bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of crop density on maize grain yield
Authors: Mandic Violeta , Bijelic Zorica , Krnjaja Vesna , Tomic Zorica , Stanojkovic-Sebic Aleksandra , Stanojkovic Aleksandar , Caro-Petrovic Violeta
Published: May 2016

The aim of this investigation was to estimate the effects of crop density on
the plant height (PH), ear height (EH), leaf number per plant (LN), ear
length (EL), number of rows per ear (NRE), number of grain per row (NGR),
number of grain per ear (NGE), grain weight per ear (GWE), cob weight (CW),
1000-grain weight (1000-GW), ear diameter (ED) and grain yield (GY) in
staygreen maize hybrid Dijamant 6 (FAO maturity group 600). Three crop
densities (51020 plants ha-1, 59524 plants ha-1 and 71429 plants ha-1) were
tested. The field experiment was carried out during 2006 and 2007 at Srem
region (Putinci: latitude 44? 59? 19" N; longitude 19? 58? 11" E). Plots were
organized as completely randomized block system design in four replications.
PH (284.3 cm), EH (119.9 cm), LN (13.9), EL (20.8 cm), GWE (232.5 g), CW
(56.4 g), 1000-GW (378.4 g) and GY (13.56 t ha-1) were significantly higher
in 2006 (favorable climatic conditions) than in 2007 (258.5 cm, 112.8 cm,
13.2, 17.9 cm, 192.9 g, 46.9 g, 232.7 g and 11.50 t ha-1, respectively).
Increasing crop density significantly increased the PH, EH and GY, and
significantly decreases the EL, NGR, NGE, GWE, CW and 100-GW. The crop
density of 71429 plants ha-1 is the optimal for growing this hybrid in Srem
region. On that crop density hybrid more efficiently used available resources
and achieved the highest grain yield.
Wave digital models of ideal and real transformers
Authors: Stosic Biljana
Published: May 2016

In this paper, the wave digital filter (WDF) theory is applied for
development of the wave digital models of ideal and real transformers which
can be used for modeling of more complex structures. The transformers wave
digital networks are described and developed here based on scattering
variables and two-port and three-port networks of parallel and series
adaptors. WDF-based model of a real transformer includes parasitic resistors
and inductors, which are usual in low-frequency transformer equivalent
circuit.
LCR of SC receiver output signal over α-κ-μ multipath fading channels
Authors: Suljovic Suad , Milic Dejan , Panic Stefan
Published: May 2016

Wireless mobile communication system with selection combining (SC) diversity
receiver is investigated in this paper. Received signal envelope experiences
?-?-? short term fading resulting in system performance degradation. Level
crossing rate (LCR) and average fade duration (AFD) of SC receiver output
signal envelope are obtained as rapidly converging infinite series
expressions. Numerically evaluated results are presented graphically, in
order to discuss the effects of transmission parameters: multipath fading
severity, dominant component power and nonlinearity propagation parameter on
observed LCR performance of dual SC.
Centralized detection of pre-alarm state in telephone network of electric power utility
Authors: Mitic Dragan , Matic Vladimir , Lebl Aleksandar , Stanic Mihailo , Markov Zarko
Published: May 2016

In this paper we consider the mixed telephone network of electric power
utility consisting of IP, ISDN and Power Line Carrier links. Very important
demand in the network is high availability. The central detector of IP and
ISDN link failure (pre-alarm) is presented. The detector function is based on
the prolonged response time of the network in the case of IP and ISDN link
failure. We define undesirable events in the detector operation: false
pre-alarm and miss detection, and we derive the expressions for their
probability calculation. It is indicated that centralization of this detector
is merit, which facilitates testing of the whole network from one location.
The effect of air temperature on forest fire risk in the municipality of Negotin
Authors: Zivanovic Stanimir , Gocic Milena , Ivanovic Radomir , Martic-Bursac Natasa
Published: May 2016

Fires in nature are caused by moisture content in the burning material, which
is dependent on the values of the climatic elements. The occurrence of these
fires in Serbia is becoming more common, depending on the intensity and
duration have a major impact on the state of vegetation. The aim of this
study was to determine the association between changes in air temperature and
the dynamics of the appearance of forest fires. To study the association of
these properties were used Pearson correlation coefficients. The analysis is
based on meteorological data obtained from meteorological station in Negotin
for the period 1991-2010. Research has found that the annual number of fires,
correlating with an average annual air temperature (p = 0.317, ? = 0.21).
Also, it was found that the annual number of fires positive, medium
intensity, correlate with the absolute maximum air temperature (p = 0.578, ?
= 0.26), but not statistically significant (p> 0.05).
New media in teaching of geography: Literature review
Authors: Andjelkovic Sladjana , Pavlovic Dragana
Published: May 2016

This paper provides an overview of published scientific papers in refereed
journals on the use of new media in teaching geography. Relevant previous
research on the application of GIS in the process of teaching at the
secondary and higher education is considered from critical aspects. The main
objective of this theoretical study is to systematically and chronologicaly
point to the central themes that were dealt with by researchers in the
context of the study of GIS in teaching geography. Research has shown that
the interest of researchers for GIS in education studies is growing in line
with the development of information and communication technologies, that
study topics of the problem varied, and that the number of research and range
of topics increases after 2000.
Some problems of the methodology of sociological research: Hommage to Vojin Milic
Authors: Ilic Vladimir , Veljkovic Marta
Published: May 2016

This article aims to achieve two main goals. Firstly, authors have tried to
reconstruct the position of Vojin Milic (1922-1996) in the development of
thought about (research) method. Therefore, they compared his standpoint with
those developed one generation earlier (Znaniecki), those of his
contemporaries (Good and Hatt), as well as with the work of present-day
authors (Bryman). Special attention was paid to the importance of Milic?s
study of the history of methodological thought and epistemology regarding the
emergence of his ideas on data collecting methodology and procedures relevant
for the analysis of causality. Secondly, along with this historical and
scientific study, and guided by Merton?s critics of adumbrations, authors
undertook a systematic examination of relationships between various research
and analytical procedures within sociology: primary (original) experience,
observation, sequential analysis, grounded theory, comparative method and
multiple-case study.
Neo-endogenous development and ecological paradox: Case study of six cities in Serbia
Authors: Petrovic Mina , Tokovic Milena
Published: May 2016

Postindustrial develoment and postfordist model of capitalism led to the
shift in city development model, from programs that were strategically
developed on a national level (top-down perspective) to a new concept that
insists on locally based or neo - endogenous city development. The main aim
of this paper is to shed light on a different conceptual and contextual
approaches to the notion of the neo - endogenous development in European
context, and to give an answer to the question whether and how Serbian cities
(Kragujevac, Zrenjanin, Uzice, Sabac, Sombor and Novi Pazar) are moving
towards this new development model. Attitudes of local experts and city
evelopment strategies are in the main anaytical focus. In the first part,
concepts of localised and localy based or neoendogenous development are
discussed and related to the concepts of territorial capital,
teritorialization, ecological paradox. In the second part, these concepts are
contextualised through discusson based on strategic commitments of the EU,
and relevant characteristics of post-socialist transformation of European
countries, including Serbian society. In the third part, the goals and method
of conducted empirical research are stated, and the results presented. The
final part briefly synthesises the similarities and differences in
manifesting ecological paradox among the researched cities, which are related
to the perceived development potentials and obstacles in acordance to neo -
endogenous development model. The paper is informed by qualitative based on
the survey research conducted by Institute for Sociological Research of
University of Belgrade - Faculty of Philosophy in 2013/14.
Image of the city between consensus and tension: Six Serbian cases
Authors: Backovic Vera , Spasic Ivana
Published: May 2016

Starting from the concept of urban identity, defined as a set of unique
features characterizing a city/town that set it apart from others and ensure
its continuous recognizability, the paper takes the example of six urban
centers in Serbia (Kragujevac, Sabac, Uzice, Novi Pazar, Sombor and
Zrenjanin) to examine the degree of consensus or divergence concerning these
identities. Three dimensions i.e three kinds of tension that can arise
within, or in relation to, the established image of the locality are singled
out: 1) Crystallization: is a given urban identity clearly embodied in a
single symbol, and how coherent are the meanings of the constituent symbolic
elements? 2) Contention: is the city image disputed among various social
groups within its population? 3) Comparisons: how do these urban identities
relate to other urban centers and their respective identities? The analysis
is based on quantitative and qualitative data collected during 2013 and 2014
within the project? Characteristics of Territorial Capital in Serbia? of the
Institute for Sociological Research, Faculty of Philosophy, Belgrade.
Older parents and adult children: Traditional relationship or closeness throug or at distance?
Authors: Dragisic-Labas Sladjana
Published: May 2016

A good relationship between older parents and adult children is an important
part of active aging. This relationship is being transformed in different
ways through all stages of life. Closeness, support and care of elderly
parents by children and the other way around of descendants, both children
and grandchildren by their parents and grandparents definitely facilitates
and reduces the amount of care to be delivered from the community and wider
society as such. However, the state often conveys its own part of
responsibility to the elderly or the children, whereas the traditional
culture presupposes a reciprocal care to be a moral norm, hence we get the so
called ?nonsense? situation i.e., overloaded and exhausted adult children or
burdened parents on the one side and preserved ?state? of well-being, on the
other. In this work, we will consider the relationship between older parents
and adult children using the collected data from 52 interviews (with content
analysis method applied) conducted with people over 65, from Belgrade. It
becomes clear that this relationship marks the everyday life - work,
reproductive activities, leisure, health, i.e., the most relevant aspects of
our respondents? lives. The so called ?distant closeness? proved to be
efficient in Western societies and referring to our research, it is described
as desirable but not always feasible. . It is also more preferable for female
than for male respondents. The male respondents have higher expectations from
their children when it comes to care and help. Sharing of more responsibility
over needs of elderly and their children by society, could significantly
enable the realization of what we here labelled ?distant closeness?.
Contemporary sociology and the challenge of LGBT perspective
Authors: Radoman Marija
Published: May 2016

This paper analyzes certain theoretical and methodological problems in the
research of (homo) sexuality. It also provides an overview of some of the
conclusions about LGBT parenting. There are both theoretical and practical
reasons behind making connections between the topics of parenting and
problems of a different sexual orientation. On the one hand, there is a need
to expand the knowledge of the LGBT population and same-sex families in
domestic sociology (considering that these issues are present for more than a
decade in our society), while on the other hand, LGBT parenting problem
analytically refers to the study of homosexuality because these two issues
are inseparable in the public discourse. In general, the aim of this paper is
to introduce LGBT perspectives in sociology and sociology of the family by
pointing out the epistemological importance of studying non-heterosexual
orientation and alternative family forms of LGBT. The first part includes the
analysis of certain theoretical and methodological problems in the study of
the LGBT population, and the second part gives an overview of contemporary
research on same-sex families.
Effects of Mo and Vc on the microstructure and properties of nano-cemented carbides
Authors: Chen Jian , Liu Wei , Deng Xin , Wu Shanghua
Published: May 2016

In this study, four unique groups of nano-cemented carbides with 8 wt.% Co
and trace amount of Mo and VC have been successfully synthesized. The effect
of Mo and VC has been investigated comprehensively on both the
microstructure and mechanical behavior of nano-cemented carbide. The results
show that Mo significantly increases hardness but decreases the fracture
toughnesses and VC slightly increases hardness and strongly increases
fracture toughness of nano-cemented carbide. It is found that the optimum Mo
and VC contents are both 0.5 wt.%. The average WC grain size is about 370
nm. The hardness is about 2350 HV30 and the fracture toughness is about 11.2
MPam-1/2.
Managing Process Safety in Facilities Design
Authors: Unnikrishnan G.
Published: May 2016

It takes usually 3 to 4 years on an average to build a complex oil and gas facility from concept to commissioning. All critical features of the facility are decided during the early stages of the project. In fact the concept stage can be called as the stage when the DNA of the facility is cast. During rest of the project all that is being done is to develop and translate this DNA to reality. Very little can be done in later stages to correct safety problems buried in concept itself.

Are we paying enough attention to process safety during this stage? Projects are implemented under several constraints and process safety sometimes takes a backseat. While there are several methods of Process Hazard Analysis by which process hazards are checked during design, how far are they effective? As the project accelerates towards completion all focus will be usually on the schedule. Are project teams able to see the compromises made on process safety during the fast track implementation? This paper will review the current practices for ensuring process safety during project implementation. Further it will present case histories of projects where hazards where buried deep inside design in spite of safety reviews that were carried out.

The paper will argue the case for deeper understanding of process safety and the need for better management of the same during project implementation. Summary of latest research on the subject from diverse fields of Technical Safety, Behavioral Science and Systems theory will be included in the paper.

In conclusion, the paper will provide better ways of understanding the complex issues and demonstrate several important factors that will help in ensuring process safety during project implementation.
Integrating Pressure Transient Analysis and Production Analysis for Dynamic Reserve Evaluation in Tazhong 1 Ordovician Carbonate Gas Field, Tarim Basin
Authors: Hedong Sun , Ying Shi , Shiyin Li , Bo Kang , Linlin Lu , Zhicheng She , Yanchun Li
Published: May 2016

Tazhong ?gas field is a typical vug-fractured marine carbonate gas condensate reservoir with characteristics of high heterogeneity and complex geological& dynamics, of which grand challenges face the development by using the classic evaluation method of dynamic reserves. On the basis of literature research, a formal definition about dynamic reserves is given. Besides, a workflow of dynamic reserve for carbonate gas condensate reservoirs is built relying on the long-term low accuracy data of daily production and short-term high-accuracy data of pressure build-up testing, which integrates full lifecycle short-term pressure transient analysis and long-term production analysis combined with the geological understanding. The factors affecting reserve estimate are analyzed based on a field application on Tazhong ?gas field, including initial formation pressure, PVT, the error of pt~pwf conversion, production time, producing water and routine of work. The simulation results show that the gas-liquid two-phase pseudo-pressure method is more appropriate than the pseudo-single phase method for calculating dynamic reserves for low gas-oil ratio gas condensate wells. The workflow can improve data utilization ratio, reduce the uncertainty of reserve estimation, avoid the development risk, optimize the development plan, and contribute the enhanced oil recovery in the late stage. It can be also used in other marine carbonate reservoirs. Recently, three thousand large-scale condensate gas fields have been discovered in the Ordovician carbonate reservoir of the Tazhong area, which is located in the middle part of the central uplift belt in the Tarim Basin?1-2?. However, the traditional material balance method for doing what is not applicable in this area due to many factors. First, the type of reservoirs is various, including cavity, fracture-vug, cleavage and matrix pore (dominant). Second, the flow mechanism is complicated, including seepage and conduit flow. Besides, fluid property is complex in nature, leading to low-, middle-, high condensate and volatile gas reservoirs. Third, controllability is low during the development, the production model involves non-constant pressure and non-constant rate. Fourth, it is difficult to calculate the bottom hole flowing pressure due to the small difference between the formation pressure and the dew point pressure, there is the retrograde condensation phenomenon in formations, and multi-phase flows happen in the wellbore. Fifth, there are few hydrostatic gradient data, and they do not decrease monotonically. Therefore, a great challenge facing developers is how to evaluate the dynamic production of complex carbonate gas condensate wells under the complex production status.
Productivity Improvement Using Combination of Static and Dynamic Underbalanced Perforation in Tahe Oilfield, Tarim Basin, West China
Authors: Fuqiang Lei , Lian Liu , Li Liu , Yong Hu , Gang Zhao
Published: May 2016

In concern with the skin factor value, the key significant components which do not directly depend on the nature of the reservoir properties are drilling/completion fluid invasion damage and perforating induced damage. The oil &gas industry has been tried to eliminate the fluid invasion issue by applied deep penetration perforating to bypass the invasion zone and reach un-invaded reservoir. Lots of experiences and lab analysis shows that perforation performance is not meet the expectation of the productivity because of the perforation induced damage. As for now, static underbalanced perforation has been recognized by industry as one of the method to obtain clean perforation tunnel. However, static underbalanced perforation method is not always giving the expected productivity result.

Experiments showed that the cleanup of the perforation tunnel was not totally dominated by the static under-balance pressure but also the transient pressure during the first 100 milliseconds of perforation or dynamic under-balance. The dynamic under-balance can be obtained by creating an instantaneous drop in pressure around the guns during perforating. The combination of static and dynamic underbalanced perforation with deep penetration charges which be able to bypass an invasion zone, can create a clean tunnel, and significantly reduce the post-perforating damage by killing fluid, and finally maximized the productivity.

This combination of the static and dynamic under balance method has been applied in Tahe Oilfield. Tahe oilfield is located in Tarim basin with reservoir horizon depth of 4100m-4600m, temperature of 94–103, and pressure gradient is about 1.1MPa/100m. The payzone is Triassic clastic reservoir with middle porosity and permeability quality. The static underbalanced with different deep penetration charges of perforating system has been applied in Tahe oilfield to improve the productivity. However, the statistic showed that productivity is not reaching the expectation range by static underbalanced perforating. The combination method of static and dynamic under-balance perforation along with deep penetration charges was applied in 2011 to WELL-1. The well productivity was exceeded the expectation and the PI value is almost 2.5 times compare to offset wells which only using static under-balance perforation method. The pressure transient analysis result proved the improvement by showing negative skin value.

This paper will describe the application of this technique in Tahe oil field including: suitable job design, execution of the job and provide the results summary of this successful application. The evaluations of the method are based on productivity improvement and skin value from pressure transient analysis.
Real World Solutions Effective Fracture Treatment Design in Horizontal Wells
Authors: Sturms Jason M. , Smith Charles H. , Ziane Lynda
Published: May 2016

Horizontal wells have altered the ability to deliver production from marginal reservoirs. Although reservoirs with permeability values in the 0.1 to0.01 millidarcy range had been identified in many producing basins, these reservoirs could not be exploited until horizontal drilling became a commercial reality. Drilling these reservoirs became an engineering process that could be applied with great success in many different basins and rock types.

The completion of these resources proved to be a different matter, however. Wells that were drilled with excellent vertical control within the reservoir did not exhibit a consistent response to treatment stimulation along the entire traverse of the horizontal sections. However, reservoirs that were considerably different lithologically were always expected to provide a diversity of completion challenges. Pump-in tests were used in many cases in an attempt to under stand this lack of consistency.

More troubling are the reservoirs that appear to be homogeneous that do not respond well to similar treatment designs along the length of the horizontal section. In some cases, pump-in tests followed by treatment designed from that data failed to yield the expected production results. Sometimes, breakdown could not be achieved in the reservoir.

This paper describes how to apply data derived from dipole sonic logs in horizontal sections of a well to establish the anisotropy along the length of the horizontal section. This information is then used to define the brittleness properties of each section of the wellbore. Perforations are selected to take advantage of this brittleness, and effective fracture treatments are designed and pumped.

Two reservoirs are examined where this application is used. These case studies occurred in different basins, but both were difficult and troubling reservoirs. The fracture treatment success increased from 50 to 60% to 100%,with reduced breakdown pressures.
An Integrated Approach of Fractured Reservoir Modelling Based on Seismic Interpretations and Discrete Fracture Characterisation
Authors: Gong Bin , Li Junchao , Shan Ying
Published: May 2016

An integrated approach of fractured reservoir modeling is presented. First, the fracture density and azimuth distribution of the entire reservoir is mapped from seismic anisotropy analysis and image log calibrations. Then we apply a dynamic workflow to construct the discrete fracture model by connecting fracture elements laterally and vertically. A tetrahedral grid is then generated for detailed reservoir simulation that fully resolves the discrete fracture characterization. Finally the flow simulation is performed on an actual carbonate reservoir block in the Mideast. This study presents a systematic way of modeling and simulating fractured reservoirs.

Introduction

Fractured reservoir modeling remains a challenge given that realistic fracture characterization is difficult due to no highly-recognized algorithms to derive field-scale fracture properties from seismic processing results. Recent advances in seismic and image log interpretations enable realistic modeling of naturally fractured systems, though with significant uncertainty. Consequently, it is possible, to certain extent, to represent actual fracture distribution in reservoir modeling and run detailed simulation via a discrete modeling approach (Gong, 2006 and 2008).
Knowledge Management in Engineering Activities of an Operating Company
Authors: DiLiddo G. , Gabetta G. , Ponti F. , Cavassi P. , Fassina P.
Published: May 2016

A better Management of Knowledge is an actual need in the Oil&Gasindustry. In the past years, as a matter of fact, the amount of information available to engineers and scientists increased exponentially thanks to developments of the ICT tools making therefore harder to handle it. On the other hand, industry practice is to keep the plant running, implying that decisions have to be made quickly and time is short to collect and examine all the possible information.

A solution to these challenges is Knowledge Management, which is defined as the ensemble of processes that allow to capture, validate, consolidate, archive, re-use and diffuse knowledge in order to improve both business processes and innovation processes. To make it happen, new ICT tools and mindsets need to be developed and exploited.

In Eni E&P Division, a Knowledge Management System (KMS) is operating since 2004 with the aim at facilitating and speeding-up the sharing of best practices, lessons learned and other Know How across the organisation; several ICT tools are employed, such as forums, mailing lists, SharePoint websites, webinars etc. The KMS is based on several Communities of Practice, which have the aim of conveying technical debate transversally to different disciplines and to the entire eni group, which is heterogeneous due to geographical location, culture, industrial sectors and discipline involved. The resulting interactions, moreover, bring the advantage of making explicit (and durable) all the personal knowledge of the members that would otherwise got lost due to turnover and distance among the employees.

Taking into account the results of the first few years of implementation of the KM system in the engineering area, this paper will summarize the successes and lessons learned during the operating life of the Communities, to trace a road map for the future work.
Mitigation of Deepwater Shallow Hazards with Simplified Cement System: South China Sea Case Study
Authors: Ellis Todd B. , Acorda Edgar Paul R.
Published: May 2016

Cementing is one of the most critical steps in the well construction phase. Qualified cement integrity is considered a barrier to inhibit fluid migration to surface. For conventional wells, cement in addition to barriers such as BOPs (Blow Out Preventers), fluid hydrostatic pressure, and mechanical methods are used to ensure fluid migration is inhibited. For top-hole sections of deepwater exploration wells however, cementing is your only barrier to mitigate uncontrolled fluid flow to the seabed. During the top-hole operations (typically 36-in. and 26-in. hole sections), the bore hole is drilled without a riser and returns are taken to seabed. This creates difficultly in controlling shallow hazards such as gas hydrates and shallow water flow because the well cannot be killed using conventional methods. To assure mitigation of shallow hazards, an emphasis is made on achieving short transition times for cement designs.

For South China Sea operations, it is common practice to incorporate cenospheres (dry blended lightweight additive) into the cement design to ensure suitable properties are achieved. However, the use of cenospheres requires blending onshore and excess blends to be shipped offshore for contingency purposes. Although required slurry properties can be achieved with cenospheres; logistical issues, left over disposal concerns, costs, and low cenosphere pressure ratings create a complex operation. In addition, cement systems should be designed to incorporate loss of lightweight material during transfer offshore, and must account for higher down-hole densities due to crushing of lightweight cenospheres. All of these processes require great emphasis on Quality Assurance / Quality Control (QA/QC) and economic concessions.

Other unique challenges that must be accounted for are low temperatures, commonly around 4°C (50° F) at seabed, low fracture gradients, enlarged hole sizes due to high rate of penetration (ROP) drilling, and environmental regulations due to returns at seabed. The cement system must be designed for all the above aspects, and still maintain excellent integrity to enable the BOP stack to be installed upon a firm foundation.

This study will describe a new simplified cement system which exhibits excellent slurry properties necessary for a deepwater environment. Laboratory results and engineering procedures will be reviewed to demonstrate that all necessary qualities for mitigation of shallow hazards are met. Furthermore, logistical and HSE advantages will be highlighted, and two case histories will be discussed.
Harnessing Intelligent Field Capabilities for Early Understanding of Reservoir Behavior and Proactive Decision
Authors: Abu-Hassoun Amer H. , Shamrani Sultan S.
Published: May 2016

With recent advancements in field instrumentation technologies and the expansion of Saudi Aramco's state-of-the-art intelligent field infrastructure, a wealth of valuable knowledge is being derived from integrating intelligent field capabilities with best-in-class reservoir management practices. Intelligent field applications have already leveraged real-time reservoir surveillance data to enable timely responses and fast interventions for events observed from real-time data. As richer and more granular datasets are collected from the field, deeper insights and understanding of the reservoirs are gained at fractions of the needed time where intelligent field capabilities are not present. The abundance and timely processing of intelligent field data enables more tactical adjustments in reservoir management strategy. This type of real-time reservoir management has already shown great value in reservoir performance optimization.

This paper discusses several cases in which an intelligent field enabled early detection of anomalies and shortened the time-cycle for an analysis, decision and action. The first case discusses the early detection of localized pressure support anomalies due to poor rock quality. This timely detection, facilitated by intelligent field infrastructure, enabled quick decision making and actions to overcome the anomaly. The second case shows how real-time monitoring of reservoir pressure propagation has helped to detect over-injection in two injectors with malfunctioned meters. This has allowed timely action to ensure uniform pressure propagation and repair of faulty equipment. The third case shows that the utilization of real-time data has assisted in detecting a casing leak in a short time, which helped in making a corrective action to restore the well's capacity.

In all three cases, had an intelligent field not been there, the time-cycle from detection to analysis, and to decision and action, would have been substantially longer, resulting in higher operational costs and an impact on reservoir performance.
Influence of Micro-Computed Tomography Image Resolution on Petrophysical Properties
Authors: Alyafei Nayef , Gharbi Oussama , Qaseminejad Raeini Ali , Yang Jianhui , Iglauer Stefan , Blunt Martin J.
Published: May 2016

Micro-CT scanning is a non-destructive technique that can provide three-dimensional images of rock pore space at a resolution of a few microns. However, these grey scale images cannot be directly input into simulators to predict flow properties; they require image processing to segment the solid and void space in the rock. Dynamic and static single phase properties can then be computed using the images directly or on extracted equivalent network models. In this paper, we study the effect of imaging resolution (five different voxel sizes ranging from 6–20 μm) of Clashach and Doddington sandstone on predicted single phase properties (porosity and absolute permeability) and network properties. Experimental data is used to validate the predictions. The results suggest that the computed porosity was largely independent of resolution and in good agreement with the measured value, while image resolutions of a few microns are sufficient to determine the permeability of a high-permeability rock such as Doddington but may not be sufficient for lower permeability samples. The topologically representative networks are sensitive to resolution, adding additional smaller pores and throats as the resolution is increased. This latter reason was confirmed by a network extraction analysis that indicated the average throat radius was 6 µm, similar to the highest resolution used and insufficient to image all important features of the pore space properly.
Calculations of Equivalent Circulating Density in Underbalanced Drilling Operations
Authors: Ettehadi Osgouei Reza , Yoong William Liew Sin , Ozbayoglu Evren M.
Published: May 2016

Underbalanced drilling using gasified fluids is one of the most widely used methods to drill depleted, low pressure and highly fractured formations. For ensuring a safe and successful underbalanced drilling operation, accurate prediction of the equivalent circulating density (ECD) is very important. Nevertheless, estimating ECD of gasified fluids is not easy due to the complexity of the two-phase fluid flow inside the wellbore. In this study, there are two major focuses considered; i) validation of the accuracy of Beggs& Brill (1973) model on the prediction of pressure losses of gasified fluids in under balanced drilling operation, and modification of Beggs &Brill (1973) model for pressure loss estimation inside the wellbore, and ii) to propose an ECD calculation procedure for gasified fluids by using modified Beggs & Brill (1973) model.

To validate the accuracy of Beggs & Brill (1973) model, experiments were carried out using Middle East Technical University (METU) Cuttings Transport Facility to obtain the pressure losses of gasified fluids in an annulus and their corresponding flow patterns. Air-water mixtures were used with various in-situ air and water flow velocities of 0–120 ft/s and 0–10 ft/s, respectively, at wellbore inclinations of 90°, 75°, 60°, 45° and 12.5° without inner pipe rotation. Pressures were recorded at several points along the annular test section, and pressure distribution along the test section was measured. Meanwhile, flow patterns were determined by the help of a high speed digital camera.

Results showed that although Beggs & Brill (1973) model can estimate pressure losses in low gas and liquid flow rates and low slip ratio between two phases for horizontal and near horizontal annular sections with a reasonable accuracy, this model cannot accurately calculate pressure losses at inclined and vertical annular sections. With some modifications, improved Beggs & Brill (1973)model (by applying suggested procedure) can be used to predict ECD and annular pressure losses of gasified fluids inside the annulus accurately. This information can be directly applied for underbalanced drilling operations when gasified fluids are used.
SMS Skyscrapers
Authors: Khan Jamal , Amidenau Gary
Published: May 2016

This paper offers methodology, guidelines and tools to assist Oil/ Gas plants and other industrial facilities to develop organize and improve local safety programs (SMS) that comply with corporate elements of safety management as in the 11 elements of the "Saudi Aramco Safety Management System". The development is done through a consistent method and format for writing the system elements and its processes. For simplicity, the model is represented by a Skyscraper building "SMS Skyscraper". All model processes include definition of crucial characteristics which are: Purpose, Applicability, Description, Flowcharts, Responsibilities, Training, Performance Indicators, Supporting Tools, Documentation and References.

Once the model is used, it helps achieve and sustain quality in defining HSE processes. The quality of processes drive quality in execution of safety activities. This in turn paves the path for proper identification Hazards and evaluation Risk every addition to improving the accountability culture. The overall objective is to help organizations develop customized "Safety Management Systems" that capture the knowledge and "know-how" in addition to providing tools that foster world class execution. In time, and with the right leadership, this will transform organizational and community safety culture and consequently reduce incidents ON and OFF the Job.

The "SMS Skyscraper" model has been used to develop 100 Safety Management Processes for Khursaniyah Gas Plant Safety Management System (KGP SMS) in the period between February 2009 to March 2010 and is now available on Saudi Aramco intranet portal at http://KGP/SMS. The model has helped Khursaniyah Gas Plant achieve level of ownership of our local SMS in addition to placing the department on the leading edge of safety management in Saudi Aramco. It also helped young individuals in the organization substantially grow their knowledge in safety management.

The model has been reviewed and acknowledged by a handful of safety professionals. It has also been recognized by the Upstream business line in Saudi Aramco as the "go-by" model for development of safety processes. Many other departments in Saudi Aramco are now moving towards the Skyscraper model for comprehensive development of local SMS processes.
Production Optimisation with Hydraulic Fracturing: Application of Fluid Technology to Control Fracture Height Growth in Deep Hard Rock Formation
Authors: Al-Dhamen Mohammad , Makmun Areiyando , Hilal Ahmed
Published: May 2016

Hydraulic fracturing is frequently used to create the reservoir-wellbore connectivity required to produce the hydrocarbon from tight formations. Many factors can be considered as risks to the success of operations. One arises in reservoirs with a water-bearing zone in close proximity to the net pay. Many times, the risk of fracture growth into the water zone limits the stimulation options and eliminates the option of a hydraulic fracturing treatment, thereby constraining the well's future production. The challenges increase when the reservoirs are deep, hot, and exhibit a high Young's modulus. Under these conditions, it greatly increases the risk of an early screenout, and the introduction of fracturing fluid into the formation before a high-conductivity proppant pack is fully placed will damage the formation and hinder production.

In Saudi Arabia, a well in a relatively new field encompassed all three challenging characteristics. The target reservoir section was between two water-bearing zones, had high bottomhole temperature, and high Young's modulus. Traditional polymer-based crosslinked fluids would address the challenges from the perspective of proppant placement. However, these thick crosslinked fluids would also risk in uncontrolled fracture growth into the water zones. A polymer-free, high-temperature visco elastic surfactant (VES) fracturing fluid was used to balance the risks of incomplete proppant placement, formation damage, and fracture growth that would result in water production.

The VES fluid selected for treatment of Well SH-3 has a low viscosity compared to that of a traditional crosslinked fluid; it therefore generates less net pressure and thus lowers the risk of the fracture growing into the water zones. It also has excellent capacity to carry and suspend proppant. To increase its efficiency, the VES fluid was further enhanced by using a degradable fluid-loss additive.

Pumped on a conservative schedule, the hydraulic fracturing treatment placed 61,500 lbm of proppant into the thin reservoir section between two water-bearing zones without any operational issues. The Minifrac analysis, stress profile calculation, and fracture geometry characterization, as well as no water production, has confirmed the controlled fracture height growth. Furthermore, pre- and post-stimulation analyses validated the improved productivity, giving a successful stimulation option for the development of this field.
Mitigating Challenges in Resolving 7" Liner Leak-Case Study
Authors: Al-Muailu Husain Al , Zorbalas Konstantinos , Al Yateem Karam , Garcia Javier
Published: May 2016

An evaluation process was conducted in assessing various solutions towards remedial action to a 7" liner with an identified leak in a water injector well. The leak to the 7" liner was identified through pressure testing of the well. A comprehensive investigation and analysis was performed to identify the liner condition, exact leak location and the extent of the leak. It was accomplished by analyzing all previous activities performed during the life of the well and through running special pressure testing as well as logging the well with ultrasonic and physical logs.

The problem identification and proposed solutions were focused on curing the leak and bringing the well back on injection with the least operational risk and highest possibility of success. Corrosion and cement bond logs were ran and showed a better picture in regards to the extent of the corroded section and the quality of cement behind it. A caliber log was also run in the open hole which showed a washed out area near the 7" liner shoe.

Several solutions that could repair the 7" liner leak were assessed including: i) cement squeeze in the leak zone, ii) setting an off bottom 4.5" liner and iii) using a 5.5" expandable liner. The evaluation process included eachsolution's impact on the future injectivity of the well, the effectiveness of each option, operational challenges and associated risks. Moreover, nodal analysis was performed to evaluate possible reduction of the injection rate associated with each solution.

The final decision to repair the leak was to run an expandable liner and it was based on its advantages and deployment challenges. Lessons learned from this operation included the methods used to identify and assess the damage of the casing leak. Proper preparation and cleanout of the corroded section and the operation procedures performed to expand the liner are summarized in this paper.
CSEM Inversions Using the Gauss Newton Method and a Model Compression Scheme
Authors: Abubakar Aria , Lin Yun , Li Maokun , Habashy Tarek M.
Published: May 2016

We present a model compression scheme for improving the efficiency of the regularized Gauss-Newton inversion algorithm for marine controlled-source electromagnetic applications. In this scheme the unknown model parameters (the resistivity distribution) are represented in terms of a basis such as Fourier, cosine, or wavelet. By applying a proper truncation criterion, the model may then be approximated by a reduced number of basis functions, which is usually much less than the number of the model parameters. Furthermore, since the controlled-source electromagnetic measurements have low-resolution, we will show that for inversion it is sufficient to only keep the low-spatial frequency part of the image. This model compression scheme accelerates the computational time as well as reduces the memory usage of the Gauss-Newton method. For demonstration purposes, we show both synthetic and field data inversions. The results show that we are able to significantly reduce the algorithm computational complexity without compromising the quality of the inverted models.
Optimising Offshore Gas Field Development with Large Well Bore Completion
Authors: Al-Baqawi Ahmed , Ashri Amjad , Al-Utaibi Abdullah , Al-Kanan Adnan
Published: May 2016

During 2008–2009, Saudi Aramco recorded two major nonassociated gas field discoveries in the Arabian Gulf. The initial plan was to develop both fields with deviated extended reach 7" completion wells, which will be drilled from multi-well platforms. Based on the challenging subsurface conditions of the problematic highly fractured shallow horizons, in addition to the thick, highly fractured, and excellent carbonate Khuff reservoir quality, the decision was carefully made to develop both fields with vertical large bore wells completed as monobore with 9?" pre-perforated uncemented liner across the pay zone and9?" production tubing to the surface. The large bore wells are planned to be drilled from single-well platforms that can be strategically located around the two fields to allow efficient spacing and depletion to produce initial gas rates up to 300 MMscfd per well.

The large bore well design has a potential for maximizing the gas production from each well and reducing the overall field development costs down by 45% by minimizing the number of wells and facilities required without jeopardizing the production, safety or integrity of the development projects.

The shallow horizons in the newly discovered fields, along with the targeted Khuff reservoir, are considered to be highly faulted structures with many associated fractures that can continuously cause drilling problems with lost circulation and differential sticking. The newly planned vertical large borewells tend to reduce drilling problems. Nevertheless, those planned vertical large bore wells are still capable of producing the required high gas rates.

The intent of this paper is to highlight the multiple challenges faced during the early exploration and delineation phase of the fields and to share the experience of planning new offshore field development strategies for large bore wells with high reservoir temperature and pressure (T&P). Transforming from the original development plan to the optimized large wellbore completion plan, takes advantage of the excellent reservoir quality and high flow capacity, allowed for many optimization efforts. Such optimizations have changed the entire project strategy to accelerate the official on stream start update without any compromises.