bluuebunny/crossref_metadata_2025 huggingface dataset:
Hong Kong Literary History and the Construction of the Local in Xi Xi’s I City
Authors: Shen Shuang
Published: December 2012

Hong Kong literary history presents a polemical case study for a contemporary rethinking of national literary history: Is it a local history or a global history? How should we describe the complex connections between the city’s sinophone literature and the literatures of mainland China and other sinophone locations? This essay recognizes the significance of the Hong Kong identity discourse constructed around the 1997 “Handover,” but it argues that a historical narration of localness should not be confined by this discourse. Rather, it is important to consider the interactions between the local and the nonlocal and to examine how knowledge is made in and transacted between specific places. Taking I City, a 1975 nationalist allegory of Hong Kong, as an example, the essay shows that the principle of modernist collage enables Xi Xi to construct a narrative of the local that retains myriad complex connections with nonlocal places. Collage can be understood as the poetics of Hong Kong literary history.
Network Theory Circa 1800: Charles Brockden Brown'sArthur Mervyn
Authors: Margolis Stacey
Published: December 2012

This essay investigates an early instance of “network theory” in order to argue that such theories did not, as most scholars suggest, emerge exclusively in the digital age. Charles Brockden Brown's Arthur Mervyn (1799–1800) attempts to theorize the information networks of the early American republic by comparing the spread of information to the spread of yellow fever. Unlike other novels that focus on the spread of contagious disease (such as Dickens's Bleak House), Arthur Mervyn refuses to trace a clear path of transmission from person to person. Instead, the randomness of the fever's spread gives Brown a stark, dramatic way of visualizing the unpredictability built into all such chains of transmission. Rather than a mark of nostalgia for an earlier age of “face-to-face” communication, this interest in casual and ephemeral channels of communication (and indifference to print) is a mark of the text's modernity. What Brown recognizes in his analysis of emergent networks is the power of the city to reorder social connection, enabling individuals to bypass official sources of information, play a role in the process of transmission, and become (often unwitting) participants in a transformed public sphere. In Arthur Mervyn, the yellow fever epidemic works as a fantasy of exposure, an impossible kind of social transparency that ultimately serves as a map for comprehending the mysterious workings of a “connected age.”
Comparison Between Linear and Non-parametric Regression Models for Genome-Enabled Prediction in Wheat
Authors: Pérez-Rodríguez Paulino , Gianola Daniel , González-Camacho Juan Manuel , Crossa José , Manès Yann , Dreisigacker Susanne
Published: December 2012

In genome-enabled prediction, parametric, semi-parametric, and non-parametric regression models have been used. This study assessed the predictive ability of linear and non-linear models using dense molecular markers. The linear models were linear on marker effects and included the Bayesian LASSO, Bayesian ridge regression, Bayes A, and Bayes B. The non-linear models (this refers to non-linearity on markers) were reproducing kernel Hilbert space (RKHS) regression, Bayesian regularized neural networks (BRNN), and radial basis function neural networks (RBFNN). These statistical models were compared using 306 elite wheat lines from CIMMYT genotyped with 1717 diversity array technology (DArT) markers and two traits, days to heading (DTH) and grain yield (GY), measured in each of 12 environments. It was found that the three non-linear models had better overall prediction accuracy than the linear regression specification. Results showed a consistent superiority of RKHS and RBFNN over the Bayesian LASSO, Bayesian ridge regression, Bayes A, and Bayes B models.
Natural Variation in the Yeast Glucose-Signaling Network Reveals a New Role for the Mig3p Transcription Factor
Authors: Lewis Jeffrey A , Gasch Audrey P
Published: December 2012

The Crabtree effect, in which fermentative metabolism is preferred at the expense of respiration, is a hallmark of budding yeast’s glucose response and a model for the Warburg effect in human tumors. While the glucose-responsive transcriptional repressors Mig1p and Mig2p play well-characterized roles in the Crabtree effect, little function for the related Mig3p transcription factor has been uncovered, despite numerous investigations of laboratory yeast strains. Here we studied a wild isolate of Saccharomyces cerevisiae to uncover a critical role for Mig3p that has been lost in S288c-derived laboratory strains. We found that Mig3p affects the expression of hundreds of glucose-responsive genes in the oak strain YPS163, both during growth under standard conditions and upon ethanol treatment. Our results suggest that Mig3p may act as a multifunctional activator/repressor that plays separate roles under standard vs. stress conditions and that this function has been largely lost in the lab strains. Population analysis suggests that the lab strain and several wild strains harbor mutations that diminish Mig3p function. Thus, by expanding our attention to multiple genetic backgrounds, we have uncovered an important missing link in a key metabolic response.
Differentiation-Driven Nucleolar Association of the Mouse Imprinted Kcnq1 Locus
Authors: Fedoriw Andrew M , Calabrese J Mauro , Mu Weipeng , Yee Della , Magnuson Terry
Published: December 2012

The organization of the genome within the mammalian nucleus is nonrandom, with physiologic processes often concentrated in specific three-dimensional domains. This organization may be functionally related to gene regulation and, as such, may play a role in normal development and human disease processes. However, the mechanisms that participate in nuclear organization are poorly understood. Here, we present data characterizing localization of the imprinted Kcnq1 alleles. We show that nucleolar association of the paternal allele (1) is stimulated during the differentiation of trophoblast stem cells, (ii) is dependent upon the Kcnq1ot1 noncoding RNA, (3) does not require polycomb repressive complex 2, and (4) is not sufficient to preclude transcription of imprinted genes. Although nucleolar positioning has been proposed as a mechanism to related to gene silencing, we find that silencing and perinucleolar localization through the Kcnq1ot1 noncoding RNA are separable events.
Assessing the Genome-Wide Effect of Promoter Region Tandem Repeat Natural Variation on Gene Expression
Authors: Elmore Martha H , Gibbons John G , Rokas Antonis
Published: December 2012

Copy number polymorphisms of nucleotide tandem repeat (TR) regions, such as microsatellites and minisatellites, are mutationally reversible and highly abundant in eukaryotic genomes. Studies linking TR polymorphism to phenotypic variation have led some to suggest that TR variation modulates and majorly contributes to phenotypic variation; however, studies in which the authors assess the genome-wide impact of TR variation on phenotype are lacking. To address this question, we quantified relationships between polymorphism levels in 143 genome-wide promoter region TRs across 16 isolates of the filamentous fungus Aspergillus flavus and its ecotype Aspergillus oryzae with expression levels of their downstream genes. We found that only 4.3% of relationships tested were significant; these findings were consistent with models in which TRs act as “tuning,” “volume,” or “optimality” “knobs” of phenotype but not with “switch” models. Furthermore, the promoter regions of differentially expressed genes between A. oryzae and A. flavus did not show TR enrichment, suggesting that genome-wide differences in molecular phenotype between the two species are not significantly associated with TRs. Although in some cases TR polymorphisms do contribute to transcript abundance variation, these results argue that at least in this case, TRs might not be major modulators of variation in phenotype.
A Discovery Resource of Rare Copy Number Variations in Individuals with Autism Spectrum Disorder
Authors: Prasad Aparna , Merico Daniele , Thiruvahindrapuram Bhooma , Wei John , Lionel Anath C , Sato Daisuke , Rickaby Jessica , Lu Chao , Szatmari Peter , Roberts Wendy , Fernandez Bridget A , Marshall Christian R , Hatchwell Eli , Eis Peggy S , Scherer Stephen W
Published: December 2012

The identification of rare inherited and de novo copy number variations (CNVs) in human subjects has proven a productive approach to highlight risk genes for autism spectrum disorder (ASD). A variety of microarrays are available to detect CNVs, including single-nucleotide polymorphism (SNP) arrays and comparative genomic hybridization (CGH) arrays. Here, we examine a cohort of 696 unrelated ASD cases using a high-resolution one-million feature CGH microarray, the majority of which were previously genotyped with SNP arrays. Our objective was to discover new CNVs in ASD cases that were not detected by SNP microarray analysis and to delineate novel ASD risk loci via combined analysis of CGH and SNP array data sets on the ASD cohort and CGH data on an additional 1000 control samples. Of the 615 ASD cases analyzed on both SNP and CGH arrays, we found that 13,572 of 21,346 (64%) of the CNVs were exclusively detected by the CGH array. Several of the CGH-specific CNVs are rare in population frequency and impact previously reported ASD genes (e.g., NRXN1, GRM8, DPYD), as well as novel ASD candidate genes (e.g., CIB2, DAPP1, SAE1), and all were inherited except for a de novo CNV in the GPHN gene. A functional enrichment test of gene-sets in ASD cases over controls revealed nucleotide metabolism as a potential novel pathway involved in ASD, which includes several candidate genes for follow-up (e.g., DPYD, UPB1, UPP1, TYMP). Finally, this extensively phenotyped and genotyped ASD clinical cohort serves as an invaluable resource for the next step of genome sequencing for complete genetic variation detection.
Nuclear Gene Variation in Wild Brown Rats
Authors: Ness Rob W , Zhang Yao-Hua , Cong Lin , Wang Yu , Zhang Jian-Xu , Keightley Peter D
Published: December 2012

Although the brown rat (Rattus norvegicus) is widely used as a model mammal throughout biological sciences, little is known about genetic variation in wild rat populations or the relationship of commonly used inbred strains to their wild relatives. We sampled wild brown rats from the species’ presumed ancestral range in NW China and from a derived population in the UK and estimated nucleotide diversity and population subdivision, based on the sequences of 30 autosomal protein-coding loci. Neutral genetic diversity was close to 0.2% in both populations, which is about five times lower than diversity at the orthologous sites in a population of wild house mice from the species’ putative ancestral range in India. We found significant population differentiation between UK and Chinese populations, as assessed by Fst and the program STRUCTURE. Based on synonymous diversity and divergence between the brown rat and house mouse, we estimate that the recent effective population size in brown rats is approximately 130,000 (approximate 95% confidence interval 85,000-184,000), about fivefold lower than wild house mice.
Increasing awareness of Clostridium difficile infection among patients with acute gastroenteritis admitted to a department of infectology
Authors: Fodor Domonka , Ume Kiddy Levente , Matkó Mónika , Nacsa Enikő , Urbán Edit , Hajdú Edit
Published: December 2012

Introduction:Clostridium difficile infection is known as the primary cause of nosocomial gastroenteritis, which accounts for approximately 20–25% of all diarrhea. Infection can lead to a potentially fatal disease and the incidence of that is increasing worldwide. Aim: The aim of the authors was to examine retrospectively the growing importance of Clostridium difficile infections at the Infectology Department of the University of Szeged, Hungary. Methods: Patients with acute gastroenteritis admitted to the Department from 2005 to 2006 and from 2008 to 2011 were studied. Results: In 2005 and 2006, Salmonella infections occurred most frequently, followed by Campylobacter species and toxin-producing Clostridium difficile infections. From 2008 the authors witnessed a continuous increase in the incidence of Clostridium difficile infections. As a result, toxin positive Clostridium difficile became the leading pathogenic agent among patients with acute gastroenteritis by the year of 2009. Besides demonstrating the increasing incidence and severity of Clostridium difficile infection, prognostic factors such as co-morbidities and laboratory parameters of inflammation were also identified. Conclusion: The results confirm the increasing importance of Clostridium difficile infection among patients with acute gastroenteritis. Orv. Hetil., 2012, 153, 1992–1997.
Synthesis and Physical Properties of Skutterudite Superlattices
Authors: Williams Joshua R. , Johnson David C. , Kaeser Michael , Tritt Terry , Nolas George , Nelson E.
Published: December 2012

Predicted and observed reductions in thermal conductivity of materials with superlattice structure have prompted interesting research into the possibility of using these materials as higher efficiency thermoelectrics. Synthesis of superlattice materials is challenging however, as the structure itself is generally not very stable at high temperatures as it is prone to interdiffusion. Presented here is the successful synthesis and characterization of a superlattice composed of two materials with the skutterudite structure, IrSb3 and CoSb3.
Removal of Total Organics and Grease from Oil Production Effluents by an Adsorption Process
Authors: Moore Lucas R. , Cardoso Cynthia , Costa Marcelo , Mahmoudkhani Amir
Published: December 2012

Oilfield produced water accounts for 98% of all waste generated in oil and gas exploration and processing. This process water may contain up to 1000 ppm total oil and grease, which must be treated prior to discharge. A novel inorganic adsorbent was designed to have high affinity towards such organics. Lab scale evaluations of this adsorbent on production effluents obtained from an onshore site consistently yields TOG removal > 96%. This was found to be a significant improvement over the chemically assisted DAF at 74% in similar lab scale evaluations. This novel technology has the potential to provide a substancial reduction in capital and operating costs for water treatment.
Evaluation of the Effects of Molecular Diffusion in Recovery from Fractured Reservoirs during Gas Injection
Authors: Alkhansa Z.. , Ghorbae S. Zare
Published: December 2012

The matrix blocks in fractured reservoirs are the primary storage of hydrocarbons, so matrix-fracture transfer mechanisms are of crucial importance in recovery from fractured reservoirs. During gas injection into fractured reservoirs, fractures are filled with injected gas while matrix blocks contain the reservoir fluid. In this condition due to compositional difference between the gas in fractures and the fluid in matrix, diffusive exchanges of components between matrix and fracture may have significant contribution on matrix oil recovery in addition to gravity drainage or other transfer mechanisms.

In this work, to evaluate the significance of molecular diffusion, the laboratory experiment of "Gas Injection into Fractured cores" is simulated using a compositional model and this model is used to run several experiments which help in understanding the way that each recovery mechanism acts. The advantage of running simulation in core scale is that in this way there is the possibility of using small grid size which significantly reduces the issues of numerical dispersion. And more over the existing experimental data can be used for model adjustment. In the experimental works the procedure is to place a core sample into a core holder in such a way that the annulus space between the core boundary and the core holder is very small. This annulus space is representative of the fracture surrounding the matrix blocks in the reservoir. Then after using special techniques the core is saturated with the representative reservoir oil, and after this primary core initialization, gas is injected into the annulus and the amount of recovered oil is measured versus time.

This study reveals that, molecular diffusion acts like a catalyst and improves the recovery mechanism by enhancing the gas movement within matrix. At the prevalent conditions of this work, the main recovery mechanisms are the miscibility effects (Condensing or Vaporizing gas drives) that are enhanced by molecular diffusion. Sensitivity analysis done in this work reveals that significance and contribution of molecular diffusion in recovery changes with different parameters such as matrix permeability and porosity, gas composition, etc.

Fractured reservoirs contain a significant portion of the world’s reserves, and Gas injection is a common recovery practice in these reservoirs and understanding the recovery mechanisms is of crucial importance for correct simulation of this process. This study shows, although significance of molecular diffusion changes with reservoir parameters, any way neglecting it in simulation studies will result in underestimation of gas injection efficiency.
Lessons Learnt From Root Cause Analysis of Gulf of Mexico Oil Spill 2010
Authors: Garg Tanu , Gokavarapu Swetha
Published: December 2012

Root cause analysis (RCA) is a class of problem solving methods aimed at identifying the root causes of problems/ incidents. By directing corrective measures at core causes, it is hoped that the chances of problem recurrence will be minimized. Thus, RCA is frequently considered to be an iterative process, and is frequently viewed as a tool of continuous improvement. RCA, initially is a reactive method of problem detection & solving. This means that, the analysis is done after an incident has occurred. By gaining proficiency in RCA it becomes a pro-active method. This means that RCA is able to estimate the possibility of an incident even before it could occur. Root cause analysis mainly consists of three steps A): Define the problem. B): Analyze the problem. C): Find the solutions for the problem.

In view of the accident which took place recently i.e. Gulf of Mexico oil spill 2010, there were eight catastrophic failures which led to the explosion that destroyed the Deepwater Horizon drilling rig in the Gulf of Mexico. These failures included the sending of unofficial cement by specialist cementing services, no indications of testing done on the surface by drilling rig provider company before deploying it, pressure test which would have revealed problems in the drill was incorrectly deemed as a success by operator company and drilling rig provider company rig personnel. A complex and interlinked succession of mechanical failures, human judgments, engineering design, operational implementation and team interfaces caused this tragedy. Consequences of these plain errors were quite hazardous. It affected the humanity, environment, economy and also the settlements.

The core objective of the paper is to bring about a detailed analysis so as to throw light on new techniques and how they can be utilised to prevent such disasters. To achieve this objective we acknowledged all the possible solutions for this issue so that the most excellent solutions can be selected and the challenges that are to be faced are studied thoroughly and examined to prevent future errors. However, it is recognized that complete prevention of reappearance by a single intrusion is not always possible. On the belief that problems are best solved by attempting to correct or eliminate root causes, as opposed to merely addressing the immediately obvious symptoms.
Future Oil Prices, Where to? A Systematic Modeling Tool for Decision Makers
Authors: Belhaj Hadi , Aljarwan Abdulla , Al Ali Mona Yousif , Abdulkadir Nader
Published: December 2012

The global economy continues its journey of evolution and progression driven by industrialism as its primary force. With such a fast pace of development and recovery from several recessions over a number of years, dependency on energy sources became inevitable to satisfy the rising demand. This paper represents a proposed global energy price model that has the flexibility of modeling the energy price, using data from specific regions of the world, as well as the global energy pricing equation. The ANM (Alternate Novel Model) is presented here.

The model focuses mainly on oil price modeling, since oil accounts for more than 84% of the current world energy supply. The model duration is 50 years; starting from 1980 to 2030, model matching period from 1980 to 2011, and the prediction period is from 2012to 2030.

The modeling approach used in ANM adopts weighted averaging of individual factors and it relies on line regression technique. Therefore, future trends are being predicted based on the cyclic nature of the market and historical data "the future is reflection of the past". ANM can then preduct the future oil prices, depending on the factors and variables that have been placed in the process for the output results.

The paper aims to propose a reliable model that accounts for most governing factors in the global energy pricing equation. All steps followed and assumptions made will be discussed in detailto clarify the working mechanism for this model and pave the road for any future modifications.
Multilateral TAML Level 4 Junction Provides Maximum Flexibility for Drilling and Intelligent Completions
Authors: Samie Mohamed , Siham Ahmed , Gavin Bruce
Published: December 2012

A multilateral (MLT) well with an advanced intelligent completion string was recently completed in the Middle East. The well was designed as a "stacked" dual producer in the upper and lower reservoir, and was drilled using the latest geo-steering techniques to accurately place the wellbore in a highly faulted and geologically complex structure. Rotary-steerable drilling systems (RSS) were used in several of the hole sections, along with advanced logging-while-drilling (LWD) tools including multi-pole acoustic, azimuthal deep resistivity, and resistivity at bit. Encounters with unstable shale and faults made the drilling difficult, but the decisions made in real-time to navigate the well resulted in a very high percentage of net pay in both laterals.

This well combined TAML Level 4 multilateral (MLT) technology with passive inflow control devices in the laterals and an advanced intelligent completion system in the mainbore. The TAML Level 4 multilateral junction was cemented to isolate unstable shale above the reservoir and to provide zonal isolation from the lateral completions, which were compartmentalized into stages with proprietary swellable packers and inflow control devices (ICDs). The intelligent completion was run in the mainbore with two interval control valves (ICVs) and isolation ball valve (LV ICV) to manage the production from each of the two laterals independently. The ICVs and LV ICV are controlled hydraulically through four control lines to surface, which were run in a flat-pack with one electric line to control a downhole gauge package for each lateral. Finally, the well was configured to allow the installation of a large electric submersible pump (ESP) to be run inside the upper 9-5/8-in. production tubing.

This project required intensive planning and coordination for more than a year in advance, which made the project successful despite the difficult drilling conditions and resulted in very little NPT for wellbore construction operations. This paper will focus on the planning, execution and lessons learned from the project.
Using the Laser Irradiation to Improve the Rate of Production of Iran South West Formation
Authors: Bazargan M.. , Habibpour M.. , Jalalyfar H.. , Geranmayehrad A..
Published: December 2012

whole level of the erosion and the resistance of rocks which were composed closured have been studied, besides, the impact of temperature and laser irradiation for more investigation about this issue has been involved before all. This subject more reveals the matter which laser absorption on the laboratory scale using laser to what extent can cause the augment of the relative permeability and secondary porosity of reservoir rock, that of the vertical and horizontal useful connectivity and eventually that of the positive transferability.

This research has been carried out in the form of case study on one of Iranian south west formations in north east of Behbahan city in Iran, either the rate or generation of forming the subtle and large fractures has been studied by considering and preparing this section from rocks of stratified sequence of the laboratory area before and after the laser irradiation operation and various analyzer by the means of Spectrophotometer and advanced electron microscope. It should be noted that during the erosion and ablation in the laser drilling operation in the experimental rocks of considered field, given the capability of the field, the formation and field lithology we observed the creation of fractures at the level of micro and nano simultaneously whose vacant spaces were positive, and reservoir and some others were neutral, this fractures can be created by the rate of crude oil absorption. The main purpose of this study is to advance the operations towards the higher technology in order to the better efficiency in the field of the well completion to be gained improving the rate of oil production by the introduction of this modern method of improving and fracturing reservoir which uses certain specialized parameters and indicators, and, finally, the certain method that might be a better way to use laser irradiation on our chosen formation of Iran.
Application of Sustainable Foaming Agents to Control the Mobility of Carbon Dioxide in Enhanced Oil Recovery
Authors: Rafati Roozbeh , Hamidi Hossein , Idris Ahmad Kamal
Published: December 2012

Carbon dioxide (CO2) flooding is a conventional process in which the CO2 is injected into the oil reservoir to increase the quantity of extracting oil. This process also controls the amount of released CO2 as a greenhouse gas in the atmosphere which is known as CO2 sequestration process. However, the mobility of the CO2 inside the hydrocarbon reservoir is higher than the crude oil and always viscous fingering and gravity override problems occur during a CO2 injection. The most common method to overcome these problems is to trap the gas bubbles in the liquid phase in form of aqueous foam prior to CO2 injection. Although, the aqueous foams are not thermodynamically stable, the special care should be considered to ensure about bulk foam preparation and stability. Selection of a proper foaming agent from a large number of available surfactants is the main step in the bulk foam preparation. To meet this purpose, many chemical and crude oil based surfactants have been reported but most of them are not sustainable and have disposal problems. The objective of this experimental study is to employ Lingosulfonate and Alkyl Polyglucosides (APGs) as two sustainable foaming agents for the bulk foam stability investigations and foam flooding performance in porous media. In the initial part, the bulk foam stability results showed that APGs provided more stable foams in compare with Lingosulfonate in all surfactant concentrations. In the second part, the results indicated that the bulk foam stability measurements provide a good indication of foam mobility in porous media. The foaming agent’s concentration which provided the maximum foam stability also gave the highest value of mobility reduction in porous media.
Permeable Tar Mat Formation Within the Context of Novel Asphaltene Science
Authors: Dumont Hadrien , Mishra Vinay , Zuo Julian Y. , Mullins Oliver C.
Published: December 2012

Tar mats at the oil-water contact (OWC tar mats) in oilfield reservoirs can have enormous, pernicious effects on production due to possibly preventing of any natural water drive and precluding any effectiveness of water injectors into aquifers. In spite of this potentially huge impact, tar mat formation is only now being resolved and integrated within advanced asphaltene science. Herein, we describe a very different type of tar mat which we refer to as a "rapid-destabilization tar mat"; it is the asphaltenes that undergo rapid destabilization. To our knowledge, this is the first paper to describe such rapid-destabilization tar mats at least in this context. Rapid-destabilization tar mats can be formed at the crest of the reservoir, generally not at the OWC and can introduce their own set of problems in production. Most importantly, rapid-destabilization tar mats can be porous and permeable, unlike the OWC tar mats. The rapid-destabilization tar mat can undergo plastic flow under standard production conditions rather unlike the OWC tar mat. As its name implies, the rapid-destabilization tar mat can form in very young reservoirs in which thermodynamic disequilibrium in the oil column prevails, while the OWC tar mats generally take longer (geologic) time to form and are often associated with thermodynamically equilibrated oil columns. Here, we describe extensive data sets on rapid-destabilization tar mats in two adjacent reservoirs. The surprising properties of these rapid-destabilization tar mats are redundantly confirmed in many different ways. All components of the processes forming rapid-destabilization tar mats are shown to be consistent with powerful new developments in asphaltene science, specifically with the development of the first equation of state for asphaltene gradients, the Flory-Huggins-Zuo Equation, which has been enabled by the resolution of asphaltene nanostructures in crude oil codified in the Yen-Mullins Model. Rapid-destabilization tar mats represent one extreme while the OWC tar mats represent the polar opposite extreme. In the future, occurrences of tar in reservoirs can be better understood within the context of these two end members tar mats. In addition, two reservoirs in the same minibasin show the same behavior. This important observation allows fluid analysis in wells in one reservoir to indicate likely issues in other reservoirs in the same basin.
Using Real Time Automated Optimisation & Diagnosis to Manage an Artificially Lifted Reservoir - A Case Study
Authors: Cudmore Julian
Published: December 2012

The time taken to safely optimise a reservoir produced by artificial lift can be measured in weeks or months.

Typically the well by well process is as follows: Well testingAmalgamation of the well test data with down hole gauge and ESP controller dataAnalysis of the data to find the existing operation conditionsAnalysis of the ESP pump curve operating point and optimisation limitationsSensitivity studies in software to assess the optimum frequency and WHPNotification for the field operations to action the changesFurther well tests to verify the new production data.Analysis of the data to ensure the ESP and well are running optimally and safely at the new set points

New technology enables this process to be performed in real time across the entire reservoir or field, significantly shortening the time to increased production and enabling real time reservoir management.

Each artificially lifted well in the reservoir was equipped with an intelligent data processing device programmed with a real time model of the well. The processors were linked to a central access point where the operation of field could be remotely viewed in real time.

Each well’s processor was provided with a target bottom hole flowing pressure to enable the optimum production of the reservoir. The real time system automatically compared the desired target drawdown values with the capability of the pumping system installed in each well, and automatically suggested the optimum operating frequency and well head pressure to achieve the target. Where the lift system was not capable of producing to the target bottom hole pressure, a larger pump was automatically recommended. As production conditions change the system adapted its recommended operating points to compensate and maintain target production.

This paper discusses three case studies where real time optimisation and diagnosis lead to improved production from the reservoir.
EOR vs. Infill Well Drilling: Field Application of New Decision Making Technique
Authors: Alusta Gamal , Mackay Eric , Fennema Julian , Armih Khari , Collins Ian
Published: December 2012

This study has focused on the development of a method to test the economic viability of Enhanced Oil Recovery (EOR) versus infill well drilling where the challenge is to compare polymer flooding scenarios with infill well drilling scenarios, not just based on incremental recovery, but on Net Present Value as well.

In a previous publication (Alusta et al., 2011, SPE143300) the method was developed to address polymer flooding, but it can be modified to suit any other EOR methods. The method has been applied to a synthetic scenario with constant economic parameters, which has demonstrated the impact that oil price can have on the decision making process.

The method was then applied and tested (Alusta et al., 2012, SPE150454) with varied operational and economic parameters to investigate the impact in delaying the start of polymer flooding to identify whether it is better to start polymer flooding earlier or later in the life of the project. Consideration was also given to the optimum polymer concentration, and the impact that factors such as oil price and polymer cost have on this decision. Due to the large number of combined reservoir engineering and economic scenarios, Monte Carlo Simulation and advanced analysis of large data sets and the resulting probability distributions had to be developed.

In this paper the methodology is applied to an offshore field where the choice has already been made to drill infill wells, but where we test the robustness of the method against a conventional decision making process for which there is historical data. We do this by performing calculations that compare the infill well scenario chosen with a range of polymer flooding scenarios that could have been selected instead, to identify whether or not the choice to drill infill wells was indeed the optimum choice from an economic perspective.

We conclude from all the reservoir simulations and subsequent economic calculations that the decision to drill infill wells was indeed the optimum choice from an economic perspective.
Intelligent Real-time Drilling Operations Classification Using Trend Analysis of Drilling Rig Sensors Data
Authors: Arnaout A.. , Fruhwirth R.. , Esmael B.. , Thonhauser G..
Published: December 2012

Detection of oilwell drilling operations is an important step for drilling process optimization. If drilling operations are classified accurately, detailed performance reports not only on drilling crews but also on drilling rigs can be produced. Using such reports, the management can evaluate the drilling work more precisely from performance point of view.

Mud-logging systems of modern drilling rigs provide numerous sensors data. Those sensors measurements are considered as indicators to monitor different states of drilling process. Usually real-time measurements of the following sensors data are available as surface measurements: hookload, block position, flow rates, pump pressure, borehole and bit depth, RPM, torque, rate of penetration and weight on bit.

In this work, collected sensors measurements from mud-logging systems are used to detect different drilling operations. Detailed data analysis shows that the surface sensors measurements can be considered as a main source of information about drilling operations. For this purpose, a mathematical model based on polynomials approximation is constructed to interpolate sensors data measurements.

Discrete polynomial moments are used as a tool to extract specific features (moments) from drilling sensors data. Then we use these moments for each drilling operation as pattern descriptor to classify similar operations in drilling time series. The extracted polynomial moments describe trends of sensors data and behavior of rig’s sub-systems (Rotation System, Circulation System, and Hoisting System). Furthermore, this paper suggests a method on how to build patterns base and how to recognize and classify drilling operations once sensors data received from mud-logging system. Drilling experts compare the results to manually classified operations and the results show high accuracy.
Facies Based Approach to Amin Reservoir Characterization In A Heavy Oil Field In The South Of Oman
Authors: Lukmanov Rinat
Published: December 2012

The field X is a brown heavy oil field producing under strong bottom water drive since the mid-1980. Production is from a combination of Amin aeolian and Al Khlata glacial reservoir sediments. At present, the development is focused on drilling horizontal infill wells. One of the biggest challenges is the unfavorable mobility contrast between the heavy oil and water causing early water breakthrough.

The Amin Formation, the primary reservoir, is characterized by a high net to gross ratio and an average porosity of 30 %. However the initial hydrocarbon saturation at the same porosity often varies by 20 % in different parts of the field. Furthermore, core measurements show an order of magnitude scatter in permeability at the same porosity, indicating the presence of different facies. In early studies these variations were attributed mainly to the grain size variations. A later petrographical study found that the abundance of clays and feldspars could also severely reduce permeability, but may retain high porosity.

In the current Study it was found that the rocks have variable radioactivity due to the presence of radioactive Potassium isotope associated with feldspars. A fare correlation was observed between the grain size and the content of feldspars from core. A novel approach to reservoir characterization integrating core and logs was developed leading to a major breakthrough in the reservoir characterization including: Enhanced permeability prediction using normalized Gamma Ray (GR) log as 3rd parameter;Facies identification using normalized Gamma Ray cut-off;Facies based Saturation-Height models.

This work is a good example of advances in reservoir characterization achieved by integrating core and log data. It results in better understanding of reservoir properties distribution, optimization of completions of new wells and improvement of further development scenarios. In particular, abnormally high gross production and high water cut in the north of the field is currently in line with new facies scheme.
Intelligent Completion Technology Enables Selective Injection for Pressure Maintenance in Mature Field in South China
Authors: Wee Keith Heng , Finley Douglas B.
Published: December 2012

Pressure maintenance support in mature fields where permeability heterogeneity is present requires proper distribution of injected water into the respective zones of interest. This process can be extremely challenging, if no method for allocating the proper amount of water into each zone is available. An operator in the South China Sea, who had initiated a water injection project using legacy single-string two-zone completion technologies, found himself in this predicament, since no selective control for pressure maintenance had been considered for the project.

During the past few years, the application of intelligent completion (IC) technology has increased rapidly. This acceptance has been due primarily to its proven capabilities for reservoir monitoring and corresponding optimization of well performance without well interventions. Historically, the majority of IC applications have been in production wells; however, an increasing number of operators have started adopting IC technology for their injector wells.

This paper presents a case study in which IC technology was successfully applied in an offshore field in the South China Sea to provide an efficient water-injection method for optimizing pressure support as well as sweep. The operator selected this technology, as it presented a solution for optimizing the water injection. In addition to eliminating problems experienced with the incapability of the legacy completion technology to monitor water allocation and pressure maintenance for each zone, the IC technology would allow selective well testing for each zone. By evaluating the reservoir properties and characteristics of each zone independently, an intelligent completion would provide another key benefit to the operator, since it would comply with the platform size restrictions for the pumping equipment.

The paper will discuss field objectives, the conceptual design, the design obstacles, and the operational challenges experienced during the job execution.
Increasing Oil Recovery with CO2 Miscible Injection: Thani Reservoir, Abu-Dhabi Giant Off-Shore Oil Field Case Study
Authors: Aljarwan Abdulla , Belhaj Hadi , Haroun Mohamed , Ghedan Shawket G.
Published: December 2012

This paper aims to study the miscibility features of CO2 miscible injection to enhanced oil recovery from Thani-III reservoir. A Comprehensive simulation model was used to determine multi contact miscibility and suitable equation of state with CO2 as a separate pseudo component using one of the industry’s standard simulation software. Experimental PVT data for bottom hole and separator samples including compositional analysis, differential liberation test, separator tests, constant composition expansion, viscosity measurements and swelling tests for pure CO2 were used to generate and validate the model. In addition to that, simulation studies were conducted to produce coreflooding and slimtube experimental models, which were compared with the conclusions drawn from experimental results. Results of this study have shown comparable results with the lab experimental data in regards to minimum miscibility pressure (MMP) calculation and recovery factor estimation, where the marginal errors between both data sets were no more than 7% at its worst. Results from this study are expected to assist the operator of this field to plan and implement a very attractive enhanced oil recovery program, giving that other factors are well accounted for such as asphaltene deposition, reservoir pressure maintenance, oil saturation, CO2 sequestering and choosing the most appropriate time to maximize the net positive value (NPV) and expected project gain.
An Iterative Solution to Compute Critical Velocity and Rate Required to Unload Condensate-Rich Saudi Arabian Gas Fields and Maintain Field Potential and Optimal Production
Authors: Al-Jamaan Hamza , Zillur Rahim , Bandar Al-Malki , Adnan Al-Kanan
Published: December 2012

Saudi Arabian non associate gas reservoirs produce various amounts of condensate depending upon field and reservoir. In most cases, these wells are hydraulically fractured and at the initial stage after such stimulation treatment, each well needs to unload high quantity of the pumped fluid to ensure full potential. If the liquid starts accumulating in the wellbore during production, the well productivity will gradually decrease and eventually may stop producing. If the gas flow velocity in the production string is high enough, the gas will continue flowing and will carry the liquid droplets up the wellbore to the surface. The minimum velocity and critical gas rate (Qcrit) are therefore the determining factors while producing a well or several wells from a condensate-rich field so as to ensure the stable field production rate and maintain production plateau.

An analytical model has been developed to iteratively compute the critical velocity (Vcrit) and Qcrit, for given flowing wellhead pressure (FWHP), tubing diameter, and many other reservoir and completion properties. If the FWHP is set and a certain production rate is expected of a well, the program automatically computes the pressure drop due to friction, dynamic hydrostatic head, and the bottomhole pressure. Simultaneously, both Vcrit and Qcrit to unload the fluids are calculated. If the Qcrit is above the expected production rate, a different wellbore completion is automatically selected and computation is continued until Qcrit is lower than the expected rate of the well. If this is not possible, the program will display appropriate message.

Several wells from a condensate gas reservoir are analyzed from a field that has to maintain certain production potential for a given number of years. The analyses show that the wells that are producing without intervention are those that are confirmed by this model to be flowing above the Qcrit. For wells that were intermittently producing and ultimately could not sustain production were producing at rates below the critical values. Using this iterative model, those rates are automatically adjusted or new completion string is suggested to bring them back into production.
Estimating Flow Rates Based on ESP Down Hole Sensor Data
Authors: Caicedo Sergio , Montoya Cesar
Published: December 2012

At Kuwait Oil Company (KOC) most of the ESP wells are running with downhole sensors to enhance the daily monitoring routine and for having a better knowledge of the pumps performances. However, one of the most important parameter of these ESP Wells is only known after a time period within 3-6 months: The Flow Rate. Production Tests are obtained using Multiphase Flow Testing Units which usually last between 4 and 6 hours that are also utilized to conduct some sensitivities such as choke size and motor speed changes. At Well Surveillance Group, a tailored fit model was developed from which the ESP flow rate can be estimated based on the downhole sensor data and basic fluid properties with an overall deviation below 2% (when they are compared to the results obtained from the Testing Unit). In this sense, flow rate monitoring can be performed at any time and flow testing time and associated cost can be reduced among other benefits. The method requires knowing the ESP model and total number of stages installed in the well, and then using the corresponding performance curve of the ESP model usually provided by the manufacturer, the data is processed and the calculation performed. This work aims to show how this model works, advantages, limitations, implementation status and future improvements.
A New Correlation to Calculate Oil-Water Interfacial Tension
Authors: Ling Kegang , He Jun
Published: December 2012

The oil-water interfacial tension (IFT) is by all means important in capillary pressure estimation and fluid-fluid and fluid-rock interactions analysis. Observations from experimental data indicate that oil-water IFT is a function of pressure, temperature, and compositions of oil and water. A reliable correlation to estimate oil-water IFT is highly desire. Unfortunately to our best knowledge no correlation that uses the compositions of oil and water as inputs is available. Our work is to fill this gap.

In this research, we collected data from former studies and investigations and developed a correlation for oil-water IFT. In the proposed correlation oil-water IFT is a function of system pressure, temperature, and compositions of oil and water. Error analysis was conducted to check the accuracy of the equation by comparing the calculated values with the experimental data. The results indicated that the new correlation predicts reliable oil-water IFTs. Our correlation calculates the oil-water IFT from system pressure, temperature, and compositions of oil and water. It addresses the effect of composition of oil on IFT, which is not presented in existing correlations. Therefore it can not only be applied in the calculation of capillary pressure in the compositional simulation, but also be used in daily petroleum engineering calculation such as waterflooding analysis.