bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elemental Modeling of a Process Combining EOR with In-Situ-Upgrading in a Naturally Fractured Reservoir
Authors: Chávez-Morales Silvia , Pereira-Almao Pedro 
Published: April 2016

Abstract
The purpose of this research work is to show laboratory experiments conducted at 1500 psi and 3501C, experimentally simulating a reservoir located in the Gulf of the Mexico. The experiments conducted used a novel process that involved a hot fluid to be injected with an ultra-dispersed nano catalyst. The results obtained showed that API gravity can be improved permanently as well as its viscosity, with the advantage of no coke or solid deposits formation. Laboratory analyses showed that by using this new process it is possible to enter into the matrix zone, expelling at least partially the oil confined inside.
As a consequence of the temperature increase, matrix rock may expand and expel its oil; while temperatures decrease, the pores in the matrix could be contracted, generating additional oil expulsion from this area. As a consequence of this expansion-contraction in the reservoir the reserves could be increased. Also, a change in the permeability appears due to the temperature increases.
The present study was focused in oil matrix extraction and in situ oil upgrading from a naturally fractured reservoir of heavy oil as a result of a hot fluid injection with nano catalyst. Moreover, the effects of capillary pressure, mobility, viscous effects, wettability, and gravitational drainage on the process were analyzed. Another aspect that was studied is how the thermal expansion generated as a consequence of the process could expel the oil confined in the matrix.
Generally Applicable Method For Calculation Of The Matrix-fracture Fluid Transfer Rates
Authors: Heinemann Zoltán E. , Mittermeir Georg M. 
Published: April 2016

Abstract
The paper presents a practical method for calculating the matrix-fracture fluid transfer correctly, applicable under expansion, solution gas, capillary and gravitational drives and their combinations, considering water, gas and oil as displacing agents. The method is an improvement of the Reiss (1973) formulation based on time-depending recovery functions. Reiss could not consider depletion drive in combination with water and gas displacement. Kazemi et al. (1976) extended the Warren-Root shape factor approach to multi-phase cases, but without satisfying the conditions under which the single-phase solution is correct. Since that continuous efforts were made for improvement including diversification and making the shape factor time-dependent. Many publications demonstrated that these efforts are futile. Su et al. (2013) clearly postulated "a change of focus to the improvement of the transfer function would be a path to explore". The paper is an attempt in this sense with encouraging results. The suggested approach determines on fine gridded single matrix block (SMB) models recovery curves. Those are used directly in dual continuum models.
Multiscale Fracture Integration into a Multiple-Porosity Model: Fracture Lumping and Optimal Number of Scales
Authors: Legrand N. , Kamp A. M. , Gosselin O. R. 
Published: April 2016

Abstract
Reservoir models for fractured reservoirs are mainly dual-porosity models, and assume a unique equivalent fracture scale. However, fractured reservoirs are generally characterized by a multitude of fracture scales, ranging from small-scale diffuse fractures to large-scale seismic faults. This paper presents a methodology to extend single-fracture-scale dual-porosity models to situations with more scales, and investigates the optimal number of fracture scales.
We focus on what happens at local level (zero-dimensional system of one cell) in case of a singlephase sequential flow through different fracture levels with some fracture pattern assumptions. Different options to turn a continuous fracture distribution into a given number of discrete levels are investigated. Eventually, based on dimensionless coefficients, an optimal number of fracture scales is determined by lumping levels with similar behaviour. Rate-limiting transfer occurs between these lumped levels.
The dimensionless parameters that are defined are similar to the dimensionless parameter lambda used in dual porosity well test interpretation. They are a dimensionless representation of transfer rates. Each rate is also characterized by a dimensionless time, which is the reciprocal of the dimensionless transfer coefficient. The lumping of scales is thus done in between groups that are separated by low dimensionless transfer coefficients (slow transfer). Examples are shown of cases in which a 5-scale representation can be lumped to two scales (dual porosity) or three scales (triple porosity fracture- fracture-matrix).
This study is a first step towards a reservoir modelling representing more than one single fracture scale, and sets a general methodology for lumping scales in a single-phase context. However for practical application the multiscale issue is even more relevant for multi-phase flow, and must be addressed. Such extension will be part of future work, which will also include implementing multiple scale models in 3D reservoir simulation.
Redevelopment of the Pembina Cardium Field by CO2-EOR Using Existing Wells
Authors: Qin Tianjie , Chen Zhangxin , Zhang Kai , Han Jiabei , Wu Keliu 
Published: April 2016

Abstract
CO2-EOR, combined with multi-stage fractured horizontal wells has been considered as the most promising and environmentally-friendly technique for unlocking tight oil resources (Ghaderi et al., 2013). With more than 2,500 horizontal wells drilled into the Cardium formation within the Pembina field (CDL, 2016), adapting and utilizing existing wells and infrastructure for future CO2-EOR development is economically attractive. Nevertheless, the drilling, completion and hydraulic fracturing design and practices can vary greatly as a result of different geological conditions, operator preference and technology advancements through the years. This paper presents an effective workflow that selects hydraulically fractured horizontal wells suitable for CO2-EOR in consideration of both reservoir and completion qualities. The process of identifying refracturing candidates and potential risk associated with CO2-EOR performance is also developed.
Two groups of parameters - the reservoir quality group (remaining oil in place, permeability, reservoir depth and a fluid type) and the completion quality group (well lateral length, well spacing, fracture spacing, SRV and a skin factor) - are first defined. A fully compositional simulator is applied to study the effects of these parameters on reservoir responses to CO2 injection. A Fuzzy Analytic Hierarchy Process (F-AHP) is then employed to rank candidate horizontal well pads for CO2-EOR. The ranking results and simulated oil recovery factor for each candidate show significant agreement. In addition, with the help of crossplots, the horizontal wells with below-average completion quality, but relatively good reservoir quality, are selected as refracturing candidates.
A risk analysis reveals that the presence of conglomerate on the top of the Cardium formation plays a significant role, resulting in upward moving of CO2 and hence a lessened chance of contacting and displacing oil contained in the lower sands. Additionally, permeability heterogeneity has an adverse effect on CO2 sweep efficiency and can add uncertainty to the success of a recovery process. These factors should be further evaluated after the initial screening process.
Catalogue of Well Test Responses in a Fluvial Reservoir System
Authors: Walsh J. L. , Gringarten A. C. 
Published: April 2016

Abstract
Well test analysis has greatly improved over the years. It remains the most suitable source for determining the hydraulic connectivity and effective permeability in large reservoir volumes, and has become an important tool for reservoir characterization, especially with the recent development of complex interpretation models which account for detailed geological features.
Well test analysis in fluvial reservoirs is still challenging, however, due to a depositional environment conducive to significant internal heterogeneity. Analytical models used in conventional analysis are limited to simplified channel geometries and therefore fail to capture key parameters such as sand body dimensions, orientations and connectivity which control fluid flow and pressure behaviour. This paper aims at a better understanding of the impact of channel content in complex fluvial channel systems on well test derivative responses. To achieve this, a catalogue of 870 drawdown type curves was generated (using a 3D numerical simulator) for different channel contents, body shapes, body dimensions and permeability contrasts.
The paper also illustrates how geological reservoir parameters can be identified, using data from a fluvial North Sea reservoir. A workflow is described for matching field test data with the type curves generated in this study to obtain the fluvial channel characteristics. This then enables the geological description in a full field simulation model to be constrained to well test data, thus reducing uncertainty, aiding development decisions, and improving predictions of the final recovery. Because the match is non-unique, a large number of geological realizations is required, which can be reduced by a good geological understanding of the reservoir.
Organic Cultivation of Jasmine and Tea Increases Carbon Sequestration by Changing Plant and Soil Stoichiometry
Authors: Wang Weiqi , Min Qingwen , Sardans Jordi , Wang Chun , Asensio Dolores , Bartrons Mireia , Peñuelas Josep 
Published: April 2016

Organic cultivation methods would be a good alternative to conventional cultivation, avoiding the use of industrial fertilizer and reducing the risk of eutrophication, but its impacts on soil elemental composition and stoichiometry warrants to be clearly stated. This study was conducted to determine the effects of long‐term organic cultivation on soil elemental composition, stoichiometry, and C storing capacity and CO2 emissions in the plant‐soil systems of jasmine (Jasminum spp.) and tea [Camellia sinensis (L.) Ktze.] plantations in Fujian and other regions in China. We examined the impact of organic cultivation on the concentrations, contents and stoichiometric relationships among C, N, P, and K. Organic cultivation was associated with lower plant N and P concentrations, and P mineralomasses and with higher total plant C/N, C/P, C/K, and N/P ratios and higher soil N and P concentrations and contents at some depths. Organic cultivation was thus associated with a shift of P from plants to soil and with a higher nutrient‐use efficiency in biomass production, mainly of P. Soil CO2 emissions were higher under organic cultivation, but the soil was able to accumulate more C with no changes in C storage in plant biomass, suggesting that organic cultivation could increase the overall C sequestration, thereby mitigating climate change and enhancing soil nutrient content. Our results thus showed that the organic cultivation of jasmine and tea in Fujian can improve soil fertility and C accumulation, reduce the use of industrial fertilizers and phytosanitary products, and improve product quality without loss of economical profits.Core Ideas

Jasmine and tea cultivation have a long history in Fujian and other regions in China
We explored their organic cultivation for the future viability of these crops
Organic cultivation increased nutrient‐use efficiency
Soil was able to accumulate more C under organic cultivation
Organic cultivation improved soil fertility without affecting economic profits
Long‐Term Effects of Controlled‐Release Urea on Crop Yields and Soil Fertility under Wheat–Corn Double Cropping Systems
Authors: Zheng Wenkui , Sui Changling , Liu Zhiguang , Geng Jibiao , Tian Xiaofei , Yang Xiuyi , Li Chengliang , Zhang Min 
Published: April 2016

The long‐term effects of controlled‐release urea (CRU) on crop yields and soil properties were investigated in lysimeters under wheat and corn rotation system from 2009 to 2014 in northern China. The CRU included polymer‐coated urea (PCU), sulfur‐coated urea (SCU), and polymer coating of sulfur‐coated urea (PSCU) was applied at 147, 210 kg N ha−1 for wheat and 262.5, 375 kg N ha−1 for corn and the urea was applied at 210 kg N ha−1 for wheat and 375 kg N ha−1 for corn. Results showed that the N release characteristics of three kinds of CRU in field condition were all closely matched to the N requirement of crops. Consequently, the CRU treatments improved wheat and corn yields by 3.2 to 10.1% and 4.9 to 11.1%, increased apparent N use efficiency by 45.9 to 53.8% in wheat, and 36.2 to 45.4% in corn, respectively, compared with urea. Furthermore, the PSCU achieved the highest and the most stable crop yields among CRU. Even reducing CRU rate by 30% produced the same yields as with the 100% rate of urea. In addition, soil total N and organic matter contents in CRU were effectively increased in the topsoil of 0 to 20 cm after 5 yr. Therefore, long‐term application of CRU had great potential to increase wheat–corn yields, N use efficiency, reduce application frequency, improve soil fertility, decrease the leaching of soil NO3−–N and NH4+–N, and also relieve soil pH decreased.Core Ideas

The long‐term effect of controlled‐release urea on crop yield and soil chemical properties was studied.
The N release rates of controlled‐release urea were closely matched to the demand for N during the whole growth periods of crops.
The wheat and corn yields were increased by 3.2 to 10.1% and 4.9 to 11.1% by controlled‐release urea fertilization, compared with urea treatment.
Surface Runoff of Pesticides from a Clay Loam Field in Sweden
Authors: Larsbo Mats , Sandin Maria , Jarvis Nick , Etana Ararso , Kreuger Jenny 
Published: April 2016

Pesticides stored at or close to the soil surface after field application can be mobilized and transported off the field when surface runoff occurs. The objective of our study was to quantify the potential pesticide losses in surface runoff from a conventionally managed agricultural field in a Swedish climate. This was achieved by measuring surface runoff volumes and concentrations in runoff of six spring‐applied pesticides and autumn‐applied glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Measurements were performed for 3 yr both during the growing seasons and during intervening winter snowmelt periods on a clay loam field close to Uppsala. During growing seasons, surface runoff was generated on only five occasions during one 25‐d period in 2012 when the infiltration capacity of the soil may have been reduced by structural degradation due to large cumulative rainfall amounts after harrowing. Concentrations in surface runoff exceeded Swedish water quality standards in all samples during this growing season for diflufenican and pirimicarb. Surface runoff was generated during three snowmelt periods during the winter of 2012–2013. All of the applied pesticides were found in snowmelt samples despite incorporation of residues by autumn plowing, degradation, and leaching into the soil profile during the period between spraying and sampling. Concentrations of glyphosate ranged from 0.12 to 7.4 μg L−1, and concentrations of AMPA ranged from 0 to 2.7 μg L−1. Our results indicate that temporal changes in hydraulic properties during the growing season and when the soil freezes during winter affect pesticide losses through surface runoff.Core Ideas
Pesticide concentrations often exceeded Swedish water quality standards.
All of the applied pesticides were found in samples taken during snowmelt.
Total pesticide losses were small due to small surface runoff volumes.
Temporal changes in hydraulic properties affected losses in surface runoff.
Sample Sizes to Control Error Estimates in Determining Soil Bulk Density in California Forest Soils
Authors: Han Youzhi , Zhang Jianwei , Mattson Kim G. , Zhang Weidong , Weber Thomas A. 
Published: April 2016

Core Ideas
Sample sizes varied from 3 to 17 to achieve ±10% error at a 95% confidence level.
Bootstrapping is more robust for estimating sample size than the traditional method.
Soil variability must be considered before sampling.
Characterizing forest soil properties with high variability is challenging, sometimes requiring large numbers of soil samples. Soil bulk density is a standard variable needed along with element concentrations to calculate nutrient pools. This study aimed to determine the optimal sample size, the number of observation (n), for predicting the soil bulk density with a precision of ±10% at a 95% confidence level among different soil types. We determined soil bulk density samples at three depths at 186 points distributed over three different 1‐ha forest sites. We calculated n needed for estimating means of bulk density using a traditional method. This estimate was compared to a bootstrapping method n where the variance was estimated by re‐sampling our original sample over 500 times. The results showed that patterns of soil bulk density varied by sites. Bootstrapping indicated 3 to 17 samples were needed to estimate mean soil bulk density at ± 10% at a 95% confidence level at the three sites and three depths. Sample sizes determined by the bootstrap method were larger than the numbers estimated by the traditional method. Bootstrapping is considered theoretically to be more robust, especially at a site with more variability or for site measures that are not normally distributed.
High-Intensity Interval Training and Moderate-Intensity Continuous Training in Ambulatory Chronic Stroke: Feasibility Study
Authors: Boyne Pierce , Dunning Kari , Carl Daniel , Gerson Myron , Khoury Jane , Rockwell Bradley , Keeton Gabriela , Westover Jennifer , Williams Alesha , McCarthy Michael , Kissela Brett 
Published: April 2016

AbstractBackgroundPoststroke guidelines recommend moderate-intensity, continuous aerobic training (MCT) to improve aerobic capacity and mobility after stroke. High-intensity interval training (HIT) has been shown to be more effective than MCT among healthy adults and people with heart disease. However, HIT and MCT have not been compared previously among people with stroke.ObjectiveThe purpose of this study was to assess the feasibility and justification for a definitive randomized controlled trial (RCT) comparing HIT and MCT in people with chronic stroke.DesignA preliminary RCT was conducted.SettingThe study was conducted in a cardiovascular stress laboratory and a rehabilitation research laboratory.PatientsAmbulatory people at least 6 months poststroke participated.InterventionBoth groups trained 25 minutes, 3 times per week, for 4 weeks. The HIT strategy involved 30-second bursts at maximum-tolerated treadmill speed alternated with 30- to 60-second rest periods. The MCT strategy involved continuous treadmill walking at 45% to 50% of heart rate reserve.MeasurementsMeasurements included recruitment and attendance statistics, qualitative HIT acceptability, adverse events, and the following blinded outcome variables: peak oxygen uptake, ventilatory threshold, metabolic cost of gait, fractional utilization, fastest treadmill speed, 10-Meter Walk Test, and Six-Minute Walk Test.ResultsDuring the 8-month recruitment period, 26 participants consented to participate. Eighteen participants were enrolled and randomly assigned to either the HIT group (n=13) or the MCT group (n=5). Eleven out of the 13 HIT group participants attended all sessions. Participants reported that HIT was acceptable and no serious adverse events occurred. Standardized effect size estimates between groups were moderate to very large for most outcome measures. Only 30% of treadmill speed gains in the HIT group translated into overground gait speed improvement.LimitationsThe study was not designed to definitively test safety or efficacy.ConclusionsAlthough further protocol optimization is needed to improve overground translation of treadmill gains, a definitive RCT comparing HIT and MCT appears to be feasible and warranted.
Responsiveness of the Balance Evaluation Systems Test (BESTest) in People With Subacute Stroke
Authors: Chinsongkram Butsara , Chaikeeree Nithinun , Saengsirisuwan Vitoon , Horak Fay B. , Boonsinsukh Rumpa 
Published: April 2016

AbstractBackgroundThe reliability and convergent validity of the Balance Evaluation Systems Test (BESTest) in people with subacute stroke have been established, but its responsiveness to rehabilitation has not been examined.ObjectiveThe study objective was to compare the responsiveness of the BESTest with those of other clinical balance tools in people with subacute stroke.DesignThis was a prospective cohort study.MethodsForty-nine people with subacute stroke (mean age=57.8 years, SD=11.8) participated in this study. Five balance measures—the BESTest, the Mini-BESTest, the Berg Balance Scale, the Postural Assessment Scale for Stroke Patients, and the Community Balance and Mobility Scale (CB&M)—were used to measure balance performance before and after rehabilitation or before discharge from the hospital, whichever came first. The internal responsiveness of each balance measure was classified with the standardized response mean (SRM); changes in Berg Balance Scale scores of greater than 7 were used as the external standard for determining the external responsiveness. Analysis of the receiver operating characteristic curve was used to determine the accuracy and cutoff scores for identifying participants with balance improvement.ResultsParticipants received 13.7 days (SD=9.3, range=5–44) of physical therapy rehabilitation. The internal responsiveness of all balance measures, except for the CB&M, was high (SRM=0.9–1.2). The BESTest had a higher SRM than the Mini-BESTest and the CB&M, indicating that the BESTest was more sensitive for detecting balance changes than the Mini-BESTest and the CB&M. In addition, compared with other balance measures, the BESTest had no floor, ceiling, or responsive ceiling effects. The results also indicated that the percentage of participants with no change in scores after rehabilitation was smaller with the BESTest than with the Mini-BESTest and the CB&M. With regard to the external responsiveness, the BESTest had higher accuracy, sensitivity, specificity, and posttest accuracy than the Postural Assessment Scale for Stroke Patients and the CB&M for identifying participants with balance improvement. Changes in BESTest scores of 10% or more indicated changes in balance performance.LimitationsA limitation of this study was the difference in the time periods between the first and the second assessments across participants.ConclusionsThe BESTest was the most sensitive scale for assessing balance recovery in participants with subacute stroke because of its high internal and external responsiveness and lack of floor and ceiling effects.
Adverse events following school-based vaccination of girls with quadrivalent human papillomavirus vaccine in Slovenia, 2009 to 2013
Authors: Šubelj Maja , Učakar Veronika , Kraigher Alenka , Klavs Irena 
Published: April 2016

Adverse events following immunisation (AEFIs) with qHPV reported to the Slovenian AEFI Registry for the first four school years of the vaccination programme were analysed. We calculated annual reporting rates for 11–14 year-old vaccinees with AEFIs, using the number of qHPV doses distributed within the school-based vaccination programme as the denominator. Between September 2009 and August 2013, 211 AEFIs that occurred in 89 vaccinees were reported, a rate of 149.5 vaccinees with AEFI per 100,000 qHPV doses distributed. For five vaccinees, serious AEFIs (8.4 per 100,000 doses distributed) were reported. The highest reporting rates were for fatigue, headache, and fever (≥ 38.0⁰) (53.8, 40.3, and 35.3 per 100,000 qHPV doses distributed, respectively). As no AEFI resulted in permanent sequelae and they all were categorised as serious only due to the criterion of a minimum of one day of hospitalisation, this provides reassurance for the safety of our school-based HPV vaccination programme. Further AEFI surveillance is warranted to provide data for HPV vaccination programme monitoring and evaluation of its safety.