bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Approach for Handling Unstable Wara Shale in Sabiriyah Field, North Kuwait
Authors: Nair Sajan , Alam Harry , Sitinjak Eri Sarmantua , Nugroho Cahyo
Published: October 2017

This article attempts to summarize measures that are required to be adopted in order to have safe drilling practices mainly in unstable shale formation and have a smooth landing section in target reservoir below the shale. For the last three years in North Kuwait, the number of geo-steering jobs increased significantly and some encountered problems while drilling Wara shale that may end up in losing tools and eventually the hole itself. This paper focuses on information regarding problems encountered in geo-steering jobs and the best practices followed to achieve goals. Stratigraphically, Wara shale lies underlying Tuba and overlying Mauddud carbonates. It has thickness variation in between 80 to 110 feet TVD. Wara shale in North Kuwait is generally unstable and very sensitive to mud properties and creates instability of the wellbore. A wide range of drilling data from well placement jobs were documented and analyzed in order to get an idea of the behavior of shale section, how to drill safely across this layer and mitigate possible risks that may harm the well as well as the tool. Detailed scrutiny was done to compare the drilling parameters, log responses, inclination and trajectory direction between stable and unstable wells. The results were integrated with regional tectonic regime in the area. The methodology and learning curve continuously improved with assimilation of new drilling data and information. Integrated study on all aspects in drilling that involving geo-steering engineers, drilling team, geologists and field engineers on-site has enhanced the ability to understand the situation in the hole and ultimately able to provide faster decision. It was observed that there is strong relationship of building inclination, direction of the well and mud weight in some wells when crossing Wara shale. Wells that have East - West or Northwest - Southeast direction tend to be unstable when compared to wells in North - South or Northeast - Southwest direction. Low incident angle (high inclination) will mostly cause more problems in drilling than high incident angle due to longer section of exposure as well as overburden. Compressional tectonic regime of the area dictate the recommendation of well trajectory should go towards maximum horizontal stress. Recommended to cross it with low inclination and consequently approaching the target reservoir with high dogleg severity tool was to maintain the stability of the wellbore. These findings will help service provider and client to make proper planning, adopt best practice, take proper decision and thereby successfully execute well operations. Indeed saving rig and delivery time that fulfill business objectives as planned.
An Engineered Workflow to Optimize an Openhole Multistage Acid Frac Design in Unconventional Horizontal Wells in North Kuwait
Authors: Ashqar Ayham , Chin Chao , El-Aziz Sabry Abd , Al-Ajmi Moudi , Robles Fernando , Mauro Rick , Nada Mohamed
Published: October 2017

Openhole (OH) multistage (MS) technologies can maximize reservoir contact and productivity by optimizing the distribution of acid across the formation matrix. Successful completion of these reservoirs can be challenging. This paper discusses the recommended practice for optimizing OH fracture stages and cluster placement distribution within heterogeneous unconventional oil carbonate reservoirs based on formation, completion properties, and reservoir fluid distribution.

Completion technology is based on distributing intelligent packers along the lateral section to develop the MS fracturing stages. Intelligent packer displacement influences fracture effectiveness and conductivity. Typical packer placement can undermine formation potential and productivity results. Packers and their ports are placed based on the formation's petrophysical and mechanical properties to increase the cumulative production in a shorter timeframe and help improve recovery. The workflow followed was based on analysis of the reservoir properties (porosity and permeability). These were later integrated with the measured rock mechanical properties. The developed integrated model was used to divide the rock into segments that share similar properties.

The use of an advanced azimuthal sonic with a high signal-to-noise ratio and wider frequency response helped improve the accuracy in assessing formation mechanical properties. Additionally, conventional logs, when combined with formation mobility measurements, help calibrate the permeability model and classify the formation into distinctive clusters. These clusters are then grouped according to their mechanical and brittleness properties to form a separate unit with a selected fracture port to help ensure the necessary fracture length. The developed method provides an opportunity to determine the necessary fracture stages and reduce the risks of over or underplacement. It also improves stage integrity, helps ensure better distribution of the acid across the formation matrix, and provides effective propagation of the fracture network.

The applied procedure follows an innovative workflow to optimize the fracture stage and cluster placement distribution across the reservoir using a new combination of advanced and conventional data acquisition and interpretation. The discussed case study demonstrates the benefits of engineered fracturing stage placement compared to a geometric displacement.
Sour Gas Compositions from the Analysis of Core Samples
Authors: Nederlof Peter , Fiorentini Pietro
Published: October 2017

A detailed understanding of the composition of sour gas accumulations is essential for facility design and for production forecasting. Compositional data like H2S and CO2 contents, net sales gas volume and condensate gas ratio also form the basis for all project economics. The acquisition of high quality fluid compositions is therefore a priority in all sour gas well evaluations. For conventional gas accumulations, PVT analysis of down-hole or well-head samples provides accurate and representative compositions of reservoir fluids. But in many sour gas accumulations, like the Marrat in North Kuwait, the prediction of future production streams is a difficult task. H2S levels are highly variable and the ‘point measurements’ from MDT fluid samples may not be representative for the entire reservoir unit. This paper describes a new approach to derive gas compositions from the analysis of core samples so that PVT compositions can independently be verified and H2S concentrations can be extrapolated away from the down-hole sampling points. The method is illustrated with two wells from an ultra-sour gas field in the Arabian Gulf region.

Core and cuttings samples from gas reservoirs contain trace amounts of adsorbed gas and condensate, which can be thermally extracted. The desorbed fluids can then be analyzed using existing geochemical technology and the molecular compositions of the condensate can be used to derive the composition of the gas that was trapped in the reservoir. Carbon isotope ratios can be measured on the gas that is desorbed from core samples and provide a second, independent parameter to estimate the original gas composition. The obtained fluid distributions are used to reconstruct the filling history of the sour gas accumulation.

The isotopic signature of the gas, together with the composition of the organo-sulfur compounds in the condensate, allow the reconstruction of fluid compositions, which are a critical input parameter for the reservoir simulators. Combining the results from the geochemical analysis with existing PVT data allows the extrapolation of the fluid compositions and the reconstruction the field-wide compositional gradients.

With H2S and CO2 concentrations varying between 5 and 35%, the production forecasting of sour gas accumulations can be subject to large uncertainties. Reconstructing the gas compositions from core and cuttings samples with geochemical techniques substantially reduces these uncertainties.
Engineered Bit Design and Drilling Parameters Mark Breakthrough Drilling Performance in Interbedded Damaging Carbonates
Authors: Agawani Waleed , Al-Ajmi Abdullah M. , Fawaz Wasim , Al-Rushoud Abdulaziz , Pandya Mehul , Al-Haj Hussain Ali , Abdelhamid Atef , El-Sherif Mohammed
Published: October 2017

West Kuwait's 22-in. section comprises a vertical hole through 3,500 feet of interbedded carbonates varying significantly in compressive strength, and drilled commonly with minimal or no fluid returns. The section is typically drilled with roller-cone tungsten carbide insert (TCI) bits because large polycrystalline diamond compact (PDC) bits are extremely costly and require expensive performance motors to support their generated torque. PDC bits are also at risk of impact damage when drilling through the interbedded formations in this interval. Operators tend to apply higher drilling parameters while in the lower compressive strength intervals to achieve higher rates of penetration (ROP). Consequently, when the TCI bit enters the following harder formations with the same high operating parameters, it often suffers severe cutting structure damage. The result is reduced ROP. Greater weight on bit is then applied, causing further bit damage and possible sealed bearing failure.

An engineering project was launched to develop a TCI bit specifically for the interbedded carbonates of this section. The primary challenges of the project were:

Ensure the bit finishes the section in one run Improve dull condition of bit coming out of hole Surpass current field average ROP consistently Maintain efficient cleaning at lower flow rates for drilling in complete fluid-loss scenario

Based on data and experience in drilling the application, an engineering process took place where several designs improvements with potential to improve performance were identified and trialled. Field engineers then worked onsite to identify how to drill the interval with optimal parameters for each sub-layer. The final design included:

Specialized TCI cutting structure for carbonate drilling High impact-resistant insert geometry Simulated hydraulic efficiency to improve hole cleaning Improved high aspect ratio elastomer seals designed to endure longer runs Specialized tungsten carbide to improve cutting structure durability

The engineering process yielded a design that successfully drills the complete section in one fast run - the fastest of the section - with an improved field average penetration rate to 63%, saving the operator more than 38% in associated cost for drilling the section. The application-engineered cutting structure enabled the use of lower drilling parameters than normal, thereby improving drilling efficiency and enhancing the post-drilling dull condition from the average of 3-3-BT to 1-2-WT.

The paper shows a case study in Kuwait demonstrating the engineering and results of designing a TCI bit matched to application.
Striving For Production-Injection Balance in a Giant Carbonate Reservoir in North Kuwait: Lessons Learnt, Smart Mitigations & Way Forward
Authors: Al-Shuaib Mariam , Chetri HB , Al-Sirri Dalal , Chong Mizan , Al-Zaabi Hamad
Published: October 2017

North Kuwait is an active asset with Sabiriyah Mauddud as the largest reservoir undergoing development using water flood. Initially with inverted 5 spot; followed by inverted 9 spot and ultimately with Produce High-Inject Low (PHIL) concept, Mauddud had witnessed a continuous testing of as to what is the best strategy to maximize sweep & recovery. The current focus is on striking a balance between production and injection so as to beat the impact of delays in water injection projects.

Several techniques for evaluation of rock, pressure-production; fluid/ PVT; injection water quality; segment reviews; network modelling for producer as well injection network have been either matured to top class stature or initiated with the help of IOC consultants. Out of box solutions to have more injection in needy segments; deferment of drilling of new producers in pressure sink areas; ESP upsizes in segments with excellent pressure support or inversely ESP downsizing in low pressure areas had been the tested options without significantly impacting the trajectory of production build up. Due diligence was conducted to have comprehensive integration & optimization of resources and setting up associated priorities based on the depletion indices, injection efficiency and Voidage replacement trend. Exercise was done to assess the volume of water being re-circulated without sweep benefits so as to mitigate via conformance actions. MOCs have been initiated to fast track injection into the reservoir, even before the major project for water injection facility comes up. Opportunities for aggressive dump flood have been investigated and action plan under implementation. Change in scope from producers to injectors in the drilling plan for 2017/18 & 2018/19 have been proposed for the health of the reservoir.

Sabiriyah Mauddud is the single largest producer of oil in North Kuwait since last 2 years as a result of effective water flood management. Grey areas and gaps, as evident from the present performance and upcoming challenging production targets are quickly being bridged so as to encash the subsurface booty of STOOIP in Sabiriyah Mauddud - SAMA.
Smart Entry into Multilateral Wells with Coiled Tubing Fiber Optic Telemetry
Authors: Coss Gabriel , Cruickshank Doran , Danish Syed , Ambrosi Giuseppe , Garcia Alexis
Published: October 2017

Verifying that conventional coiled tubing (CT) has entered the correct lateral of a multilateral well can be a time-consuming and tedious challenge. While passing the kickoff point (KOP), surface pressure sensors may not clearly identify that a hydraulic knuckle joint has entered the lateral. To verify which lateral has been entered, the CT must be run-in-hole (RIH) to tag the unique total depth (TD) of the lateral. It can be difficult to prove that the correct lateral has been entered if the TDs for two laterals do not differ significantly. If the CT tags before or after the expected TD is reached, then the operator must pull out of hole (POOH) and repeat this process.

This paper presents an improved method for detecting which lateral has been entered shortly after passing the KOP by using a real-time, fiber optic cable (RTFO) bottomhole assembly (BHA). The RTFO BHA is equipped with sensors for gamma radiation (GR), tool inclination, tool face, casing collar locator (CCL), internal and external pressure, and temperature. These readings enable the operator to use the CCL and gamma detector to correlate to the desired lateral’s pipe joints using an existing CCL/GR log. The tool face reading theoretically predicts which angle the knuckle joint should be indexed. The internal pressure sensor provides clear indication of pressure changes when a hydraulic knuckle joint has entered the lateral and the inclination sensor verifies that the inclination of the BHA matches the inclination of the desired lateral.

This paper discusses two dual-lateral water injection wells; the TDs of the laterals in the first well were equal, with no trait that conventional CT would be able to distinguish. In addition, the inclination of each lateral was very close to the other, making the difference of pipe weight, read from the surface, not significantly different enough to verify which lateral had been entered. However, with the RTFO BHA, the correct lateral was easily entered and verified, significantly reducing time, risk, fluids, and CT pipe fatigue, while providing assurance that the stimulation fluid was accurately placed.

This paper describes the first time that a flow-through gamma, inclination, tool face sensor module was deployed to accurately enter, identify, and stimulate a casedhole multilateral well without cycling the CT at the KOP, and without relying on tagging TD to confirm that the BHA is inside the desired lateral. The new process proved to be a better, more cost effective, and efficient way to stimulate multilateral wells. This solution can be used by operators to extend the life of their mature fields.
How to Use Drill String Vibration Data to Reveal Geology Phenomena in Geosteering Jobs: An Application Sensor at the Bit
Authors: Sitinjak Eri Sarmantua , Kurniawan Baladika , Besol Yusuf
Published: October 2017

Drillstring vibration information can be used to define the geology of the well. Some geological phenomena in horizontal wells can be revealed from drill string vibration data. Examples include faults, exiting and entering the reservoir, different lithology and rock strength. This paper aims to gather vibration data from drilled horizontal wells and classify them based on the geological and lithological environment in which they were observed. Uncontrolled vibrations can limit the optimization of drilling performance, for instance increasing the possibility of stuck pipe, affecting wellbore stability, reducing drilling tool life, and causing tool failure. Three major kinds of vibrations result from horizontal drilling; axial vibration, lateral vibration, and torsional vibration. We collect all vibration data and group them to relate the vibration behavior to the geology of the horizontal well. This information can then be helpful in geo-steering. We compare the vibration behavior in different geological situations; for example in clastic and carbonate environments, drilling through changing lithology, exiting the reservoir, and passing through a series of faults.

The objective of this paper is to enable engineers to characterize the vibration data according to potential risk factors that may be encountered during real-time geo-steering, and to take actions that optimize the drilling operation. Observations have revealed a strong correlation between vibration behavior and geological phenomena in the Kuwait oil fields. These observations enable confirmation of a variety of geological features from geo-steering modelling. Furthermore, adjusting drilling parameters and implementing good drilling practice this minimizes the tool exposure to excessive vibrations in order to avoid tool failure, and optimizes drilling operation. An understanding of the vibration data also can be used to help to geo-steer and support the justification for any adjustment in the lateral section. This will not be a proactive adjustment but more of a reactive adjustment. An additional objective is to find the best tool configuration in certain horizontal well environments, thereby improving the drilling optimization and enabling optimum procedures when encountering excessive vibrations. These findings will help drilling to control the well and contribute to the wellbore stability. This will be the first paper to characterize vibration behavior in relation to the geology phenomena in horizontal wells in Kuwait.
Water-Oil Emulsions with Fines in Smart Water Enhanced Oil Recovery
Authors: Arshad Muhammad Waseem , Loldrup Fosbøl Philip , Shapiro Alexander , Thomsen Kaj
Published: October 2017

Smart water flooding is an advanced method for enhanced oil recovery (EOR) in which the composition of injected brine is altered by varying the concentration of selected ions that can increase the oil recovery from various carbonate reservoirs. Besides wettability alteration mechanism, the formation of water-soluble oil emulsions has been reported as a possible reason to explain the observed increase in oil recovery using smart water. The formation of water-soluble oil emulsions takes place on the interaction of insoluble salts (fines) with oils. However, the interaction of these fines with the crude oil is not very well studied for carbonate reservoirs. This work presents emulsion formation in water-oil systems in the presence of water-insoluble fines. The effect of amount of fines on emulsion formation is also examined.

Synthetic seawater (SSW) and deionized water (DIW) were used as water phase, two model oils (decane (D) and 1:1 vol. ratio of hexane-hexadecane (HH) mixture) and North Sea crude oil (NSCO) were used as oil phase, and fines of CaCO3 (≤ 30 µm) and CaSO4 (≈ 44 µm) were used as solid phase. Branson Sonifier® SFX250 was used for emulsion formation (based on the principle of ultrasonic processing). All the experiments were performed for the same conditions of 5 minutes of ultrasonic processing at an output power of 30 W by using 6.5 mm tapered microtip (sonication probe). Emulsion characterization was done by using an optical microscope (Axio Scaope.A1).

Several combinations of water-oil-fines were tested. The tests consisted of control experiments (in which only water-oil without any fines were tested) and water-oil-fines experiments. In the control experiments (without fines), SSW did not show any tendency to emulsify neither with the model oils nor with NSCO. However, DIW showed clear tendency to emulsify with model oils and NSCO. Amongst model oils, DIW emulsified with HH better compared to decane. Similar results were observed in the water-oil-fines experiments. SSW did not form any emulsion with the model oils in the presence of fines of CaCO3 and CaSO4. However, significant amounts of emulsion formation were observed when DIW was sonicated with model oils and fines. HH formed more emulsions compared to decane. For NSCO case, both SSW and DIW formed a significant amount of emulsions with both types of fines (CaCO3 and CaSO4). An increase in amount of fines showed an increase in emulsion formation and a better emulsion stabilization. Sonication is a quick and reliable technique to screen out emulsion formation in different combinations of water-oil-fines.

This work will further develop our understanding of emulsion formation in the water-oil-fines systems.
Chemo-Thermo-Poromechanical Wellbore Stability Modelling Using Multi-Component Drilling Fluids
Authors: Ibrahim Adamu , Akanji Lateef , Hamidi Hossein , Akisanya Alfred
Published: October 2017

This project intends to develop an improved wellbore stability model based on poromechanics and non-equilibrium thermodynamics which describes the physico-chemical interactions between a multi-component drilling fluid and a reactive shale formation. Through finite element modelling, this model can be employed in wellbore stability studies in order to optimise drilling fluid formulation and mud weight selection. Specifically, we present the results of finite-element-finite colume based analysis of thermal and solute diffusion associated with wellbore heating and cooling effect on the reservoir system by drilling fluid over a period of time. Then, we solve the heat driven solute diffusion equation with thermal osmosis and solute diffusion coefficients.

This preliminary investigation indicates a gradual but steady increase in temperature in the near wellbore region during during heat energy disspation from the far-field region. A reverse process was observed during the cooling process with both indicating a constant solute mass fraction over the time limit
Evaluation of a Chemical Enhanced Oil Recovery EOR Application in A Heterogeneous and Low Permeable Oil Reservoir: Advanced Screening by Reservoir Simulation
Authors: Elhajjaji R. R. , Swedan A.. , Behr Aron , Awofodu D. D. , Hincapie R..
Published: October 2017

The potential of CEOR application in mature oil fields can be investigated using sector models of an appropriate boundary conditions. In this paper, we present an evaluation of feasibility study of surfactant and estimation of the incremental recoverable oil in a mature Libyan oil field assuming the availability of surfactant formulation with optimal performance at reservoir conditions. Overall permeability of reservoir rock is rather low which limits the applicable areas of CEOR applications.

Reservoir properties were characterized using an established optimization approach to define pilot areas that exhibit favorable conditions for chemical EOR flooding. An intensive study was accomplished to generate a sector model of an optimum boundary conditions that provide pronounced results to the Full Field Model (FFM). Typical laboratory data were used to design surfactant model at an ultra-low interfacial tension (IFT) of 10−3 mN/m. Furthermore, main parameters that could influence the results of surfactant model were optimized: flow rates, residual oil saturation (Sorc), correlated Capillary De-Saturation Curve (CDC), adsorption, and grid size effect.

Interstitial velocity of displacing fluid and capillary number were correlated to describe the effect of permeability variation on the ultimate residual oil saturation. Additional recovery by surfactant at current reservoir conditions appeared to be strongly affected by changing the correlated CDC. The estimated macroscopic efficiency of surfactant by the coarse and fine grid models indicates that the surfactant is being smeared in the coarse model, and consequently different pressure distribution in both models was observed after certain time of injection. Moreover, the predicted results illustrate the influence of any heterogeneity feature in reservoir properties on both microscopic (ED) and macroscopic (EV) sweep efficiencies of CEOR flooding.

In Addition to the lessons learned of proper simulation at field scale, a developed approach to evaluate the potential of CEOR at challenging reservoir conditions is introduced in this paper.
Application of Value Engineering and Life Cycle Costing Techniques for Offshore Topside Facility Projects: Towards Sustainability
Authors: Al-Yafei Ezeldine , Ogunlana Stephen , Oyegoke Adekunle
Published: October 2017

Most existing studies and literature show that both value engineering and life cycle costing concepts are not used in the upstream sectors of oil and gas, in particular in offshore brownfield projects. This paper will highlight the importance of applying these concepts at the conceptual stage of offshore topside facility projects in order to achieve quality at the lowest possible cost over the product design life, as well as considering the aspect of sustainability. The value engineering methodology and life cycle costing analysis stages are presented.

The paper presents four alternatives for structural materials to demonstrate the optimal solution from value engineering and life cycle costing concepts. The case application focused on steel grating as the traditional material used in offshore platforms, versus glass reinforced plastic (GRP) and aluminium gratings as new alternative materials. This method will provide the end users with an effective tool to select among competing alternatives.

This paper attempts to fill the gap in the existing knowledge in the upstream sector of the oil and gas industry, focusing on topside facility projects for offshore platforms by contributing to the following areas: applying value engineering and life cycle costing concepts to offshore topside projects at the conceptual and/or design stage.
Application of Noise and High Precision Temperature Logging Technology to Detect Tubing Leak in an Oil Well - A Case Study
Authors: Jalan Shiv Narayan , Al-Haddad Saud , Ali Shareefa Mulla , Al-Hamli Dalal , Prosvirkin Sergey , Aristov Sergey
Published: October 2017

Leak in well bore tubulars & packers leads to communication between tubing/casing or Short/Long strings thus causing enormous production losses in Oil & Gas industry. Moreover, it can cause cross flow between different reservoirs. Sometimes leak may lead to charging of shallow formations thus posing a big threat to well integrity. The detection of the source of communication presents a big challenge to the industry. Knowing the precise location of a leak helps in designing an effective remedial action thus reducing downtime and repair costs.

When a fluid leaks, it moves from the high-pressure side through the leak point to the low-pressure side, where it expands rapidly and produces a turbulent flow creating noise and temperature changes. Conventional noise and temperature tools are not capable of detecting the leak point with high confidence. However, the new generation Noise and Temperature logging tools have been able to locate such leaks precisely.

This paper presents successful use of Spectral Noise Logging in combination with High Precision Temperature logging (HPT-SNL) in a dual-completion oil well in Kuwait Oil Company for identifying communication between the long and the short tubing strings. The acoustic tool contains a new-generation, high-sensitivity hydrophone – a piezo crystal element that records noise in a wide frequency range (0.1 – 60 kHz). Temperature tool utilizes a super-sensitive platinum sensor with a response time of less than one second. Leak was detected at the bottom blast joint of the long string that was causing water entry into the short string thus killing the well. The technology can be used in critical oil and gas wells to identify tubing and casing leaks and address well integrity issues. It can also be used in water injection wells to identify the zones of water intake.
Application of Memory Concept on Petroleum Reservoir Characterization: A Critical Review
Authors: Miah Mohammad Islam , Deb Pulok Kanti , Rahman Md. Shad , Hossain M. Enamul
Published: October 2017

Petroleum reservoir rock and fluid properties vary during any pressure disturbances or thermal actions in the reservoir formation. It is important to consider the rock properties such as permeability, porosity, etc. and fluid properties such as viscosity, PVT properties etc. as a function of time for applications including geothermal actions, chemical reactions, and other geological activities in the sub-surface of the reservoir complex structure. Memory is the effect of past events on the present and future course of developments. The continuous alteration of rock/fluid properties can be characterized using memory concept. It is also significant to consider the rock, and fluid properties as a function of time, and the inclusion of recently introduced memory concept in petroleum engineering study. In this paper, a detailed review of the existing techniques and models of reservoir characterization is presented. This study will provide an inclusive information on the present status of memory-based fluid flow modeling, rock and fluid properties models development under spurious assumptions during reservoir characterization. The variations of porosity and permeability over the distance are presented which are from the wellbore towards the outer boundary of the reservoir with time in actual reservoir conditions. Reservoir porosity and permeability are directly related to the reservoir formation depth and pressure. Reservoir porosity and pressure are decreasing over time. Permeability is changed over distance because it is directly related to the pressure of the complex reservoir system. In addition, the viscosity is a function of temperature of crude oil. Since memory-based diffusivity equation through porous media is more rigorous, as it incorporates continuous alteration of rock and fluid, and viscosity of oil predicts results from memory models should be preferred and reliable during the convergence process in reservoir simulators. This paper also aids as an insight of the future research opportunity toward developing models for reservoir properties, and models for fluid flow through porous media in the complex reservoir by the application of memory concept.
Research Advances on Tall Fescue Salt Tolerance: From Root Signaling to Molecular and Metabolic Adjustment
Authors: Amombo Erick , Li Huiying , Fu Jinmin
Published: October 2017

Soil salinity is one of the major abiotic stress factors that constrain plant growth and limit crop productivity. About a quarter of the global land area is affected by salinity; therefore, there is increased need to develop salt-tolerant crops. Tall fescue (Festuca arundinacea) is one of the most important cool-season turfgrasses, which has medium tolerance to salinity and has a promising potential to be used as a turfgrass under saline conditions. However, up to now, the maximum use of tall fescue under salinity stress is still limited by inadequate scientific literature. Recent studies have attempted to identify various adaptive responses to salinity stress at molecular, cellular, metabolic, and physiological levels in tall fescue. The successful integration of information concerning signal sensing, molecular tools with recent advances in -omics would certainly provide a clue for creating salt-tolerant tall fescue. Because salinity limits water availability to plants via hindering water absorption, and by inducing physiological drought, here we review and propose a probable mechanism of tall fescue response to salinity stress and to similar effects induced by drought based on published literature.
Photochemical Acclimation of Three Contrasting Species to Different Light Levels: Implications for Optimizing Supplemental Lighting
Authors: Zhen Shuyang , van Iersel Marc W.
Published: October 2017

Photosynthetic responses to light are dependent on light intensity, vary among species, and can be affected by acclimation to different light environments (e.g., light intensity, spectrum, and photoperiod). Understanding how these factors affect photochemistry is important for improving supplemental lighting efficiency in controlled-environment agriculture. We used chlorophyll fluorescence to determine photochemical light response curves of three horticultural crops with contrasting light requirements [sweetpotato (Ipomea batatas), lettuce (Lactuca sativa), and pothos (Epipremnum aureum)]. We also quantified how these responses were affected by acclimation to three shading treatments-full sun, 44% shade, and 75% shade. The quantum yield of photosystem II (ΦPSII), a measure of photochemical efficiency, decreased exponentially with increasing photosynthetic photon flux (PPF) in all three species. By contrast, linear electron transport rate (ETR) increased asymptotically with increasing PPF. Within each shading level, the high-light-adapted species sweetpotato used high light more efficiently for electron transport than light-intermediate lettuce and shade-tolerant pothos. Within a species, plants acclimated to high light (full sun) tended to have higher ΦPSII and ETR than those acclimated to low light (44% or 75% shade). Nonphotochemical quenching (NPQ) (an indicator of the amount of absorbed light energy that is dissipated as heat) was upregulated with increasing PPF; faster upregulation was observed in pothos as well as in plants grown under 75% shade. Our results have implications for supplemental lighting: supplemental light is used more efficiently and results in a greater increase in ETR when provided at low ambient PPF. In addition, high-light-adapted crops and crops grown under relatively high ambient light can use supplemental light more efficiently than low-light-adapted crops or those grown under low ambient light.
Downregulating a Type I Metacaspase in Petunia Accelerates Flower Senescence
Authors: Chapin Laura J. , Moon Youyoun , Jones Michelle L.
Published: October 2017

Metacaspases are cysteine proteases from plants, fungi, and protozoans that have structural similarity to metazoan caspases. They play a critical role in programmed cell death (PCD) induced by developmental cues and environmental signals. In this study, a type I metacaspase (PhMC1) was identified and characterized from Petunia ×hybrida ‘Mitchell Diploid’ (MD) (petunia). The recombinant PhMC1 had activity against the metacaspase substrate Boc-GRR-AMC (GRR). Activity was highest at pH 7–9 and was dependent on the active site C237. Quantitative polymerase chain reaction (qPCR) showed that PhMC1 transcripts increased at a later stage of petal development, when corollas were visibly senescent in both pollinated and unpollinated flowers. Gene expression patterns were similar to that of the senescence-related gene PhCP10, a homolog of Arabidopsis thaliana (arabidopsis) AtSAG12. PhMC1 transcripts were upregulated in the petals by ethylene treatment. This ethylene regulation did not require protein synthesis, indicating that PhMC1 is a primary ethylene response gene. Metacaspase-like activity against Boc-GRR-AMC increased in protein extracts from senescing petals. RNAi was used to knock down the expression of PhMC1. Transgenic PhMC1 petunias had no abnormal, vegetative growth phenotypes under normal greenhouse conditions, but flower senescence was accelerated by an average of 2 days.
Winter Wheat Yield Prediction Using Normalized Difference Vegetative Index and Agro‐Climatic Parameters in Oklahoma
Authors: Zhang Ning , Zhao Chen , Quiring Steven M. , Li Jinlin
Published: October 2017

Core Ideas

Normalized difference vegetative index has a stronger correlation with yield than moisture and temperature indices.

Optimal winter wheat model includes normalized difference vegetative index, moisture and temperature variables.

All three variables have different periods during which they are important.

Model can accurately predict winter wheat yield one month before harvest.

Gridded data outperform station‐based data for county‐level yield prediction.

This article develops a model for predicting winter wheat (Triticum aestivum L.) yield variations in Oklahoma, based on vegetation, moisture, and temperature conditions. A common model structure is identified using stepwise regression with one vegetation indicator (normalized difference vegetative index, NDVI) during wheat jointing and anthesis stages (March and April), one moisture indicator at emergence period (October and November), and one temperature indicator (temperature index, TI) at emergence, jointing and anthesis stages (October, March, and April). The final model accounts for ∼70% of the variation in winter wheat yield and can be used to forecast yields 1 mo before harvest. Spatially, it performs best in the northern and central portions of the Oklahoma winter wheat belt. Model performance is similar regardless of which moisture index is used. The correctly predicted yield variations in at least 9 of the 14 counties every year, and in the best case it correctly predicted yield variation in all counties. Our results also demonstrate that the gridded meteorological data generally outperforms the station‐based data for yield prediction at county level. The methods used in this study can be applied to identify the most significant variables and growth stages for winter wheat yield prediction in other regions.
Late‐Split Nitrogen Applications Increased Maize Plant Nitrogen Recovery but not Yield under Moderate to High Nitrogen Rates
Authors: Mueller Sarah M. , Camberato James J. , Messina Charlie , Shanahan John , Zhang Hao , Vyn Tony J.
Published: October 2017

Core Ideas

Late‐split N applications at V12 increased total N uptake and N recovery efficiency.

Gains in N recovery with late‐split N came from increased post‐silking N uptake.

Increased whole‐plant N accumulation by R6 did not result in increased grain yields.

Grain yield was not sensitive to in‐season N timing in this single‐location study.

Newer (2012, 2014) and older (1993, 1995) hybrids respond similarly to late‐split N.

Theoretically, N losses are reduced by synchronizing fertilizer additions with plant uptake requirements. We investigated the impacts of supplemental, late‐season N applications on nitrogen fertilizer recovery efficiency (NRE), and N accumulation and partitioning in maize (Zea mays L.) at silking (R1) and physiological maturity (R6). Also tested was whether modern hybrids responded differently to split‐N applications compared to hybrids released 20 yr ago. We compared 3 to 4 N rates ranging from 0 to 245 kg N ha−1 applied either in a single application at V3, or split with the last 45 kg N ha−1 delayed until V12, over 3 yr. Two newer hybrids (2012 and 2014) and two 1990 era hybrids (1991 and 1995) were compared at all N treatment combinations. Additional plant N accumulation following late‐split N applications was already apparent at R1, particularly in stems. Late‐split N application increased both whole‐plant R6 N accumulation and NRE through higher post‐silking N uptake. However, these benefits were rarely accompanied by increased grain yields. We found little evidence of differential hybrid responses to N rate or timing treatments. Principal component analysis revealed that the most consistent predictor of high post‐silking N uptake was lower N remobilization during grain‐fill; these had a strong inverse relationship. Therefore, gains from N management programs aiming to increase post‐silking N uptake are most likely in environments where whole‐plant N accumulation at R1 (and, consequently, potential N remobilization) is reduced. Further studies of late‐split N approaches are most warranted at lower total‐season N rates.
Species‐Specific Contributions to Productivity and Weed Suppression in Cover Crop Mixtures
Authors: Holmes Ashley A. , Thompson Ashley A. , Wortman Sam E.
Published: October 2017

Core Ideas

Mustard, oat, sudangrass, and buckwheat were the most productive cover crops.

Excluding mustard from spring mixtures sometimes increased weed biomass.

Excluding sudangrass from summer mixtures sometimes increased weed biomass.

Forage radish was less productive, but suppressed weeds in monoculture and mixture.

Cover crops can provide many ecosystem services and on‐farm adoption is increasing. Cover crop mixtures are popular, but little is known about the functional contributions of individual species in mixture. On‐farm field studies were conducted across 3 yr (2014–2016) and two locations (organic farms in central and northern Illinois) to assess the productivity and weed suppressive capacity of 12 cover crop species planted in monoculture and in mixture. Species were split into two equal (six species each) and seasonally appropriate groups (cool vs. warm season), planted in all possible monocultures and five‐way mixtures (divided proportionally to monoculture rates), and compared with a weedy control. Mustard [Brassica juncea (L.) Czern.] and oat (Avena sativa L.) were among the most productive (as much as 4.48 and 3.95 Mg ha−1, respectively) and weed suppressive spring cover crops. In 2 of 5 site‐years, excluding mustard from five‐way mixtures resulted in increased weed biomass. Sudangrass [Sorghum bicolor (L.) ssp. Drummondii] and buckwheat (Fagopyrum sagittatum Moench) were typically the most productive summer cover crops (as much as 8.78 and 7.11 Mg ha−1, respectively) and also reduced weed biomass. In 2 of 6 site‐years, excluding sudangrass from the mixture led to increased weed biomass. Forage radish (Raphanus sativus L.) had less aboveground biomass, but reduced weed biomass by 45 to 100%. Results are among the first to document species‐specific contributions to an ecosystem service in cover crop mixtures, and can be used to inform recipes for mixtures designed for greater productivity and weed suppression.
Soil Salinity of an Urban Park after Long‐Term Irrigation with Saline Ground Water
Authors: Ganjegunte Girisha K. , Clark John A. , Sallenave Rossana , Sevostianova Elena , Serena Matteo , Alvarez Guillermo , Leinauer Bernhard
Published: October 2017

Core Ideas

Changes in soil salinity after 46 yr of irrigation.

Using electromagnetic induction to map soil salinity and sodicity.

Correlate soil salinity with irrigation system distribution uniformity.

Chamizal National Park, located in El Paso, TX, extends over 140,000 m2 and has been irrigated with saline water for 46 yr. In recent years, turf areas in the park have severely degraded and bare spots have developed. Root zone salinity and sodicity were suspected to be the main reasons for the turf conditions. Developing salinity management and remediation strategies to improve turf quality requires information on the distribution of salinity (ECe) within the turf root zone. Electromagnetic induction (EMI) uses apparent electrical conductivity (ECa) to delineate salinity distribution, and is reportedly superior to traditional wet chemistry analyses. This study was conducted to investigate the spatial distribution of soil salinity and sodicity using the EMI technique. In addition, we assessed irrigation distribution uniformity and compared findings with root zone salinity and sodicity. The EMI data correlated well with saturated paste results and indicated that root zone salinity ranged from <1 to 43 dS m−1. In several parts of the park, ECe exceeded the threshold values for bermudagrass of 15 dS m−1. Root zone sodium adsorption ratio values ranged from <1 to 21 mmol1/2 L−1/2 and in areas where increased runoff and surface ponding were observed, values exceeded the threshold level of 12 mmol1/2 L−1/2. Correlation analysis between irrigation uniformity parameters and standard deviation of ECe and SAR values revealed that more than 90% of the variability of EC and SAR in the top 30 cm of the root zone could be explained by irrigation uniformity.
Calibration of Pasture Forage Mass to Plate Meter Compressed Height Is a Second‐Order Response with a Zero Intercept
Authors: Rayburn Edward B. , Shockey William L. , Seymour David A. , Smith Brad D. , Basden Thomas J.
Published: October 2017

Core Ideas

Forage density has a linear relation to pasture height.

The regression of forage density to pasture height is a measure of plant morphology within the sward.

Forage mass is the product of forage density and pasture height resulting in a second‐order relation with zero intercept.

The form of the second‐order relation of forage mass to pasture height can be diminishing return, linear, or exponential, depending on the distribution of forage density within the pasture.
Salicylic Acid‐Mediated Synthetic Elicitors of Systemic Acquired Resistance Administered to Wheat Plants at Jointing Stage Induced Phenolics in Mature Grains
Authors: Ramos Oscar F. , Smith C. Michael , Fritz Allan K. , Madl Ronald L.
Published: October 2017

Wheat (Triticum aestivum L.) grain contains phenolic compounds that act as antioxidants when the bran is included in the human diet. Plants produce phenolics as a defense response to, among other factors, insect and fungal attack, presumably acting through systemic acquired resistance (SAR). This study investigated this hypothesis using synthetic elicitors of SAR. Elicitor solutions known to express molecular markers of SAR were sprayed on plants of the hard red winter wheat cultivars ‘Karl 92’ and ‘Ike’ at the jointing stage (Zadoks scale 31). Treatments included 50 mM thiamine, 0.5 mM riboflavin, 0.7 mM 2,6‐dichloropyridine‐4 carboxylic acid (DCPCA), 1 mM benzo(1,2,3)thiadiazole‐7‐carbothioic acid S‐methyl ester (BTH), 44 mM methyl jasmonate, and 50 mM sodium salicylate (SS). Bran extracts from these plants were analyzed for total phenolic content with the Folin Ciocalteau assay. Thiamine, BTH, DCPCA, and SS treatments significantly increased total phenolic content in wheat bran extracts compared with unsprayed control plants, but only the salicylic acid analogs BTH and DCPCA enhanced the phenolic concentration by 22 and 17%, respectively, compared with solvent‐only plants (P < 0.004167). These findings support the hypothesis that salicylic acid‐mediated SAR is responsible for the phenolic response in wheat grains.