bluuebunny/crossref_metadata_2025 huggingface dataset:
Parallel Estimation of Surface Subsidence and Updated Reservoir Characteristics by Coupling of Geomechanical & Fluid Flow Modeling
Authors: Al-Mudhafer Wathiq J.
Published: April 2013

Determining of reservoir surface subsidence is a crucial problem especially for soft and unconsolidated formations. For long time production with water injection and/or water influx, the pore pressure decreases with increasing in effective stress leading to reservoir compaction and vertical surface subsidence. In this paper, a Tank Capacitance-Resistive Model (TCRM) has been done to estimate the history of vertical subsidence in the upper sandstone member/main pay of South Rumaila oil field in Iraq. It is a mature oil field with around 58 years of production with 40 producing wells and it has also 20 injection wells located only at the east flank. The average surface area for this reservoir is 142 km2. The reservoir is modeled considering an infinite acting aquifer at the east and west flanks. A commercial reservoir simulator has been adopted parallel with the Tank Capacitance-Resistive Model to estimate the subsidence in very active aquifer. The Carter-Tracy water influx model has been adopted to calculate the water influx rate. The TCRM depends on the concept of continuity equation that considers the difference between the water injection and oil production as reservoir input and output, respectively. So, the simulator calculates the total water injection rate and water influx to be treated as water injection in the continuity equation.

The results demonstrated that reservoir formation has plastic deformation because it has recurrence subsidence in the reservoir thickness. The current subsidence for this reservoir in the current time after 58 years of predict is 1.5 ft at the crest of the reservoir and it is approximately close to the local subsidence at each grid in the reservoir crest.
Developing Realistic Depletion Plan of Senoro Field using Coupled Reservoir - Surface Network Simulation
Authors: Suwono Sugiyanto Bin , Wijaya Rahmat , Masbudi Herryadi , Muttaqin Muttaqin , Prasetyo Hadi
Published: April 2013

Based on current approved development plan of Senoro gas field, the field will be produced at rate 300 MMSCFD (net) to fulfill the gas demand. Existing study based on black oil reservoir simulation conducted on developing depletion plan of Senoro Field give an unexpected result of plateau time which is only 11.7 years while the field has gas delivery contract for 13 years. This possibility of shortfall gas tends to risk the company to get a penalty as termed in the contract.

Further analysis of the existing development plan also shows that the gas depletion plan is not yet optimal. It is indicated by the unbalance recovery factor between southern and northern reservoir area as it is shown by a significant difference of its reservoir pressure at the end of contract year. Furthermore, the design of production network planned for Senoro Field also indicating huge pressure losses will be encountered by the southern area wells.

To solve the problem, a new study has been conducted to optimize the development plan. The method used in this study is dynamic coupling simulation by connecting reservoir simulation and surface network system into a single package of simulation run. This study has successfully optimized the Senoro field depletion plan to achieve the target 13 years of plateau time. Strategies used to achieve the target are by rescheduling well, utilizing pressure booster in southern area, installing gas compressor after 9th years of production, introducing horizontal well S-22hw to substitute well S-22, and reducing the number of well to 19 from the original plan of 21 wells.
Introducing a Producible Oil Water Contact (POWC) for Better Assessment of Moveable Oil in the Transition Zone
Authors: Doerband Robert
Published: April 2013

An exploration campaign of RWE Dea AG has discovered several oil fields in carbonate reservoir layers. Log analysis shows that most of the wells have a very long transition zone above Oil Water Contact (OWC). The lower part of the oil column above OWC contains significant amounts of non-producible oil. The length of this zone may falsify the economic significance of the oil column, which appears as too large.

An additional hydrocarbon contact is defined and named „Producible Oil Water Contact - POWC". The differentiation between moveable and unmoveable oil in the transition zone helps to identify and assess the producible oil in a more appropriate way. This level may be determined by using fractional flow curves. In this case the contact level is a derived value for water saturation that relates to a specific water cut at surface conditions. If dynamic reservoir modeling is available the POWC can be also determined based on 3D-simulation results, at the lowest level where oil begins to flow.

In order to comply with the industry standards for definition of OWC the methods available will be discussed and it will be verified if the newly introduced POWC fulfills common best practice and can be used as supplement.

The effect of applying the POWC on oil-in-place calculations and recovery factor is shown with an example for application in reservoirs with long transition zones. It is aimed to concentrate resource calculations to the levels with economically producible oil, in order not to artificially inflate oil-in-place volumes and keep recovery factors reasonable. Furthermore, improved contour mapping based on new POWC can help to find locations for wells with better oil productivity.
Effect of Capillary Pressure on the Numerical Simulation of Conventional and Naturally Fractured Reservoirs
Authors: Shams M.. , El-Banbi A. H. , Khairy M..
Published: April 2013

Engineers involved in numerical reservoir simulation studies typically use capillary pressure for model initialization. However, the effects of capillary pressure on reservoir performance may not be fully understood for different drive mechanisms.

The aim of this work is to show the effect of both oil-water and gas-oil capillary pressures on reservoir performance for reservoirs producing under natural depletion, water injection, and gas injection recovery processes over a wide range of reservoir and production parameters. Both conventional and naturally fractured reservoirs are studied.

For fractured reservoirs, both matrix and fracture capillary pressures effects were investigated when capillary pressure imbibition is the only drive mechanism and when both capillary pressure imbibition and gravity drainage recovery mechanisms are active together. To quantify this effect, simulation results of large and small transition zones were compared with models of zero transition zones and three difference indicators were calculated for each run. Hundreds of runs were made to quantify these effects in a variety of reservoir heterogeneity levels.

It was found that capillary pressure effects are different for different recovery processes. While capillary pressure is usually important for initialization, it may not be as important during flow calculations in every situation. Capillary pressure was more important in depletion runs than in most displacement runs. No clear correlation exists between capillary pressure effects and the level of reservoir heterogeneity. It was also found that fracture gas-oil capillary pressure effects increase in certain conditions for naturally fractured reservoirs. A real reservoir model was also used to confirm the results obtained from hypothetical models and validate the study conclusions. Finally, guidelines were developed to show when capillary pressure was important and when it can be ignored.
Overcoming the Typical Operational Problems & Cost of Water Injection Using Dumpflooding
Authors: Helaly Rami , Bekheit A.. , Farahaty M.. , Tawfik M..
Published: April 2013

Meleiha North East oil Field is located in the Egyptian Western Desert. Its estimated value for the OIIP is 125.5 MMSTBO. The field started production in the year 1986 and was subjected to 4 years of natural depletion. The reservoir mainly consists of three producing layers; all are heterogeneous with local poor horizontal connectivity and low natural pressure support. Consequently, and during that period of natural depletion, the recovery of only 14.7 MMSTBO caused the reservoir pressure to decline from an initial value of 2300 Psi to 1000 Psi; a slope of approximately (-325 Psi/year). After applying water-injection in the year 1990, the pressure decline-slope got reduced to (-30 Psi/year). Currently the field contains 27 producers and 3 injectors. The distance to the nearest water-source well is approximately 10 Kilometers.

Maintaining continuous injection remained a challenge due to the typically associated operational problems; the long length of the injection lines increased the frequency of line leakage, corrosion, and blockage. Both water-source and injection wells require regular maintenance operations to handle problems such as casing leaks and ESP's maintenance. The necessity of flushing the injection lines after each operation results in additional time losses. Other problems maybe related to issues with the injection plant. All of these operational difficulties eventually affect the reservoir pressure performance and consequently decrease the production performance.

As an attempt to improve the performance of water injection, a dump-flood project was initiated. The idea is based on using the pressure differential between the perforated intervals within a single well to drive the water coming from a relatively high pressure water-bearing zone to a lower-pressure oil-bearing zone(s). Well NE-41 was initially drilled as water injector. The RFT measurements indicated that the pressure in three oil bearing zones (B-I, III & IV) averaged around 400 Psi, while the pressure in a water-bearing zone (B-VI) was found to be 2250 Psi. Hence, the well was selected to be a pilot for dumpflooding. After completing the well as planned, a PLT was performed and its results indicated that the water-bearing zone produced 1100 BWPD that were distributed among the three recipient zones. The project therefore was considered successful for the following reasons: Avoiding all the typical operational problems such as surface leakages, casing leakages, and ESP's maintenance,Providing a minimum cost for supplying the reservoir pressure by water injection.
Downhole Testing Tools in Extreme Hostile Environments: HP/HT Offshore Well - Northeast Brazil
Authors: Marcançola Fernando , Pontes Thiago , Adriano Marcio
Published: April 2013

Hydrocarbon production and exploration has ventured into deeper, more hostile environments, and this change has required continual operational change to enable operators to address the challenges presented by the more hostile environments into which exploration has now moved. Testing technology has had to redefine the operating envelopes for its scenario to meet the requirements presented by the more extreme conditions in the newer environments. Not only high-pressure and high-temperature tools have been needed, but tools that are more debris-tolerant have been needed as well.

This paper discusses the application of downhole testing tools in formation evaluation jobs in extremely hostile environments; these include testing in such conditions as: Ultra-deep waterExtreme high-pressureExtreme high-temperatureDebris presence.

Case history information will also be presented where a downhole testing operation was performed in a high pressure and high temperature offshore well northeast of Brazil.

The definition of ultra-deep water is when wells have at least 10,000 feet of water depth, and HP/HT well environments include those with bottomhole pressures above 10,000 psi and bottomhole temperatures above 300° F. When environments have bottomhole pressures above 15,000 psi and temperatures above 350° F, the wells are considered as extreme HP/HT.

Many testing operations have been severely challenged by these scenarios as downhole tools available for standard projects only could function efficiently to approximately 350° F and up to 10,000 psi of pressure. Now, special tools are available for conditions with temperatures of up to 450° F and 30,000 psi of hydrostatic pressure with maximum 15,000 psi of differential pressure. To function in higher pressures and temperatures, the drill-stem test (DST) string design should meet its capabilities and scenarios variation should be considered.

The addition of these tools has enabled high-quality well testing to be performed safely, and when the tools are used in wells where solids problems are not anticipated and unexpected debris does occur, they can avoid the unexpected rig time previously required to clean the well, further enhancing economic efficiency. Debris-tolerant tools also have allowed fracturing and acid operations to be performed with a test string, and with the same string, the well can be opened to a well-testing operation without compromising the functioning of the downhole tools. This capability saves time and adds economic value to the job.

This paper also discusses how formation evaluation jobs now can be performed satisfactorily in extremely hostile wells using the improved technology and the best practice information that has now been gained concerning testing in in this type of scenario.
Permanent Magnet Motor application for ESP Artificial Lift
Authors: Refai Ahmed , Abdou Hesham A.M. , Seleim Ahmed , Biasin Giovanni , Reda Walid , Letunov Dmitry
Published: April 2013

The majority of Western Desert wells (Agiba Petroleum Company) are completed with artificial lift systems and several kind of pump: ESP, Sucker Rod, PCP (about 40 ESP, 250 Sucker Rod and 10 PCP). A new technology - Permanent Magnet Motor (PMM) - has been developed for ESP motors as alternative to conventional asynchronous induction motor in the last years. PMM is synchronous motor in which the stator manufacturing technique is similar to that of conventional asynchronous motor, but rotor has permanent magnets (instead of copper winding). PMM has more benefit of conventional induction motor: high efficiency (90 94%) vs. induction motors up to 86%; smaller size and weight; wider ranges of rotation frequency regulation (100-1000, 1000-4200 and 3000-6000 r.p.m.); reduced energy consumption and rating of surface equipment (Power Saving); stable torque over wide operation range; Power factor is near to 1; lower specific heat release due to higher efficiency. Also indirect benefits are: a) low heat release (minimum cooling fluid velocity 0.05 ft/s); b) less size for cable and lower power rating for transformer and VSD; c) decreased reactive power; d) improved system Power factor. All Agiba ESP wells are equipped with conventional induction motor. In the middle of June of 2012 Agiba performed a trial installation of Novomet PMM replacing an ESP unit with induction motor on well North Nada 1 x (oil well - Qg =315 BFPD, Qn=173 BOPD) of North Nada field. The installation was successful achieving the expected results and benefits in term of low power consumption. Successful key point: keeping electrical system stability and minimize the number of shutdowns; minimum cost for power consumption and production.
Moving Towards Innovative Waste Water Treatment and Disposal Technologies: Field Study for In Situ Waste Water Treatment and Evaporation Technology
Authors: A. Moati Wael Hamed , Ibrahim Shaban
Published: April 2013

Produced waste water in oil and gas fields is a chronic headache from operational and HSE points of views. Many companies spend a lot of efforts and money to seek for the best produced water treatment and disposal. Whatever the technology applied; the main scope is to treat water and dispose it respecting the specifications imposed by the environmental affairs agency. However; this isn't the end of the story where the water disposal itself into water bodies or disposal wells can trigger in serious problems if water hasn't been treated well. Other companies -due to limitation of their existing waste water treatment plant capacities-are forced to trucking solution to transfer untreated water to other waste water plants operated by service companies.

In situ water treatment and evaporation of waste water is an innovative solution that allows to get rid of produced waste water in a safe and economical matter. The paper introduces a field study carried out in gas processing plant "El Gamil plant" located at Portsaid city on the Northern east coast of Egypt. The waste water production of the producing gas fields increased from 500 m3/d to about 3,000 m3/d. The existing waste water treatment plant capacity was limited to 500 m3/d, the matter that implies to seek for further solutions to avoid trucking option. In situ water treatment and evaporation was selected to apply in a pilot project with capacity of 500 m3/d to expand it in case of successful implementation.

The results show that technology is reliable but in certain applications and sites. In particular; if the oil content of the waste water is in the form of free phase where the water treatment will be based on physical separation in settling tanks and oily water separator to remove the oil phase and dispose water in to atmosphere using atomizers.

The paper will study with the parameters that can affect the success of this process highlighting the appropriate conditions for its applications.
Production Enhancement in the Egyptian Western Desert using the Channel Fracturing Technique – A Field Case Study
Authors: Samir M.. , Kamal M.. , Mathur A.. , Semary M.. , Yosry M.. , Bernechea J. M. , Kamar A.. , Mokhtar A..
Published: April 2013

The Abrar field in the Egyptian Western Desert produces mainly from the Abu Roash formation that is characterized as a complex, thin-bedded sequence with heterogeneous laminated siltstones. Hydraulic fracturing has traditionally been employed to produce hydrocarbons from these marginal reservoirs. This paper describes the application for the first time of a novel channel fracturing technique combined with rod-shaped proppant in selected production targets in the Abrar field. The channel fracturing technique introduces channels within the proppant pack that increase conductivity and effective half-length leading to increased productivity. Rod-shaped proppant when used as tail-in in fracturing treatments increases near-wellbore fracture conductivity and prevents proppant flowback due to its particular geometry.

Many sedimentary features of hydrocarbons in the Western Desert in Egypt are characterized as multi-layered, deltaic, thinly and tight laminated sandstones and siltstones consisting of sands with limited lateral and vertical extension with an average permeability of 1-3 mD and Young's modulus in the order of 2.5 – 3.0 million psi.

The channel fracturing technique was first introduced in the Egyptian Western Desert in late 2011. Since then several wells have been fractured using this technique and the production evaluation of these wells has been compared to offset wells fractured with conventional hydraulic fracturing techniques. Further, the application of rod-shaped proppant has provided excellent proppant flowback control as demonstrated by zero proppant flowback. Initial and long-term normalized production of the wells fractured with this technique increased significantly over offsets fractured conventionally. The positive results from implementation of this combined stimulation technique have led to a vigorous expansion of its utilization throughout Egypt's Western Desert area.
Best Practice to Design and Interpret Interference Tests Based on Features of the Line-Source Solution: Theory and Application
Authors: Maizeret Pierre-David
Published: April 2013

Interference testing is the oldest, but still the most effective, way of establishing communication between wells and determining the interwell reservoir transmissibility. However, these tests are not frequently run because the results are commonly difficult to analyze due to unforeseen complications.

This paper presents several practical methods to design and interpret effective interference tests based on the properties of the line-source solution. In single-well transient tests, early-time features of the exponential integral function occur at times that are too early to be observed. However, the distinctive pressure transient derivative features appear at an observation well much later during an interference test, and can be used to estimate the storativity and transmissibility ratios of the reservoir. The pressure response and the log-derivative of the pressure intersect on the log-log diagnostic plot for the observation well and the pressure response itself exhibits an inflection point. Based on these characteristics, simple geometrical methods are proposed to estimate reservoir parameters. Moreover, we formulate a new expression for the "travel time", or delay in the response. The particular case of fall-off or buildup is studied in detail, as the time lag in reservoir response can bring extra information. A field example is included to demonstrate the application of these methods in a field case and their usefulness to a practicing well test engineer.
An Effective Knowledge Sharing Framework in Oil Sector: A Case Study from Sudapet
Authors: Ali Arif Abdelwhab , Wadidi Elfatih
Published: April 2013

Knowledge as ancient concept is used for leading decision making and projects set up. The possessed efforts in different projects conducted in oil sector resulted in a huge amount of data and knowledge within different types of handling media, where needs of knowledge sharing is raised and considered as one of the main objectives of the companies. The recognition of the Sudapet Company as a national company in this fields tends to set a framework for experience and knowledge sharing in a proper and scientific manner.

This paper explores the methods used in Sudapet Co. to frame the activities for knowledge sharing and setup the framework for the oil industry in Sudan. The key success factors are discussed such as top management support as well as the staff commitement. Several knowledge sharing techniques have been embedded into the framework to support ceating a learning organization. In addition, the challenges which have been facing the implementation of this framework have been highlighted.
Engineered LCM Design Yields Novel Activating Material for Potential Application in Severe Lost Circulation Scenarios
Authors: Savari Sharath , Kumar Arunesh , Whitfill Donald L. , Miller Matthew , Murphy Robert J. , Jamison Dale E.
Published: April 2013

Particulate lost circulation materials (LCM) that work for severe-to-total losses are difficult, if not impossible, to find. Solutions that are effective for lower loss rates do not perform well at higher loss rates. Many LCM formulations have been used to treat severe losses, but their design and use has been more trial and error based mostly upon successful case histories. This paper describes the development of a combination of materials that is used in conjunction with other Engineered, Composite Solutions (ECS) to further enhance their performance.

A novel combination of swelling materials, retarder, and fibers with a large aspect ratio is proposed as an activator that can be deployed with ECS typically available on the rig. The activator was designed and tested under conditions that qualitatively resemble severe lost circulation scenarios (large fractures). A shale swell meter was modified to qualitatively compare the swelling behaviour of different materials under different temperatures and retarder concentrations. A polyacrylamide-based swelling material was found to be sensitive to both temperature and retarder concentration. A newly sourced, potentially reservoir-friendly swelling material was found to be sensitive to temperature only. The activator-ECS combinations were tested for plugging capability with Permeability Plugging Apparatus (PPA) test equipment using different size tapered slots. Data from these modified PPA tests were used to determine the best combination of activator and ECS for plugging a particular-sized fracture simulated by the tapered slot.

Field applications of systems that led to this proposed approach are discussed along with laboratory data comparing the swelling behaviour of different materials as related to mixing and pumping times.
Characterizing Coal Bed Methane Using Pressure Buildup and Falloff Data Acquired with Wireline Formation Testers: Case Studies
Authors: Harfoushian Jack , Osman Magdy Samir , Zerba Cesar
Published: April 2013

Over the past few years there has been a surge of interest in coal bed methane (CBM) resources in many parts of the world. Also known as coal seam gas (CSG), CBM has become an important source of energy because of increasing global demand for cleaner fuels. CBM is distinct from conventional hydrocarbon reservoirs as methane is stored within coals by adsorption. With matrix porosity generally lower than 4%, cleats and fractures are the main conduits for production from coals. Given differences in structure compared to conventional reservoirs, drilling into coal seams requires the use of minimum overbalance and nondamaging fluids. In addition, evaluation of CBM reservoirs has many technical challenges. One of the main challenges is to ascertain coal cleat behavior and estimate permeability and ultimately productivity of a target zone. Traditionally this has been done by production or injection tests using conventional testing techniques. In Australia, a wireline-deployed straddle packer configuration was used to address this challenge, with demonstrated benefits for determining permeability and productivity.

Unlike traditional methods of conducting a closed chamber test across a large interval, this methodology uses a straddle packer with a downhole pump in a toolstring deployed on wireline. The packer spacing can be adjusted prior to deployment to suit the expected height of the coal bed to be tested. The tool is capable of both injection into and production from a coal bed interval with a much smaller storage volume compared to conventional test strings. Pressure is continuously monitored in real time ensuring that acceptable limits are not exceeded during either the injection or drawdown phases, to avoid excessive force on a coal seam while maintaining single-phase flow. The analysis of both drawdown-buildup and injection-falloff results reveals the strengths and limitations of the two techniques.
New Analytical Equations of Recovery Factor for Radial Flow Systems
Authors: Zhang He , Ling Kegang , Acura Herman
Published: April 2013

This paper presents analytical algorithms to calculate ultimate recovery factors for radial flow systems. The approaching method is similar to the well-recognized Buckley-Leverett equations, but it's accurate for matured fields, especially peripheral water-flooding reservoirs.

Buckley-Leverett displacement equations have been derived strictly from linear flow systems, and have been verified by linear flow experiments only. However, nowadays, it's very common to observe multiple water injectors drilled around producers to enhance the recovery factor in mature fields. New analytical equations that consider non-linear flow patterns are more appropriate for these types of operations.

The new equations proposed in this paper have been verified with real field data. The original Buckley-Leverett equation generally results in much lower recovery factors that barely match the cumulative production. Consequently, the estimated ultimate recovery (EUR) by volumetric methods tends to be too low. As a result, the production projections according to match this EUR are not reasonable when compared to the historical performance of the wells and Decline Curve Analysis (DCA). The proposed analytical model improves the prediction of reservoir performance. It works as an important supplement to the Buckley-Leverett method for oil fields worldwide.
Hydraulic Pumping Units Proving Very Successful in Deliquifying Gas Wells in East Texas
Authors: Beard David
Published: April 2013

Intensified US exploration and production activity in the liquids-rich shale plays has tended to overshadow issues with base gas production, particularly the continuing struggle to remediate liquid loading and return pressure-depleted wells to production. In recent years, Devon Energy has intensified efforts to maximize base gas production through deliquification of its mature East Texas wells. Accordingly, the operator has realized tremendous success with artificial lift, which is generating an average 50% rate of return and effectively breathing new life into many of its old and struggling wellbores. More recently, Devon has focused its efforts on the use of Hydraulic Pumping Units (HPU), which have recorded an amazing track record in deliquifying and returning to production low-rate gas wells that no longer respond to plungers, soap or velocity strings.

This paper examines Devon's experience using HPU to deliquify East Texas wells in reservoirs that vary from very low bottomhole pressure with high permeability to higher pressure with very low permeability and everything in between. The targeted wells range in depth from 5,000 ft to 10,000 ft with wellbores between 2 7/8 to 7 in. diameters. All of these well types have been put on pump and responded very favorably.

The authors will review case histories from several divergent East Texas well types to illustrate the efficiency of pumping units in restoring production to these lower fluid rate wells. The discussion will focus on a newly engineered HPU, which comprises a vertical hydraulic cylinder on the wellhead to reciprocate the rods and pump and offers a number of HSE, operational and economic advantages over conventional pumping units. The specific features that make the HPU a very viable and often preferred alternative to conventional pumping units will be detailed, as will the growing pains and subsequent lessons learned in the East Texas deliquification campaign. Owing largely to the impressive results in the East Texas production-restoration program, HPU technology has since expanded throughout other US gas basins where liquid loading has become a predominate issue.
Physiological Response of Forage Sorghum to Polymer under Water Deficit Conditions
Authors: Rostampour M. Fazeli , Yarnia M. , Khoee F. Rahimzadeh , Seghatoleslami M. J. , Moosavi G. R.
Published: April 2013

Sorghum [Sorghum bicolor (L.) Moench] is among the most important warm‐season forages that is grown in mainly arid and semiarid regions of southeastern Iran. Irrigation water is an energy‐intensive input and it is also becoming scarce and costly in this country. Soil application of polymeric materials such as Superab A200 (SAP) can increase soil water storage capacity and increase water use efficiency (WUE). The objective of this study was to investigate the effect of different rates of SAP and irrigation regimes on dry matter yield, WUE, and some physiological and yield‐related traits of Speedfeed sorghum. The experiment was conducted in Zahedan, Iran, during the 2009 and 2010 seasons under limited irrigation regimes (irrigation after 40, 60, 80, and 100% crop evapotranspiration = ETc) and four rates of SAP application (0, 75, 150, and 225 kg ha–1). Results indicated significant effects of irrigation regimes, SAP levels, and their interaction. The analysis for dry matter, WUE, and benefit/cost ratio showed that applying SAP at 100% ETc had no effect on these traits, but in the treatments with water deficit, it improved all the studied traits of sorghum. With regard to economic analysis, applying 75 kg ha–1 SAP for a decrease in the sorghum’s water requirement of as much as 20% is economically justified at moderate water deficits.
Integrating Cotton and Beef Production in the Texas Southern High Plains: III. An Economic Evaluation
Authors: Johnson Phillip , Zilverberg Cody John , Allen Vivien G. , Weinheimer Justin , Brown Philip , Kellison Rick , Segarra Eduardo
Published: April 2013

Economic viability of an agricultural economy is dependent on the availability of soil and water resources and how these resources are allocated within production systems. The semiarid Texas High Plains has highly productive soil and water resources from the southern Ogallala aquifer. Sustainability of its agricultural economy is threatened by depletion of the Ogallala aquifer, which underlies much of the region. The predominant production system within the region is monoculture cotton (Gossypium hirsutum L.). Long‐term (1999–2008), replicated research compared water use, productivity, and energy efficiency of a cotton monoculture system and an integrated cotton–forage–beef cattle (Bos taurus) system. Evaluation of the two production systems using mean input and output prices indicated that profitability during the 10‐yr period was not significantly different. During the last 6 yr, however, the cotton monoculture was more profitable due to the introduction of higher yielding cotton cultivars. The integrated system used 24% less applied irrigation, with irrigation efficiency similar to the cotton monoculture as measured by gross margin per hectare. Results indicate that where water availability is adequate, the cotton monoculture system has higher profitability than the integrated system, primarily due to the introduction of higher yielding cotton cultivars. The integrated system could be a viable alternative in areas of the region where irrigation is limited due to aquifer depletion and/or pumping regulation. The integrated system had less economic risk associated with the variation in profitability and added ecological diversity that benefited soil health and wildlife populations.
Soil Phosphorus Effects on Forage Harvested and Nitrogen Fixation on Canadian Organic Dairy Farms
Authors: Main Michael Hugh , Lynch Derek H. , Voroney R. Paul , Juurlink Shelly
Published: April 2013

Declining soil‐test phosphorus (STP) levels on eastern Canadian organic dairy farms is a concern because of potential negative impacts on forage growth and biological nitrogen fixation (BNF). This study examined the relationship between STP, forage productivity, and BNF on organic or transitional‐organic dairy farms in Ontario (ON) and Nova Scotia (NS). More than two‐thirds of 28 legume–grass mixed forage fields in the study were low in available P by provincial soil‐test guidelines. Averaged across all fields over 2 yr, forage legume proportion was 46%, forage harvested 5.9 Mg ha–1, BNF 64 kg ha–1, and N harvested 153 kg N ha–1. Forage tissue P concentrations were clearly correlated with STP in the low soil‐test categories (<10 mg Olsen P kg–1 of soil in ON; <30 mg Mehlich‐3 P kg–1 of soil in NS), above which there was little response. Inclusion of soil total P or organic P did not improve the fit of regressions. However, STP explained a very small fraction of variation in forage harvested and BNF. Ninety percent of tissue P concentrations were above 2 g P kg–1 of tissue, a frequently cited critical minimum, and the only apparently P deficient forage crops were on fields that received no manures or fertilizers for more than 5 yr. In the term of this study, low STP was apparently not having a significant impact on forage harvested or BNF on the majority of eastern Canadian organic dairy farms. This result may not apply to seedling‐year forages or other crops.
Impacts of Thirty‐Seven Years of Stocking on Soil Phosphorus Distribution in Bermudagrass Pastures
Authors: Silveira Maria Lucia , Rouquette F.M. , Haby Vincent A. , Smith Gerald R.
Published: April 2013

Pasture management affects soil properties, but information concerning the effects of long‐term stocking and fertility regimens on soil P in pastures is limited. This study investigated changes in extractable soil P concentrations from Coastal and common bermudagrass [Cynodon dactylon (L) Pers.] pastures stocked for 37 yr at different intensities on an Ultisol. From 1969 through 2004, pastures were continuously stocked during February to September to achieve high, medium, and low herbage mass. Annual fall‐applied P averaged 44 kg ha–1 from 1969 to1984 and 51 kg ha–1 from 1998 to 2004. Extractable soil P concentrations in the 0‐ to 15‐cm depth increased (P ≤ 0.0001) from 5 mg kg–1 (very low) in 1975 to 43 mg kg–1 in 2004 (high), and deeper depths showed 14 to 36% increased P levels. Elimination of P fertilizer for 13 yr, 1985 to 1997, decreased (P ≤ 0.0001) extractable soil P in the 0‐ to 15‐cm depth by 30 and 47% in common and Coastal bermudagrass pastures, respectively. An interaction between year and stocking rate was evident as extractable P levels increased after 20 yr at high stocking rates. After 37 yr, extractable P levels at the 0‐ to 120‐cm soil depth followed the order high > medium ≥ low stocking rate. Despite the effect of stocking rate on soil P, 37 yr of continuous stocking showed no evidence of excessive P accumulation at levels that may pose an environmental threat. Phosphorus recycled through the soil–forage–animal system sustained adequate forage and animal productivity.
In Vivo Assessment of Pulmonary Arterial Wall Fibrosis by
Intravascular Optical Coherence Tomography in
Pulmonary Arterial Hypertension:
A New Prognostic Marker of Adverse Clinical Follow-Up§
Authors: Domingo Enric , Grignola Juan C , Aguilar Rio , Montero María Angeles , Arredondo Christian , Vázquez Manuel , López-Messeguer Manuel , Bravo Carlos , Bouteldja Nadia , Hidalgo Cristina , Roman Antonio
Published: April 2013

Background:

The aim is to correlate pulmonary arterial (PA) remodeling estimated by PA fibrosis in PA hypertension (PAH) with clinical follow-up. Histology of PA specimens is also performed.

Methods:

19 patients, aged 54±16 (4 men), functional class II-III were studied with right heart catheterization, PA Intravascular Ultrasound and optical coherence tomography (OCT) in inferior lobe segment. PA wall fibrosis was obtained by OCT ( area of fibrosis/PA cross sectional area × 100). Patients follow-up was blind to OCT. Events were defined as mortality, lung transplantation, need of intravenous prostaglandins or onset of right ventricular failure.

Results:

OCT measurements showed high intra- and interobserver agreement. There was a good correlation between OCT and histology in PA fibrosis from explanted lungs. Area of fibrosis was 1.4±0.8 mm2, % fibrosis was 22.3±8. Follow-up was 3.5 years (2.5-4.5). OCT %Fib was significantly correlated with PA capacitance (r=-0.536) and with pulmonary vascular rsistance (r=0.55). Patients were divided according to the median value of PA fibrosis. There were 10 patients with a high (≥ 22%) and 9 with a low fibrosis (<22%). Events occurred in 6 (1 death, 1 lung transplantation, 2 intravenous prostaglandins, 2 right heart failure) out of 10 patients with high and in 0 out of 9 patients with low fibrosis (p<0.01).

Conclusions:

In PAH, the severity of PA remodeling assessed by OCT wall fibrosis was significantly predictive of severely unfavorable clinical outcome. In vivo assessment of pulmonary arterial wall fibrosis by intravascular OCT in PAH is a promising new prognostic marker of adverse clinical outcome.
Dioxidovanadium(V) complexes with pyridoxalaminoguanidine: Synthesis, spectral and structural characterization
Authors: Lalovic Mirjana , Leovac Vukadin , Vojinovic-Jesic Ljiljana , Rodic Marko , Jovanovic Ljiljana , Cesljevic Valerija
Published: April 2013

Three square-pyramidal complexes of dioxidovanadium(V) with
pyridoxalaminoguanidine (PLAG), of the formulas NH4[VO2(PLAG?2H)]?H2O (1),
VO2(PLAG?H) (2) and K[VO2(PLAG?2H)]?H2O (3) have been synthesized and
characterized by IR and UV-Vis spectral analysis and in case of 1 and 3 by
X-ray crystallography as well. The reaction of aqueous ammoniacal solution of
NH4VO3 and PLAG resulted in formation of 1, which in MeOH undergoes
spontaneous transformation into 2, which, in turn, in the reaction with KOH
transforms into 3. In these complexes PLAG is coordinated in a common
tridentate ONN mode, via phenoxide oxygen atom and nitrogen atoms of
azomethine and imino groups of the aminoguanidine fragment. In all previously
characterized complexes PLAG was coordinated in neutral form. However, here
we have proven that this ligand can be coordinated in both mono- (2) and
doubly deprotonated form (1 and 3) as well. [Projekat Ministarstva nauke
Republike Srbije, br. 172014].
Improving the public transit system for routes with scheduled headways
Authors: Chuang Jones , Chu Peter
Published: April 2013

This research contributes to the improvement of the optimal headway solution
for the transit performance functions (e. g., minimize total cost; maximize
social welfare) derived from the traffic model proposed by Hendrickson. The
purpose of this paper is threefold. First, we prove that that model has a
unique solution for headway. Second, we offer a formulated approximation for
headway. Third, numerical examples illustrate that our formulated
approximation performs more accurately than the Hendrickson?s.
Changes in Basal Body Temperature and Simple Reaction Times during the Menstrual Cycle
Authors: Šimić Nataša , Ravlić Arijana
Published: April 2013

Previous studies have shown cyclic changes in the activation levels and performance of different tasks throughout the menstrual cycle. The aim of this study was to examine if changes in the reaction time to both light and sound stimuli may be associated with basal body temperature changes and subjective assessments of General and High Activation during the different phases of a menstrual cycle characterized by high (preovulatory and midluteal phase) and low (menstrual and early follicular phase) levels of oestrogen and progesterone. The study included measurements of basal body temperature, simple reaction times to light and sound and self-assessment of General and High Activation during the menstrual, early follicular, late follicular and luteal phase. The sample consisted of 19 female subjects with regular menstrual cycles. The results obtained in this study indicate lower basal body temperature values during phases with low sex hormone levels, while the activation assessments suggest stable levels of both General and High Activation throughout the menstrual cycle. Similar patterns of change have been shown for reaction times in visual and auditory sensory modalities. Reaction times were shorter during phases characterized by high sex hormone levels, while phases with low hormone levels were associated with longer reaction times. From the modified text on correlations in the data analysis section, it is evident that they were calculated from averaged data from all phases of the menstrual cycle. Therefore, they do not reflect intraindividual but rather interindividual variations between the observed variables, and are not related to the hypotheses of this paper.
Biochemical and Histological Changes in Rat Liver Caused by Cypermethrin and Beta-Cyfluthrin
Authors: Bhushan Brijender , Saxena Prabhu N. , Saxena Nishi
Published: April 2013

Cypermethrin and beta-cyfluthrin are two most widely used multipurpose pyrethroids. After determining their oral LD50 (416.98 mg kg-1 and 354.8 mg kg-1 body weight, respectively), we assessed their hepatotoxicity in Wistar rats following acute (0.1 LD50 for 1 day) and sub-acute (0.1 LD50 for 7, 14, 21 or 28 days) poisoning. The assessment was based on hepatic marker enzymes AST, ALT, LDH, ALP, glycogen, total proteins, total lipids, cholesterol, free fatty acids, and phospholipids. AST, ALT, LDH, total lipids, cholesterol, phospholipids, and free fatty acids in hepatic homogenate increased following pyrethroid stress. In contrast, hepatic proteins, glycogen, and ALP activity decreased due to lysis of structural proteins and leakage of enzymes into the blood stream. Biochemical data were consistent with histological alterations (cytoplasmic vacuolisation, nuclear polymorphism, eccentric nucleus, karyolysis, karyorrhexis, and sinusoidal dilation). Comparatively greater hepatocellular damage was noted in beta-cyfluthrin than in cypermethrin-treated rats, which is probably related to the fluorine atom in beta-cyfluthrin.
Exposure to Urban Air Pollution and Bone Health in Clinically Healthy Six-year-old Children
Authors: Calderón-Garcidueñas Lilian , Mora-Tiscareño Antonieta , Francolira Maricela , Torres-Jardón Ricardo , Peña-Cruz Bernardo , Palacios-López Carolina , Zhu Hongtu , Kong Linglong , Mendoza-Mendoza Nicolás , Montesinoscorrea Hortencia , Romero Lina , Valencia-Salazar Gildardo , Kavanaugh Michael , Frenk Silvestre
Published: April 2013

Air pollution induces systemic inflammation, as well as respiratory, myocardial and brain inflammation in children. Peak bone mass is influenced by environmental factors. We tested the hypothesis that six-year-olds with lifetime exposures to urban air pollution will have alterations in inflammatory markers and bone mineral density (BMD) as opposed to low-polluted city residents when matched for BMI, breast feeding history, skin phototype, age, sex and socioeconomic status. This pilot study included 20 children from Mexico City (MC) (6.17 years ± 0.63 years) and 15 controls (6.27 years ± 0.76 years). We performed full paediatric examinations, a history of outdoor exposures, seven-day dietary recalls, serum inflammatory markers and dual-energy X-ray absorptiometry (DXA). Children in MC had significantly higher concentrations of IL-6 (p=0.001), marked reductions in total blood neutrophils (p= 0.0002) and an increase in monocytes (p=0.005). MC children also had an insufficient Vitamin D intake and spent less time outdoors than controls (p<0.001) in an environment characterized by decreased UV light, with ozone and fine particulates concentrations above standard values. There were no significant differences between the cohorts in DXA Z scores. The impact of systemic inflammation, vitamin D insufficiency, air pollution, urban violence and poverty may have long-term bone detrimental outcomes in exposed paediatric populations as they grow older, increasing the risk of low bone mass and osteoporosis. The selection of reference populations for DXA must take into account air pollution exposures.
Tree Pollen Spectra and Pollen Allergy Risk in the Osijek-Baranja County
Authors: Sikora Magdalena , Valek Marina , Šušić Zdenka , Santo Vera , Brdarić Dario
Published: April 2013

The forests of north-eastern Croatia, as well as various plants and trees in the parks and streets of the Osijek-Baranja County, produce large amounts of pollen during the pollen season, which can cause allergy symptoms in pollen sensitive individuals. The aim of this study was to determine the most frequent types of pollen in this area and estimate possible health risks, especially the risk of allergy. In 2009 and 2010, the staff of the Health Ecology Department of the Osijek Public Health Institute monitored tree pollen concentrations in four cities from the Osijek - Baranja County (Osijek, Našice, Đakovo and Beli Manastir) using a Burkard volumetric instrument. The results were affected by weather conditions. Windy and sunny days facilitated the transfer of pollen, whereas during rainy days, the concentration of pollen grains decreased. High pollen concentrations of Cupressaceae/Taxaceae, Betulaceae, Salicaceae and Aceraceae could be the cause for symptoms of pollen allergy. In 2009, conifers, birch and poplar pollen were dominant at all monitoring stations with 5000 pollen grains (PG), 3188 PG and 3113 PG respectively. The highest number of pollen grains was recorded at measuring site Osijek. The variations in airborne pollen concentration between pollen seasons were recorded at all monitoring stations. The most obvious variations were recorded at measuring site Osijek. The usual pollination period lasts two to three months, which means that most pollen grains remain present from February to early June. However, the Cupressaceae / Taxaceae pollination periods last the longest and their pollen grains remain present until the end of summer. The risk of allergy was determined at four monitored measuring stations and the obtained data confirmed that the largest number of days with a high health risk was at the Đakovo measuring station for a species of birch. The research information aims to help allergologists and individuals allergic to plant pollen develop preventive measures and proper treatment therapies.