bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Shutoff Treatment in Mega Rich Horizontal Well With Coiled Tubing Inflatable Packer for North Caspian
Authors: Burdin K. , Kichigin A. , Mazitov R. , Lobov M. , Bravkov P. , Stepanov V. , Eliseev D. , Zemchihin A. , Byakov A.
Published: October 2015

The Caspian Sea region, which includes Russia, Azerbaijan, Kazakhstan, Turkmenistan, Uzbekistan, and Iran, is one of the oldest oil-producing areas in the world and is an increasingly important source of global energy production. The area has significant oil and natural gas reserves from both offshore deposits in the Caspian Sea itself and onshore fields in the region.

Korchagin oilfield is located in the northern part of the Caspian Sea. Drilled wells are mega-reach (MD/TVD ratio greater than 3.0), with measured depths (MD) up to 23,622 ft and vertical depths of only 5,118 ft. This presents a great challenge for any well interventions, even for Coiled Tubing (CT) equipped with state-of-the-art hydraulic tractors. Limited working area, weight restrictions, challenging well geometry, completion features and lack of experience in offshore CT operations in the North Caspian Sea, required complex pre-job activities to optimize job design, select proper downhole tools and prepare a robust layout plan. This paper illustrates North Caspian project preparation challenges, on-the-job troubleshooting and workflow, supported by the well case studies and results from the first CT operation in North Caspian Offshore. Lessons learnt from the project, where all defined objectives were achieved with zero HSE (health, safety and environment) incidents, were also captured to assist in future campaigns with similar operational environment.
Marginal Commercial Reserves Estimation for Offshore Arctic Projects
Authors: Nagaytsev E. A. , Makarenko A. V. , Ushmaev O. S. , Bochkov A. S. , Varavva A. I. , Samolovov D. A.
Published: October 2015

Arctic offshore development can be characterized relative high capital expenditures for wells drilling, field infrastructure, and often small duration of drilling season. These features restrict ability of oil fields exploration in this region and there is a requirement of comprehensive uncertainty analysis before exploration program is started.

In this work a solution for optimal well spacing calculation for statistically distributed parameters of reservoir is presented. Exponential model of well productivity decline taking into account well lift maximum rate is used for analytical calculation. Using these solutions, it is possible to calculate reserves, NPV and minimal rental reserves distribution. Compared distribution of reserves and minimal rental reserves it is possible to estimate risk of exploration program and prioritize projects.
Waterflood Optimization Principles for Fields with Low-amplitude Tectonic Faults
Authors: Pichugin O. N. , Rodionov S. P. , Solyanoy P. N. , Gavris A. S. , Kosyakov V. P. , Kosheverov G. G.
Published: October 2015

In this paper, the authors demonstrated, using the Nelson criterion, that in case when 50% of cumulative oil production is provided by 5–15% of the wells many fields with terrigenous type of reservoir are characterized by a significant influence of fracturing on reserves recovery. In addition to seismic attributes, the technological performance of wells and logging data were analyzed (the ratio of the actual and estimated flow rates, the frequency of oil rate surge, the ratio of buffer pressure and injectivity, local deviation of OWC, the proportion of active thickness, the quality of cement sheath) which allows to specify the location of the decompression zone. Relation of these characteristics to abnormal well operation was confirmed by the method of statistical hypothesis testing. A high correlation between seismic attributes, which characterize disjunctive faults, and the well performance was observed (oil and liquid rate, water cut), as well as geological structure features (net pay thicknesses, net sand and macro-heterogeneity). Based on the development analysis of one of the fields in Kazakhstan the authors demonstrated a strong dependence between production performance of the area and well placement system, as well as the injectivity of displacing agent in a faulted reservoir. The dependence between the displacement efficiency and injection rate was theoretically confirmed by using the displacement characteristics obtained within this study on the basis of the equation for water saturation in fractured porous media [17]. The fundamental possibility and technological efficiency of waterflood systems transformation based on localization of decompression zones was demonstrated.
Defining Potentially-Productive Intervals and Evaluating Petrophysical Properties of the Tight-Oil Bazhenov Formation in Western Siberia Using a Suite of Modern Wireline Logs
Authors: Melnikov L. , Martinov M. , Demin V. , Cherevko M. , Zaray E. , Ezersky D. , Karpekin E. , Weinheber P. , Filimonov A. , Novikov S. , Blinov V. , Mikhaltseva I.
Published: October 2015

Using advanced logging methods combining NMR and spectroscopy an Oil Saturation Index (OSI) is computed that correlates well with the productive layers of the Bazhenov formation. This article describes a method of estimating the OSI from log data, proposes a model for log interpretation in the Bazhenov Formation sediments and compares the results to core analysis. We present results from three wells.
Features of Gas Well Testing in Reservoir with Low Permeability
Authors: Davletbaev A. Y. , Zhilko E. Y. , Islamov R. R. , Murtazin R. R. , Loznyuk O. A. , Shaybakov R. A.
Published: October 2015

Gas object T is characterized by poor reservoir properties and high horizontal and vertical heterogeneity. Therefore, the development of this reservoir is economically unfeasible with the conventional technologies of production applied to the majority of gas fields in Russia. Besides, by the beginning of the welltests this gas deposit had not been in production.

In order to ensure a deeper assessment of the target reservoir and work out robust engineering decisions, a Target Innovative Project under the title Selection of the development technology for the Turonian low-permeability gas deposit was carried out by Rosneft from 2012 to 2014. Under the pilot project, three different production wells were drilled: a vertical well with a hydraulic fracture (HF), a horizontal well completed with a slot-hole filter, and a horizontal well with a three-stage HF assembly.

This paper discussed the results of field welltests in a low-permeability gas reservoir characterized by high heterogeneity. The welltests were carried out in wells with different completions, estimates were received, and comparison of productivities performed. The paper also discusses the assessment of solid particle sloughing and validates a maximum pressure drawdown for the target reservoir. Pressure-transient tests enabled estimating the permeability of the reservoir, the effective length of the non-HF horizontal well (HW), the parameters of fractures in the vertical HF well and the horizontal three-stage HF well. Effects of nonlinear flow in wells with various completions are considered.

The paper also demonstrates the results of an interference test. This test confirms the existence of hydrodynamic connection between the pilot wells in the target low-permeability gas reservoir.
A Multistage Stimulation Operation to Unlock the Gas Potential of the Turonian Siltstone Formation in Western Siberia
Authors: Loznyuk O. , Surtaev V. , Sakhan A. , Murtazin R. , Latkin K. , Sitdikov S. , Pestrikov A. , Gusakov V. , Politov M. , Yudin A. , Vernigora D. , Olennikova O. , Bulova M.
Published: October 2015

One of the strategic targets in Yamal autonomous district, the Turonian siltstone formation, lies above the Cenomanian formation and is separated by a massive argillite barrier. Successful stimulation experience in vertical wells in the North-Kharampurskoe field during 2008 to 2010 encouraged the operator planning the next step of field exploration to consider horizontal well completions using multistage stimulation. The paper will describe pilot campaign in details.

The Yamal Turonian formation was formed in a coastal marine environment with slow deposition rates and is composed primarily of siltstone. The major challenges of the Turonian formation are low permeability (∼0.5 md) and extremely high clay content—chlorite, kaolinite, illite, and mixed-layer illite-montmorillonite. The low temperature of the Turonian formation (below 80°F) also presents a significant challenge for gas production. An operator must produce at minimum drawdown to avoid hydrates creation. The shallow reservoir depth (∼ 3,000 ft) restricts recovering potential energy stored inside of the formation (initial reservoir pressure of about 1600 psi); therefore, hydraulic fracturing is a must for economic development of the Turonian formation. Selecting the correct fracturing fluid required extensive laboratory tests for compatibility and rheology adjustments. Thorough optimization of the fracturing fluid with clay stabilizer was applied during the course of this project. Additional challenges included proppant flowback tendency and inefficiency of conventional methods (resin-coated proppant) at such low temperatures.

The project began by stimulating a vertical well that was used as a reference for the fracture horizontal well that was stimulated in three stages. Coring and a full logging suite were performed on the reference well, including acoustic measurements, post-frac, to obtain fracture height growth. It was shown that fracture is vertical at such depth and that it covers the whole interval without vertical growth into argillaceous barriers. Bottom hole gauges were used to complete the precise mechanical modeling of the stimulated reference well. Evaluation of the mechanical and properties were completed using E&P software platform-based simulator to optimize the multistage fracturing design in the horizontal well.

This paper includes a detailed sequence of the operations performed and explains conclusions made concerning fracture geometry. The lessons learned during the assessment campaign are described. This stimulation project performed in the North-Kharampurskoe field is fundamental in development of the field and serves as important step toward unlocking the gas potential of other Turonian siltstones.
Possibility of Kerogen Decomposition Using Termo-Gas Wave Stimulation in Bazhenov Formation
Authors: Dieva N. , Dmitriev N. , Kravchenko M. , Muradov A.
Published: October 2015

Significant attention paid recently to development of Bazhen reservoir fields is obviously a result of qualitative leap not only in cognition to geology of such reservoirs, but also a result of so called innovative technologies of O&G fields development of non-conventional hydrocarbons, which includes heavy oil, low permeable reservoirs oil an shale O&G fields. By geological properties, generation conditions and possibilities of development these fields are quite different, but could be combined in common group not only because of huge reserves amount that exceeding conventional hydrocarbon sources, but also by development technologies similarity.

Due to low porosity and permeability of kerogen containing reservoirs, high degree of anisotropy and low percentage of recoverable reserves it is necessary to develop new recovery technologies specially designed for complex and low-permeable reservoirs development. Main target of such methods is structure properties alteration of reservoir and filtration properties improvement of contained fluids. Besides technology should contribute to liquid hydrocarbons generation in source rock. Pilot projects of kerogen-containing Bazhen suite O&G field's development based mostly on chemical, calorific and thermal-chemical methods.

Authors of the article conducted a research of low-permeable reservoirs current development state, analyzed of laboratory experiments and field data of kerogen matrix dissolution with liquid hydrocarbon excretion were also performed. Basing on analysis results mathematical model of kerogen decomposition process in reservoir under thermal-gas-wave influence, representing modern methods of thermal and chemical EOR, was generated. Mathematical modeling research includes a stimulation of inflow to well by injection of chemically-active substances into reservoir for decomposition kerogen conditions.
Multi-Stage Fractured Horizontal Well Numerical Simulation and Its Application in Tight Shale Reservoirs
Authors: Guo Chaohua , Wang Jiaqi , Wei Mingzhen , He Xiaoming , Bai Baojun
Published: October 2015

Unconventional tight shale reservoirs have been developed during recent years due to increasing shortage of conventional resources and a large number of multi-stage fractured horizontal wells (MsFHW) have been drilled to enhance reservoir production performance. Gas flow in tight shale reservoirs is a multi-mechanism process, including: desorption, diffusion, and non-Darcy flow. The productivity of the shale gas reservoir with MsFHW is influenced by both reservoir condition and hydraulic fracture properties. In this paper, a dual-porosity-dual-permeability model was presented to estimate the effect of parameters on shale gas production. Three flow mechanisms have been considered in this model: gas diffusion in nano scale pores, Darcy flow in macro scale pores, and non-Darcy flow in near wellbore hydraulic fractures. Langmuir isotherm was used to simulate the gas desorption process. Hydraulic fractures were performed by Local Grid Refinement (LGR) method.

To conduct sensitivity anlaysis on production performance of tight shale reservoirs with MsFHW, parameters influencing shale gas production were classified into two categories: reservoir properties (including matrix permeability, matrix porosity, natural fracture porosity, rock compressibility, gas desorption) and hydraulic fracture properties (including hydraulic fracture spacing, fracture half-length, fracture conductivity, and fracture height). Typical ranges of these parameters have been reviewed. Sensitivity checks for each parameter were performed to analyze the effect of factors on the cumulative gas production. It can be found that matrix porosity is the most influencing reservoir parameter which has greatest effect on cumulative production among reservoir parameters. And hydraulic fracture spacing, fracture half-length, fracture conductivity, and fracture height are all significant parameters. Result of this study can be used to improve the efficiency of history matching process. Also, it can contribute to the design and optimization of hydraulic fracture treatment design in unconventional tight reservoirs.
Optimization of Cyclic Steam Stimulation (CSS) Under Geomechanics-Dependent Permeability
Authors: Temizel Cenk , Gorucu S. Emre , Erdogan Sinem Setenay , Tiwari Aditya
Published: October 2015

Objectives/Scope:

Since its accidental discovery in Venezuela during a steamflood procedure, and despite the high costs associated with using steam. CSS has been widely used throughout the world in heavy-oil reservoirs, especially in Alberta, California, and Venezuela. It has turned out that it is also important to understand the degree of impact of geomechanics as it is a key parameter in reservoirs with geomechanical response. This makes the optimization process more valuable in terms of the application of crucial operational constraints and parameters, such as injection rate, cycle size, cycle life, and well spacing, not only for the reservoir but also the wellbore, which are important for delivering steam to the subsurface while ensuring minimum heat loss along with reservoir integrity and permeability variation.

Methods, Procedures, Process

The CSS recovery method is influenced by complex reservoir geologies, where a CSS well can penetrate multiple layers having significantly different properties, including permeability. It is important to have a solid understanding of the impact of multiple layers on recovery when using CSS, not only to help maximize recovery but also net-present value because of the high cost of steam generation. In this study, a commercial full-physics reservoir simulator is used to simulate the effect of multiple layers with varying permeabilities under different operating conditions.

Results, Observations, Conclusions

CSS helps to increase recoveries up to 20 to 25% by means of certain mechanisms, including but not limited to viscosity reduction thermal expansion of oil, blocking removal, and gravity drainage. Although it is generally valid that higher steam qualities and shorter soak times provide higher recoveries, the main stages of cyclic steam stimulation (CSS)—injection, soaking, and production—should be carefully optimized because the efficiency of this technique is reduced after the first few cycles. The influence of geomechanics turns out to be a significant parameter in this process.

Novel/Additive Information

The results and sensitivities are compared and discussed in light of a comprehensive literature review of CSS with different process optimization methods, including sequential CSS and cumulative average daily profit methods. The significance of all major parameters are outlined using tornado charts to serve as a practical example for optimization of similar future applications.
Re-fracturing Considerations of Horizontal Well Multi Stage Fractured Completions in Mid Permeability Formations
Authors: Butula K.K. , Yudin A. , Klyubin A.
Published: October 2015

The oil and gas industry in Russia started facing a complex problem of productivity decline from horizontal multi stage fracture completed wells drilled in the low to mid permeability reservoirs. To enhance hydrocarbon flow from these formations, aggressive production using artificial lift is supported with active water flooding. Nevertheless, operators have acknowledged that the horizontal well multi stage fracture (HW MSF) completions do not live to their expectations.

The application of HW MSF completions started in 2008, but widespread acceptance followed several years later. Today, in Russia, about 300 horizontal wells are drilled and completed annually bringing the total number of HW MSF to more than 1200 wells. All these wells are potential candidates for re-fracturing treatments and re-completion, but while re-fracturing of vertical wells is a well proven success in Russia, the industry today has no clear understanding how to address the multitude of potential productivity difficulties in HW MSF.

During the work published in this paper, the team has analyzed all the known potential engineering problems and technical risks and clearly defined the domains of further investigation and set recommendations on measurements that are needed to understand the impact of re-fracturing. The analysis was based on field measurements made, analytical calculation and numerical simulations, modeling in all details the key processes defining the productivity of HW MSF completions. The results indicate that pressure influenced stress changes in a mostly isotropic system and resulting fracture placement within the horizontal wellbore are key contributors to the complexity of the problem.

The paper presented here is a genuine attempt for the industry streamline further search for solutions and novel methodology to effectively re-fracture the existing completion systems and bring these wells to profitable production.
A Novel Automated and Probabilistic EOR Screening Method to Integrate Theoretical Screening Criteria and Real Field EOR Practices Using Machine Learning Algorithms
Authors: Tarrahi Mohammadali , Afra Sardar , Surovets Irina
Published: October 2015

To make promising operational decisions for reservoir exploitation, oil and gas industry relies heavily on predicting the performance of various enhanced recovery processes. Decisions on recovery strategies should be taken in an early stage of field development planning. To select an appropriate recovery technique based on reservoir and fluid characteristics, EOR screening criteria are used as a reliable decision making approach. A dependable first order screening evaluation algorithm enables critical decision making on potential enhanced oil recovery strategies with the limited reservoir information.

In this study, we propose to solve the EOR screening problem by machine learning or pattern recognition methods, which are well-established in computer science literature. We perform a comprehensive study on the application of various machine learning methods such as Bayesian Classifier, K-nearest Neighbor Classifier, Minimum Mean Distance Classifier, and Artificial Neural Networks.

The proposed data-driven screening algorithm is a high-performance tool to select an appropriate EOR method such as steam injection, combustion, miscible injection of CO2 and N2, based on different reservoir and fluid properties such as permeability, depth, API, and viscosity. In this innovative approach, we integrate both theoretical screening principles such as Taber criteria and successful field EOR practices worldwide. Not only this algorithm proposes an appropriate EOR method for a specific reservoir condition but it also gives the probability of success or success rate corresponding to each EOR method. In addition, the proposed algorithm is able to address environmental, economical, geographical and technological limitations.

The proposed algorithm permits integration of different types of data, eliminates arbitrary approach in making decisions, and provides accuracy and fast computation. The suitability of the proposed method is demonstrated by different synthetic and real field EOR cases. This novel EOR screening method is capable of evaluating the effectiveness of different EOR scenarios given a specific reservoir condition. We showed that the proposed EOR screening algorithm is able to predict the appropriate EOR method correctly in more than 90% of cases. We also ranked the proposed screening algorithms based on their screening performance.
Systematic Approach to the Aplication of Chemical EOR in JSC "Rosneft"
Authors: Zakharyan A. G. , Musin R. M. , Cimic M. , Ganiev I. M. , Ismagilov T. A.
Published: October 2015

This article describes a systematic approach used to improve efficiency of water shutoff treatments application in JSC Rosneft. The description of the main stages of this approach as well as n tools and techniques used in it is given.

The approach proposed consists of three main stages. The first stage - the creation of a rating of waterflooding patterns which require application of water shutoff treatments, the second stage - the selection of optimal technologies for a given reservoir properties, which includes an analysis of previous studies, tracer studies, laboratory testing and modeling of the effects of treatments, third stage - monitoring of the operations and probabilistic estimation of incremental oil recovery.
Physical and Chemical Processes During the Carbonated Water Flooding in the Oilfields
Authors: Barenbaum A. A. , Zakirov S. N. , Zakirov E. S. , Klimov D. S. , Serebryakov V. A.
Published: October 2015

Physical and chemical processes in oilfield reservoirs developed by carbonated water flooding were much more complex than previously thought. We have shown that these processes are directly related to the problem of hydrocarbons origin. Over the long time, this problem has not been solved in the debate between supporters of the "organic" and "inorganic" hypotheses.

We adhere to the concept of biosphere origin of oil and gas, which allows to solve this problem differently. It considers the origin of oil and gas not only as long geological process, but also as a modern phenomenon, which is closely associated with the geochemical cycling of carbon through the Earth's surface with meteogenic waters.

One of these processes is phenomenon of decomposition of carbonated water on surface of mechanically activated matrix of rocks, which occurs with formation of free hydrogen (H2) and low temperature synthesis of hydrocarbons from carbon dioxide (CO2) and water (H2O).

In recent decades, it was accumulated many facts in support of the biosphere concept. However, some issues of hydrocarbon origin in this concept demanded special study. Our laboratory experiments performed in the dynamic and stationary modes allow to successfully solving this problem.

We present the results of measurements of the rate decomposition of carbonated water under conditions simulating activated rocks of sedimentary cover. In our experiments, in a role "activator" of rocks we used an iron shaving. The experiments were performed at room temperature and atmospheric pressure.

The research results are useful for technologies to improve oil recovery by maintaining reservoir pressure due to carbon dioxide (CO2) injection and recycling CO2 technologies, and storage of carbon dioxide in depleted oilfields, as well as technology to justify the production in oilfields with low-permeability reservoirs. Our research suggest that under certain conditions, injection of carbonated water (as well as CO2 in gas form) into reservoir beds, due to synthesis of hydrocarbons by the reaction CO2 + H2O, permits to increase oil recovery of depleted oil fields as well as increase the effectiveness of CO2 disposal in water-bearing stratum of the gas fields.
Well Logging and Ground Geophysics for Safe Operation of Oil and Gas Fields Within Permafrost Area
Authors: Petr Alekseev
Published: October 2015

Annotation

Conduct engineering research in the conditions of permafrost due to the nature of the area requires further development and inclusion of additional studies, since the standard set of studies unable to identify potentially dangerous areas with a possible thawing in the process of drilling and exploitation. As a result of such interactions may form hopper sagging in testing parts of the holes (fig. 1), voids within the entire range of frozen rocks that leads to a rise in drilling operations, in addition, can lead to the loss of longitudinal stability of wells, and, as a consequence, to the accident.

In order to avoid additional costs and reduce the risk of accidents, it is proposed to conduct additional work in the process engineering research that will lead to the structuring of tasks and techniques associated with operation of well pads in the conditions of development of permafrost. Bringing a systematic approach to this task group in the early stages of field development will minimize the number of potentially dangerous cases due to sustained and coherent works.

For these types of works carried out a pilot project on 10 sectional sites fields in Western Siberia. Implementations of additional Geophysics were practically and economically profitable.

The research work of this type is recommended for implementation in other projects of OAO NK Rosneft.
Nonequilibrium Phase Transitions in BlackOil
Authors: Zubov V. R. , Indrupskiy I. M.
Published: October 2015

The paper argues in favor of the need to adjust pVT properties of the hydrocarbon system and apply non-equilibrium models of phase transitions for purposes of upscaling and history-matching flow simulation models (FSMs) to actual production data. Since most of FSMs are based on the Black Oil model, it features prominently in the paper.

The paper considers certain information from laboratory experiments and production data that points to non-equilibrium phase transitions in the in-situ hydrocarbon mix. Provided are also the results of numerical experiments demonstrating the need for upscaling the fluids' pVT properties, and evidence of non-equilibrium effects from the enlarged size of cells in the FSM computational grid. In conclusion, the paper considers capabilities of various commercial flow simulators and new approaches to simulation of non-equilibrium phase behavior effects in the Black Oil model.
The Application of the Fuzzy Sets Theory for Candidate Wells Selection
Authors: Kashapov Azat
Published: October 2015

The paper represents the way the conventional method of candidate well selection can be optimized with the fuzzy sets theory applied.

At late stages of any oil field life the most efficient way to support high hydrocarbon production level tends to be well stimulation procedures carried on the continuing basis. Considering any well stimulation treatment prospective the main thing is the issue of oil remaining recoverable reserves in-place.

At present time there are two methods for well stimulation treatment candidate selection used in Tomskneft JSC. The first method is reservoir simulation modelling (RSM), this allows determination of the areas where appreciable amount of recoverable reserves is located and which well is better to retrieve them. However, the crucial disadvantage of this approach is its dependence on how good the model is adopted. The calculations made by reservoir simulation are rarely confirmed when a real well is run.
Simulation of Well Trajectory while Drilling by the TBS Method
Authors: Tikhonov Vadim , Bukashkina Olga , Abaltusov Nikolay
Published: October 2015

Bent-housing positive displacement motors (PDM) keep the leading position among tools for drilling directional wells. The efficiency of drilling deviated wells can be greatly enhanced by the method of Targeted Bit Speed (TBS). This method enables well deviation with the continuous drillstring rotation by means of amplitude modulation of PDM's rpm, which is provided by controlling the fluid flow oscillations in its working chamber. In those cases when the required dog-leg severity cannot be achieved with TBS technology, the system's operation can be suspended without retrieving the BHA to the surface with further directional drilling by conventional PDM orientation method.

In order to control and direct a well trajectory in an efficient manner, it is essential to be able to assess effect of the system parameters on deviation. The paper proposes a numerical model of a BHA equipped by TBS. The model is based on the universal 3-D dynamic drillstring-in-hole model DYNTUB, which has been previously developed by the authors. For implementing TBS technology the latter model has been refined to integrate the modulation of motor rpm with the specified amplitude setting the rate of inclination angle increase/decrease and with the phase determining horizontal angle. The deflection increment of the drilling vector against the previous position is determined by averaging the inclination and horizontal angles in one revolution of the drillstring. The model accounts for the dependence between the ROP and the bit rpm composed of constant drillstring rpm and PDM rpm, which value is subject to periodic changes during rotation.

The developed program was used to analyze the build-up rate of wells drilled by TBS and oriented assembly. The analysis covered straight wellbores with different orientation in the initial state (vertical and horizontal), various types of near-bit section to kink, as well as the effect of the PDM rpm modulation amplitude and the lateral bit milling capacity. Despite of the fact that in most instances the build-up rate with TBS was slightly lower than when drilling with an oriented assembly, this was compensated by a far more valuable advantage of a significant reduction in drag force during drillstring rotation. Examples of calculating the drilling directional control of S-shaped well sections at Vostochno-Urengoysky area in Yamalo-Nenets Autonomous District drilled by the TBS method and their comparison with the planned and actual trajectories are presented. The ways to improve the efficiency of well drilling by the TBS method are provided.
Effect of Genotype, Environment, and Genotype × Environment Interaction on Tocopherol Accumulation in Soybean Seed
Authors: Shaw Eric J. , Kakuda Yukio , Rajcan Istvan
Published: October 2015

Soybean seeds [Glycine max (L.) Merrill] are a major source of tocopherols that provide many human health benefits including decrease in lung cancer risk and osteoporosis. The objectives of this study were: (i) to determine the impact of genotype, environment, and genotype × environment on soybean seed tocopherols and (ii) to evaluate relationships between agronomic traits and tocopherols. Seventy‐nine recombinant inbred lines (RILs) from the cross OAC Bayfield × OAC Shire were grown in three field locations in southern Ontario, Canada, in 2009 and 2010. Agronomic and seed quality data were collected in each location. Significant differences (P < 0.001) for the α‐, γ‐, δ‐, and total tocopherol concentrations were found in the seed of RILs using combined ANOVA for 2009 and 2010. Of the two parental lines, OAC Bayfield accumulated more total tocopherol at most environments. Genotype, location, and year differences were significant as well as genotype × location, location × year, and line × year interactions. Broad‐sense heritability estimates were 0.38 for α‐, 0.47 for γ‐, and 0.35 for δ‐tocopherol. None of the agronomic traits were consistently correlated with any of the tocopherol components; however, oil and protein concentration were correlated to some tocopherols in some of the environments. The wide range in values for α‐, γ‐, δ‐, and total tocopherols among the RIL population that exceeded both parents provided evidence for transgressive segregation. Our results suggest that soybean producers should take locations and genotypes into account when growing soybean for enhanced tocopherol production.
Chromosome Number, Genomic Variation, and Molecular Markers to Assess Genetic Diversity of Brachiaria Species
Authors: Nitthaisong Pattama , Ishigaki Genki , Tanaka Hidenori , Akashi Ryo
Published: October 2015

The genus Brachiaria contains approximately 100 identified species, including economically important tropical grasses; however, there is not much accessible information about the genetics or genomes of the genus. In this study, we determined the chromosome number and genome size by cytological analysis and flow cytometry, respectively, and estimated the molecular variability using intersimple sequence repeat (ISSR) markers for 28 accessions representing 11 Brachiaria species. The chromosome number of 10 species agreed with previous reports, and the chromosome number for B. xantholeuca was evaluated (2n = 4x = 36) for the first time. Genome size expressed as C values differed among these species (0.89 to 4.02 pg/2C) and increased with increasing ploidy levels. In contrast, the genome size given as a Cx value tended to decrease with increasing ploidy levels in polyploid plants. A total of 441 ISSR fragments were generated with 10 primers to assess the molecular variability of Brachiaria species. All 11 Brachiaria species clustered into three groups with the neighbor‐joining (NJ) method. We found no correlation between the clusters and the region from where the plants were collected. Nevertheless, the clustering of accessions was clearly correlated with ploidy level and reproductive mode (sexual and apomictic) except for a few accessions. Furthermore, evolution of the Brachiaria genome and genetic diversity within the genus were discussed.
Systematic overview of cost–effectiveness thresholds in ten countries across four continents
Authors: Schwarzer Ruth , Rochau Ursula , Saverno Kim , Jahn Beate , Bornschein Bernhard , Muehlberger Nikolai , Flatscher-Thoeni Magdalena , Schnell-Inderst Petra , Sroczynski Gaby , Lackner Martina , Schall Imke , Hebborn Ansgar , Pugner Karl , Fehervary Andras , Brixner Diana , Siebert Uwe
Published: October 2015

Aim:To provide an overview of thresholds for incremental cost–effectiveness ratios (ICERs) representing willingness-to-pay (WTP) across multiple countries and insights into exemptions pertaining to the ICER (e.g., cancer). To compare ICER thresholds to individual country's estimated ability-to-pay.Materials & methods:We included AHRQ/USA, BIQG-GOEG/Austria, CADTH/Canada, DAHTA@DIMDI/Germany, DECIT-CGATS/Brazil, HAS/France, HITAP/Thailand, IQWiG/Germany, LBI-HTA/Austria, MSAC/Australia, NICE/England/Wales and SBU/Sweden. ICER thresholds were derived from systematic literature/website search/expert surveys. WTP was compared with ATP using Spearman's rank correlation.Results:Two general and explicitly acknowledged thresholds (England/Wales, Thailand), implicit thresholds in six countries and different ICER thresholds/decision-making rules in oncology were identified. Correlation between WTP and ability-to-pay was moderate.Discussion:Our overview supports country-specific discussions on WTP and on how to define value(s) within societies.
Potential of intercropping for management of some arthropod and nematode pests of leafy vegetables in Kenya
Authors: Linguya Kimaru , Moraa Onyango , Wangai Kimenju , Chao Kilalo
Published: October 2015

African leafy vegetables (ALVs) play an important role as income and food
security crops in many households in Kenya. However, their potential in
alleviating poverty and ensuring household food and nutrition security has
not been fully exploited. The objectives of this study were to identify some
arthropod and nematode pests that infest ALVs and to evaluate the
effectiveness of intercropping of susceptible and resistant plants for the
management purposes. Three vegetable types: African nightshade, sunn hemp and
spider plant were used in determining the efficacy of an intercrop of
susceptible and non-susceptible types in reducing arthropod and nematode pest
effect. The treatments in the field experiment consisted of different
intercrop designs and a sole crop design as control while data was taken
based on five different variables. Crops in the field were infested with
arthropod pests and eight different species were enumerated. The same row and
hill intercropping designs were the most effective in reducing the effect of
arthropod and nematode pests compared to the control plots. Spider plant and
African nightshade intercrops recorded the least arthropod pest damage,
higher fresh and dry shoot yields and differed significantly (P?0.05) to
African nightshade planted as a sole crop. A similar trend was observed when
the experiment was repeated with a sunn hemp and African nightshade
intercrop. It is concluded from this study that intercropping of different
crops can be integrated with other methods to provide an easily adaptable
technology to apply for effective management of arthropod and nematode pests
with low external inputs.
Mechanisms Linking Glucose Homeostasis and Iron Metabolism Toward the Onset and Progression of Type 2 Diabetes
Authors: Fernández-Real José Manuel , McClain Donald , Manco Melania
Published: October 2015

OBJECTIVE

The bidirectional relationship between iron metabolism and glucose homeostasis is increasingly recognized. Several pathways of iron metabolism are modified according to systemic glucose levels, whereas insulin action and secretion are influenced by changes in relative iron excess. We aimed to update the possible influence of iron on insulin action and secretion and vice versa.

RESEARCH DESIGN AND METHODS

The mechanisms that link iron metabolism and glucose homeostasis in the main insulin-sensitive tissues and insulin-producing β-cells were revised according to their possible influence on the development of type 2 diabetes (T2D).

RESULTS

The mechanisms leading to dysmetabolic hyperferritinemia and hepatic overload syndrome were diverse, including diet-induced alterations in iron absorption, modulation of gluconeogenesis, heme-mediated disruption of circadian glucose rhythm, impaired hepcidin secretion and action, and reduced copper availability. Glucose metabolism in adipose tissue seems to be affected by both iron deficiency and excess through interaction with adipocyte differentiation, tissue hyperplasia and hypertrophy, release of adipokines, lipid synthesis, and lipolysis. Reduced heme synthesis and dysregulated iron uptake or export could also be contributing factors affecting glucose metabolism in the senescent muscle, whereas exercise is known to affect iron and glucose status. Finally, iron also seems to modulate β-cells and insulin secretion, although this has been scarcely studied.

CONCLUSIONS

Iron is increasingly recognized to influence glucose metabolism at multiple levels. Body iron stores should be considered as a potential target for therapy in subjects with T2D or those at risk for developing T2D. Further research is warranted.
Definitions of Metabolic Health and Risk of Future Type 2 Diabetes in BMI Categories: A Systematic Review and Network Meta-analysis
Authors: Lotta Luca A. , Abbasi Ali , Sharp Stephen J. , Sahlqvist Anna-Stina , Waterworth Dawn , Brosnan Julia M. , Scott Robert A. , Langenberg Claudia , Wareham Nicholas J.
Published: October 2015

OBJECTIVE

Various definitions of metabolic health have been proposed to explain differences in the risk of type 2 diabetes within BMI categories. The goal of this study was to assess their predictive relevance.

RESEARCH DESIGN AND METHODS

We performed systematic searches of MEDLINE records for prospective cohort studies of type 2 diabetes risk in categories of BMI and metabolic health. In a two-stage meta-analysis, relative risks (RRs) specific to each BMI category were derived by network meta-analysis and the resulting RRs of each study were pooled using random-effects models. Hierarchical summary receiver operating characteristic curves were used to assess predictive performance.

RESULTS

In a meta-analysis of 140,845 participants and 5,963 incident cases of type 2 diabetes from 14 cohort studies, classification as metabolically unhealthy was associated with higher RR of diabetes in all BMI categories (lean RR compared with healthy individuals 4.0 [95% CI 3.0–5.1], overweight 3.4 [2.8–4.3], and obese 2.5 [2.1–3.0]). Metabolically healthy obese individuals had a high absolute risk of type 2 diabetes (10-year cumulative incidence 3.1% [95% CI 2.6–3.5]). Current binary definitions of metabolic health had high specificity (pooled estimate 0.88 [95% CI 0.84–0.91]) but low sensitivity (0.40 [0.31–0.49]) in lean individuals and satisfactory sensitivity (0.81 [0.76–0.86]) but low specificity (0.42 [0.35–0.49]) in obese individuals. However, positive (<3.3 in all BMI categories) and negative (>0.4) likelihood ratios were consistent with insignificant to small improvements in prediction.

CONCLUSIONS

Although individuals classified as metabolically unhealthy have a higher RR of type 2 diabetes compared with individuals classified as healthy in all BMI categories, current binary definitions of metabolic health have limited relevance to the prediction of future type 2 diabetes.
10-m Shuttle Ride Test in Youth With Osteogenesis Imperfecta Who Use Wheelchairs: Feasibility, Reproducibility, and Physiological Responses
Authors: Bongers Bart C. , Rijks Ester B.G. , Harsevoort Arjan G.J. , Takken Tim , van Brussel Marco
Published: October 2015

Background

Physical fitness levels in youth with osteogenesis imperfecta (OI) who use wheelchairs are unknown. The 10-m Shuttle Ride Test (SRiT) has recently been introduced as a field test to determine cardiorespiratory fitness in children with cerebral palsy who self-propel a wheelchair.

Objective

The purpose of this study was to investigate the feasibility and reproducibility of the SRiT, as well as the physiological responses to the SRiT, in youth with moderate-to-severe OI between 8 and 25 years of age who self-propel a wheelchair at least for long distances.

Design

A test-retest design was used.

Methods

Thirteen patients with OI (8 boys, 5 girls; mean±SD values for age=15.5±6.4 years) using a manual wheelchair performed 2 SRiTs within 2 weeks. Adverse events, reached stage, peak heart rate (HRpeak), peak respiratory exchange ratio (RERpeak), peak oxygen uptake (V̇o2peak), and peak minute ventilation (V̇epeak) were the main outcome parameters.

Results and Discussion

All participants performed a maximal effort at both SRiTs (mean±SD values for HRpeak of 195±9 beats per minute [bpm], RERpeak of 1.32±0.16, V̇o2peak of 25.4±5.6 mL·kg−1·min−1, and V̇epeak of 47.9±18.6 L·min−1), without adverse events. The intraclass correlation coefficient of the reached stage showed excellent reliability (.95). Limits of agreement (LoA) analysis revealed acceptable LoA for reached stage (mean bias=−0.58, range=−2.50 to +1.35). There was a low correlation between reached stage and V̇o2peak (r=.61 and r=.45 for the first and second SRiTs, respectively).

Limitations

The influence of wheelchair properties and individually adjusted wheelchair designs was not examined.

Conclusions

The SRiT appears to be a feasible, safe, and reproducible maximal field test in youth with OI using wheelchairs at least for long distances. This field test might be useful to provide an indication of physical fitness and to assess the efficacy of interventions on physical fitness in these patients.
Exercise Improves Mood State in Normobaric Hypoxia
Authors: Seo Yongsuk , Fennell Curtis , Burns Keith , Pollock Brandon S. , Gunstad John , McDaniel John , Glickman Ellen
Published: October 2015

BACKGROUND: The purpose of this study was to quantify the efficacy of using exercise to alleviate the impairments in mood state associated with hypoxic exposure.METHODS: Nineteen young, healthy men completed Automated Neuropsychological Assessment Metrics-4th
Edition (ANAM4) versions of the mood state test before hypoxia exposure, after 60 min of hypoxia exposure (12.5% O2), and during and after two intensities of cycling exercise (40% and 60% adjusted Vo2max) under the same hypoxic conditions. Peripheral oxygen saturation
(Spo2) and regional cerebral oxygen saturation (rSo2) were continuously monitored.RESULTS: At rest in hypoxia, Total Mood Disturbance (TMD) was significantly increased compared to baseline in both the 40% and 60% groups. TMD was significantly decreased during
exercise compared to rest in hypoxia. TMD was also significantly decreased during recovery compared to rest in hypoxia. Spo2 significantly decreased at 60 min rest in hypoxia, during exercise, and recovery compared to baseline. Regional cerebral oxygen saturation was also reduced
at 60 min rest in hypoxia, during exercise, and recovery compared to baseline.DISCUSSION: The current study demonstrated that exercise at 40% and 60% of adjusted Vo2max attenuated the adverse effects of hypoxia on mood. These findings may have significant applied value,
as negative mood states are known to impair performance in hypoxia. Further studies are needed to replicate the current finding and to clarify the possible mechanisms associated with the potential benefits of exercise on mood state in normobaric hypoxia.Seo Y, Fennell C, Burns K, Pollock
BS, Gunstad J, McDaniel J, Glickman E. Exercise improves mood state in normobaric hypoxia. Aerosp Med Hum Perform. 2015; 86(11):976–981.
Peritoneal Dialysis Fluid and Some of its Components Potentiate Fibrocyte Differentiation
Authors: Herlihy Sarah E. , Starke Hannah E. , Lopez-Anton Melisa , Cox Nehemiah , Keyhanian Katayoon , Fraser Donald J. , Gomer Richard H.
Published: October 2015

Long-term peritoneal dialysis (PD) often results in the development of peritoneal fibrosis. In many other fibrosing diseases, monocytes enter the fibrotic lesion and differentiate into fibroblast-like cells called fibrocytes. We find that peritoneal tissue from short-term PD patients contains few fibrocytes, while fibrocytes are readily observed in the peritoneal membrane of long-term PD patients. The PD fluid Dianeal (Baxter Healthcare Corporation, Deerfield, IL, USA) contains dextrose, a number of electrolytes including sodium chloride, and sodium lactate. We find that PD fluid potentiates human fibrocyte differentiation in vitro and implicates sodium lactate in this potentiation. The plasma protein serum amyloid P (SAP) inhibits fibrocyte differentiation. Peritoneal dialysis fluid and sodium chloride decrease the ability of human SAP to inhibit human fibrocyte differentiation in vitro. Together, these results suggest that PD fluid contributes to the development of peritoneal fibrosis by potentiating fibrocyte differentiation.