bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated Surveillance and Diagnostic Workflow for the Management of Water Production in Naturally-Fractured Carbonate Reservoirs
Authors: Cinar Y. , Shehab M. A. , Dallag M. M. , Jama A. A. 
Published: September 2016

Abstract
This paper presents a new automated workflow to diagnose and evaluate water production signatures for a mix of vertical and lateral wells in a carbonate reservoir under water-flooding. The workflow can be used for rate optimization, remedial intervention planning and for reservoir description. The workflow basically includes decline curve analyses for oil and water productions, Chan analysis for water production signature, and evaluation of the combined decline curves and water signatures for estimating well ultimate cumulative oil and reservoir description. This enables reservoir engineers in optimizing the production rate and in planning future remedial actions to prolong well life and maximize recovery. A new event-based Chan analysis is proposed to better assess the change in water production signature after each remedial event such as acid treatment, water shut-off or sidetracking.
The study reveals that the benefits of the automated workflow are significant for reservoir engineers who deal with complex reservoirs with numerous wells. The well ultimate cumulative oil is estimated more accurately using the combined decline curves of oil and water production. Using the proposed event-based Chan analysis, it is possible to identify the change in water production signatures of wells of different types before and after well events. The water problem diagnostics are also helpful to understand the highly-conductive features in complex carbonate reservoirs.
Examining the Geomechanical Implicaitons of Pre-Existing Fractures and Simultaneous-Multi-Fracturing Completions on Hydraulic Fractures: Experimental Insights into Fracturing Unconventional Formations
Authors: Alabbad Emad A. , Olson Jon E. 
Published: September 2016

Abstract
The presence of preexisting fractures and the need to place multiple hydraulic fractures in relatively close proximity from each other make stimulating unconventional formations a challenge. This paper experimentally reviews the geomechanical factors governing the hydraulic fracture interactions with the formation's preexisting fractures and the fracturing completion's simultaneous hydraulic fractures. The methodology followed in this study uses a series of laboratory fracturing tests. The experimental tests used rock samples made of synthetic, gypsum-based cements, such as hydrostone and plaster, and were performed in a number of experimental settings to investigate some geomechanical factors of relevance. Among such factors, the preexisting fracture's cementation, aperture, and relative height as well as the design of the fracturing stage completion were examined in the course of the experimental portion of the work. As a result of the laboratory experiments, it has been found that a hydraulic fracture crossing the preexisting fracture is largely dictated by the preexisting fracture's cement fill type relative to the matrix of the host rock. Likewise, the height of the hydraulic fracture relative to the preexisting fracture may govern their intersection mode, however, there seems to be an insignificant impact of the preexisting fracture aperture on the intersection outcome. Moreover, the fracturing stage completion design was found to have considerable impact on the hydraulic fracturing outcome. Stress interference between the fracturing sources in a stage highly affects the outcome of each fracturing source. Middle fracturing sources tend to result in inhibited hydraulic fracture propagations while outer fracturing sources achieve hydraulic fracture propagations with outward curvatures. Overall, the experimental data and findings enable us to validate some theories, calibrate numerical simulators, and answer some pressing questions. The results discussed in this paper provide very useful insights into fracturing unconventional formations.
Diagnostics of Reservoir Fluid-Fill Cycle and Relevance for Tailoring Field Developments in Oman
Authors: Ferrero M. Boya , Kawar R. , Hadhrami M. , Dhahli A. , Neidhardt J. , Pentland C. 
Published: September 2016

Abstract
The development of reservoirs that are not in hydrostatic equilibrium or that have suffered deviations from primary drainage over geological time requires appropriate challenges to standard assumptions in order to optimize the field's full potential. Such circumstances are more frequent than usually acknowledged since the Earth is not static, structures get buried or change with tectonic activity and fluids re-arrange themselves to achieve a state of minimum potential energy.
The focus of this paper is three fold: a) highlight geological processes that may affect fluid distribution and pressure regime in a reservoir; b) provide a template workflow and diagnostic tools for identification of alternative fluid-fill cycle and equilibrium state scenarios; c) illustrate through actual field examples the relevance of recognising tectonic imprint on fluid distribution, in particular for reservoirs with low permeability, oil wettability or low porosity. A companion paper1 published at the same time discusses methods to model saturation changes in some of such complex fields.
In summary, the interpretation of variable contacts within a field can result in changes to development decisions (see fig 1): consequences are not limited to volumetric assessment but they can actually change the development, well count and well placement as well as impacting the design of the facilities. Based on risk and opportunity management optimization we advise against indiscriminate standard assumptions of primary drainage or hydrostatic equilibrium for all reservoirs in all basins.
SAGD Operation in Interbedded Sands With Application of Horizontal Multistage Fracturing; Reservoir Engineering Aspects
Authors: Saeedi Majid , Settari A. Tony 
Published: September 2016

Abstract
Steam assisted gravity drainage (SAGD) is a widely used thermal recovery method. During steam injection in interbedded sands, the portion of the deposits above the vertical permeability barriers is likely not recoverable with current practices. This paper examines the reservoir engineering aspects of using multistage fracturing in SAGD operations in interbedded sands such as IHS, where the vertical permeability barriers impede the gravity drainage process.
Assuming that the permeability barriers can be targeted and broken with vertical hydraulic fracturing treatments before steaming, it is very likely that the steam can pass through the shales, effectively heat the otherwise isolated oil, and eventually drain it. The flow mechanism and the recovery response of a fractured SAGD well are discussed and it is shown that the suggested process has a great potential to improve production rate and recovery factor. The desired fracture properties and expected production rates are obtained by using both analytical and numerical reservoir engineering techniques. Some quick assessment criteria are also introduced.
Analytical equations to estimate the SAGD peak rate were derived for various sand-shale sequences and fracture configurations. The analytical equations can be used for quick evaluation of the fracturing potential in such SAGD wells. A correction factor was suggested to compensate for simplifying assumptions.
Through numerical simulation, a matrix of sensitivity cases was developed with variation of key parameters such as fracture permeability, fracture half-length, fracture spacing and orientation. It was shown that fractures with short half-length but high conductivity are required for the process to work. Using the sensitivity results, an optimum range for key fracturing parameters was determined. Furthermore, a dimensionless fracture conductivity criterion was used as a general design criterion. The issues around fracturing design and sand-shale geomechanics are presented in a separate paper.
The multistage fracturing technique in horizontal wells was first used in tight and shale gas plays, and different variations of the field execution of this technique are now widely available. To our knowledge, this work is the first detailed examination of the potential of multistage fracturing for improving SAGD in interbedded pays. It is shown that, if this technique can be combined with in-situ steam operations, some of the problems with steaming interbedded pays can be addressed. In particular, it is shown that the recovery can be substantially improved to be comparable to clean sands. However, the use of multistage fracturing in SAGD process also introduces unique execution challenges that require thorough analysis and design, which were the focus of the companion paper (Saeedi and Settari, 2016).
Combined Technology of Weak Gel Flooding assisting Thermal Huff and Puff Enhances Oil Recovery for Offshore Heavy Oil Field
Authors: Pan Guangming , Chen Jianbo , Zhang Caiqi , Liu Dong , Wu Jintao , Li Hao , Fang Zhou , Qu Jifeng , Zhang Junting 
Published: September 2016

Abstract
South part of NN reservoir, locating at Bohai Bay of China, has geology characteristics of flat structure, complex oil-water contact system. The formation oil viscosity reaches as high as 413~741mPa•s. At initial production stage, daily oil of vertical well and horizontal well reached 21m3/d and 35m3/d, respectively. Due to complex oil-water relationship and high formation oil viscosity, oil production rate of whole reservoir decreased from 0.6% to 0.3% after one year.
Combinatorial development techniques including thermal huff-puff and weak gel flooding have been optimized for further enhancing oil recovery. Considering the platform space limit, thermal huff-puff uses multiple thermal fluid(nitrogen, dioxide, hot water) instead of conventional steam. Twelve new horizon wells have been carried out in the pure oil zone for thermal huff-puff pilot. Until now, there have been twelve wells which completing the first cycle huff-puff, and six wells have completed the second cycle. Meanwhile, in order to keep the formation pressure and reduce the channeling risk, selected three high water-cut production wells were changed into injection wells for weak gel flooding pilot.
After carried out combinatorial development techniques, the rate of oil production of whole reservoir has increased from 0.3% to 0.7%. Thermal huff-puff heated oil during the huff process then decreases the formation oil viscosity, and finally increasing the production ability of horizon wells in the puff process. Compared with natural energy production, peak oil production and periodic oil production of thermal production respectively increases to 3 times and 1.6 times in the first cycle. Weak gel flooding increases viscosity of the injected fluid and reduces the difference of water-oil mobility ratio, the average resistance coefficient of three injection wells reaches as high as 1.74. Around the three injection wells, there are nine wells increasing the oil production, and incremental oil production for single well has reached 0.45×104m3~2.12×104m3 in the past few years. Also, there is a positive synergistic effect between thermal huff-puff and weak gel flooding. The artesian flow days of one thermal well extends 76 days in the help of weak gel flooding.
Our experiences show that such combinatorial development techniques are effective for enhancing oil recovery of heavy oil fields and meet the demand of high speed development for offshore oil fields.
Numerical Modeling of Multiphase Flow Toward Fractured Horizontal Wells In Heterogeneous Nanoporous Formations
Authors: Holy R. W. , Ozkan E. 
Published: September 2016

Abstract
This paper presents an anomalous diffusion based approach for modeling two-phase oil/water flow in fractured nanoporous media, such as that encountered in unconventional oil and gas reservoirs. Production is assumed to be from a multiply fractured horizontal well and the focus of the discussions is 1D linear flow in the region between hydraulic fractures. To account for the complexity and heterogeneity of the fractured medium, anomalous diffusion is considered in the flow domain between hydraulic fractures. To do so, the conventional Darcy phase fluxes are replaced by more general fractional flux laws which incorporate the non-local and hereditary nature of flow by means of fractional space-time phase and capillary pressure gradients. A modified IMPES scheme is derived for linear oil/water flow under specified terminal pressure production, and the impact of sub- and super-diffusion on phase rates, as well as pressure and saturation distributions across the system is studied.
Surfactant‐Modified Soil Amendments Reduce Nitrogen and Phosphorus Leaching in a Sand‐Based Rootzone
Authors: Shaddox Travis W. , Kruse Jason K. , Miller Grady L. , Nkedi‐Kizza Peter , Sartain Jerry B. 
Published: September 2016

United States Golf Association putting greens are susceptible to nitrogen (N) and phosphorus (P) leaching. Inorganic soil amendments are used to increase moisture and nutrient retention and may influence N and P leaching. This study was conducted to determine whether N and P leaching could be reduced using soil amendments and surfactant‐modified soil amendments. Treatments included a control (sand), sand–peat, zeolite, calcined clay, hexadecyltrimethylammonium–zeolite, and hexadecyltrimethylammonium–calcined clay. Lysimeters were filled with a 30‐cm rootzone layer of sand–peat (85:15 by volume), below which a 5‐cm treatment layer of amendments was placed. A solution of NO3–N, NH4–N, and orthophosphate‐P (2300, 2480, and 4400 μg mL−1, respectively) was injected at the top of each lysimeter, and leachate was collected using an autocollector set to collect a 10‐mL sample every min until four pore volumes were collected. Uncoated amendments, sand, and peat had no influence on NO3–N retention, whereas hexadecyltrimethylammonium‐coated amendments reduced NO3–N leaching to below detectable limits. Both coated and uncoated amendments reduced NH4–N leaching, with zeolite reducing NH4–N leached to near zero regardless of hexadecyltrimethylammonium coating. Pure sand resulted in a 13% reduction of applied orthophosphate‐P leaching, whereas peat contributed to orthophosphate‐P leaching. Surfactant‐modified amendments reduced orthophosphate‐P leaching by as much as 97%. Surfactant‐modified soil amendments can reduce NO3–N, NH4–N, and orthophosphate‐P leaching and, thus, may be a viable option for removing leached N and P before they enter surface or ground waters.Core IdeasSoil amendments did not reduce NO3–N leaching.Modified soil amendments reduced NO3–N, NH4–N, and orthophosphate‐P leaching.Zeolite was most effective at reducing NH4–N leaching.
Physical Soil Structure Evaluation based on Hydraulic Energy Functions
Authors: Armindo Robson André , Wendroth Ole 
Published: September 2016

Core Ideas
Five indices and two hydraulic energy cumulative functions are examined to evaluate SPQ.
With these indices and functions, it is possible to assess soil structure through spatial and temporal effects.
The volumetric water content at field capacity was calculated based on a flux drainage criterion.
The script for SWRC fitting parameters and all presented indices is provided.
Qualitative analyses of physical, chemical, or biological variables are difficult and often ambiguous. Soil physical quality (SPQ) indices are not an exception to this rule. There is no unique revealing parameter or index that enables evaluating soil structure. In high‐intensity biomass production systems, SPQ indices are useful tools for management decisions because they indicate the sustainability of soil organic matter dynamics, drainage, infiltration, heat transfer, and storage processes. This work examines five energy parameters and two hydraulic energy functions for evaluating physical quality in terrestrial vegetative ecosystems. These indices are based on numerical integration of the soil water retention curve (SWRC) and on soil water content at field capacity, and they manifest the absolute aeration energy, the absolute water retention energy, the relative aeration energy, the relative water retention energy, and the relative air‐water energy. This integration technique includes the use of all points of the SWRC. A script for fitting the parameters of the van Genuchten equation and for solving all the presented indices in this work was developed and made available. The energy indices and hydraulic functions were derived and validated for SWRCs, from several German, US, and Brazilian soils under different management, comparing them with other previously published SPQ indices. Our findings reveal that the energy indices and functions can be applied to assess the energy associated with the soil physical structure.
The Directional Components of Splash Erosion at Different Raindrop Kinetic Energy in the Chinese Mollisol Region
Authors: Hu Wei , Zheng Fenli , Bian Feng 
Published: September 2016

Core Ideas
Directional components of splash erosion and effects of raindrop kinetic energy were investigated.
Lateral splash erosion played a significant role in supplying detached particles to adjacent areas.
We fit equations for total and net splash erosion to rainfall physical parameters.
We used cross‐validation to test the equations.
Splash erosion is an important process of hillslope erosion. However, there is little information available in the literature to show how rainfall physical parameters affect the directional components of splash erosion. Therefore, the objectives of this study were to investigate the effects of rainfall physical parameters (rainfall intensity [RI], raindrop kinetic energy [KE], and raindrop diameter) on the directional components (upslope, lateral, downslope) of splash erosion characteristics in the Chinese Mollisol region. A specially designed soil pan, which can measure the directional components of splash erosion, was subjected to designed rainfall intensities of 50 and 100 mm h−1 and varying raindrop KE. The results showed that the total splash erosion (downslope plus upslope plus lateral splash erosion), directional components of splash erosion, and net splash erosion (downslope minus upslope erosion) on hillslopes significantly increased as RI and raindrop KE increased (p < 0.05). Furthermore, splash erosion from downslope, lateral slope, and upslope contributed 32.2, 26.3, and 14.5%, respectively, of total splash erosion. Additionally, raindrop KE and raindrop median volume diameter (D50) were the key indicators affecting both total and net splash erosion. The equations between total and net splash erosion with both parameters of raindrop KE and raindrop D50 were fitted. The cross validation results showed that the two equations had acceptable accuracy. Therefore, preventing raindrop impact by using conservation tillage methods, such as retaining crop residue or mulch cover, can effectively reduce splash erosion in the Mollisol region of Northeast China.
TEMPORAL VARIABILITY FROM THE TWO-COMPONENT ADVECTIVE FLOW SOLUTION AND ITS OBSERVATIONAL EVIDENCE
Authors: Dutta Broja G. , Chakrabarti Sandip K. 
Published: September 2016

ABSTRACT
In the propagating oscillatory shock model, the oscillation of the post-shock region, i.e., the Compton cloud, causes the observed low-frequency quasi-periodic oscillations (QPOs). The evolution of QPO frequency is explained by the systematic variation of the Compton cloud size, i.e., the steady radial movement of the shock front, which is triggered by the cooling of the post-shock region. Thus, analysis of the energy-dependent temporal properties in different variability timescales can diagnose the dynamics and geometry of accretion flows around black holes. We study these properties for the high-inclination black hole source XTE J1550-564 during its 1998 outburst and the low-inclination black hole source GX 339-4 during its 2006–07 outburst using RXTE/PCA data, and we find that they can satisfactorily explain the time lags associated with the QPOs from these systems. We find a smooth decrease of the time lag as a function of time in the rising phase of both sources. In the declining phase, the time lag increases with time. We find a systematic evolution of QPO frequency and hard lags in these outbursts. In XTE J1550-564, the lag changes from hard to soft (i.e., from a positive to a negative value) at a crossing frequency (ν
c) of ∼3.4 Hz. We present possible mechanisms to explain the lag behavior of high and low-inclination sources within the framework of a single two-component advective flow model.
A DEEP X-RAY VIEW OF THE BARE AGN ARK 120. I. REVEALING THE SOFT X-RAY LINE EMISSION
Authors: Reeves J. N. , Porquet D. , Braito V. , Nardini E. , Lobban A. , Turner T. J. 
Published: September 2016

ABSTRACT
The Seyfert 1 galaxy Ark 120 is a prototype example of the so-called class of bare nucleus active galactic nuclei (AGNs), whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep (>400 ks exposure), high-resolution X-ray spectroscopy of Ark 120 is presented from XMM-Newton observations that were carried out in 2014 March, together with simultaneous Chandra/High Energy Transmission Grating exposures. The high-resolution spectra confirmed the lack of intrinsic absorbing gas associated with Ark 120, with the only X-ray absorption present originating from the interstellar medium (ISM) of our own Galaxy, with a possible slight enhancement of the oxygen abundance required with respect to the expected ISM values in the solar neighborhood. However, the presence of several soft X-ray emission lines are revealed for the first time in the XMM-Newton RGS spectrum, associated with the AGN and arising from the He- and H-like ions of N, O, Ne, and Mg. The He-like line profiles of N, O, and Ne appear velocity broadened, with typical FWHMs of ∼5000 km s−1, whereas the H-like profiles are unresolved. From the clean measurement of the He-like triplets, we deduce that the broad lines arise from a gas of density n
e ∼ 1011 cm−3, while the photoionization calculations infer that the emitting gas covers at least 10% of 4π steradian. Thus the broad soft X-ray profiles appear coincident with an X-ray component of the optical–UV broad-line region on sub-parsec scales, whereas the narrow profiles originate on larger parsec scales, perhaps coincident with the AGN narrow-line region. The observations show that Ark 120 is not intrinsically bare and substantial X-ray-emitting gas exists out of our direct line of sight toward this AGN.
Anaesthesia and deep brain stimulation
Authors: Bindu Barkha , Bithal Parmod 
Published: September 2016

AbstractDeep brain stimulation (DBS) is becoming an increasingly popular minimally invasive surgical procedure for various movement disorders, especially Parkinson’s disease. Different nuclei have been identified depending on patients’ symptoms, but the success or failure of the procedure depends on various other factors such as proper patient selection and risk-benefit analysis. While various techniques of anaesthesia including monitored anaesthesia care, conscious sedation and general anaesthesia are being used routinely, no clear-cut evidence exists as to the best technique for this procedure. This review article discusses the surgical procedure of DBS, devices currently available, perioperative anaesthetic concerns and techniques, effect of anaesthetic drugs on microelectrode recordings and macro-stimulation and associated complications.