bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory Quality Optical Analysis in Harsh Environments
Authors: Jones Christopher , Freese Bob , Pelletier Mickey , Perkins David , Chen Dingding , Shen Jing , Atkinson Robert
Published: December 2012

Significant advances have been made in formation testing since the introduction of wireline pumpout testers (WLPT), particularly with respect to downhole fluid compositional measurements. Optical sensors and the use of spectroscopic methods have been developed to improve sample quality and minimize sampling time in downhole environments. As a laboratory technique, spectroscopy is a ubiquitous and powerful technology that has been used worldwide for decades to measure the physical and chemical properties of many materials, including petroleum, geological, and hydrological samples. However, laboratory-grade, high-resolution spectrometers are incompatible with the hostile environments encountered downhole, at wellheads, and on pipelines. Only limited resolution techniques are available for the rugged conditions of the oil field. This paper introduces a new optical technology that can provide high-resolution, laboratory-quality analyses in harsh oilfield environments.

A new technology for optical sensing, multivariate optical computing (MOC), has been developed and is a non-spectroscopic technique. This new sensing method uses an integrated computation element (ICE) to combine the power and accuracy of high-resolution, laboratory-quality spectrometers with the ruggedness and simplicity of photometers. Many modern sensors typically merge the sensor with the electronics on an integrated computing chip to perform complex computations, resulting in an elegant yet simplistic design. Now, optical sensing using ICE features an analogue optical computation device to provide a direct, simple, and powerful mathematical computation on the optical information, completely within the optical domain. Because the entire optical range of interest is used without dispersing the light spectrum, the measurements are obtained instantly and rival laboratory-quality results.

A proof of concept MOC with ICE has been demonstrated, logging more than 7,000 hours, in nearly continuous use for 14 months. Oils with gravities ranging from 14 to 65°API have been measured in downhole environments that range from 3,000 to 20,000 psi, and from 150 to 350°F. Hydrocarbon composition measurements, including saturates, aromatics, resins, asphaltenes, methane, and ethane, have been demonstrated using the MOC configuration. As compositional calculations therein, GOR and density are validated to within 14 scf/bbl and 1%, respectively. The paper discusses the details of the new ICE-based sensor and describes its adaptations to downhole applications.
A New Strategy of Well Pattern Design and Adjustment to Enhance Production of Oil Fields with Vertical Multiple Series of Reservoirs.
Authors: Anzhu Xu , Longxin Mu , Lun Zhao , Zlfei Fan , Xuanyu Yang , Ling He , Xia Xue
Published: December 2012

The well patterns and pattern types of well placement issue in a productive formation is an important aspect of the effective field development. The problem solution is impossible on the intuitive level due to the reservoir inhomogeneity. At present the well pattern is accepted to be located basing on the famous criteria, specialist experience and hydrodynamical simulation on a reservoir model. The designer should analyze many field development variants with different well spacing during limited time interval. The adjustment of large-scale multiwell field-development projects is challenging because the number of adjustment variables and the size of the search space can become excessive. This difficulty can be circumvented by considering well patterns and then optimizing parameters associated with pattern type and geometry. In this paper, we introduce a new framework for accomplishing this type of adjustment for vertical two or three reservoirs. The development of vertical multiple reservoirs were usually by a separate well pattern for every reservoir, or through reservoir-by-reservoir from bottom to top by only one well pattern. A separate well pattern for every reservoir requires drilling many more wells and higher investment costs, while development through reservoir-by-reservoir from bottom to top by one well pattern made oil recovery rate and development efficiency very low and uneconomic. Consideration on fully developing every reservoir well efficiently, firstly, an inverted-nine well pattern was designed for every reservoir and the well space was L (L was defined as an optimal well space for respective reservoir) and the distance between adjacent well patterns was L. Secondly, all wells were drilled to the bottom of the lowest reservoir. Thirdly, when average water-cut of producers in every two well patterns was greater than 80%, the two well patterns interchanged reservoirs. Finally, when all reservoir interchange was completed, every reservoir was developed by the new equivalent infilled well pattern with well space of L. The adjustment strategy made the required number of drilling wells in the whole field can be reduced by 50% and achieved better development effect. This strategy was put into practice on North Buzachi oil field in Kazakhstan and average oil rate of single well was increased by 20%, oil recovery rate has an increment by 12 percent, the recovery factor was increased by 6.7%, economic profit is 1.8 times that of one separate well pattern for every reservoir, the effect was perfect. This work analyzed the performance of this new strategy of well pattern design and adjustment to effectively develop vertical multiple series of reservoirs and the methods to determine the reasonable time of two well patterns interchanging reservoirs through simulation study and current application effects.
Paradigm Shift in Reducing Formation Damage: Application of Potassium Formate Water Based Mud in Deep HPHT Exploratory Well
Authors: Al-salali Yousef Zaid , Al-Bader Haifa , Vidyasagar D.. , Manimaran A.. , Packirisamy S.. , Al-Ibrahim Abdulla
Published: December 2012

This paper discusses the outstanding performance achieved in a deep HPHT Jurassic formation drilled using Potassium Formate based fluid. This paper also describes methodology adopted for short term testing and stimulation of an exploratory well and finally the field results.

Drilling and completion of deep Jurassic formations in the state of Kuwait is generally done with Oil Base Mud (OBM) weighted with Barite. During drilling, barite causes significant formation damage to the carbonates with natural fractures and it is essential to stimulate the well to evaluate the real reservoir potential. Formation damage is usually treated with matrix acid stimulation, however barite does not respond to acid. Kuwait Oil Company (KOC) was in search for an alternative drilling fluid causing relatively less formation damage and also responds to remedial actions. Potassium Formate brine with suitable weighting agent to achieve sufficient mud weight around 16ppg was selected for field trial in one of the exploratory wells. Formate based brine is a high-density Water Base Mud (WBM) which maintains rheological stability at high temperature and minimizes formation damage.

Last 2,000 feet in 6" hole section of 18,000 feet well was drilled using 15.9 ppg Potassium Formate WBM. During short term testing, acid wash alone was sufficient to remove the formation damage and productivity has tripled which is unlikely in case of wells drilled with OBM.

This case study shows how Potassium Formate based mud enhanced the productivity and reduced the testing time and cost. Based on the successful field test results, it is planned to drill future Jurassic deep formation with Potassium Formate based fluids in future.
Where Process Safety Must Move
Authors: Johnston Stuart
Published: December 2012

Process safety has long embodied the adage, "If you always do what you’ve always done, you’ll always get what you've always got." Despite the development of sophisticated technical and management systems in recent decades, major catastrophic incidents continue to occur. Study of these events show us that the technical failures that led to these events were in fact enabled by organizational failures. Yet process safety systems too often exist in isolation from the wider organization, and indeed from other safety activities themselves. In order to achieve next-level improvement, catastrophic event prevention must move from its position of sole (or disproportionate) focus on the safety technical and management systems to a comprehensive focus that encompasses the broader elements of organizational safety as well. This talk presents the problem facing process safety practitioners today and outlines seven principles that can guide leaders both in aligning the organization to support process safety functioning and in assuring the integrity of process safety systems themselves.
Use of Integrated Modeling for Production Optimization in KOC North Kuwait Jurassic Gas Field
Authors: Malik Satinder , Al-Mai Noura , Dashti Qasem
Published: December 2012

The North Kuwait Jurassic Gas (NKJG) reservoirs are currently under development by KOC. The fractured carbonate reservoirs contain gas condensate and volatile oil at pressures up to 11,500 psi with 2.9% H2S and 1.5% CO2. Currently around 20 active wells are producing to an Early Production Facility (EPF-50) that falls short of achieving the desired capacity and capability to handle production efficiently.

To understand wells and field performance, an integrated system model comprising of wells, flow line and gathering system separator network was created. The setting up a model and its use is an integral subset of WRFM (Wells, Reservoir and Facilities Management) process that is essential for effectively managing the current asset and for further field development.

The application of the model is to be an enabler for wider implementation of the WRFM process in KOC and a tool to meet the following objectives: It should closely match the EPF-50 throughputIt should identify problem wellsIt should identify well intervention and data gathering opportunitiesIt should be a tool for training engineers on nodal analysis and WRFMIt can be used for back allocationIt could be used to benchmark against any existing models

The model has shown close approximation with field metered production and is already achieving many of its desired objectives.

This paper describes the use of integrated nodal analysis model to generate data gathering and well intervention opportunities not only to operate the facilities efficiently but understand well and reservoir behavior for input to full field development plan.
Formation Damage Caused by Thread Compound from Casing and Tubing
Authors: De Franceschi Esteban , Castiñeiras Tomás , Benedetto Fabián , Funes Alejandro , Figini Fernando , Economides Michael J.
Published: December 2012

Thread compound "dope" in the vernacular, has been used routinely in assembling joints of casing and tubing. The practice in almost universal application in the oil and gas industry involves the manual application of the lubricant in a fashion that is rudimentary, non-systematic and unquantifiable. There is evidence presented in this paper that damage to the near-well zone and other unpleasant events may be associated with the thread compound.

This paper presents the results of both laboratory and field investigations quantifying the effects of the dope on near-well damage. During the assembly of tubing and casing a portion of the thread compound is exuded inside and outside the connection and gets access to the well fluids through the tubing and annular space. Studies presented here show that the dope forms a suspension which penetrates and damages the formation. The studies used standard fluid circulation velocities during typical completion operations.

To characterize and quantify the problem, core samples from the El Tordillo field, with different permeabilities were used. The samples were subjected to the circulation of the suspension created by the thread compound and the completion fluid, measuring the change in the core permeability. The work simulated the well conditions during water injection for water injection wells and during acid treatments for producer wells. A significant reduction in permeability, manifested by a fast and a very large increase in pressure, was measured, at the front face of the core sample. The same measurements showed a far smaller impact in the core body suggesting very minor penetration of dope particles.

This paper describes the laboratory and field work, with description of the test protocols, well conditions and laboratory emulation of field conditions that were used.
Improved Oil Recovery by Nanofluids Flooding: An Experimental Study
Authors: Hendraningrat Luky , Engeset Bjørnar , Suwarno Suwarno , Torsæter Ole
Published: December 2012

In a past decade, various nanoparticle experiments have been initiated for improved/enhanced oil recovery (IOR/EOR) project by worldwide petroleum researchers and it has been recognized as a promising agent for IOR/EOR at laboratory scale. A hydrophilic silica nanoparticle with average primary particle size of 7 nm was chosen for this study. Nanofluid was synthesized using synthetic reservoir brine. In this paper, experimental study has been performed to evaluate oil recovery using nanofluid injection onto several water-wet Berea sandstone core plugs.

Three injection schemes associated with nanofluid were performed: 1) nanofluid flooding as secondary recovery process, 2) brine flooding as tertiary recovery processs (following after nanofluid flooding at residual oil saturation), and 3) nanofluid flooding as tertiary recovery process. Interfacial tension (IFT) has been measured using spinning drop method between synthetic oil and brine/nanofluid. It observed that IFT decreased when nanoparticles were introduced to brine.

Compare with brine flooding as secondary recovery, nanofluid flooding almost reach 8% higher oil recovery (% of original oil in place/OOIP) onto Berea cores. The nanofluid also reduced residual oil saturation in the range of 2-13% of pore volume (PV) at core scale. In injection scheme 2, additional oil recovery from brine flooding only reached less than 1% of OOIP. As tertiary recovery, nanofluid flooding reached additional oil recovery of almost 2% of OOIP. The IFT reduction may become a part of recovery mechanism in our studies. The essential results from our experiments showed that nanofluid flooding have more potential in improving oil recovery as secondary recovery compared to tertiary recovery.
Delivering Optimal Brownfield Development Strategies: Use of Multi-Constrained Optimisation Combined with Fast Semi-Analytical and Numerical Simulators
Authors: Alvi A.. , Tilke P.. , Bogush A.. , Kolupaev A.. , Jilani S. Z. , Banerjee R.. , Bolanos N.. , Wu J..
Published: December 2012

Assessing the waterflood, monitoring the fluids front, and enhancing sweep with the uncertainty of multiple geological realisations, data quality, and measurement presents an ongoing challenge. Defining sweet spots and optimal candidate well locations in a well-developed large field presents an additional challenge for reservoir management. A case study is presented that highlights the approach to this cycle of time-lapse monitoring, acquisition, analysis and planning in delivery of an optimal field development strategy using multi-constrained optimisation combined with fast semi-analytical and numerical simulators.

The multi-constrained optimiser is used in conjunction with different semi-analytical and simulation tools (streamlines, traditional simulators, and new high-powered simulation tools able to manage huge, multi-million-cell-field models) and rapidly predicts optimal well placement locations with inclusion of anti-collision in the presence of the reservoir uncertainties. The case study evaluates proposed field development strategies using the automated multivariable optimisation of well locations, trajectories, completion locations, and flow rates in the presence of existing wells and production history, geological parameters and reservoir engineering constraints, subsurface uncertainty, capex and opex costs, risk tolerance, and drilling sequence.

This optimisation is fast and allows for quick evaluation of multiple strategies to decipher an optimal development plan. Optimisers are a key technology facilitating simulation workflows, since there is no ‘one-approach-fits-all’ when optimising oilfield development. Driven by different objective functions (net present value (NPV), return on investment (ROI), or production totals) the case study highlights the challenges, the best practices, and the advantages of an integrated approach in developing an optimal development plan for a brownfield.
Simulations of Thermal Upgrading Methods for Oil Shale Reservoirs
Authors: Youtsos M. S. , Cant R. S. , Mastorakos E..
Published: December 2012

This paper analyzes reaction and thermal front development in porous reservoirs with reacting flows, such as those encountered in shale oil extraction. A set of dimensionless parameters and a 3D code are developed in order to investigate the important physical and chemical variables of such reservoirs when heated by in situ methods. This contribution builds on a 1D model developed for the precursor study to this work. Theory necessary for this study is presented, namely shale decomposition chemical mechanisms, governing equations for multiphase flow in porous media and necessary closure models. Plotting the ratio of the thermal wave speed to the fluid speed allows one to infer that the reaction wave front ends where this ratio is at a minimum. The reaction front follows the thermal front closely, thus allowing assumptions to be made about the extent of decomposition solely by looking at thermal wave progression. Furthermore, this sensitivity analysis showed that a certain minimum permeability is required in order to ensure the formation of a traveling thermal wave. It was found that by studying the non-dimensional governing parameters of the system one can ascribe characteristic values for these parameters for given initial and boundary conditions. This allows one to roughly predict the performance of a particular method on a particular reservoir given approximate values for initial and boundary conditions. Channelling and flow blockage due to carbon residue buildup impeded each method’s performance. Blockage was found to be a result of imbalanced heating.
Optimisation of Clean-Up of Limestone Production Zones: New Observations
Authors: Davidson Eric , Blattel Steve , McMillan D. Nelson , Morrison Alexandra
Published: December 2012

During recent years there has been a significant increase in the use of filter cake removal systems that involve in-situ release of formic or lactic acid during the clean-up stages of the reservoir section, particularly in limestone formations. Furthermore, there have been opportunities to compare the field performance of these relatively small applications of weak, organic acids with significantly larger application volumes of highly concentrated hydrochloric acid (HCl). Surprisingly, some results showed that the smaller volumes of the weaker, organic acids could have equivalent or better performance than that produced by the more traditional HCl-based treatments. In particular this relationship was also observed in cases where the volume of HCl applied had significantly greater power to dissolve limestone than was the case for treatment with the more successful organic acid.

It is well known that productivity of wells in carbonate reservoirs is usually greatly improved by treatments designed to remove the filter cake and the low-permeability zone created by the drilling process, but it is not obvious why smaller volumes per foot of weak organic acid should be more effective than larger volumes per foot of stronger and more concentrated mineral acid.

It has been observed that the acid precursors which release the in-situ acids are applied to the formation in a neutral condition. The paper discusses the implications of using neutral acid precursors, and laboratory data is presented showing the effects of such treatments on the near-wellbore matrix permeability.
Improved Producibility after Delayed Filter Cake Breaker Treatment in the Safaniya Offshore Field in Saudi Arabia
Authors: Zubail M. A. , Al-Kuait A. M. , Al-Yateem K. S. , El Bialy M.. , Maghrabi S.. , Olivares T.. , Ezell R. G.
Published: December 2012

Safaniya is one of largest offshore oil fields located north of Dhahran in Saudi Arabia. It is 50 km by 15 km in size and began production in 1956. Lately, a few wells drilled in this field showed reservoir damage where the production dropped or the well had no flow. Workover operations were performed on six wells and two new wells were drilled. For all eight wells, 6⅛-in. laterals were drilled through the reservoirs with an engineered invert emulsion drilling fluid (RDF). The RDF design was controlled to ensure an acid-soluble, thin, external filter cake with no fines invasion. The vulnerability of the filter cake to be attacked by the acid was fundamental to this RDF design. A delayed filter cake breaker fluid was then designed for use on the 6⅛-in. laterals; this fluid consisted of an organic acid precursor (OAP) and a water wetting additive. The OAP released acid in a delayed manner, whereas the water wetting additive made the oil-based filter cake water wet, to make it vulnerable to acid attack. With this approach, the filter cake was removed uniformly in all subject laterals across the reservoir. The production data on the eight wells treated with the OAP show an improved oil production rate of more than 4,000 B/D for six of the eight wells, which exceeds the key performance indicator (KPI) set for the laterals. In previous years from 2005-10, the six workover wells showed, on average, very low oil production rates (OPR) comparatively. In addition, after the OAP treatment, these six wells show higher well flow head pressures than in 2005–10. The water cut percentage on these laterals was 0 or less than 1, compared to 2005–10, when the water cut percentage varied from 8% to 50% for these workover wells. This paper discusses the workover operation of the six wells and the drilling and delayed stimulation treatment on two new wells in the Safaniya field, including laboratory evaluation, field application and production data.
Results from a Pilot Water Flood of the Magwa Marrat Reservoir and Simulation Study of a Sector Model contribute to understanding of Injectivity and Reservoir Characterization
Authors: Al-Kandari I.. , Al-Jadi M.. , Lefebvre C.. , Vigier L.. , De Medeiros M.. , Dashti H. H. , Knight R.. , Al-Qattan A.. , Chimmalgi V. S. , Datta K.. , Hafez K. M. , Turkey L.. , Bond D. J.
Published: December 2012

A pilot water flood was carried out in the Marrat reservoir in the Magwa Field. The main aim of this pilot was to allow an assessment of the ability to sustain injection, better understand reservoir characteristics. A sector model was built to help with this task.

An evaluation of the injectivity in Magwa Marrat reservoir was performed with particular attention to studying how injectivity varied as injected water quality was changed. This was done using modified Hall Plots, injection logs, flow logs and time lapse temperature logs.

Data acquisition during the course of the pilot was used to better understand reservoir heterogeneity. This included the acquisition of pressure transient and interference data, multiple production and injection logs, temperature logging, monitoring production water chemistry, the use of tracers and a re-evaluation of the log and core data to better understand to role of fractures.

A geological model using detailed reservoir characterization and a 3D discrete fracture network model was constructed. Fracture corridors were derived from fractured lineaments interpreted from different seismic attribute maps:

A sector model of the pilot flood area was then derived and used to integrate the results of the surveillance data. The main output is to develop an understanding of the natural fracture system occurring in the different units of the Marrat reservoir and to characterize their organization and distribution. The lessons learned from this sector modeling work will then be integrated in the Marrat full field study.

The work described here shows how pilot water flood results can be used to reduce risk related to both injectivity and to reservoir heterogeneity in the secondary development of a major reservoir.
Creating a Secure IT Infrastructure for the Kuwait Intelligent Digital Field
Authors: Saleem H.. , Al-Shammari R.. , Zolotavin A.. , Bonilla J. C. , Ali Z.. , Robert H.. , Farid A..
Published: December 2012

As oilfields mature and new fields come into operation, real time asset management of reserves is providing ongoing challenges to Kuwait Oil Company (KOC). Fewer engineers are managing more wells under increasingly tougher environmental conditions and compliance regulations. The combination of these factors has driven the need for KOC to make a step change in its approach to operations by incorporating digital field concepts to transform the way engineers are working. The result is the Kuwait Intelligent Digital Field initiative.

To enable KwIDF, new technologies were deployed in both mature and immature assets, creating issues in terms of interoperability and integration thereby increasing the strain on the legacy IT infrastructure. In addition, there was the requirement to isolate the SCADA industrial networks from the corporate business networks while automating traffic control with the various enterprise data systems. This ‘managed’ separation complicated the delivery of productivity tools to employees and posed the greatest challenge to creating a transparent, seamless KwIDF infrastructure.

The KwIDF Jurassic project was particularly challenging since it had the most limited existing infrastructure, requiring the design and deployment of an entirely new architecture scattered over significant distances and business areas. This in turn created significant hurdles in terms of integration and compatibility with the remainder of KOC’s proprietary systems and technologies. Specific efforts were required to allow KOC’s network infrastructure to be capable of embracing such solutions and technologies with proper security measures in place.

Developing a network infrastructure to enable real time solutions for KwIDF Jurassic involved analyzing the specific business drivers of the asset to ensure that the capital investment not only delivered results, but did so within a secure environment. This paper presents the methodology employed by KOC’s Corporate IT Group (CITG) to deliver the right network infrastructure, along with lessons learned, for enabling the Kuwait Intelligent Digital Field Jurassic project.
Modeling of Regional Aquifer System Allows Decision on Early Pressure Support to be Made for the Burgan Minagish Reservoir, Kuwait
Authors: Al-Faresi F. A. , Wang J. T. , Clark W.. , Belobraydic M. L. , Yaser M.. , Iwere F. O. , Gomez E.. , Gurpinar O. M. , Datta K.. , Mudavakkat A.. , Hayat L.. , Al-Sahlan G. A. , Husain R.. , Prakash A.. , Crittenden S. J. , Bond D. J.
Published: December 2012

The Burgan Minagish reservoir in the Greater Burgan Field is one of several reservoirs producing from the Minagish formation in Kuwait and the Divided Zone. The reservoir has been produced intermittently since the 1960s under natural depletion. A powered water-flood is currently being planned. The pressure performance of the reservoir has proved hard to explain without invoking communication with other reservoirs. Such communication could be either with other reservoirs through the regional aquifer of through faults to other reservoirs in the Greater Burgan field. Recent pressures are close to the bubble point.

A coarse simulation model of the nearby fields and the regional aquifer was constructed based on data from the fields and regional geological understanding. This model could be history matched to allow all regional pressure data to be broadly matched, a result which supports the view that communication is through the regional aquifer. Using this model to predict future pressure performance suggested that injecting at rates that exceeded voidage replacement by about 50 Mbd could keep reservoir pressure above bubble point. It was recognized that the process of history matching performance was non-unique. This is a particular concern in the context of this study because the model inputs that were varied in the history matching process included aquifer data that was very poorly constrained. To address this problem multiple history matched models were created using an assisted history matching tool. Using prediction results from the range of models has increased our confidence that a modest degree of over-injection can help maintain reservoir pressure.

This paper demonstrates the utility of computer assisted history match tools in allowing an assessment of uncertainty in a case where non-uniqueness was a particular problem. It also emphasizes the importance of understanding aquifer communication when relatively closely spaced fields are being developed.
The Mystery of Vanishing MWD/LWD Tools in Downhole: Interaction of Heavy WBM, Complex Petrophysical Formation Properties and Tool Metallurgy in Deep Kerogen-rich Carbonates
Authors: Acharya Mihira N. , Kabir Mir R. , Al-Ajmi Saad A. , Al-Doheim Arif A. , Dashti Qasem , Al-Anzi Ealian H.
Published: December 2012

Robustness of measurement while drilling (MWD) and logging while drilling (LWD) tools is laboratory-tested and rigorously field-tested for the expected operating and measurement specifications. Such tools have been used in the industry for decades with proven track record of stability. However, a typical tool string deployed as a part of bottom-hole assembly (BHA) has recently failed to withstand the unexpected BH conditions during drilling of the pilot hole using potassium formate mud (KFM), a heavy water based mud. The failure occurred within a deep-fractured calcareous kerogen section (CKS).

The tools had multiple surface communication failures; the first one was resolved as debris was found obstructing the rotorstarter part before drilling the CKS. The second failure occurred in the back-up tools, after drilling into the CKS and remained unexplained throughout drilling with the expectation of BH data recorded on memory. Inspection of the tool components, once the drilling was completed, revealed two major findings: First, some parts of the BHA, specifically the components of the CuBe tool had "vanished". Secondly, the recovered tool parts had further damage due to corrosion and pitting. In addition, an unexpected color change in metal body parts was observed.

In the paper, the authors explain the unique mystery of tool eating "down-hole ghost". Similar tools were previously used without an issue at comparable high pressure and temperature conditions and in geological sections alike in Kuwait in drilling with oil-based mud. The service provider's operational experience elsewhere has failed to explain the bizarre outcome, as they had not encountered similar incidents of vanishing tool parts and down-hole color change. The claim was that similar tools were successfully operated in water-based mud drilling including KFM. This claim was confirmed prior to the field execution with metallurgical compatibility tests carried out by the mud supplier.
Quality restoration of waste polyolefin plastic material through the dissolution-reprecipitation technique
Authors: Hadi Jasim , Najmuldeen Faisal , Ahmed Iqbal
Published: December 2012

This study examines the restoration of waste plastic polymers based on LDPE,
HDPE or PP through dissolution/reprecipitation. Experimental conditions of
the recycling process, including type of solvent/non-solvent, original
polymer concentration and dissolution temperature were optimized. Results
revealed that by using the different prepared solvents/non-solvents at
various ratios and temperatures, the polymer recovery was always greater than
94%. The FTIR spectra and the thermal properties (melting point and
crystallinity) of the polymers before and after recycling were measured using
Differential Scanning Calorimetry (DSC). Mechanical properties of the waste
polymer before and after recycling were also measured. Besides small
occasional deviations, the properties did not change. The tensile strength at
maximum load was 7.1, 18.8, and 7.4 MPa for the recycled LDPE, HDPE and PP,
respectively and 7.78, 18.54 and 7.86 MPa for the virgin polymer. For the
waste, the strength was 6.2, 15.58 and 6.76 MPa.
Photographic study of bubble departure diameter in saturated pool boiling to electrolyte solutions
Authors: Peyghambarzadeh S.M. , Hatami A. , Ebrahimi A. , Fazel Alavi
Published: December 2012

Bubble departure diameters during saturated pool boiling to pure water and
three different electrolyte solutions including NaCl, KNO3, and KCl aqueous
solutions are experimentally measured. Variable heat fluxes up to 90 kW/m2
and different salt concentrations from 10.6 to 69.6 kg/m3 are applied in
order to investigate their effects on the bubble size during pool boiling
around the horizontal rod heater. Visual observations demonstrated that
larger vapor bubbles generate on the heat transfer surface at higher salt
concentrations and lower heat fluxes in all of the solutions tested while in
distilled water bubbles become slightly larger with increasing heat flux.
Furthermore, the effects of different important physical properties like
surface tension, viscosity, and density of the solutions on the bubble
departure diameter are also discussed. NaCl solutions have surface tension
higher than the other electrolyte solutions. Furthermore, the addition of
NaCl to distilled water slightly increases the viscosity of the solution
whereas other salts have no measurable effect on the viscosity. Therefore, it
is expected that larger bubbles to be appeared on the heat transfer surface
during the boiling of NaCl solutions which is in agreement with the
experimental results.
Availability of some trace elements (Pb, Cd, Cu and Zn) in relation to the properties of pasture soils in Stara Planina mountain
Authors: Belanovic Snezana , Cakmak Dragan , Kadovic Ratko , Beloica Jelena , Perovic Veljko , Alnaass Nuri , Saljnikov Elmira
Published: December 2012

The research presented in this paper was aimed at better understanding of the
relationship between soil properties and the availability of trace elements
in pasture soils. The research was conducted in several localities of Stara
Planina mountain (Babin zub, Javor I, Javor II and Prelesje), where the
dominant soil type is acid humus siliceous soil (Dystric leptosol)
characterized by the presence of the Agrostietumvulgaris (capillaris)
community Z. Pavl., 1955. In all localities the soil sampling was performed
at fixed depths of 0-5, 5-10, 10 -20 and 20 - 40 cm. The pseudo-total
contents of trace elements (Pb, Cd, Cu and Zn) (extracted with aqua regia
solution), as well as the available contents (extracted with the DTPA
chelating agent) in the soil were measured by AAS. The pseudo- total content
of trace elements in the soil studied are lower or within the limits for
multifunctional land use. A correlation was established between the content
of available trace elements in soil and the content of pseudo-total trace
elements, as well as between these contents and the properties of the soils
studied.
Metal rings and discs Matlab/Simulink 3D model for ultrasonic sandwich transducer design
Authors: Jovanovic I. , Mancic D. , Paunovic V. , Radmanovic M. , Mitic V.V.
Published: December 2012

Metal-endings are integral part of different ultrasonic sandwich transducers.
In this paper a new Matlab/Simulink 3D model of the finite metal rings and
discs of various dimensions is realized. With this model, which describes
both the thickness and the radial resonant modes, and the coupling between
them, mechanical impedance of the sample can be easily computed. Resonance
frequency-length curves for rings and disks with various materials and for
different selected dimensions are given. Also, comparisons of the different
approaches in determining of their resonant frequencies are shown. The
proposed Matlab/Simulink model requires simpler implementation than other
analytical models. That enabled modifying of 1D theory and simplified
modelling and projecting of the ultrasonic sandwich transducers with
short-endings. Finally, the computed and experimental results are compared.
Study of dielectric behavior and electrical properties of hematite α-Fe2O3 doped with Zn
Authors: Nikolic M.V. , Slankamenac M.P. , Nikolic N. , Sekulic D.L. , Aleksic O.S. , Mitric M. , Ivetic T. , Pavlovic V.B. , Nikolic P.M.
Published: December 2012

The effects of Zn-doping on the dielectric behavior and electrical properties
of bulk ?-Fe2O3 have been studied. X-ray diffraction analysis revealed the
presence of two phases in all samples: hematite and spinel ZnFe2O4, with the
amount of spinel phase increasing with increasing Zn content. Scanning
electron microscopy analysis combined with energy dispersive X-ray
spectroscopy showed that the Zn-bearing phase occurred in the form of
individual spinel ZnFe2O4 grains in a hematite matrix. DC conductivity was
measured in the temperature range 25-225oC (298-498 K). Impedance
spectroscopy measurements in the same temperature range were carried out in
the frequency range 100Hz to 10 MHz. Increase in the Zn content resulted in
increased electrical conductivity and higher values of the dielectric
constant. The resistance and capacitance of grains and grain boundaries were
analyzed by modeling the experimental results using an equivalent circuit.
‘Community’ and ‘Democratic Practice’ in Early Childhood Education and Care: A Critique and Possibility through the Optic of Roberto Esposito
Authors: Millei Zsuzsa
Published: December 2012

‘Community’ is a pervasive concept around the globe in early childhood education and care that remains mostly unchallenged. The notion of ‘community’ is widely utilised in theories and practices to describe the context and the social world of young children and their carers and educators. It is also a familiar term used in relation to curriculum and pedagogical frameworks and practices. Another concept that appears increasingly in the literature and in practical considerations is the possibility for early childhood settings to be places of ‘democratic practice’. Democratic practice is hoped to prevent autocracy, to ensure pluralism and cater for diversity, and to enable collaborative knowledge production. However, community and ‘democratic practice’ are not without contention. This article considers the nexus and the contention between concepts of ‘community’ and ‘democratic practice’. With Roberto Esposito's notion of communitas, it offers a possible theorisation of community that enables community to serve as a backdrop to ‘democratic political practice’ in early childhood education and care.
Measuring Teacher Quality: Listening to Young Children in Singapore
Authors: Harcourt Deborah
Published: December 2012

Early childhood research and policy are focusing increasingly on issues of ‘quality’ in early childhood education. Much of the focus, however, has been on adult-generated notions of quality, with little attention being devoted to children's own views of their experience in early childhood settings. Conducted in the context of early childhood education in Singapore, this research seeks to contribute children's own insights into their experience in two early childhood classrooms in Singapore. Informed by the sociology of childhood conceptualisation of child competence, the research methodology draws upon contemporary approaches to researching with children. The findings of this study were generated by beginning with the understanding that young children have the competence to articulate their ideas using a range of symbolic literacies. They formed views and constructed theories about their preschool experiences, in particular about teachers, and give a clear indication of what constitutes good quality in this domain. This study calls for those engaged with children, particularly teachers, to act upon the contributions offered by this group of children to the understanding of quality.
Looking into Early Childhood Education and Development Spaces: Visual Ethnography's Contribution to Thinking about Quality
Authors: Cleghorn Ailie , Prochner Larry
Published: December 2012

Discussions about what constitutes a quality early childhood (EC) environment rarely focus on visual or spatial aspects, except to provide background information for talking about EC practice and children's development in the preschool years. There is a need to look beyond the usual quality indicators, which tend to focus on poverty and children's developmental potential so that context and cultural dimensions are often omitted in the discussion. This article thus explores the contribution of visual ethnography for thinking more about, or rethinking, some of the prevailing notions of quality in early childhood education (ECE). To do so, culture is seen as central to the discussion. This includes the organisation of space and the use of materials in EC settings. The idea in this article is to present images that stand in contrast to some of the current globalising discourse about what is good for the world's children. In so doing, the authors thread together seemingly disparate ideas stemming from the centrality of culture and space theory, to the organisation of space, to the use of materials and to transitions in ECE.
Asian Childhoods: Exploring the Lifeworlds of Students in Contemporary Hong Kong
Authors: Yelland Nicola , Muspratt Sandy , On Christine Chan Yee , Gilbert Caja
Published: December 2012

In this article, the authors discuss the findings of two surveys that were conducted with 10-year-old primary students and their parents in Hong Kong. They sought to gather empirical data about how the students spend their time in out-of-school contexts in order to interrogate the view that Asian students often spend much of their time studying, with little leisure time. The authors were concerned that there was an absence of empirical data on this topic. Increasingly, there is a recognition that Asian students perform well in high-stakes international tests, and a widely held view is that this is because they dedicate so much time to intensive academic study in contrast to their ‘Western’ counterparts. The social and cultural capital derived from doing well in school systems is an established feature of many global contexts. In the competitive environment that characterises education in Hong Kong, progression through the system is based solely on examination scores, and justified on the basis that this is both equitable and allows the best students to thrive. Tutorial schools that train attendees in the art of testing are multimillion-dollar industries – but who are the clients? In this article, the authors reveal that at 10 years of age, the out-of-school lives of the students surveyed contain many and varied activities. They attend school and, in out-of-school contexts, complete homework, participate in activities that both incorporate new media (for example, television and computers) and others (for example, indoor and outdoor play), and do not.
Childhood Spaces in a Changing World: Exploring the Intersection between Children and New Surveillance Technologies
Authors: Rooney Tonya
Published: December 2012

Children are at the forefront of the rapidly changing technological landscape, living in a world where both physical and virtual spaces are an intertwined part of daily experience. As an example of a child's changing relationship with new technologies, this article explores the increasing presence of surveillance technologies in the day-to-day spaces children inhabit. It suggests that childhood experience needs to be understood in the context of fluid and interdependent relations with others and the worlds around them, including their relationships with new technologies in the surrounding environment. At the same time, it is important to retain a view of the child that is more complex than what is simply gleaned through their relationship with new technologies, even as this becomes a prominent mode of interaction with others and the world around them.
When the PCAOB Talks, Who Listens? Evidence from Stakeholder Reaction to GAAP-Deficient PCAOB Inspection Reports of Small Auditors
Authors: Abbott Lawrence J. , Gunny Katherine A. , Zhang Tracey Chunqi
Published: December 2012

Section 104 of the Sarbanes-Oxley Act (SOX) created the Public Company Accounting Oversight Board (PCAOB). The PCAOB conducts inspections of registered public accounting firms that provide audits for publicly traded companies. The results of the inspection process are summarized in publicly available reports at the PCAOB website. Using these reports, we categorize the inspection reports into three levels of increasing severity: clean, GAAS-deficient, and GAAP-deficient. We examine the potential use of GAAP-deficient PCAOB inspection reports as perceived audit quality signals for the clients of GAAP-deficient auditors that are inspected on a triennial basis by the PCAOB. Our investigation is predicated on the notion that audit quality is generally not directly observable. Thus, the clients of these auditors may seek to signal their desire for audit quality by dismissing their GAAP-deficient auditors. Our results suggest that the clients of GAAP-deficient, triennially inspected auditors are more likely to dismiss these auditors in favor of triennially inspected auditors that are not GAAP-deficient. In addition, we find that greater agency conflicts, the presence of an independent and expert audit committee, and outside blockholdings magnify this effect. Interestingly, we find no evidence that the clients use GAAP-deficient reports to procure a subsequent-year audit fee discount or more favorable going-concern auditor reporting treatment. Our evidence indicates that PCAOB inspection reports created heterogeneity in auditor brand name among a group of non-Big N/non-national auditors that did not previously exist and are universally treated by prior research as “other auditors.”
Effect of placement angle on the stability of loaded titanium microscrews in beagle jaws
Authors: Xu Zhenrui , Wu Yeke , Zhao Lixing , Zhou Yuqiao , Wei Xing , Tang Na , Feng Xiaoxia , Tang Tian , Zhao Zhihe
Published: December 2012

Objective:

To evaluate the effect of insertion angle on stability of loaded titanium microscrews in beagle jaws.

Materials and Methods:

Forty-eight microscrews were inserted at four different angles (30°, 50°, 70°, and 90°) into the intraradicular zones of the mandibular first molars and third premolars of 12 beagles and immediately loaded with a force of 2 N for 8 weeks. Microcomputed tomography (micro-CT) and biomechanical pull-out tests were used to assess osseointegration of the interface.

Results:

All micro-CT parameters and maximum pull-out force (FMAX) of the microscrews were affected by insertion angles of microscrews. Higher micro-CT parameters and FMAX were seen for implants inserted at angles between 50° and 70° (P < .05). Excessive oblique and vertical insertion angles resulted in reduced stability (P < .05).

Conclusion:

An insertion angle of 50° to 70° is more favorable than excessive oblique or vertical angles to achieve stability of microscrews.
Editorial Vol.9
Authors: Adhikari Devendra
Published: December 2012

DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7142BIBECHANA 9 (2012)