bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Fast and Robust Technique for Accurate Measurement of the Organic-Rich Shales Characteristics under Steady-State Conditions
Authors: Zamirian M. , Aminian K. , Fathi E. , Ameri S. 
Published: October 2014

Abstract
This paper introduces a robust and accurate technique for the steady-state permeability and porosity measurements in ultra-low permeability shale core samples. A laboratory set-up was designed and assembled which has a resolution of one nano-darcy for the permeability and one-hundredth cubic centimeters for pore volume measurements. Extremely accurate differential-pressure transducers are used to measure the flow of gas passing through the core sample under in-situ conditions. The in-situ conditions are achieved by maintaining isothermal conditions and the application of the confining stress on the core sample. The laboratory set-up is fully automated to eliminate any human error and more importantly maintains the temperature stable within the enclosed unit.
A series of measurements were performed on a Marcellus Shale core sample under wide range of pore and confining pressures using Helium (He) as a non-adsorbent and Nitrogen (N2) and Carbon Dioxide (CO2) as adsorbent gases. The measured gas permeability under steady-state condition is generally higher than the absolute permeability due to gas slippage (Klinkenberg 1941). Recent experimental and numerical studies indicate that permeability values for organic rich shale obtained by using different gases are much larger than the absolute permeability predicted by Klinkenberg the slippage theory. In ultra-tight formations such as organic rich shale, the measured "apparent" permeability is not a linear function of reciprocal of pressure as predicted by Klinkenberg. Thus, a new method based on the double gas slippage theory in nano-capillaries has been proposed for reliable estimation of the shale absolute permeability.
In this study both Klinkenberg and double slippage corrections were applied to the steady-state permeability measurements. The results indicated that application of Klinkenberg to the permeability measurements lead to negative absolute permeability for shale samples. However, the double-slippage correction resulted in physically plausible values for absolute permeability of shale samples. Finally, the measurement results with adsorbent gases indicated that the adsorbed gas layer thickness can significantly impact the gas transport and storage in organic rich shale reservoirs and needs to be considered for hydrocarbon in place calculation and production predictions.
Time-Dependent Initiation of Multiple Hydraulic Fractures in a Formation with Varying Stresses and Strength
Authors: Bunger Andrew P. , Lu Guanyi 
Published: October 2014

Abstract
The premise of classical hydraulic fracture breakdown models is that hydraulic fracture growth can only commence when the wellbore pressure reaches a critical value, sufficient to overcome the tensile strength of the rock. However, rocks are well-known to exhibit static fatigue, that is, delayed failure at stresses below the tensile strength. In this paper we explore the consequences of delayed failure on initiation of multiple hydraulic fractures. Specifically, given a certain breakdown pressure, we investigate the conditions under which subsequent hydraulic fracture(s) can initiate within the timeframe of a stimulation treatment in regions of higher stress and/or strength due to delayed failure mechanisms. The results show that wells completed in shallower formations are more sensitive to variations in strength while wells completed in deeper formations are more sensitive to variations in stress. Furthermore, cases in which all hydraulic fractures breakdown according to the same pressurization regime, that is, all are "fast" (non-fluid-penetrating) pressurization or else all are "slow" (fluid-penetrating) pressurization cases, are highly sensitive to small stress/strength variability. On the other hand, if the first hydraulic fracture initiation is in the "fast" pressurization regime and subsequent fracture(s) are in the "slow" pressurization regime, then the system is robust to a much higher degree of variability in stress/strength. Practically, this work implies that methods aimed at moderately reducing the variability in stress/strength among the possible initiation points (i.e. perforation clusters) within a particular stage can have a strong impact on whether multiple hydraulic fractures will initiate. Additionally, this analysis implies that pumping strategies that encourage "fast", non-penetrative breakdown of the first initiation point followed by the opportunity for fluid-penetrating, "slow" breakdown of subsequent initiation points could be highly effective at encouraging multiple hydraulic fracture initiation.
Innovative Method of Analyzing the Dynamic Behavior of PDC Bits on Bent Motor BHAs Results in Improved Drilling Performance in the Marcellus Shale Play
Authors: Mortimer Laurence 
Published: October 2014

Abstract
Horizontal drilling and hydraulic fracturing are commonplace in the shale plays across the United States with successful wells efficiently yielding large volumes of shale gas and oil at minimum time and cost. Typical well profiles involve building a curve and then drilling long horizontal sections to TD, with the horizontal section taking up to 7000ft to complete. One of the most cost effective means to drill such wells is with Positive Displacement Motor (PDM) Bottom Hole Assemblies (BHAs) consisting of PDMs with bend angles for directional control.
When addressing drilling efficiency; a major contributor is BHA selection and the ability to select the most efficient combination of bit, PDM and stabilizer arrangement for each specific application. It is this selection process that forms the basis of this paper which details how a new suite of analysis tools were developed to analyse the dynamic behavior of a PDC bit on PDMs with variable bend angles and stabilizer configurations. Drilling on a bent motor in rotational mode has long proven challenging for both PDM and bit and the complex dynamic behavior has rarely been fully understood let alone analyzed.
At the heart of the new suite of tools is the capability to analyse the complex trajectory of the cutting structure of the bit to simulate the Bottom Hole Pattern (BHP) created in the rock. Having understood the transient behavior of the bit, an analysis tool was then developed to analyse the drilling behavior of the bit and BHA which resulted in a new approach to PDC bit design for bent motor BHA applications with the design intent of providing smoother drilling, increased durability and higher rates of penetration.
The first run of the new design of bit resulted in improved drilling performance, allowing the customer to drill the complete section to TD using a 2.38° bent motor BHA for the first time in the Marcellus. The negated need for multiple trips ultimately saved the customer up to 25% in completion time resulting in a cost saving of approximately $128k.
Acid Gas Prediction Methodology, Result of Steam Injection Implementation in Heavy Oil Reservoirs
Authors: Lizcano Q. Cesar 
Published: October 2014

Abstract
The increase in the value of crude oil and the insatiable need for energy sources have been an incentive to develop and promote technologies related to the extraction of heavy oil, especially thermal recovery methods. Currently, Thermal methods are being implemented in the Orinoco Oil Belt and it is important to know and be aware of the impact of these kinds of technologies in the field. The following investigation focuses on the development of a methodology for predicting acid gas volumes, Carbon Dioxide (CO2) and Hydrogen Sulfide (H2S), produced by the effect of aquathermolysis reactions of heavy oil with API° 7, in steam injection conditions, using a numerical simulator. This research is based on defining the kinetic parameters of the aquathermolysis reactions through laboratory batch tests carried out in a core from Boyacá block. The aquathermolysis reactions was charged in a numerical simulator using the laboratory data in order to compare the acid gas volume obtained from steam stimulation of extra heavy crude oils and adjust the kinetic parameters of the reactions and take them to a field scale. Finally, multiple simulations with different steam injection techniques are performed, such as cyclic and continuous steam stimulation in horizontals wells, varying also kinetic parameters and steam injection parameters, to determine which exploitation scenario will have the best behavior, and how to manage the acid gas emissions in this kind of reservoirs. In this way, This methodology can be a important tool to obtain acid gas volumes according to the reality of the reservoir, contributing extensively on the reservoir management due to avoid undersizing or oversizing steam injection projects, having an impact on profitability and environmental protection.
Gas Well Testing with Wellbore Storage and Skin: a Line Source Solution Using the Green's Functions Approach
Authors: dos Santos Sousa Emilio Paulo 
Published: October 2014

Abstract
Even when written in terms of a pseudo-pressure function, the diffusivity equation for flow of gases through porous media is, rigorously speaking, non-linear because the viscosity-compressibility product is pseudo-pressure dependent. However, several techniques and analysis procedures neglect such non-linearity. A new methodology for constructing solutions for gas reservoirs through the Green's Function technique has been recently proposed in the literature. Such methodology handles the viscosity-compressibility product variation rigorously and it has been applied to solve several gas well tests problems successfully. However, wellbore storage and skin effects have not been considered yet in this new approach.
In this work, the Green's Function technique is applied to obtain a new solution for an infinite homogeneous isotropic gas reservoir being produced through a single vertical well with wellbore storage and skin. The solution, however, does not consider non-Darcy flow effects. Even though the wellbore storage introduces a new non-linearity to an already non-linear problem, this work presents two accurate approximate solutions compared to the results from a commercial numerical simulator.
This work also shows that wellbore pseudo-pressure dimensionless solution is a function of the correlating groups CDexp(2S) and tD/CD, exactly like the wellbore dimensionless liquid solutions are. Liquid and gas dimensionless solutions under these correlating groups are not equal, though.
Dependence of Organic Pore Wettability on Kerogen Maturity: A Water Droplet Microscopic Simulation Study
Authors: Hu Yinan 
Published: October 2014

Abstract
Wettability in the organic pores of shales, known as kerogen, is essential information required for hydrocarbon estimation, multiphase flow transportation modeling, and the prediction of the recoveries and placement of hydraulic fracture water, especially in intermediate maturity oil shales. The process of kerogen maturation is accompanied by the loss of functionalized molecules, leading to a reduction of H/C and O/C values. These ratios are typically reflected in the van Krevelen diagram and are used to classify types of kerogen depending on their maturity degree. Recent studies have documented laboratory evidence of water content in kerogen. This leads to key questions of whether kerogen may have mixed-wet characteristics and how it is likely to depend on kerogen maturity.
In this paper, we present a pore-scale study analyzing the role of kerogen maturity on the wettability of organic pore systems. The traditional graphene model is chosen as a proxy for the organic matter. By grafting varying amounts of functionalized groups onto this surface, we construct the kerogen with varying degrees of maturity. We then study droplets of pure water on different surfaces and determine contact angles to quantify wettability.
We find that the contact angle variations of water droplets have a strong dependency on kerogen maturity. As the density of the surface functionalized groups increases, the wettability in kerogen could possibly be altered from hydrocarbon-wetting, to neutral-wetting, or even become hydrophilic. Additionally, we also demonstrate that there is a critical density of surface functionalized groups beyond which the kerogen pore system may be considered to be largely water-wet when water forms sheets adjacent to the pore wall. Our results indicate that the wettability in kerogen is very likely to be mixed-wetting.
Application of 3D diffraction imaging
Authors: Zhuravko N. 
Published: October 2014

Summary
I propose a method for velocity model building based on kinematic analysis of seismic diffractions. The main idea is separation of reflected/diffracted waves in 3D data and following velocity estimation. The proposed method works in the post-stack domain as opposed to the conventional pre-stack velocity analysis using CMP hyperbolas and semblance function. I demonstrate the option of using diffractions on real example when traditional velocity analysis is difficult. Moreover, the construction of a high-quality velocity model allows me to create the optimal conditions for subsequent diffraction imaging, which provides high-resolution structural information.
Maxillary arch changes with transpalatal arch treatment followed by full fixed appliances
Authors: Raucci Gaetana , Pachêco-Pereira Camila , Grassia Vincenzo , d’Apuzzo Fabrizia , Flores-Mir Carlos , Perillo Letizia 
Published: October 2014

ABSTRACT

Objective:
To evaluate short- and long-term maxillary dental arch dimensional changes in patients treated with a transpalatal arch (TPA) during mixed dentition followed by full fixed appliances in the permanent dentition compared with an untreated sample.

Materials and Methods:
Dental casts and lateral cephalograms obtained from 36 consecutively treated patients before TPA treatment (T0), after TPA treatment (T1), after fixed appliance treatment (T2), and a minimum of 3 years after fixed appliance treatment (T3) were analyzed. The control group was matched as closely as possible. Arch widths, perimeter, and length, as well as crowding and incisor proclination, were evaluated.

Results:
In the treated group, intercanine, interpremolar, and intermolar widths and arch perimeter increased significantly at T1. At T2, only the intercanine width increase was still significant. At T3 all arch dimensions decreased, remaining larger than they were at T0. The arch length increased after T1, significantly decreased at T2, and slightly decreased at T3. The crowding decreased significantly at T1, was eliminated at T2, and increased at T3. At T3, 50% of the patients showed relapse with crowding ranging from 0.5 to 2 mm. In the control group at T1, only slight changes were noted but crowding increased. At T2, crowding and upper incisor inclination increased but arch length decreased. At T3, intercuspid width, arch perimeter, and arch length continued to decrease, thereby increasing crowding.

Conclusion:
Maxillary dental arch dimensions changed significantly after TPA followed by treatment with fixed appliances. Relapse occurred to some extent, especially in intercanine width and arch perimeter, but most of the dental arch changes remained stable.
Investigation of the Indirect Hypercube as Natural Architecture for Parallel Algorithms of a Transpose Type for FFT and Other Fourier-Related Transforms
Authors: Philipov Ph. , Lazarov V. 
Published: October 2014

Abstract
The natural architectures are architectures, derived from the signal graph of the corresponding algorithm. That is why they are considered to be the most appropriate architectures for parallel realization of this algorithm. For Fast Fourier Transform algorithm (FFT) two types of natural architectures are known – the direct and the indirect hypercube. The direct hypercube has been investigated and analyzed a long time ago. The development of the concept of Indirect Hypercube, although quite old, is too difficult, controversal and still unfinished. Fast Hartley transform (FHT)/Real-valued Fast Fourier transform (RFFT) algorithms are important Fourier-related transforms, because they lower twice the operational and memory requirements when the input data is real-valued. These types of algorithms, however, have an irregular computational structure, which makes their parallel implementation a very difficult task. The aim of this paper is, based on the results achieved so far, to present further development of the concept Indirect Hypercube. A method of parametric synthesis of an indirect hypercube is described as a model of parallel FFT algorithms of a transpose type with different granularity/radix. This method is generalized for relevant RFFT/FHT and FCT algorithms. Two types of SIMD array architectures are described (radix-2 and radix-4), based on the indirect hypercube concept. These architectures are implemented as fast FFT/RFFT/FHT processors for real time applications. The performance estimation, as well as the estimation of resource utilization is carried out.
Higher Dialysate Matrix Metalloproteinase-2 Levels are Associated with Peritoneal Membrane Dysfunction
Authors: Cho Yeoungjee , Johnson David W. , Vesey David A. , Hawley Carmel M. , Pascoe Elaine M. , Clarke Margaret , Topley Nicholas 
Published: October 2014

♦ Background Peritoneal dialysis (PD) patients develop progressive and cumulative peritoneal injury with longer time spent on PD. The present study aimed to a) describe the trend of peritoneal injury biomarkers, matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1), in incident PD patients, b) to explore the capacity of dialysate MMP-2 to predict peritoneal solute transport rate (PSTR) and peritonitis, and c) to evaluate the influence of neutral pH, low glucose degradation product (GDP) PD solution on these outcomes. ♦ Methods The study included 178 participants from the balANZ trial who had at least 1 stored dialysate sample. Changes in PSTR and peritonitis were primary outcome measures, and the utility of MMP-2 in predicting these outcomes was analyzed using multilevel linear regression and multilevel Poisson regression, respectively. ♦Results Significant linear increases in dialysate MMP-2 and TIMP-1 concentrations were observed ( p < 0.001), but neither was affected by the type of PD solutions received (MMP-2: p = 0.07; TIMP-1: p = 0.63). An increase in PSTR from baseline was associated with higher levels of MMP-2 ( p = 0.02), and the use of standard solutions over longer PD duration ( p = 0.001). The risk of peritonitis was independently predicted by higher dialysate MMP-2 levels (incidence rate ratio [IRR] per ng/mL 1.01, 95% confidence interval [CI] 1.005 – 1.02, p = 0.002) and use of standard solutions (Biocompatible solution: IRR 0.45, 95% CI 0.24 – 0.85, p = 0.01). ♦ Conclusion Dialysate MMP-2 and TIMP-1 concentrations increased with longer PD duration. Higher MMP-2 levels were associated with faster PSTR and future peritonitis risk. Administration of biocompatible solutions exerted no significant effect on dialysate levels of MMP-2 or TIMP-1, but did counteract the increase in PSTR and the risk of peritonitis associated with the use of standard PD solutions. This is the first longitudinal study to examine the clinical utility of MMP-2 as a predictor of patient-level outcomes.
Effects of Fructo-Oligosaccharide Supplementation on Constipation in Elderly Continuous Ambulatory Peritoneal Dialysis Patients
Authors: Meksawan Kulwara , Chaotrakul Chorsakon , Leeaphorn Napat , Gonlchanvit Suthep , Eiam-Ong Somchai , Kanjanabuch Talerngsak 
Published: October 2014

♦ Background Fructo-oligosaccharides (FOS) exhibit soluble-fiber properties that beneficially affect bowel function and relieve constipation. The effects of FOS supplementation on constipation and biochemical parameters were examined in elderly continuous ambulatory peritoneal dialysis (CAPD) patients. ♦ Methods This randomized, double-blind, placebo-controlled, cross-over study was performed in elderly CAPD patients (5 males and 4 females) with chronic constipation. All subjects were randomly assigned to receive either 20 g FOS or placebo daily for 30 days. After a 14-day washout period, the patients were switched to the other substance for 1 more month. Before and after each treatment period, frequency of defecation, characteristics of feces, and colonic transit were evaluated. Biochemical parameters were also assessed. ♦Results Fructo-oligosaccharides significantly increased the frequency of defecation (10.5 ± 2.0 vs 6.2 ± 1.4 times per week, p < 0.005) and changed the feces’ appearance from type 1 (nut-like) to type 4 (sausage–like). The colonic transit determined by geometric center (GC) was augmented after FOS supplementation (3.9 ± 0.3 vs 3.2 ± 0.4, p < 0.05). Fructo-oligosaccharides had no effects on biochemical parameters. Fructo-oligosaccharides caused mild discomforts which were well tolerated after dose adjustment. ♦ Conclusions Fructo-oligosaccharide supplementation is effective, well tolerated, and can be an alternative to other laxatives in CAPD patients with constipation. Further studies are needed to better assess the biochemical effects of FOS in the chronic kidney disease population.
Peritoneal Dialysis can be an Option for Dominant Polycystic Kidney Disease: An Observational Study
Authors: Janeiro Darío , Portolés Jose , Tato Ana María , López-Sánchez Paula , Del Peso Gloria , Rivera Maite , Castellano Inés , Fernández-Reyes Maria J. , Pérez-Gómez Vanessa , Ortega Mayra , Martínez-Miguel Patricia , Felipe Carmen , Caparrós Guadalupe , Ortiz Alberto , Selgas Rafael 
Published: October 2014

Background Autosomal dominant polycystic kidney disease (ADPKD) has been considered a relative contraindication for peritoneal dialysis (PD), although there are few specific studies available. Methods A multicenter historical prospective matched-cohort study was conducted to describe the outcome of ADPKD patients who have chosen PD. All ADPKD patients starting PD ( n = 106) between January 2003 and December 2010 and a control group (2 consecutive patients without ADPKD) were studied. Mortality, PD-technique failure, peritonitis, abdominal wall leaks and cyst infections were compared. Results Patients with ADPKD had similar age but less comorbidity at PD inclusion: Charlson comorbidity index (CCI) 4.3 (standard deviation [SD] 1.6) vs 5.3 (SD 2.5) p < 0.001, diabetes mellitus 5.7% vs 29.2%, p < 0.001 and previous cardiovascular events 10.4% vs 27.8%, p < 0.001. No differences were observed in clinical events that required transient transfer to hemodialysis, nor in peritoneal leakage episodes or delivered dialysis dose. The cyst infection rate was low (0.09 episodes per patient-year) and cyst infections were not associated to peritonitis episodes. Overall technique survival was similar in both groups. Permanent transfer to hemodialysis because of surgery or peritoneal leakage was more frequent in ADPKD. More ADPKD patients were included in the transplant waiting list (69.8 vs 58%, p = 0.04) but mean time to transplantation was similar (2.08 [1.69 – 2.47] years). The mortality rate was lower (2.5 vs 7.6 deaths/100 patient-year, p = 0.02) and the median patient survival was longer in ADPKD patients (6.04 [5.39 – 6.69] vs 5.57 [4.95 – 6.18] years, p = 0.024). Conclusion Peritoneal dialysis is a suitable renal replacement therapy option for ADPKD patients.