux, but led to an overestimation of snow mass later in the season. Soil temperatures were generally simulated well; freezing of the surface layers was not observed but was simulated, which affected soil water transport. Limited knowledge of the soil lower boundary conditions is acceptable for snow mass and surface soil moisture retrievals, although improvements are required for more accurate simulations of deeper soil moisture at this site. Development of a data assimilation framework to retrieve snow mass and near-surface soil moisture is discussed.
Employer Provision of Personal Protective Equipment to Latino Workers in North Carolina Residential Construction
Authors: Grzywacz Joseph G. , Quandt Sara A. , Mills Thomas , Marín Antonio , Summers Phillip , Lang Wei , Evia Carlos , Arcury Thomas A.
Published: July 2012

Despite federal regulations requiring provision of personal protective equipment (PPE) without cost to workers in the United States, very little is known about whether immigrant Latino construction workers receive no-cost PPE from their employers, and the role that employer provision plays in regular use of PPE. This study used cross-sectional data from a community-based sample of 119 Latino construction workers in western North Carolina to document receipt of employer-provided PPE by construction workers, investigate sources of variation in the receipt of employer-paid PPE, and delineate associations of employer-paid PPE with workers' regular use of PPE. The results suggest that the residential construction subsector generally fails to provide workers with PPE at no cost, as is required by regulation. Analyses also suggest that recent immigrants are least likely to receive no-cost, employer-provided PPE, and that when employers do provide no-cost PPE, Latino construction workers are more likely to use it regularly.
Reviews: Conveying Environmental Health Information and Context: Sandra Steingraber's Raising Elijah Furnishes an Example
Authors: Seymour Stephen
Published: July 2012

The effective use of scientific environmental health information is necessary to reduce exposures of vulnerable populations through changes to customary practices and to regulations. There is a need to educate the public on toxic threats to empower us to effectively advocate for such changes. There are few sources available to the general reader that present recent findings accurately, clearly, and interestingly. Sandra Steingraber's recent book, Raising Elijah: Protecting Our Children in an Age of Environmental Crisis, furnishes an example of how to meet this need, utilizing descriptive and powerful language. In this article the impact of scientific knowledge is explored through the experiences of an engaged community. Topics focused on as examples are arsenic playgrounds, sexuality and reproduction, and neurotoxins. The book focuses on the additional topics of climate change, fracking, food, plastics, and asthma.
2D simulation and analysis of fluid flow between two sinusoidal parallel plates using lattice Bolzmann method
Authors: Markovic Jelena , Lukic Natasa , Jokic Aleksandar , Ikonic Bojana , Ilic Jelena , Nikolovski Branislava
Published: July 2012

In order to obtain a better heat transfer, it is important to enhance fluid
mixing in heat exchangers. Since there are negative effects when heat
exchangers are operating in turbulent regime (like significant pressure drop,
increased size of the pump) it is necessary to apply the techniques which
would provide better fluid mixing when heat exchangers are operating in
laminar regime. Investigations have shown that use of sinusoidal instead of
flat plates results in this effect. This study is a result of two dimensional
simulation of fluid flow between two parallel sinusoidal plates. Simulation
was done with the use of modified Openlb code, based on lattice Boltzmann
method. Reynolds number was varied from 200 to 1000, and space between the
plates was varied from 3cm to 5 cm. Results showed that sinusoidal plates
enhance fluid mixing, especially with greater values of Re and smaller space
between the plates, which is in agreement with previous investigations.
The role of competition in the technoeconomic paradigm on the market
Authors: Aydın Güler , Takay Araz
Published: July 2012

Two different forms of competition theories can be distinguished: theories
that emphasize the equilibrating forces created by competition, and those
emphasizing the disequilibrating forces. This difference can be attributed,
to the differences regarding the functioning of the market economy: the basic
problem here is whether competition should be understood as a static state or
a dynamic process. This study aims to analyze the dynamic competition
theories by J. A. Schumpeter and neo-Schumpeterians which focus on the
dynamic role played by competition through creating disequilibria, endogenous
structural change and social transformation as a distinguishing
characteristic of the market system. In the first section, after examining
the static, neoclassical competition theory, Schumpeter?s theory, which is
based on the notion of ?creative destruction?, will be discussed. In the
second section, the long term fluctuations based on the creative gales of the
destruction concept will be examined in the framework of the technoeconomic
paradigm.
Stability of the relative equilibria in the generalized J2 problem
Authors: Mioc V. , Stavinschi M.
Published: July 2012

For a large class of concrete astronomical situations, the motion of celestial bodies is modelled by dynamical systems associated to a potential function ?/r + ?U (r = distance between particles, ? = real constant, ? = real small parameter, U = perturbing potential). In this paper the nonlinear stability of the relative equilibrium orbits corresponding to such a potential is being investigated using a less usual method, which combines a block diagonalization technique with the reduction procedure. The test points out certain nonlinearly stable orbits, and is inconclusive for the remaining equilibria. The latter ones are treated via linearization; all of them prove instability. The nonlinearly stable orbits remain stable under any perturbation that preserves the conserved momentum.
Life and activities of Vasilije Oskanjan (1921-1989)
Authors: Dimitrijevic M.S. , Oskanjan A.V.
Published: July 2012

The life and scientific, professional and other activities of Vasilije Oskanjan (1921-1989), one-time director of the Belgrade Astronomical Observatory, research fellow of the Belgrade and Byurakan Observatories, are presented, followed by the Bibliography of his works, the list of bibliographical items wherein his name is mentioned and the list of his name?s citations in the Science Citation Index in the period 1946 - July 1999.
Can double-peaked lines indicate merging effects in AGNs?
Authors: Popovic L.C. , Mediavilla E.G. , Pavlovic R.
Published: July 2012

The influence of merging effects in the central part of an Active Galactic Nucleus (AGN) on the emission spectral line shapes are discussed. We present a model of close binary Broad Line Region. The numerical experiments show that the merging effects can explain double peaked lines. The merging effects may also be present in the center of AGNs, although they emit slightly asymmetric as well as symmetric and relatively stable (in profile shape) spectral lines. Depending on the black hole masses and their orbit elements such model may explain some of the line profile shapes observed in AGNs. This work shows that if one is looking for the merging effects in the central region as well as in the wide field structure of AGNs, he should first pay attention to objects which have double peaked lines.
Life and works of Milan Nedeljkovic (1857-1950)
Authors: Trajkovska V. , Dimitrijevic M.S.
Published: July 2012

Activities of Milan Nedeljkovic, the founder of Belgrade Astronomical Observatory and his published works are discussed. The Bibliography of his works, as well as a Bibliography of selected works on Milan Nedeljkovic, are enclosed.
Abundance dynamics of mites (Acari) in the peatland of ‘Linie’ Nature Reserve, with particular reference to the Gamasida
Authors: Kaczmarek Sławomir , Faleńczyk-Koziróg Katarzyna , Marquardt Tomasz
Published: July 2012

Abundance dynamics of mites (Acari) in the peatland of ‘Linie’ Nature Reserve, with particular reference to the Gamasida

The research was conducted in ‘Linie’ Nature Reserve within the Lower Vistula Valley Land-scape Park in central Poland. We analysed the annual abundance dynamics of soil mites as well as changes in gamasid community parameters (abundance, age structure, species diversity). Density changes among the juvenile Gamasida greatly influenced the annual abundance dynamics of mites belonging to that order. Alternations in the abundance dynamics of Platyseius italicus and Zercon zelawaiensis were connected to the appearance of males as well as the density increase in juvenile specimens of those species.
Hydrozetes species (Acari, Oribatida) at bog ponds and pools in the Tatra National Park and Orawa-Nowy Targ Basin (Kotlina Orawsko-Nowotarska) in southern Poland
Authors: Mistrzak Marcin , Seniczak Anna , Seniczak Stanisław
Published: July 2012

Hydrozetes species (Acari, Oribatida) at bog ponds and pools in the Tatra National Park and Orawa-Nowy Targ Basin (Kotlina Orawsko-Nowotarska) in southern Poland

The Hydrozetes fauna was investigated at the edges of 4 ponds and pools with acid water in southern Poland. Mites of this genus achieved the highest mean abundance (6x104 ind./m2) at a pond in the Tatra National Park (Staw Toporowy Niżni; pH = 3.9; 1089 m a.s.l.). H. confervae dominated there (98%), accompanied by H. octosetosus and H. lacustris. The same species were also present at a nearby pond (Staw Toporowy Wyżni; pH 3.9; 1120 m a.s.l.), but in significantly lower numbers. In the bogs of the Orawa-Nowy Targ Basin, at the edge of pool in Kaczmarka (pH 3.6; 650 m a.s.l.), H. lacustris and H. octosetosus were present, and the former species dominated (73%). The latter species is interesting, because it was not recorded in Europe until recently. At the other pool, in Łysa Puścizna (pH 4.5; 650 m a.s.l.), only H. lacustris was present. The lower abundance and species richness of Hydrozetes at the bog pools in the Orawa-Nowy-Targ Basin, in comparison to the Tatra National Park, was probably caused by poorer water conditions, due to more advanced succession, peat exploitation and disturbed water conditions in the Basin.
Ecology of Hydrozetes Berlese, 1902 (Acari, Oribatida) at various water bodies near Bydgoszcz (northern Poland)
Authors: Seniczak Anna
Published: July 2012

Ecology of Hydrozetes Berlese, 1902 (Acari, Oribatida) at various water bodies near Bydgoszcz (northern Poland)

Mites of the genus Hydrozetes Berlese, 1902 are abundant and important in wet habitats and can be useful in palaeoecological studies and bioindication. However, due to problems with their identification, there is still a limited knowledge on their ecology. In this study, 5 Hydrozetes species have been investigated. The most abundant was H. lemnae (about 121 000 ind./m2), which constituted 76% of the total Oribatida at a pond shore in the Botanical Garden in Myślęcinek in Bydgoszcz. Its population density was lower in duckweed and filamentous algae on the water surface of the same pond. This species was found also in several other bodies of water, varying in water quality, but it preferred neutral pH. Hydrozetes thienemanni had a narrower ecological tolerance and was restricted only to a forest pond with neutral pH in Pruszcz, where it dominated among the Oribatida. Three other species - H. lacustris, H. octosetosus, and H. longisetosus - were found only in acid water. The last mentioned species was absent from the peat pond in Bagno Chlebowo Nature Reserve, with a high concentration of sulphur and worse oxygen conditions, but that site was suitable for H. lacustris.
Morphological abnormalities in mites of the genera Zercon and Prozercon (Acari: Gamasina) collected near caves: preliminary results
Authors: Barczyk Gabriela , Madej Grażyna
Published: July 2012

Morphological abnormalities in mites of the genera Zercon and Prozercon (Acari: Gamasina) collected near caves: preliminary results

Eleven mites of the genera Zercon C. L. Koch, 1836 and Prozercon Sellnick, 1943 with various morphological deviations (changes in chaetotaxy) are described. The mites were collected from the natural environment, near limestone caves in the Kraków-Częstochowa Upland (Wyżyna Krakowsko-Częstochowska) in southern Poland.
Analysis of Partition Coefficients of Ternary Liquid-Liquid Equilibrium Systems and Finding Consistency Using Uniquac Model
Authors: Islam Akand , Zavvadi Anand , Kabadi Vinayak
Published: July 2012

Analysis of Partition Coefficients of Ternary Liquid-Liquid Equilibrium Systems and Finding Consistency Using Uniquac Model

The objective of this study is to investigate the change in partition coefficient with a change in the concentration of the solute in a liquid system consisting of two relatively immiscible solvents. To investigate the changes in the partition coefficients, the data of the partition coefficients at infinite dilution and the ternary Liquid-Liquid Equilibrium (LLE) data at finite concentrations of the solute should be consistent. In this study, 29 ternary systems that are found in literature and for which the partition coefficients at infinite dilution and the ternary LLE data cannot be predicted accurately by the universal quasi-chemical (UNIQUAC) model are identified. On the basis of this model, some consistent and inconsistent ternary systems are introduced. Three inconsistent systems, namely hexane-butanol-water, CCl4 (carbon tetrachloride)-PA (propanoic acid)-water, and hexane-PA-water, are chosen for detailed analysis in this study. The UNIQUAC activity coefficient model is used to represent these data over a range of concentrations. The results show large errors, exhibiting the inability of this model to correlate the data. Furthermore, some ternary systems in which cross behavior of solutes between two phases observed are identified.
Brownian dynamics for calculation of the single fiber deposition efficiency of submicron particles
Authors: Sztuk Ewa , Przekop Rafał , Gradoń Leon
Published: July 2012

Brownian dynamics for calculation of the single fiber deposition efficiency of submicron particles

The motion of submicron particles involves the deterministic terms resulting from the aerodynamic convection and/or electrostatic attraction, and the stochastic term from the thermal displacement of particles. The Langevin equation describes such behavior. The Brownian dynamics algorithm was used for integration of the Langevin equation for the calculation of the single fiber deposition efficiency. Additionally the deterministic and stochastic of the particle motion were derived, using the Lagrangian and Eulerian approaches of particle movement and balance, for the calculation of the single fiber deposition efficiency due to both mechanisms separately. Combination of the obtained results allows us for calculation of the coupling effect of inertia and interception with the Brownian diffusion in a form of correlation. The results of calculation show that the omitting of the coupling effect of particular mechanism and using the simple additive rule for determination of the single fiber deposition efficiency introduces significant error, especially for particles with diameter below 300 nm.