bluuebunny/crossref_metadata_2025 huggingface dataset:
Maintenance of transposon-free regions throughout vertebrate evolution
Authors: Simons Cas , Makunin Igor V , Pheasant Michael , Mattick John S
Published: December 2007

Background

We recently reported the existence of large numbers of regions up to 80 kb long that lack transposon insertions in the human, mouse and opossum genomes. These regions are significantly associated with loci involved in developmental and transcriptional regulation.

Results

Here we report that transposon-free regions (TFRs) are prominent genomic features of amphibian and fish lineages, and that many have been maintained throughout vertebrate evolution, although most transposon-derived sequences have entered these lineages after their divergence. The zebrafish genome contains 470 TFRs over 10 kb and a further 3,951 TFRs over 5 kb, which is comparable to the number identified in mammals. Two thirds of zebrafish TFRs over 10 kb are orthologous to TFRs in at least one mammal, and many have orthologous TFRs in all three mammalian genomes as well as in the genome of Xenopus tropicalis. This indicates that the mechanism responsible for the maintenance of TFRs has been active at these loci for over 450 million years. However, the majority of TFR bases cannot be aligned between distantly related species, demonstrating that TFRs are not the by-product of strong primary sequence conservation. Syntenically conserved TFRs are also more enriched for regulatory genes compared to lineage-specific TFRs.

Conclusion

We suggest that TFRs contain extended regulatory sequences that contribute to the precise expression of genes central to early vertebrate development, and can be used as predictors of important regulatory regions.
Association between the -455T>C promoter polymorphism of the APOC3gene and the metabolic syndrome in a multi-ethnic sample
Authors: Pollex Rebecca L , Ban Matthew R , Young T Kue , Bjerregaard Peter , Anand Sonia S , Yusuf Salim , Zinman Bernard , Harris Stewart B , Hanley Anthony JG , Connelly Philip W , Huff Murray W , Hegele Robert A
Published: December 2007

Background

Common polymorphisms in the promoter of the APOC3 gene have been associated with hypertriglyceridemia and may impact on phenotypic expression of the metabolic syndrome (MetS). The rs7566605 marker, located near the INSIG2 gene, has been found to be associated with obesity, making it also a potential genetic determinant for MetS. The objective of this study is to examine the APOC3 -455T>C and the INSIG2 rs7566605 polymorphisms as potential genetic determinants for MetS in a multi-ethnic sample.

Methods

Subjects were genotyped for both the APOC3 -455T>C and INSIG2 rs7566605 polymorphisms, and classified for the presence or absence of MetS (NCEP ATP III and IDF definitions). The total study population included 2675 subjects (≥18 years of age) from six different geographical ancestries.

Results

For the overall study population, the prevalence of MetS was 22.6% (NCEP ATP III definition). Carriers of ≥1 copy of APOC3 -455C were more likely to have MetS (NCEP ATP III definition) than noncarriers (carrier odds ratio 1.73, 95% CI 1.40 to 2.14, adjusting for age and study group). The basis of the association was related not only to a higher proportion of -455C carriers meeting the triglyceride and high-density lipoprotein cholesterol criteria, but also the blood pressure criteria compared with wild-type homozygotes. Plasma apo C-III concentrations were not associated with APOC3 -455T>C genotype. The INSIG2 rs7566605 polymorphism was not associated with MetS or measures of obesity.

Conclusion

Meta-analysis of the sample of multiple geographic ancestries indicated that the functional -455T>C promoter polymorphism in APOC3 was associated with an approximately 2-fold increased risk of MetS, whereas the INSIG2 rs7566605 polymorphism was not associated with MetS.
Ginger inhibits cell growth and modulates angiogenic factors in ovarian cancer cells
Authors: Rhode Jennifer , Fogoros Sarah , Zick Suzanna , Wahl Heather , Griffith Kent A , Huang Jennifer , Liu J Rebecca
Published: December 2007

Background

Ginger (Zingiber officinaleRosc) is a natural dietary component with antioxidant and anticarcinogenic properties. The ginger component [6]-gingerol has been shown to exert anti-inflammatory effects through mediation of NF-κB. NF-κB can be constitutively activated in epithelial ovarian cancer cells and may contribute towards increased transcription and translation of angiogenic factors. In the present study, we investigated the effect of ginger on tumor cell growth and modulation of angiogenic factors in ovarian cancer cellsin vitro.

Methods

The effect of ginger and the major ginger components on cell growth was determined in a panel of epithelial ovarian cancer cell lines. Activation of NF-κB and and production of VEGF and IL-8 was determined in the presence or absence of ginger.

Results

Ginger treatment of cultured ovarian cancer cells induced profound growth inhibition in all cell lines tested. We found thatin vitro, 6-shogaol is the most active of the individual ginger components tested. Ginger treatment resulted in inhibition of NF-kB activation as well as diminished secretion of VEGF and IL-8.

Conclusion

Ginger inhibits growth and modulates secretion of angiogenic factors in ovarian cancer cells. The use of dietary agents such as ginger may have potential in the treatment and prevention of ovarian cancer.
Strand-specific 5′-O-methylation of siRNA duplexes controls guide strand selection and targeting specificity
Authors: Chen Po Yu , Weinmann Lasse , Gaidatzis Dimos , Pei Yi , Zavolan Mihaela , Tuschl Thomas , Meister Gunter
Published: December 2007

Small interfering RNAs (siRNAs) and microRNAs (miRNAs) guide catalytic sequence-specific cleavage of fully or nearly fully complementary target mRNAs or control translation and/or stability of many mRNAs that share 6–8 nucleotides (nt) of complementarity to the siRNA and miRNA 5′ end. siRNA- and miRNA-containing ribonucleoprotein silencing complexes are assembled from double-stranded 21- to 23-nt RNase III processing intermediates that carry 5′ phosphates and 2-nt overhangs with free 3′ hydroxyl groups. Despite the structural symmetry of a duplex siRNA, the nucleotide sequence asymmetry can generate a bias for preferred loading of one of the two duplex-forming strands into the RNA-induced silencing complex (RISC). Here we show that the 5′-phosphorylation status of the siRNA strands also acts as an important determinant for strand selection. 5′-O-methylated siRNA duplexes refractory to 5′ phosphorylation were examined for their biases in siRNA strand selection. Asymmetric, single methylation of siRNA duplexes reduced the occupancy of the silencing complex by the methylated strand with concomitant elimination of its off-targeting signature and enhanced off-targeting signature of the phosphorylated strand. Methylation of both siRNA strands reduced but did not completely abolish RNA silencing, without affecting strand selection relative to that of the unmodified siRNA. We conclude that asymmetric 5′ modification of siRNA duplexes can be useful for controlling targeting specificity.
Research Note—On Managerially Efficient Experimental Designs
Authors: Toubia Olivier , Hauser John R.
Published: December 2007

In most marketing experiments, managerial decisions are not based directly on the estimates of the parameters but rather on functions of these estimates. For example, many managerial decisions are driven by whether or not a feature is valued more than the price the consumer will be asked to pay. In other cases, some managerial decisions are weighed more heavily than others. The standard measures used to evaluate experimental designs (e.g., A-efficiency or D-efficiency) do not accommodate these phenomena. We propose alternative “managerial efficiency” criteria (M-errors) that are relatively easy to implement. We explore their properties, suggest practical algorithms to decrease errors, and provide illustrative examples. Realistic examples suggest improvements of as much as 30% in managerial efficiency. We close by considering approximations for nonlinear criteria and extensions to choice-based experiments.
Zero as a Special Price: The True Value of Free Products
Authors: Shampanier Kristina , Mazar Nina , Ariely Dan
Published: December 2007

When faced with a choice of selecting one of several available products (or possibly buying nothing), according to standard theoretical perspectives, people will choose the option with the highest cost–benefit difference. However, we propose that decisions about free (zero price) products differ, in that people do not simply subtract costs from benefits but instead they perceive the benefits associated with free products as higher.

We test this proposal by contrasting demand for two products across conditions that maintain the price difference between the goods, but vary the prices such that the cheaper good in the set is priced at either a low positive or zero price. In contrast with a standard cost–benefit perspective, in the zero-price condition, dramatically more participants choose the cheaper option, whereas dramatically fewer participants choose the more expensive option. Thus, people appear to act as if zero pricing of a good not only decreases its cost, but also adds to its benefits. After documenting this basic effect, we propose and test several psychological antecedents of the effect, including social norms, mapping difficulty, and affect. Affect emerges as the most likely account for the effect.
Research Note—Optimal Selling in Dynamic Auctions: Adaptation Versus Commitment
Authors: Zeithammer Robert
Published: December 2007

This paper analyzes optimal selling strategies of a monopolist facing forward-looking patient unit-demand bidders in a sequential auction market. Such a seller faces a fundamental choice between two selling regimes: adaptive selling that involves learning about remaining demand from early prices, and commitment selling that forgoes such learning and makes all selling decisions in the beginning of the game. A model of the game between the seller and the bidders is proposed to characterize the optimal regime choice. The model implies that the relative profitability of the two regimes depends on the expected gains from trade: when the expected gains from trade are low, commitment dominates adaptation, and vice versa.
Smoking Cessation: A Model of Planned vs. Actual Behavior for Time-Inconsistent Consumers
Authors: Machado Fernando S. , Sinha Rajiv K.
Published: December 2007

We offer a simple model of intertemporal choice to characterize how planned versus actual behaviors evolve for time-inconsistent smokers. Our results suggest that smokers' participation and cessation decisions are governed by the interplay between three effects. The cessation effect leads smokers to advance their plans to quit smoking, whereas the procrastination effect leads them to consecutively revise their planned quitting age upwards. Consequently, the duration of smoking is effectively governed by which one of these two effects is dominant. Finally, for certain consumer segments, a threshold effect causes an “all or nothing” type of extreme smoking behavior based on certain critical values of present-biased preferences. Our results provide some preliminary evidence that both marketing efforts by tobacco firms and public policy initiatives can have a significant influence on smoking behavior. In particular, we find that reductions in the age at which individuals start smoking may not only vastly extend their duration of smoking, but also convert potential “never smokers” into lifetime smokers. Finally, we estimate a hazard model using survey data from over 800 smokers to provide evidence in support of our theoretical model.
Optimal Strategies for Sports Betting Pools
Authors: Clair Bryan , Letscher David
Published: December 2007

Every fall, millions of Americans enter betting pools to pick winners of the weekly NFL football games. In the spring, NCAA tournament basketball pools are even more popular. In both cases, teams that are popularly perceived as “favorites” gain a disproportionate share of entries. In large pools there can be a significant advantage to picking upsets that differentiate your picks from the crowd.

In this paper, we present a model of betting pools that incorporates pool participant behavior. We use the model to derive strategies that maximize the expected return on a bet in both football pools and tournament-style pools. These strategies significantly outperform strategies based on maximizing score or number of correct picks—often by orders of magnitude.
Timing of Blood Pressure Measurement Related to Caffeine Consumption
Authors: Mort Jane R , Kruse Heather R
Published: December 2007

Objective:

To determine whether patients should wait 30 minutes after caffeine consumption to have their blood pressure measured.

Data Sources:

Literature was obtained by searching MEDLINE (1980–September 2007), International Pharmaceutical Abstracts (1980–September 2007), and the Cochrane Database of Systematic Reviews (1994–September 2007). Search terms included caffeine and blood pressure. Literature was also obtained from citations in relevant articles.

Study Selection and Data Extraction:

Articles that examined caffeine's acute effect on blood pressure were reviewed, with additional focus on caffeine tolerance and hypertensive status.

Data Synthesis:

Caffeine appears to affect blood pressure through adenosine receptor inhibition and an increased release of select neurotransmitters. Caffeine levels peak 30–120 minutes after oral intake and caffeine's half-life is 3–6 hours. The effect of caffeine on blood pressure has been examined for decades, with variable results depending on factors such as population examined (eg, hypertensive status, physical stressors, age) and study design (eg, acute effects, chronic ingestion, retrospective epidemiologic review). Caffeine tolerance diminishes the acute effect of caffeine on blood pressure, and hypertensive individuals are more susceptible to blood pressure changes. Reviews of caffeine's acute effect on blood pressure indicate changes of 3–15 mm Hg systolic and 4–13 mm Hg diastolic. Typically, blood pressure changes occur within 30 minutes, peak in 1–2 hours, and may persist for more than 4 hours.

Conclusions:

Having a patient abstain from caffeine for 30 minutes prior to blood pressure monitoring is not adequate to avoid caffeine's potential effects. An alternative approach to blood pressure monitoring would be to ask the patient about recent caffeine consumption and interpret the blood pressure reading based on this information. In addition, healthcare practitioners should provide education regarding caffeine's effects.
Use of Renin—Angiotensin—Aldosterone System Inhibitors Within the First Eight to Twelve Weeks After Renal Transplantation
Authors: Jennings Douglas L , Taber David J
Published: December 2007

Objective:

To evaluate the safety and efficacy of early initiation of inhibitors of the renin–angiotensin–aldosterone system (RAAS) in renal transplant patients.

Data Sources:

A literature search was conducted using MEDLINE (1950–September 2007), PubMed (1966–September 2007), and International Pharmaceutical Abstracts (1970–September 2007) with combinations of the following terms: angiotensin-converting enzyme (ACE) inhibitors, angiotensin II type 1 receptor blockers (ARBs), and kidney transplant Articles obtained from this search were cross-referenced and bibliographies were checked for all relevant information.

Study Selection and Data Extraction:

All articles that examined the early (within 12 wk) initiation of either an ACE inhibitor or an ARB in renal transplant patients were included.

Data Synthesis:

A search of the literature revealed 7 studies that had examined the safety or efficacy of early use of ACE Inhibitors and ARBs in posttransplant patients. One study examined only plasma levels of a common marker for tissue fibrosis and one included only patients who had early graft dysfunction. Of the other 5 studies, 3 primarily reported safety endpoints and 2 reported clinical efficacy endpoints. Safety data in patients with functioning grafts (serum creatinine ranged from <2.5 to 3.0 mg/dL) show that early therapy with inhibitors of the RAAS did not result in appreciable increases in serum creatinine or potassium levels after up to 9 months of therapy. Results from the efficacy trials indicate that early initiation of an ACE inhibitor may be more effective than a β-blocker in reducing left ventricular hypertrophy and proteinuria after 24 months of treatment.

Conclusions:

It appears that the early initiation of RAAS inhibitors is safe in posttransplant patients with functioning grafts. It is reasonable to consider these agents as first-line pharmacotherapy in patients with hypertension and compelling indications (ie, diabetes or heart failure) in the first 12 weeks following transplant. Data are insufficient to recommend these drugs in patients with early graft dysfunction.
A new subfamily of bacterial glutamate/aspartate receptors
Authors: Singh Birendra , Röhm Klaus-Heinrich
Published: December 2007

The specificity of bacterial nutrient importers of the ATP-binding cassette (ABC) type depends on external receptor proteins that not only bind the solute to be transported, but also initiate the transport process by inducing ATP hydrolysis in the cytoplasmic nucleotide-binding domains. Here we propose a mode of ligand binding to the solute-binding protein AatJ that is required for glutamate uptake by the AatJMQP transporter in Pseudomonas putida KT2440. A homology model of the AatJ-glutamate complex was constructed using the E. coli glutamine-binding protein GlnH as the template. The general validity of the model was then confirmed by alanine scanning mutagenesis of several residues predicted to interact with the ligand and by semi-quantitative binding studies with [14C]-Glu and [14C]-Asp. A database search indicated that AatJ is a member of a distinct subfamily of the family 3 solute-binding proteins with specificity towards glutamate and aspartate.
At the Nexus: Augmented Cognition, Health Care, and the Law
Authors: Glenn Linda MacDonald , Boyce Jean Ann S.
Published: December 2007

Augmented cognition, like so many new technologies, has its promises and its perils. Whereas recent literature in ethics focuses on the military origins and applications of augmented cognition and harnessing the power of a symbiotic brain-nervous system-computer system for warfare, this article analyzes this technology for applications in health care settings and research. Additionally, a delineation of how law and policy makers might respond to issues in shared culpability and responsibility is proposed.
Fracture Toughness of Hydrided Zircaloy-4 Sheet Under Through-Thickness Crack Growth Conditions
Authors: Raynaud P. A. , Koss D. A. , Motta A. T. , Chan K. S.
Published: December 2007

The susceptibility of fuel cladding to failure in the case of a postulated reactivity-initiated accident may be determined by crack initiation within a hydride blister or rim and subsequent crack growth through the thickness of the cladding. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at both 25 and 300°C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined precrack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (Kq) is sensitive to the orientation of the hydride platelets and Kq≅25 MPa√m for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, Kq is much higher (≅75 MPa√m) when the hydride platelets are oriented predominantly in the plane of the sheet and therefore normal to both the crack plane and the crack growth direction. At 300°C, the material exhibits greater ductility as the hydride particles within the matrix resist fracture such that Kq≅83 MPa√m, despite the much lower flow stress of the material.
The role of imaging methods in the pre-, intra- and postoperative evaluation protocol of living donors in liver transplantation in Hungary
Authors: Hartmann Erika , Németh Andrea , Doros Attila , Balázs György , Járay Jenő
Published: December 2007

Az élő donoros májtranszplantáció donorjelöltjeinek komplex kivizsgálási protokollja transzplantációs centrumonként némileg eltérő lehet, de a fő komponensek világszerte megegyeznek. A protokollok anamnézisfelvételt, fizikális vizsgálatot, általános laboratóriumi teszteket, valamint specifikus alvadási, vírusszerológiai, radiológiai vizsgálatokat és pszichoszociális felmérést is tartalmaznak. A donorjelölteket képalkotó vizsgálatok szempontjából először a belszervi állapotra vonatkozó általános kivizsgálásnak vetjük alá, elsősorban hagyományos röntgen- és ultrahangvizsgálatokkal. Ezután (az előbbitől nem élesen elválaszthatóan) a májspecifikus képalkotás következik, döntően UH, CT és MR segítségével, egyrészt a májparenchyma állapotának megítélésére, másrészt a térfogat meghatározására, harmadrészt pedig az érképletek és az epeutak pontos anatómiájának ábrázolására. Invazív beavatkozásokra is szükség lehet, pl. angiográfiára, májbiopsziára. A donorműtét kezdetén rutinszerűen intraoperatív vizsgálatok is történnek: cholangiographia az eperendszer anatómiájának közvetlen feltérképezésére és ultrahangvizsgálat a vena hepatica-ágak és a vena portae-rendszer lefutásának pontosítására a reszekció vonalának meghatározásához. A donorok vizsgálatai a korai posztoperatív szakban az esetleges szövődmények felderítéséhez járulnak hozzá: speciálisan a megmaradó májállomány keringésének ellenőrzésére és a műtéti területen folyadékgyülemek kimutatására UH vagy CT történhet, a mellkas kontrollálására elsősorban hagyományos röntgenvizsgálatot végzünk. A későbbi időszakban indokolt a donorok szűrő jellegű, rendszeres követése. – Intézetünk kivizsgálási protokolljának képalkotó részét foglaljuk össze.
Present Technology In Offshore Mobile Drilling Vessels And Subsea Equipment
Authors: Hammett Dillard S.
Published: December 2007

This paper presents an overview of the present technology in Offshore Mobile Drilling Vessels. Examples of the capability of these vessels' performance in environmental conditions offshore the People's Republic of China are discussed.

The evolution of mobile drilling equipment as technology developed while drilling from shallow marshes (4 ft.) to deepwater (5000 ft.) using inland barges, jackups/barges, ship-shape and semi-submersible drilling vessels is illustrated. Specific technical topics are presented on drilling in hostile ocean environments, operating limits, mooring, motion, safety, survival conditions, subsea BOP controls, well safety and personnel requirements.
Water Treating Plant Design and Operation
Authors: Caudle Danny Dearl
Published: December 2007

Produced water must be treated to remove oil and solids and to control corrosion. Treating plants to do this consist of one or more processes such as skimming/settling, flotation, filtration, coalescence, and chemical treating. Design considerations and problems with these processes are discussed. Data from several sources are used to illustrate the performance of several treating plants.
Carbonate Reservoir Description
Authors: Jardine Daniel , Wilshart John William
Published: December 2007

Carbonate reservoirs are characterized by extremely heterogeneous porosity and permeability-These heterogeneities are caused by the wide spectrum of environments in which carbonates are deposited and by subsequent diagenetic alteration of the original rock fabric. Pore systems range from thick, vuggy reservoirs in the coarse grained skeletal-rich facies of the reef margin or platform margin to highly stratified, often discontinuous reservoirs in the reef interior, platform interior and nearshore facies.

Eight pools from the Western Canada Basin have been selected to illustrate the variety of reservoir configurations which can be found. Boundary Lake and Steelman are thinly bedded sequences of cyclic nearshore carbonates which are best suited to pattern waterflood. Quirk Creek is a thick, overthrusted open platform gas pool in which fractures associated with the leading edge of the structure provide high deliverabllity in an otherwise low-permeability reservoir. Clarke Lake is a fractured, dolomitized platform margin gas reservoir which is highly susceptible to water channelling. Golden Spike, Judy Creek, Norman Wells and Redwater are reef bioherms which display the classic reservoir configuration of highly permeable reef margin facies enclosing strongly stratified reef interior sediments. With increasing reef size, the relative volume occupied by oil becomes smaller and the aquifer becomes larger and more effective.

Golden Spike was entirely filled with oil when discovered and early production was characterized by rapidly declining pressure. An initial gas flood depletion plan was followed by a gravity-controlled, gas-driven miscible flood. This was very effective until the miscible bank was broken up and dispersed by several thin impermeable beds in the reef interior which proved to be barriers to vertical flow.

Judy Creek had a small ineffective original aquifer and was produced initially by a downdip peripheral waterflood- This ultimately proved to be ineffective in repressuring the discontinuous porosity in the reef interior and was supplemented with a pattern waterflood.

Depletion plans for these pools require detailed, integrated geological-engineering studies to develop accurate reservoir models. These models are then used in computer simulation studies to forecast reservoir behavior under various depletion methods and to assist in on-going reservoir surveillance studies.
Reservoir Characterization By Areal Seismic Methods
Authors: McDonald John Andrew , Gardner Gerald H. F. , Morris Robert Irwin
Published: December 2007

The areal seismic method has been developed over the last few years as a means of correctly imaging geological structure. However it was soon realized that many of the parameters which characterized hydrocarbon reservoirs could also be measured by the use of areal techniques. In the common-depth-point method (CDP) of collecting seismic reflection data the aim is to achieve a plane of seismic information in distance along the surface and in time into the geological section. The CDP stacking method is used to improve the signal-to-noise ratio, to remove multiples and it will give a representation of the subsurface particularly if the data are collected up-or-down dip. Thus the parameters characterizing a reservoir could be measured by a CDP line but the result would be information in only one dimension, along an up-or-down dip line through the reservoir.

Data can be collected in two-dimensions in space and one in time by a variety of techniques. The objective is to adequately sample the subsurface so that changes in various parameters can be mapped areally. Methods of data collection commonly used include the dragging of a cable along lines which are sufficiently close together and the shooting into lines of detectors which are at some angle to the lines of sources. Each seismic trace then represents a sampling of the subsurface. Variations in any measured parameter such as the amplitude, phase or power in the seismic signal or the velocity of propagation can be interpreted as an indication of changes in the physical properties of the rock matrix.

Having collected and processed what is essentially a cube of information a final problem remains: this is, display and interpretation. It is possible to display this information as a series of layers cut horizontally or vertically through the earth. This may be done on a television screen for video reproduction. The addition of an interactive computer system to the video presentation enables a three-dimensional interpretation of the cube to be made. The interpretation may then also be stored for video reproduction.
Trace Inversion for Interpreting Reservoir Continuity and Lithology
Authors: Harris Donald G. , Sarg J. F. , Branisa F. , Vail P. R.
Published: December 2007

Seismic trace inversion sections show variations in acoustic impedance that might represent lithologic changes important to reservoir description. However, trace inversion techniques must be used carefully to avoid pitfalls associated with the interpretation of seismic data. Only where high-quality seismic data is available, 1ithology-impedance relationships are distinct and seismic stratigraphy procedures are utilized can trace inversion contribute to reservoir studies.
New Approaches in Well Testing
Authors: Zakirov S. N. , Indrupskiy I. M. , Zakirov E. S. , Anikeev D. P. , Tarasov A. I. , Bradulina O. V.
Published: December 2007

Modern methodology of well testing is the result of efforts of many scientists for more than 50 years. It is mainly based on the theory of single-phase flow. Few publications consider two-phase flow. However, they were also generally reduced to single-phase inverse problems.

During the last several years, authors have been developing an alternative trend in well testing. Its distinctive features are:

creation of bi-directional two-phase flow in the nearwellbore region or forced creation of two- or three-phase fluid flow; interpretation of well test results based on 1D, 2D or 3D multiphase optimization problems.

Obviously in this case well testing techniques are rather more complicated. They become science-intensive. On the other hand, they firstly extend the list of parameters and relations determined -those required for up-to-date 3D flow simulations. Added features include relative permeabilities for oil, gas and water, capillary pressures and full tensor permeability. Secondly, these parameters and relations characterize the effective (realistic) pore space. It is the effective, not absolute, pore space where the real reservoir flow processes take place. Turning to the effective pore space improves the degree of certainty in 3D modeling and enables proper use of well test results in the process of history matching 3D reservoir models.

The developed approach displayed noticeable advantages when applied to carbonate formations. In this case it enables more reliable characterization, compared to laboratory core experiments, including determination of

formation type (i.e. single- or dual-porosity) and parameters and relations required for 3D dual-porosity simulations.

In the paper the authors present a review of results obtained up to date.
New Approximate Analytical Solutions of Well Testing for Simple Boundary Shapes
Authors: Shimamoto T.
Published: December 2007

One-dimensional radial flow equation, of which permeability and porosity are in inversely proportional to the radius, is equivalent to the equation of linear flow. In other words, if we take the radial variations of permeability and porosity into consideration, we can represent the linear flow by one-dimensional radial flow equation. To expand this idea and to apply it for various types of inner and outer boundary shapes, we defined the S-function by "The functions of reservoir properties in radail direction which should be used for a radial composite model in order to represent the pressure transient behavior at the well location for given inner- and/or outer- boundary shapes". The pressure behavior of the radial multi-composite model includes lots of pressure type curves. For example, one can reproduce the pressure transient behavior of channel type, sealing fault and hydraulic fractured well, etc by the radial multi-composite model with assigning the permeability and porosity distribution along radial direction adequately.

We found that the approximate S-function can be easily estimated from steady state streamlines. The composite models with the S-functions reproduce "sealing fault", "channel type", "horizontal sink" and "the reservoir which has different transmissibility regions". We compared the results with the conventional analytical solutions by commercial software, and obtained excellent agreement.

Not only its high novelty and expandability, but its calculation speed and visibility, this methodology (S-function) will be a powerful tool for pressure transient analyses.
Quantification of Uncertainty Due to Subgrid Heterogeneity in Reservoir Models
Authors: Okano H. , Pickup G. E. , Christie M. A. , Subbey S. , Sambridge M.
Published: December 2007

Due to the lack of data, a reservoir engineer needs to calibrate unknown petrophysical parameters based on production history. However, because the observations cannot constrain all the subsurface properties over a field, production forecasts for reservoirs are essentially uncertain. In general, many parameters of the model must be adjusted in the history-matching process, and the amount of computation required to solve the inverse problem may be prohibitive.

To address this issue, we proposed a new methodology which restricts the parameter ranges of the calibration by using physically based prior information, extracted from geological and petrophysical input. The aim of the work is to have a sound basis for forecasting uncertainty in reservoir production. We demonstrate the applicability of the methodology using quarter five-spot pattern waterflooding models.

The petrophysical properties to be adjusted in this paper are coarse-scale relative permeabilities. Coarse-scale models have the disadvantage of omitting the effects of fine-scale heterogeneity and suffering from solution errors, although in practice they are often employed in field-scale simulation because of the computational cost. Here, we history-match relative permeabilities at the coarse scale in order to encapsulate physical dispersion and compensate for numerical dispersion.

The prior information was estimated from a range of possible geostatistical parameters. It allowed us not only to determine the parameterisation of the grouped relative permeabilities but also to set up the bounds of each type of curve. We used a synthetic data set for which the true solution is known. The resulting posterior expectations and P10 / P90 cut-offs of the production data and the relative permeabilities were examined in comparison with the reference results. We conclude that this new approach enabled us to quantify the uncertainty of sub-grid heterogeneity through the use of coarse-scale relative permeabilities without refining the model.
Schedule Optimisation To Complement Assisted History Matching and Prediction Under Uncertainty
Authors: Jutila H. A. , Goodwin N. H.
Published: December 2007

Recently our business has had great success in developing tools for using full physics simulators in Assisted History Matching (AHM) and prediction of future performance. However, the end user is often left wondering what to do with the large number of forecasts from these studies; any optimisation of the remaining potential has to be done manually.

This paper discusses a method in which the principles of AHM are used to optimise the development. In AHM the practitioner attempts to minimise the error between the observed and simulated data; the ‘objective function’. A large number of ‘geological’ variables to the simulator are sensitised. ‘Control’ variables are used in the predictive work. These are only limited by the scheduling features of the reservoir simulator and would normally be the number and location of development wells; change in facilities constraints; re-completion; workovers etc. The objective function for development optimisation tends to be an economic one, i.e. Net Present Value (NPV) or some other profitability indicator. The method described in this paper has an advanced feature for generating additional results based on the simulator output time series.

Schedule optimisation is known to be a very difficult problem, not amenable to standard mathematical programming algorithms, and we describe how, in conjunction with the use of a proxy model, we have successfully applied genetic algorithm optimization techniques, to solve the scheduling problem with minimal CPU processing.

The method has been used a number of times and its application is described by some case studies; optimising the number and location of development wells and timing of scheduling events. As a very large number of possible combinations of variables are used the optimisation tends to be less subjective than a manual giving generally better results.
Water Injection Methods
Authors: Mitchell Robert William , Bowyer Paul Melvin
Published: December 2007

It is generally acknowledged that the first waterflood occurred as a result of accidental water injection in the Pithole City area of Pennsylvania in 1865 (1). As long ago as 1880 it was concluded that water, finding its way into a wellbore from shallow sands, would move through oil sands and be beneficial in increasing oil recovery! Since that time waterflooding has become the dominant technique employed in world wide oil recovery operations.

An area of particular interest at the present time is the use of sea water as an injection fluid, particularly in the North Sea, where the number of offshore oil production facilities is rapidly increasing. The high expense of offshore operations plus the high capital cost of the platform very often impose severe constraints on the design engineer, particularly in terms of the size and the weight of the water treatment facilities. The final design of any system will be governed by a variety of factors, generally with economics predominating. This paper discusses the influence of external constraints and reservoir criteria on offshore water injection system design. Examples are drawn mainly from BP's 5 years operational experience with the Forties Field Sea Water Injection System.

The design of a waterflood project requires two major facets of work, the reservoir engineering aspects, to predict recovery performance by waterflooding, and the production engineering, to evaluate all the surface requirements. Work on the former is normally limited to reservoir simulation studies to determine the water injection volume and pattern requirements. An important factor in the success of a waterflood project, although often neglected in production engineering, is the quality of the water required for injection into the reservoir rock. This definition has three major considerations:
Principles of Acid Stimulation
Authors: Muecke Thomas Wayne
Published: December 2007

If properly designed and implemented, acid stimulation treatments provide a method for improving the productivity of oil and gas wells. The success of these treatments depends to a great extent upon proper acid selection and good treatment design. This can be accomplished only with a good understanding of the fundamental principles of acid stimulation. This paper reviews these important principles and includes descriptions of the basic concepts of damage removal, reservoir stimulation, acid reaction mechanisms, job design and diversion technology. Example field case histories are included to illustrate the benefits that can be derived from properly administered acid treatments.
Investigation of Well Damage Case History
Authors: Braunston R. J.
Published: December 2007

Soon after start-up of the Prudhoe Bay Field in mid-1977, a number of wells with abnormal productivity decline were recognized. Research into the problem was undertaken as a coordinated effort of the Prudhoe Bay Unit Owners involving engineering, laboratory and geological studies concurrent with an extensive field work program. Investigations over the past three years have defined a major damage mechanism and efforts are continuing toward solutions for effective long-term production capacity maintenance.
Study of Reservoir Damage Produced in Heavy Oil Formations Due to Steam Injection
Authors: McCorriston Lois L. , Demby Richard A. , Pease Eric C.
Published: December 2007

Steam injection in heavy oil reservoirs produces hydrothermal reactions which can lower producing potential by reducing permeability and causing well bore damage.

Effluents from once-through steam generators often have pH values above 12 due to the use of high bicarbonate surface waters as feeds. Injection of these high pH and low ionic strength waters causes expansion and dispersion of water-sensitive clays and solubilization of silica and aluminum minerals. The hydroxide and carbonate ions in the effluents react with magnesium, calcium and other salts in formation waters to form precipitates.

Laboratory experiments showed that these alkaline boiler effluents irreversibly reduced the permeability of cores (by up to 70%), dispersed clays and solubilized quartz sands.

In the field, large quantities of amorphous precipitates containing magnesium, calcium and aluminum as well as clays, micas and quartz grains were produced from two wells with low oil/steam ratios. The quartz grains showed substantial changes in surface morphology similar to those produced by quartz solubilization experiments in the laboratory.

To minimize reservoir damage, steam generator effluents with reduced pH and increased ionic strength are being injected at two field pilots.
New Technique for Analysis of Variable Rate or Slug Test
Authors: Soliman Mohamed Y.
Published: December 2007

This paper presents a new and simple technique to analyze a variable rate and slug test. It considers the production rate as a continuous function of time and produces an equivalent Horner plot.

Two slug tests are analyzed comparing the new and various existing techniques. Existing techniques include type curve matching of flowing period, a multi-rate test, and the Odeh-Selig variable rate technique.
Determination of Oil Saturation Distributions in Field Cores By Microwave Spectroscopy
Authors: Brost Dale Francis , Davis Lorne Arthur
Published: December 2007

Two microwave absorption spectrometers have been developed for routine monitoring of So distributions during laboratory flooding experiments in field core material. Operating frequencies are 10.525 and 24.125 GHz. Based upon low-power, mass-produced microwave components, these instruments are inexpensive, safe, very compact and rugged and require no special expertise for operation. A core sample cell has been designed which permits So distributions to be determined in narrow rectangular and cylindrical cores. An indirect calibration technique has been developed using the injection of aqueous solutions of 2-propanol to compensate for the porosity variations and irregular Soi and Sorw distributions inherent to segmented field cores. Details of the instrumentation are presented with a theoretical description of instrumental response. The practical utility of this instrumentation for the a priori detection of core defects and quantitative determination of porosity distributions is demonstrated.
Patterns of Wetting Behavior in Multicomponent Systems
Authors: Teletzke Gary F. , Scriven L. Edward , Davis H. Ted
Published: December 2007

When the equilibrium states of two coexisting fluid phases lie sufficiently near a critical point, one of the near-critical fluids is prevented from contacting any given solid or third fluid phase by a wetting film of the other near-critical fluid. We classify the possible patterns of wetting behavior in systems of two and three fluid phases and show that the observed patterns for many systems, including equilibrated microemulsion systems, are consistent with this so-called critical-point wetting behavior. Implications for petroleum recovery are discussed.
Numerical Simulation of Heterogeneous Fractured Gas Reservoir Systems with Turbulence and Closure Stress Effects
Authors: Allam Awad M. , Crichlow Henry B. , Soliman Mohamed Y.
Published: December 2007

A numerical technique for analyzing the behavior of a fractured gas reservoir system is presented. The reservoir is simulated by a fully implicit three-domensional model that incorporates the effects of turbulent flow and closure stress in a finite conductivity fracture. The model utilizes the real gas pseudo-pressure, two-point upstream transmissibilities and a stable iterative process based on a sparse matrix approach to solving the equation systems.

This paper presents a description of the model and applications to various reservoirs to illustrate the effects of fracture heights, turbulence and closure pressure on well performance.
Validity of Isochronal and Modified Isochronal Testing of Gas Wells
Authors: Mattar Louis , Lin Chung
Published: December 2007

Combining the simplified analysis and the more rigorous Laminar Inertial Turbulent (LIT) analysis of isochronal and modified isochronal tests, it has been shown that these tests are valid, within engineering accuracy, for all values of the inverse slope, n. A sequence of increasing rates produces less errors in a modified isochronal test than decreasing rates. The Absolute Open Flow (AOF) calculated by the simplified analysis and that calculated by the LIT analysis, can be significantly different. A table of correction factors has been generated, which permits conversion of the AOF obtained from the simplified analysis to the value that corresponds to the more complicated LIT analysis. When the ratio of the AOF to the test rate is less than 3 the difference between the simplified AOF and the LIT AOF is less than 10%.
Pipeline Transportation of High Pour Handil Crude
Authors: Irani Cyrus A. , Zajac Jaro
Published: December 2007

Problems related with the pipeline transportation of high pour Handil (Indonesia) crude between Huntington Beach and Santa Fe Springs, California are discussed. The result of laboratory and field studies of chemical additives for pour depression are presented. A rotational viscometer was used to establish the relevant rheological parameters of treated and untreated crude. Chemical treatment at the 200 ppm level was found to be economically more attractive than the available heating step. A turnkey operation for additive injection available through a local commercial oil field chemicals supplier was implemented and continued for a period of two years. Recently a more economically viable heating step has been introduced to minimize the cost of pipeline transportation of Handil crude. A limited discussion is also presented of the use of analytical methods for improved characterization of the wax-wax and wax-additive interactions.