bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utilizing Hybrid Surface - Downhole Seismic Networks to Monitor Hydraulic Fracture Stimulations
Authors: Baig Adam , Urbancic Ted , Viegas Gisela 
Published: February 2013

Abstract
Typically, seismic networks are deployed downhole to monitor injection-related activity and are designed to detect and analyze microseismic events at very short distances. During hydraulic fracture treatments, thousands of events can be generated with magnitudes in the range of -M4 to –M0. These networks record relatively high frequency signals (&gt; 15Hz) and use time records with a short duration; however, they are limited in low-frequency response. This lack of bandwidth results in underestimated magnitudes for events with larger magnitudes (from about –M0 to +M4) that may occur during stimulations. To correct this issue, recording with high -sensitivity, near-surface sensors with low-frequency capabilities (&gt;0.5Hz) extends the frequency range thereby allowing for the correct assessment of magnitude. In this paper, we investigate the spatial and temporal variations in seismicity associated with hydraulic fracture treatments of a shale play in North America using two different monitoring configurations, with multiple, fibre-optic based wireline arrays, each with twenty to forty-eight three-component levels of omni 15Hz geophones deployed vertically in close proximity to the treatment well and using a near-surface network of five stations consisting of three component Force Balance Accelerometers and 4.5Hz geophones. The near-surface monitoring network detected hundreds of events ranging in magnitude from M0 to M3, the largest of which were also recorded on a nearby national seismic network station. The downhole events did not see such large events, but recoreded thousands of events up to M0. Here, we compare parameters from the downhole data to the near-surface data to try to answer what role the larger events are playing in the reservoir and how they can be put into proper context with the smaller, downhole data. The failure mechanisms and scaling relationships for these large events suggest that they are the response of larger features in the reservoir, slipping in response to the stress perturbations induced by the treatment. Based on these observations, we suggest that a hybrid solution is appropriate for reservoirs with structural controls in order to appropriately assess the reservoir response to stimulations.
Cemented Multi-Stage Sleeve Completion Improves Efficiency of Fracture-Stimulation in an Eagle Ford Shale Well
Authors: Adcock Glenn , Wellhoefer Ben , Daher Said , Fruge Eric 
Published: February 2013

Abstract
To economically develop unconventional resource plays such as the Eagle Ford Shale in South Texas, multiple complex hydraulic fracturing stages must be executed in the horizontal section of the wellbore. Traditionally, a plug and perforate (P-n-P) process has been used. However, inherent difficulties in the process often limited completion cycle time and created barriers to economic delivery of the hydraulic fracturing treatment.
The Eagle Ford shale in Zavala County, Texas is similar to many high-carbonate-content oil-shale formations. As with other shale plays, the industry has preferred using cemented lateral sections as the primary means of fracture-stage isolation, coupled with the P -n-P horizontal completion technique. This paper explores an alternative completion method, cemented multi-stage sleeves (CMSS), that recently improved efficiency and reduced completion cycle time. This study discusses the process, procedures used, and lessons learned from applying this technology.
The subject well design was similar to most Eagle Ford shale wells. The completion included setting a deep surface casing string at 3030 feet, and then, drilling an 8.75-in. openhole section to MD. A 5.5-in. production casing was then set and cemented into place. The well was drilled to a measured depth of 11,965 feet with a lateral section of 5,913 feet. The well was completed using 15 stages of CMSS to fracture stimulate the entire lateral section. 3.80MM lbm of proppant with 2,901,000 gallons of fluid was used to fracture stimulate the wellbore, averaging 54 bbl/min. The 16 stage stimulation operation was completed in 24 hours with continuous pumping compared to an average of 3 days for P-n-P. The discussion also will show that production was comparable to that of offset wells, thus proving the technique viable for this type of oil-shale formation.
Proppant Placement Using Alternate-Slug Fracturing
Authors: Malhotra Sahil , Lehman Eric R. , Sharma Mukul M. 
Published: February 2013

Abstract
New fracturing techniques such as hybrid fracturing (Sharma et. al., 2004), reverse hybrid fracturing (Liu et. al., 2007) and channel (HiWAY) fracturing (Gillard et al. 2010) have been deployed over the past few years to effectively place proppants in fractures. The goal of these methods is to generate a network of open channels within the proppant pack, providing highly conductive paths for hydrocarbons to flow from the reservoir to the wellbore. This paper presents an experimental study on proppant placement using a new method of fracturing, referred to as Alternate-Slug fracturing, which involves alternate injection of low viscosity and high viscosity fluids into the fracture. Alternate-slug fracturing ensures deeper placement of proppants through two primary mechanisms: (a) proppant transport in viscous fingers formed by the low viscosity fluid and (b) an increase in drag force in the polymer slug leading to better entrainment and displacement of any proppant banks that may have formed. Both these effects lead to longer propped fracture length and better vertical placement of proppants in the fracture. In addition the method offers lower polymer costs, lower pumping horsepower, smaller fracture widths, better control of fluid leakoff and less gel damage compared to conventional gel fracs.
Experiments are conducted in simulated fractures (slot cells) to study the mixing of fluids over a wide range of viscosity ratios. Data is presented to show that the finger velocities and mixing zone velocities increase with viscosity ratio up to viscosity ratios of about 350 and the trend is consistent with Koval’s theory. However, at higher viscosity ratios the mixing zone velocity values plateau signifying no further effect of viscosity contrast on the growth of fingers and mixing zone. Fluid elasticity is observed to slow down the growth of fingers and leads to growth of multiple thin fingers as compared to a single thick dominant finger in less elastic fluids.
Experiments are conducted with fluids of different viscosity and elasticity, with proppants being carried by the low viscosity fluid. It is shown that the injection rate, slug size and viscosity ratio can be used to control the geometry of the fingers created and, therefore, the proppant distribution in the fracture. The non-uniform placement of proppant in the viscous fingers leads to the creation of high permeability paths in the proppant pack.
Asset Development Drivers in the Bakken and Three Forks
Authors: Cherian Bilu V. , Nichols Chris M. , Panjaitan Maraden L. , Krishnamurthy Jayanth K. , Sitchler Jason 
Published: February 2013

Abstract
Home to one of the largest North American deposits discovered in the last few decades, the Bakken, spanning 200,000 square miles along the borders of Saskatchewan, North Dakota and Montana is rivaling some of the largest proven reserves. As the use of long horizontal wells and multi-stage fracturing technology has significantly increased productivity and activity in the basin, the challenges associated with infill-completions, depletion and controlled fracture growth must be addressed to ensure efficient and effective practices, encouraging long-term planning without hindering investment.
In this paper, models are built to replicate well performance (fracturing and production-numerical & rate-transient) and to understand the impact of key technologies (multi-stage/completion type and multi-laterals) across the basin to demonstrate why completion strategies must be modified based on reservoir quality and stress state. Confusion between the success of sliding sleeves/plug and-perf and what drives the optimal number of stages is also addressed using fracture modeling and production modeling with emphasis on key parameters (fracture length, connectivity, number of fractures) influencing productivity. The recent focus on data acquisition and modeling in the Three Forks has presented a range of challenges and opportunities due to the laminations in this reservoir. Log up-scaling methods and simulator engines were crucial to modeling and thus evaluating propagation behavior. This paper also presents how the use of data gathering (log, routine and specialized core) and modeling has enabled us to understand how in-fill drilling can alter drainage patterns and influence production success.
Net Pressure Trends: Is it Permeability, Complexity or just Fluid Response?: A Workflow To Determine Stimulation Effectiveness in Naturally Fractured and Matrix-Based Permeability Reservoirs
Authors: Lehman Lyle V. , Al-Tailji Wadhah , Northington Neill 
Published: February 2013

Abstract
Hydraulic fracturing stimulation in unconventional reservoirs has taken on a new emphasis in the search for oil and liquids from these low permeability reservoirs. Today, we are attempting to achieve economic production from reservoirs that were passed over just five years ago. The fracture stimulation goal: to provide a conductive path between the reservoir and the wellbore.
However, these reservoirs are inherently difficult, at best, to evaluate and to fully understand the completion environment at a distance from the wellbore. Fortunately, there is a workflow that allows understanding of permeability sources as the fracture treatment is placed in real time and certainly in post-frac analysis. The toolbox uses a "planar" frac model to analyze data gathered from surface sources.
This paper will discuss a workflow to differentiate between pressure trends due to fluid and/or proppant effects on friction, and actual net-pressure change due to permeability exposure by the frac fluid in the reservoir. By understanding that fracture stimulation is a highly invasive process, the authors will examine the data that can be used as a benchmarking tool for reservoir response. We will discuss examples from the Eagle Ford formation for naturally fractured permeability reservoirs and the Wolfberry trend for matrix-based reservoirs. The workflow will aid in fracture spacing in horizontal wells and well spacing in multi-layered vertical wells.
Velocity Building for Microseismic Hydraulic Fracture Mapping in Isotropic and Anisotropic Media
Authors: Du Jing , Warpinski Norm R. 
Published: February 2013

Abstract
Microseismic hydraulic fracture mapping is a very valuable tool for monitoring hydraulic fracture growth and behavior in unconventional reservoirs. During the development of these unconventional reservoirs, there are many engineering decisions that need to be made based on the microseismic event locations. In addition to recording the microseismic data with adequate signal-to-noise ratio, measuring, calibrating, or otherwise building an accurate velocity structure through the formation layers is another key element necessary to obtain acccurate event locations for making sound engineering decisions. The velocity building process starts with an initial velocity model usually derived from a dipole sonic log. After the receivers have all been placed, source shots in known positions, such as perforations or string shots, then are used to calibrate the velocity model, which is used to solve a nonlinear and mostly underdetermined system of equations, depending on the acquisition geometry and the number of layers in the model. In this paper, a modified Newton-Raphson method coupled with singular value decomposition (SVD) is presented to optimize the velocities and anisotropic parameters for individual layers, and the effectiveness of this method is demonstrated with examples.
Fluid Selection for Energized Fracture Treatments
Authors: Ribeiro Lionel H. , Sharma Mukul M. 
Published: February 2013

Abstract
As the development of unconventional (e.g., tight gas, shales, coalbed methane) and under-pressured reservoirs has increased, so has the demand for innovative hydraulic fracture designs. The use of gases and foams has experienced a significant resurgence in popularity with the development of unconventional reservoirs and with the growing limitations on water supply in some areas. Until recently, the tools available for fracture design were not capable of modeling hydraulic fracturing with compressible fluids and non-isothermal treatments. Ribeiro and Sharma (2012b) presented a model that was capable of simulating hydraulic fracturing treatments with multi-phase, compressible fracturing fluids with changing temperature, phase behavior, and multi-phase leak-off during the treatment. The main objective of this paper is to show how such a model can be used for screening fracturing fluid candidates and for optimizing energized fracture treatments.
In conducting this study, we have combined this 3-D compositional fracturing model with a multi-phase well-productivity model for hydraulically fractured wells. This paper presents results for slick water, linear gel, gelled CO2, gelled LPG, N2 foams and CO2 foams in a low permeability reservoir. The simulations showed that good proppant placement and high fracture conductivities can be achieved with foams and gelled fluid formulations. LPG, CO2, and high-quality foams prevent water invasion so they do not impede gas recovery because of water blocking or gel induced damage. In addition, several reservoir parameters appear to control well productivity and therefore fluid selection: (1) relative permeability curves, (2) initial gas saturation, (3) reservoir pressure, and (4) sensitivity to water. The benefits and disadvantages that must be considered when selecting a fracturing fluid are highlighted in this paper and a methodology is proposed to quantify these pros and cons.
Optimum Fluid and Proppant Selection for Hydraulic Fracturing in Shale Gas Reservoirs: a Parametric Study Based on Fracturing-to-Production Simulations.
Authors: Cohen C. E. , Abad C. , Weng X. , England K. , Phatak A. , Kresse O. , Nevvonen O. , Lafitte V. , Abivin P. 
Published: February 2013

Abstract
Production from shale gas reservoirs depends greatly on the efficiency of hydraulic fracturing treatments. The cumulated experience in the industry has led to several best practices in treatment design which have improved productivity in these reservoirs. However, further advances in treatment design require a deeper understanding of the complex physics involved in both hydraulic fracturing and production, such as stress shadow, proppant placement and interaction with natural fractures.
This paper investigates the non-linear physics involved in the production of shale gas reservoirs by improving the understanding of the complex relation between gas production, the reservoir properties, and several treatment design parameters, with a focus on proppant and fluid selection. A fracturing-to-production simulation workflow integrating the Unconventional Fracture Model, with the Unconventional Production Model is presented. This workflow has shown qualitative consistency with real production data.
In this paper we applied the workflow on a realistic reservoir with characteristics from the Marcellus play, and then studied the relation between production and treatment design parameters such as proppant size, proppant concentration, the treatment volume of the treatment, fracturing fluid viscosity, pumping rate and proppant injection sequence.
Since this paper focuses on fluid and proppant selection, our methodology was to run 28 simulations to cover the 2D parametric space of proppant size and fluid viscosity for every parameter. More than four hundred simulations were run in this parametric study and the results provide guidelines for optimized treatment design.
The behaviors observed confirm several best practices in treatment design for shale. For example, combination of different sizes of proppant optimizes production by maximizing initial production and slowing down production decline. Simulations also confirm the best practice of injecting the smallest proppant first. Another key finding is that the optimum fluid viscosity increases with treatment volume, and decreases when pumping rate increases.
Propping Outside the Pay: a Process to Potentially Increase Fracture Flow Capacity, Post-Frac Production, and Net Revenue from Hydraulic Fracturing
Authors: Veatch Ralph W. , Cooke Claude E. 
Published: February 2013

Abstract
"Propping Outside the Pay" is a hydraulic fracturing procedure used or applied on or to a vertical well. For applicable wells, it has the potential to enhance/increase fracture flow capacity and the resulting: (a) producing flow rate (b) total recoverable reserves and (c) monetary returns. It introduces an added aspect to optimizing treatment, i.e., proppant pile height above the pay. Hence "Propping Outside the Pay" is a double optimization approach, i.e., fracture penetration (Xƒ) and piled proppant height above the pay (Hƒp).
The process creates more flow capacity from the pay to the wellbore through hydraulically created fractures that extend significantly outside the pay. It employs either one or both of the following: (a) injecting quantities of fracture propping material (proppant) that are greater than that normally used, and/or (b) creating more flow connections (e.g. perforations or open hole) from the wellbore to the propped fracture than are normally made.
Additional proppant piled above the pay, and in the fracture below the pay (where proppant can settle) increases the fracture total cross sectional area and flow capacity. If the entire propped fracture is connected to the wellbore, the added fracture flow capacity enhances production rates over and above that predicted by the commonly used methods that are normalized on pay.
At issue is economic viability, i.e., the additional proppant and perforating additional costs versus the monetary returns. Perforating costs are usually not significant as compared to first order proppant costs. Also, the applicable candidate wells require in-situ stress profiles such that the fracture will vertically propagate sufficiently above and/or below the pay to provide the opportunity to create additional fracture flow capacity. Experience indicates that a significant number of candidate wells exist.
Computational studies showed that net present value returns from using the process can be significantly increased. The degree of increase depends upon the relative vertical fracture height to pay ratio, rock mechanics and reservoir parameters, hydrocarbon prices, fracturing costs, well spacing, etc. Examples comparing "Typical" cases to "Propping Outside the Pay" cases are shown.
Oral treatment with etoposide in small cell lung cancer – dilemmas and solutions
Authors: Rezonja Renata , Knez Lea , Cufer Tanja , Mrhar Aleš 
Published: February 2013

Abstract
Background. Etoposide is a chemotherapeutic agent, widely used for the treatment of various malignancies, including small cell lung cancer (SCLC), an aggressive disease with poor prognosis. Oral etoposide administration exhibits advantages for the quality of life of the patient as well as economic benefits. However, widespread use of oral etoposide is limited by incomplete and variable bioavailability. Variability in bioavailability was observed both within and between patients. This suggests that some patients may experience suboptimal tumor cytotoxicity, whereas other patients may be at risk for excess toxicity.
Conclusions. The article highlights dilemmas as well as solutions regarding oral treatment with etoposide by presenting and analyzing relevant literature data. Numerous studies have shown that bioavailability of etoposide is influenced by genetic, physiological and environmental factors. Several strategies were explored to improve bioavailability and to reduce pharmacokinetic variability of oral etoposide, including desired and undesired drug interactions (e.g. with ketoconazole), development of suitable drug delivery systems, use of more water-soluble prodrug of etoposide, and influence on gastric emptying. In addition to genotype-based dose administration, etoposide is suitable for pharmacokinetically guided dosing, which enables dose adjustments in individual patient.
Further, it is established that oral and intravenous schedules of etoposide in SCLC patients do not result in significant differences in treatment outcome, while results of toxicity are inconclusive. To conclude, the main message of the article is that better prediction of the pharmacokinetics of oral etoposide may encourage its wider use in routine clinical practice.
Strange bedfellows: The new neoliberalism of catholic schooling in the United States
Authors: Burke Kevin 
Published: February 2013

Abstract
The article utilizes critical social theory and critical religious theory to examine the emergent and historically aberrant alignment between Catholic schools and neoliberal market-based reforms in the United States. The author traces the historical split between Catholic and public schooling, attending to the role of the litigious in shaping American parochial contexts. In the face of declining enrollments and vocations as well as skyrocketing tuition and a contracting share of the educational ‘market,’ Catholic leadership has sought public support through market instruments (tax credits and vouchers) in order to preserve dying religious schools. Lost in this paradigm shift is the irony of the move from proud separatism to a governmental reliance that would have seemed abhorrent thirty years ago. Missing, too, in the rhetoric of ‘saving Catholic schools’ is concern for the harm done to education on a whole when religious schools are presented as competitors with, rather than alternatives to, a free public education. Examined through the lens of the largest provider of Catholic schoolteachers in the United States, the article ultimately concludes that the public good is being sacrificed at the altar of religious pride.
Trends in Technical and Tactical Modifications Among Competitors of Various Nationalities Based on Research Conducted During the 2009 World Youth Championship in Greco-Roman Style Wrestling in Turkey
Authors: Kruszewski Artur , Kuźmicki Stanisław , Kruszewski Marek , Jagiełło Władysław 
Published: February 2013

Abstract

Introduction
. This paper discusses the relationship between the technique implemented during competition and the end result including an attempt to evaluate the technical and tactical preparation of different nationality competitors in Greco- Roman wrestling. The research was conducted during the 2009 Junior World Cup in Turkey.
Material and methods.
The research material included a video recording posted by the International Federation of Associated Wrestling Styles (FILA) on their website. The material contained recordings of 240 matches. An analysis of 212 matches with competitors from 49 countries was conducted; each team selected one competitor in each weight category (up to 8 competitors in total).
Results and conclusions
. During the competition there was strong correlation between victory and the execution of the roll-through and the combat zone and result defence, also in the ground position. Competitors from Russia and Iran, who were most successful, winning 6 and 4 medals respectively, obtained an average of 3.18 technical points in each match. Among the sample analysed this was the lowest score, indicating the optimal use of technical and tactical skills by the competitors resulting in a victory.