bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Financeira Corporativa e Performance Social Corporativa: desenvolvimento metodológico e contribuição teórica dos estudos empíricos
Authors: Boaventura João Maurício Gama , Silva Ralph Santos da , Bandeira-de-Mello Rodrigo
Published: December 2012

Um dos papéis da contabilidade é prover informações sobre o desempenho empresarial, quer seja por indicadores contábil-financeiros ou não. Dentro deste escopo do interesse da contabilidade, observa-se que a publicação de estudos teórico-empíricos sobre as relações entre Performance Corporativa Financeira (CFP) e a Performance Social Corporativa (CSP) vem crescendo nos últimos anos, sintoma do desenvolvimento deste campo de pesquisa. Entretanto, a contribuição à teoria pelos trabalhos empíricos se faz de forma pontual, uma vez que normalmente cada estudo foca um aspecto particular da teoria. Periodicamente, portanto, é necessária uma análise que avalie como, de forma agregada, os estudos empíricos contribuíram para a evolução da teoria, e elaborar essa análise constituiu o objetivo do presente estudo. O referencial teórico abrangeu: teoria dos stakeholders, relação entre CSP e CFP, good management theory e slack resource theory. Esta pesquisa abrangeu um período de 15 anos (1996 a 2010) e a coleta de dados empregou a ferramenta de busca das bases de dados: Ebsco, Proquest e ISI. O processo de amostragem obteve um conjunto de 58 artigos exclusivamente teórico-empíricos quantitativos que testam a relação CSP-CFP. Os principais resultados no campo teórico demonstram um reforço da proposição de relação positiva entre CSP e CFP e da good management theory, uma deficiência na explicação na defasagem de tempo (lag) na relação de causalidade entre CSP e CFP, e deficiências na descrição do constructo de CSP. Isto sugere estudos futuros para investigar a defasagem de tempo na relação de causalidade entre CSP e CFP e as possíveis razões que levaram diversos estudos empíricos a não atestarem uma associação positiva entre CSP e CFP.
Vigotski e Bakhtin: a ação educacional como projeto dialógico de produção de sentido
Authors: Fernandes Júlio Flávio de Figueiredo , Carvalho Mauro Giffoni , Campos Edson Nascimento
Published: December 2012

Este texto se propõe a estabelecer um diálogo entre Vigotski e Bakhtin, tomando como parâmetros o quadro referencial de conceitos associados à orientação vigotskiana sobre Zona de Desenvolvimento Imediato e à orientação bakhtiniana sobre o dialogismo da linguagem. Utilizando tais parâmetros, propõe-se a refletir sobre a fundamentação do processo educacional através de princípios teóricos ou aforismas que afirmam a especificidade da mediação com que se realiza a relação educador/educando.
The nature and origin of deep ocean clay crust from the Gulf of Guinea
Authors: KUO M. , BOLTON M.
Published: December 2012

Deep ocean sediments off the west coast of Africa exhibit a peculiar undrained strength profile in the form of a crust, albeit of exceptionally high water content, overlying normally consolidated clay. Hot-oil pipelines are installed into these crustal sediments, so their origins and characteristics are of great interest to pipeline designers. This paper provides evidence for the presence of burrowing invertebrates in crust material, and for the way sediment properties are modified through their creation of burrows, and through the deposition of faecal pellets. A variety of imaging techniques are used to make these connections, including photography, scanning electron microscopy and X-ray computer tomography. However, the essential investigative technology is simply the wet-sieving of natural cores, which reveals that up to 60% by dry mass of the crustal material can consist of smooth, highly regular, sand-sized capsules that have been identified as the faecal pellets of invertebrates such as polychaetes. Mechanical tests reveal that these pellets are quite robust under effective stresses of the order of 10 kPa, acting like sand grains within a matrix of fines. Their abundance correlates closely with the measured strength of the crust. While this can easily be accepted in the context of a pellet fraction as high as 60%, the question arises how a smaller proportion of pellets, such as 20%, is apparently able to enhance significantly the strength of a sediment that otherwise appears to be normally consolidated. A hypothesis is suggested based on the composition of the matrix of fines around the pellets. These appear to consist of agglomerates of clay platelets, which may be the result of the breakdown of pellets by other organisms. Their continued degradation at depths in excess of 1 m is taken to explain the progressive loss of crustal strength thereafter.
An extended Mohr–Coulomb (EMC) model for predicting the settlement of shallow foundations on sand
Authors: DOHERTY J.P. , MUIR WOOD D.
Published: December 2012

Predicting the settlement of shallow foundations on sand is a routine task for the geotechnical engineering profession. Despite this, there is no well-accepted solution for this very common problem. The aim of the present paper is to address this by presenting a soil model that is simple enough to be applied in routine engineering practice, but sophisticated enough to capture the important mechanical behaviour of sands relevant to the footing settlement problem. Emphasis is placed on the application of the model by presenting details of the process adopted for deriving model parameters prior to back-analysing foundation load tests.
Plugging criterion for offshore pipe pile drivability
Authors: DEAN E.T.R. , DEOKIESINGH S.
Published: December 2012

Both plugged and coring behaviours are normally considered when analysing pile drivability. However, several authors challenge the idea that pipe piles can always plug. These views are argued partly on experience and engineering judgement, and partly on measured (although often proprietary) data. This paper proposes a new, objectively calculable criterion to determine whether a pile will plug during driving. The criterion is shown to agree with engineering judgement and be relevant to published data.
Selection of Proppants for Long-Term Stability
Authors: Raysoni Neelam , Weaver Jim
Published: December 2012

Proppant is used to keep hydraulic fractures open and to maintain the conductivity of the fracture. This helps operators produce the well economically. It is normal for well productivity to decline as reservoir pressure declines. However, steeper rates of decline are often observed, which have been attributed to additional damage mechanisms, such as proppant crushing, embedment, and fines migration.

Proppant diagenesis may also be a contributing factor affecting production decline. Proppant diagenesis has been discussed previously (Weaver and Rickman 2010), where pressure solution and the compaction mechanisms are proposed to be responsible for causing diagenesis of proppant. This concept has gained momentum and has been the subject of other recent studies and discussions, particularly in the hydrothermal industry.

Choosing the correct proppant for a given formation at the reservoir temperature and stress becomes an important factor. Selection of proppant should not be based solely on the crush strength of the proppant at the applied stress value, but should also depend on the overall integrity of the proppant after being exposed to the reservoir conditions. Choosing the proper proppant for the job should be more economical for the long-term stability of the well.

This paper provides details of the testing protocols developed to provide improved understanding of proppant diagenesis under different reservoir conditions. The discussion should help operators understand the importance of the procedures used to obtain accurate results, as well as shed light on the process of selecting the correct proppant for long-term fracture stability.
3-D Modeling of Fracture Initiation From Perforated Non-Cemented Wellbore
Authors: Alekseenko O. P. , Potapenko D. I. , Cherny S. G. , Esipov D. V. , Kuranakov D. S. , Lapin V. N.
Published: December 2012

A 3D numerical model of fracture initiation from a perforated wellbore in linear elastic rock is developed, which allows one to determine the fracture initiation pressure (FIP) and the location and direction of an initial rupture. The model assumes that the fracture initiates at the point where the local maximum tensile stress exceeds the rock tensile strength. The 3D boundary element method is used for stress analysis.

The model is aiming at predicting the location of initial fractures and the difference in FIP between different perforation intervals in arbitrarily oriented non-cemented wellbores. There are many practical applications where this knowledge is required, but of particular interest for this research is the employment of differently oriented perforations for creating heterogeneity of FIP between wellbore intervals in multistage fracturing treatment. This can enable stimulation of these intervals in a sequential mode and significantly simplify current treatment diversion and completion practices.

Comprehensive analysis revealed that the main parameter that can be used for controlling FIP during multistage fracturing treatment is the angle between the direction of the perforation channel and the preferred fracture plane. The model allows obtaining the range of the angles that is the most suitable for designing and implementation of diversion between the perforated wellbore intervals. The influence of geometrical parameters of perforation (e.g. length, diameter and shape) on FIP is substantially less. Addtionally we found that against all expectations increase of perforation diameter can result in higher FIP. It was also discovered that the influence of the intermediate in-situ stress on FIP is comparable with the effect of perforation misalignment especially in the situation of horizontal wellbore and properly aligned perforations. Based on the model developed, an approximate approach to the evaluation of the impact of wellbore cementation on fracture initiation was suggested. It was discovered that taking into account the state of stress within the cement prior to well pressurization can result in both an increase and reduction of FIP depending on the parameters of perforating as well as wellbore orientation.

The presented model is the necessary step toward predictable and controllable fracture initiation, which is vital for multistage fracturing treatment diversion.
Advanced Computational Modeling of Proppant Settling in Water Fractures for Shale Gas Production
Authors: Tsai Kuochen , Fonseca Ernesto Rafael , Degaleesan Sujatha , Lake Ed
Published: December 2012

This paper shows advances in the numerical simulation of proppant transport in hydraulically stimulated fractures for oil and gas production. Water or commonly known "slickwater" hydraulic fracture treatments have become increasingly popular in shale gas. This is widely applied in the Haynesville shale in north Louisiana but, due to the large depths and high pressure, conventional wisdom requires that the intermediate strength proppants (generally 4,000 to 6,000 psi crush strength) should be used. This strength envelope is in the transition between ceramics and sand. Sand, which is lower in cost, also has the advantage of having better transport properties in water fractures.

In the paper, a 3-D computational fluid dynamics model with Lagrangian solid particle transport isused to visualize the propagation of sand and other lighter proppants in a simulated fracture. Demonstrated is the proppant settling behavior influenced by proppant density, size and flow rates. The final proppant settling patterns can vary dramatically and may result in significant changes on the fracture’s conductivity.

Model assumptions, simplifications and numerical details are discussed along with issues regardingvalidation and simulation strategy. The model geometry is highly idealized (i.e., neglectingfracture tortuosity and expansion during water fracturing, surface roughness and fluid leakoff). The importance of this work lies in the fact that the model can resolve the interactions between fracturing fluid (water) and proppants within complex 3-D geometries, thus providing a better understanding of the fracturing process to allow for possible enhancements to production procedures.
Revisiting Natural Proppants for Hydraulic Fracture Production Optimization
Authors: Yang Mei , Economides Michael J.
Published: December 2012

Proppants are essential to the success of most hydraulic fractures and often account for the overwhelming cost of the treatment. Both the mass of proppant and the selection of the right type of proppant are essential elements in gaining the highest Net Present Value (NPV).

It has been generally believed that in the lower closure stress environment (below 6,000 psi, i.e., shallow reservoirs), natural sands such as Brady and Ottawa are appropriate as proppants and, for the same mesh size, they provide essentially the same permeability. Commonly accepted notion is that manmade proppants (such as ceramics) should be applied at higher closure stress environment, invariably, deeper reservoirs.

Three types of proppants are studied for a gas reservoir of Eagle Ford basin: Brady sand, Ottawa sand and ceramic. A fracture optimization p-3D model is used to maximize well performance by optimizing fracture geometry, including fracture half length, width and height. Reduced proppant pack permeability is compensated by larger width. Non-Darcy effects in the fracture are also considered. Post-treatment well performance is then estimated, using the optimized well geometry, leading to cumulative production over the well life. Finally, NPV analysis is employed as the criterion to select the best proppant for the job.

In this project, we show there is an optimum Proppant Number corresponding to maximum NPV in various reservoir permeability. Based on that, we propose a systematic way of choosing proppant type and mass to maximize NPV in oil reservoirs. For tight gas reservoirs, we correct the prejudice that natural sand proppants cannot be applied to deeper reservoirs by showing NPV study results that are superior to those of manmade proppants. Keeping stimulation costs down, natural sands proppants have a much larger range of applicability than previously thought.
Numerical Modeling of Fracture Complexity With Application to Production Stimulation
Authors: Shen Xinpu , Cullick A. S.
Published: December 2012

The commercial exploitation of shale resources requires the design of hydraulic fracture programs to optimize the stimulated reservoir volume. Challenges include the engineering of staging, sequencing, injection volume, and proppant selection. This paper describes the development of a 3-D finite-element model to simulate growth of fracture complexes as functions of rock stress, brittleness properties, and injection conditions. The fracture complex is modeled as a major fracture, which consists of a cohesive crack and microcracks that form with variable continuum mechanical damage. Variations of permeability and porosity affect the continuum mechanical damage, which is used to investigate the fracturing sequence of three stages of injections in a horizontal well and generates three sets of fracture complexes. Inputs include a geomodel, the initial geostress, and pore pressure. Elastoplastic deformation coupled with both porous and gap flows are simulated.

The model is also used to investigate the influence of rock brittleness on the fracture complexity. Material brittleness is the product of the elasticity modulus and Poisson’s ratio. Three sets of values of material brittleness were used in the calculation for comparison. The same loads and initial conditions of the first example were used in the model. The results include two sets of distributions of fracture propagation and damage evolution for two different injection sequences, pore pressure distribution after fluid injection stimulation, three sets of numerical results of distribution of fracture, and mechanical damage corresponding to different values of brittleness. Numerical results indicate that adjusting the sequence of multi-stage fracturing significantly influences the stimulated formation volume fractured. The model can be used to design more optimal fracture programs.
Proppant Fracture Conductivity With High Proppant Loading and High Closure Stress
Authors: Rivers M. , Zhu D. , Hill A.D.
Published: December 2012

Ultra-deepwater reservoirs are important unconventional reservoirs that have the potential to produce billions of barrels of hydrocarbons, and are usually high pressure and high temperature with relatively high permeability. One major challenge of an unconventional, ultra-deepwater reservoir is pumping an effective and robust fracture stimulation treatment. Hydraulic fracturing a high permeability reservoir (>100 md) can be different from hydraulic fracturing technology used in low permeability formations (<1 md) due to their difference in purpose. The main purpose of hydraulic fracturing a low permeability reservoir is to create a long, conductive path to enhance drainage area and ensure a commericially economic well. In a high permeability formation, hydraulic fracturing is predominantly used to bypass near wellbore formation damage, control sand production and reduce near wellbore pressure drop. Such a treatment is achieved by pumping a short fracture packed with high proppant concentrations and may also aim at achieving enough fracture length to increase productivity especially when reservoir fluid viscosity is high. To pump such a job and ensure long term productivity from the fracture, understanding the behavior of the proppant pack is critical.

A series of laboratory experiments have been conducted to study conductivity and fracture width with high proppant loading, high temperature and high pressure using a Cooke conductivity cell. In thisstudy, proppant was manually placed between two core samples and fracture fluid was initially pumped through the proppant pack. Conductivity was subsequently measured by pumping oil through the manuallyplaced proppant pack to displace the fracture fluid and simulate reservoir conditions; resulting fracture fluid clean-up and proppant pack performance were studied. High strength proppant, ideal for fracture stimulations with high closure stress, was used to study the effects of proppant fracture conductivity with different proppant loadings and closure stresses. Proppant crushing and fracture width were also measured and compared to proppant pack conductivity in certain cases.

Testing results while pumping oil through the proppant pack at reservoir conditions indicated almost immediate fracture fluid clean-up. Increasing proppant concentration in the fracture showed higherconductivity values in some cases, while increasing the effective closure stress during an individualtest resulted in a significant loss in conductivity for all cases. Additionally, fracture width decreased with increased effective closure stress and time. Tests were also run to study the effect of cyclic loading and showed further degradation in conductivity and width.
A Method To Perform Multiple Diagnostic Fracture Injection Tests Simultaneously in a Single Wellbore
Authors: Martin Ross , Cramer David Daniel , Nunez Oswaldo , Roberts Neale Russell
Published: December 2012

Abstract This paper presents a unique process for deriving reservoir properties (i.e., minimum horizontal stress, kh/u and reservoir pressure) in isolated reservoir layers intersected by the same wellbore. It is based on simultaneously performing multiple diagnostic fracture-injection tests (DFIT) with extended multi-day shut-in periods using downhole shut-in tools and bottomhole memory gauges. A case study of 58 wells completed in the Mesaverde and Dakota sandstones of the San Juan Basin is used to describe and assess the above application. These intervals are gas productive, slightly to significantly sub-pressured, and possess a very low permeability pore network enhanced by natural fracture networks. As many as seven individual intervals per well were tested using the simultaneous process in an area spanning the entire San Juan Basin. Large scale, multi-stage hydraulic fracturing is necessary to establish commercial production from these intervals. The diagnostic tests were done prior to the large-scale fracture treatments, yet did not impede the subsequent implementation of the treatments. In the Dakota interval, the diagnostic testing results agreed well with the kh derived from post-frac production analysis and led to a process of treatment design optimization. In the Mesaverde interval, less agreement was found between diagnostic test and production analysis results. Despite the lack of validation, fluid leak-off rates measured during the diagnostic testing provided insight into fracture half-length differences documented in a previous study of microseismic mapping. As part of the case study, procedural guidelines and best practices developed in the process of doing over 200 tests will be discussed. Multiple Diagnostic Fracture Injection Tests Done Simultaneously in a Single Wellbore The method to perform multiple diagnostic fracture injection tests (DFIT) simultaneously in a single wellbore came from the need to characterize mature formations which were differentially pressure depleted. The majority of oil and gas reservoirs the San Juan Basin of northwestern New Mexico and southwestern Colorado were discovered in a sub-pressured state, i.e., initial reservoir pore pressure was less than the hydrostatic head of fresh water. Due to variances in sub-interval permeability and drainage area extent, seventy plus years of sustained production and multiple infill campaigns have rendered the major producing intervals substantially differentially depleted on a layer by layer basis. Using the Equation 1, Figure 1 is provided to illustrate the magnitude of intra-formation layer reservoir pressure differences that have been measured in a single wellbore for four of the producing formation in the San Juan Basin.
First Application of Just-In-Time Perforating in a Horizontal Well
Authors: Angeles Renzo , Tolman Randy , Ross Kirk , Burnham Heather , El-Rabaa Wadood
Published: December 2012

abstract

Just-In-Time-Perforating (JITP) was developed by ExxonMobil over a decade ago to improve multi-zone stimulation in vertical and S-shaped wells in the Piceance basin, Colorado. With this technology, multiple single-zone fracture stimulations are performed on a single wireline run using ball sealers and perforating guns that remain downhole during the fracturing treatment. This results in substantial cost reduction and productivity uplift because perforation intervals are individually and effectively treated one at a time with less horse power, smaller number of frac plugs, and fewer wireline runs. The method has been successfully implemented by ExxonMobil in more than 350 wells and over 10,000 treatments and is licensed to a number of service companies.

There is substantial business incentive to implement the JITP technique in horizontal wells, extensively used in unconventional gas developments. With XTO Energy joining ExxonMobil, the global gas portfolio incremented by 45 trillion cubic feet. This includes conventional gas, shale gas as well as other unconventional resources, such as tight gas, coal bed methane, and shale oil.

This paper presents the first application of JITP in horizontal wells. Operations were conducted in the Fayetteville Shale, Arkansas. The paper discusses advantages and disadvantages of the method as well as lessons learned from pre-field trials and full-well implementations. Critical to the success of the initial technology application was the enforcement of a structured approach which included technical feasibility studies, contractor qualification, pre-field trials, well candidate selection, and a deployment plan to capture learnings and best practices. Pre-field trials were executed in several wells to test potential technical/operational concerns, such as sand build-up around perforating guns, fluid diversion with buoyant and non-buoyant ball sealers, and the ability to move guns through the lateral. Preliminary field costs and production performance in horizontal wells are promising and support continued deployment of the technology.
Field Development Study: Channel Fracturing Increases Gas Production and Improves Polymer Recovery in Burgos Basin, Mexico North
Authors: Valenzuela A. , Guzmán J. , Chávez S. , Mondragón G. García , Gutiérrez L. , Exler V. , Ramírez C. , Parra P. , Peña A.
Published: December 2012

The channel fracturing technique combines fracture modeling, materials and pumping methods to generate a network of highly conductive channels within the proppant pack. These channels aim at expediting the delivery of hydrocarbons from the reservoir to the wellbore (Gillard et al., 2010). This paper provides a comprehensive summary of the implementation of this novel technique in the Burgos basin, Mexico North.

The Eocene Yegua formation in the Palmito field near Reynosa, Mexico was selected for this study. This formation comprises sandstone layers with average permeability of 0.5 mD and Young’s modulus in the order of 2.5 Mpsi. Key historical issues for the stimulation of this formation using conventional fracturing materials are limited polymer recovery and the consequential fracture conductivity impairment. Use of resin-coated proppants has also been implemented to prevent proppant flowback from these operations.

Gas production, treating pressure and polymer recovery data from a twelve-well campaign in the Palmito field (six wells treated via channel fracturing, six offset wells treated conventionally and aiming for similar fracture geometry) are summarized in the manuscript. Results indicate that the implementation of the channel fracturing technique improved fluid and polymer recovery, thus leading to increases in initial gas production by 32% and 6-month cumulative gas production by 19%. Such improvements in production were obtained with 50% less proppant per stage and smaller proppant particles. These observations are consistent with the hypothesis that the channel fracturing technique promotes the decoupling of fracture conductivity from proppant pack permeability. Positive features that were also observed during this campaign such as absence of proppant flowback issues without the use of resin-coated sand and non-occurrence of near-wellbore screen-outs are also reported and discussed.

The study concluded that the channel fracturing technique is a viable alternative to conventional fracturing methods for the stimulation of wells in the Burgos basin.
Two-Phase Production Analysis for Hydraulically Fractured Reservoirs
Authors: Klinsky A. , Callard J.
Published: December 2012

The resource play development cycle is a continuous loop that constitutes hydraulic fracture stimulation, production analysis, and redesign of subsequent stimulation treatments. Objectives of the cycle include optimizing lateral length, cluster spacing, injected volumes and types of proppants and fracturing fluids. During the stimulation process, leak-off invasion of the hydraulic fluid to the formation occurs and the fracture is left completely saturated with fracture fluid. Consequently, initial production is transient two-phase flow. One aim of this work is to improve analysis during this two -phase flow period. Production analysis has been a fundamental tool in analyzing hydraulically stimulated reservoirs. Previously presented work is based on single phase flow. For shale gas reservoirs, gas production increases during clean-up; this can occur at the end of fracture linear flow or may continue into the bilinear flow period due to the continued recovery of frac load fluid. This work investigates transient two-phase flow exhibited in multi-stage hydraulically-fractured shale gas reservoirs as well as terminal production after stage competition instigates boundary dominated flow. The effect of relative permeability, fracture storage capacity and fracture conductivity on the production behavior including bilinear and formation linear flow is investigated by the means of parametric studies utilizing numerical simulation. Cluster spacing is used as a parameter in the boundary dominated production period. This analysis is applied to field production data and case histories are presented. Results of this investigation are summarized in decline type curves.
Building Acid Frac Conductivity in Highly-Confined Carbonates
Authors: Neumann L F , Oliveira T J , Fernandes P D , de Oliveira e Sousa J L , Brandão E M
Published: December 2012

The deep and hard limestones found off-shore Brazil are being extensively evaluated, and some of them would require stimulation to enable commercial development. The main objective of this paper is to discuss the feasibility of acid fracturing stimulation in hard carbonates. Laboratory test are performed to verify whether an acid-induced fracture can withstand the high effective normal stresses expected during the exploitation stage of pre-salt development, keeping an acceptable conductivity. There is no agreement in the technical community regarding the survival of an acid fracture at closure stress greater than 5,000 psi. However, the experience that leads to this controversy is mainly based on: (1) wells on land and, (2) few published tests on rocks with mechanical properties compatible with those depths. An experimental program has been designed to evaluate these chances of acid fracture survival. A few initial essays with samples of these carbonate rocks have shown significantly higher rock strength than those commonly found in the literature. Initially, the Nierode & Kruk correlation (1973) is used to predict fracture conductivity behavior. Both mechanical strength and dissolved rock equivalent conductivity are measured from outcrops, and from soft and hard offshore carbonates samples. This work reports the results with outcrops and reservoir samples, in order to assess whether the adopted experimental methodology is consistent and reproducible. Some topics about acid fracture conductivity prediction are also addressed. Further research should be performed with pre-salt rock samples using the same procedures.
A Direct Comparison of Hydraulic Fracture Geometry and Well Performance Between Cemented Liner and Open Hole Packer Completed Horizontal Wells in a Tight Gas Reservoir
Authors: Reynolds Murray , Thomson Susan , Peyman Faezeh , Hung Allan , Quirk David , Chen Shaoyuan
Published: December 2012

The Glauconitic formation is a Cretaceous age sandstone reservoir located across a large area of central Alberta, Canada. Discovered in the late 1970’s, hydraulically fractured vertical wells could produce commercial volumes of natural gas from some of the higher permeability conventional sands. However, wide spread development of the majority of the tight gas sands was not economic with vertical wells.

With the introduction of multiple fractured horizontal well (MFHW) technology in recent years, and much better definition of the geology, a large unconventional resource play has developed in the Glauconitic, which could contain in excess of 5 tcf of gas in place plus associated natural gas liquids (Scotia Capital, 2009).

A pilot project was designed to test the completion effectiveness between a cased and cemented liner and an open hole packer system in this tight gas reservoir. Two vertical microseismic observation wells were located in close proximity to two proposed horizontal wellbores, giving ideal conditions to test how the hydraulic fractures would grow and the ultimate fracture geometry, from two different completion methods.

In this paper we will present the microseismic results of the pilot project, as well as the early production history comparison between the two wells, and the hydraulic fracture effectiveness from a reservoir engineering aspect.
Eco-Friendly Creation of Propped Hydraulic Fractures
Authors: Cooke C. E. , Watters J. T. , Watters L. T. , Wann S. R. , Zhu D. , Hwang Y. S.
Published: December 2012

A novel method for creating short, highly conductive fractures in wells to bypass formation damage has been developed. The method uses relatively small material volumes, low horsepower and pump rate, produces minimal environment effect, and leaves the formation face and proppant pack residue free. Function and application of the method present significant varia-tions in treatment design and execution compared to traditional hydraulic fracturing past damage. This paper presents results of development work to confirm the method’s applicability and to provide sufficient performance data to design initial field applications.
Fiber Optic Distributed Acoustic Sensing of Multiple Fractures in a Horizontal Well
Authors: MacPhail Warren , Lisoway Bill , Banks Kevin
Published: December 2012

This paper highlights the current state of fiber optic distributed acoustic sensing (DAS) technology by reviewing its application to hydraulic fracture diagnostics in a multi fractured horizontal well (MFHW). It will be shown that, with the advent of DAS, a gap in the feedback — which could previously occur using various hydraulic fracture diagnostic options — has been filled. Results are shared that were obtained from the first successful application of high resolution DAS during the placement of multiple hydraulic fractures in a horizontal well that was completed with an open hole packer and frac valve system.

Observations of the real time acoustic soundfield in the near wellbore (NWB) region during hydraulic fracturing are presented as high resolution images. These images have enabled an analysis of key dynamic aspects of the fracturing process. In examining the resultant data, it has become apparent that DAS has overcome some limitations intrinsic in other diagnostic tools such as distributed temperature sensing (DTS), microseismic monitoring, and tracer programs. An overview of the well design is provided as well as selected samples from the dataset which highlight some of the events that were observed during the hydraulic fracturing process. Sample images are used to demonstrate the current capability of DAS measurement, selected both from the real time soundfield display (SFD) and from processed high resolution soundfield maps. DAS processing methods are briefly discussed, as well as two categories of field observations— which highlight some of the mechanical reliability aspects of the swell packer/ball actuated frac sleeve system, as well as some aspects of the near wellbore region during hydraulic fracturing such as single or multiple fracture initiation sites and the general behaviour of wellbore fluids over the course of the fracture treatment.

Distributed acoustic sensing using a single mode optic fiber has been described in recent literature (Molenaar, 2011) for applications involving the recording of acoustic events during various stages of well completion and stimulation. The current paper provides further description on how DAS works and shares results from a high resolution DAS survey, obtained while placing multiple hydraulic fractures in a horizontal well, completed in a tight sand using an openhole ball actuated valve system with swell packers for fracture isolation. Earlier findings are supported, in particular that DAS will enable an improved understanding of in-wellbore activities and, in so doing, that it will enable optimization of hydraulic fracturing design and execution. It is recognized that much is yet to be learned in the processing of fiber optic DAS data, but also that it would be beneficial to share the work that has been completed to date to facilitate accelerated development of DAS processing technology.
Practical Data Mining: Analysis of Barnett Shale Production Results With Emphasis on Well Completion and Fracture Stimulation
Authors: Lafollette Randy F. , Holcomb William D. , Aragon Jorge
Published: December 2012

This paper documents follow-on work to an original data mining study of horizontal wells in the North Texas Barnett Shale play. In this study, the authors have analyzed well and production data beginning with over 15,000 producing Barnett wells. Study wells were grouped for similar map-based reservoir properties, normalized for the effects of well architecture, and normalized for production. The study used statistical and data mining techniques plus Geographical Information System pattern-recognition techniques to aid in interpretation of production result trends. The principal focus of the follow-on study is in the areas of completion and hydraulic fracturing. It is intended to demonstrate lessons-learned from careful analysis of large volumes of data, some of which can only be examined by proxy.

Data sets from public and proprietary data sources were collected and merged into a common database. Data elements were subjected to statistical quality control methods in order to minimize the potential for inaccurate data to be included in the analysis. Short-term production proxies were studied and decided upon in order to adequately compare well productivity values over many years of horizontal well drilling across the Fort Worth Basin.

Previous work showed that the application of practical data mining methods to a large Shale Gas data set resulted in learning key lessons that were not apparent from small data sets. The previous work also showed that certain popular beliefs did not hold up to examination of the available data. Similar to past work, this work is significant in the use of merged reservoir quality proxies, well architecture data, completion data, and stimulation data, against which production results are placed in geographical perspective for improved interpretation. This work is also significant in the application of advanced data mining methods beyond routine statistical work.
Examining Hydraulic Fracture - Natural Fracture Interaction in Hydrostone Block Experiments
Authors: Olson J. E. , Bahorich B. , Holder J.
Published: December 2012

Field experience in shale gas and some tight gas sandstones suggests significant interaction between hydraulic fractures and natural fractures. Experimental analysis of this problem has mostly focused on frictional interfaces with regard to the natural fractures. We have performed tests to examine the effect of cemented natural fractures on hydraulic fracture propagation. The motivation for this type of work is that core observations from the Barnett and some other shale gas plays suggest that natural fractures are largely cemented (or healed) and trend obliquely or orthogonally to the present day hydraulic fracture direction. We embedded planar glass discontinuities into a cast hydrostone block as proxies for cemented natural fractures. Consistent with theoretical predictions, our results show that oblique embedded fractures are more likely to divert a fluid-driven hydraulic fracture than those occurring orthogonal to the induced fracture path. Hydraulic fracture – natural fracture interaction took three forms – 1) the hydraulic fracture bypassing the natural fracture by propagating around it (via height growth, not curving), 2) the hydraulic fracture arresting into the natural fracture and then diverting along it and sometimes kinking off the end of it, and 3) a combination of bypass and diversion. We also saw some leakage of fracture fluid along the interfaces of multi-layer blocks, even though such interfaces were perpendicular to the maximum compressive stress, suggesting an analogue for laminated and shaly sedimentary sequences.
Are Two Items Sufficient to Screen for Depression within the Hospital Context?
Authors: Osório Flávia L. , Carvalho Ana C. F. , Fracalossi Thiesa A. , Crippa José A. S. , Loureiro E Sonia R.
Published: December 2012

Objective:

to determine the ability of the reduced form of a screening instrument, the Patient Health Questionnaire-2 (PHQ-2), to assess the presence of depressive disorders in patients admitted to a general hospital.

Method:

A sample of 227 patients admitted to the clinical wards of a Brazilian general university hospital were assessed with Module A of the Diagnostic Structured Interview for the DSM-IV (SCID-IV) and filled out the PHQ-9 and PHQ-2.

Results:

The PHQ-2 demonstrated an area under the ROC curve of 0.89 ( p < 0.0001), with a cutoff point of three or more being the one that best equilibrated the sensitivity (0.86) and specificity (0.75) values. The agreement index between the PHQ-2 and module A of SCID-IV was 78.4% and the Kappa value was 0.51. Regarding reliability, the Cronbach alpha value obtained was 0.64 and the intraclass correlation coefficient was 0.52.

Conclusion:

PHQ-2 proved to be an instrument with good psychometric properties comparable to those of PHQ-9, being superior to the latter regarding the rate of false-positive results. In addition, it is a brief instrument that elicits little resistance on the part of the patient, being inexpensive and requiring little time, thus being of important help to the treatment teams for the detection of depressive disorder, being suitable for incorporation into hospital admission protocols and thus possibly favoring more immediate interventions.
The Impact of Eliminating the 20-F Reconciliation Requirement for IFRS Filers on Earnings Persistence and Information Uncertainty
Authors: Kang Tony , Krishnan Gopal V. , Wolfe Michael C. , Yi Han S.
Published: December 2012

SYNOPSIS:

On November 15, 2007, the U.S. Securities and Exchange Commission (SEC) eliminated the requirement that foreign private issuers reporting under International Financial Reporting Standards (IFRS) include a reconciliation to U.S. GAAP in their 20-F filing. To the extent that the reconciliations had information content, it is possible that the information environment of IFRS filers deteriorated in the post-reconciliation period, unless they voluntarily improved disclosure quality. Using difference-in-differences tests, we examine whether there was any change in the persistence of earnings and analyst forecast dispersion after the new regulation. We find that earnings persistence increased (did not increase) and analyst uncertainty measured by the forecast dispersion did not increase (increased) for firms domiciled in weaker (stronger) investor protection countries. These results suggest that firms from a weaker investor protection environment had a greater incentive to “signal” the quality by voluntarily improving the disclosure quality in the post-reconciliation period to compensate for any possible information loss from no longer providing the reconciliation. Our findings also suggest that the elimination of the reconciliation requirement did not have a uniform effect on IFRS filers and that the effect varies with the firm's home country reporting environment.

JEL Classifications: M41
Evaluation of outcome following urethral stent placement for the treatment of obstructive carcinoma of the urethra in dogs: 42 cases (2004–2008)
Authors: Blackburn Amanda L. , Berent Allyson C. , Weisse Chick W. , Brown Dorothy C.
Published: December 2012

Objective—To evaluate the outcome following urethral stent placement for the palliative treatment of obstructive carcinoma of the urethra in dogs.

Design—Retrospective case series.

Animals—42 dogs with obstructive carcinoma of the urethra.

Procedures—Medical records for dogs in which a self-expanding metallic stent (SEMS) was used for the treatment of obstructive carcinoma of the urethra were reviewed. Signalment, diagnostic findings, clinical signs before and after SEMS placement, and patient outcome were analyzed. Fluoroscopic images were evaluated to determine the effects of stent size, obstruction length, tumor length, and urethral length and width on the incidence of incontinence or stranguria.

Results—Resolution of urinary tract obstruction was achieved in 41 of 42 (97.6%) dogs. After SEMS placement, 6 of 23 male and 5 of 19 female dogs developed severe incontinence, and 1 of 23 male and 1 of 17 female dogs developed stranguria. Stent length, diameter, and location were not associated with incidence of incontinence or stranguria. Median survival time after SEMS placement was 78 days (range, 7 to 536 days). Treatment with NSAIDs before and chemotherapeutics after SEMS placement increased median survival time to 251 days (range, 8 to 536 days).

Conclusions and Clinical Relevance—Urethral SEMS placement was an effective palliative treatment for dogs with obstructive carcinoma of the urethra; however, severe incontinence subsequently developed in 11 of 42 (26%) treated dogs. Adjunctive treatment of affected dogs with NSAIDs and chemotherapeutics significantly increased the median survival time.
Comparison of the use of scapular ultrasonography, physical examination, and measurement of serum biomarkers of bone turnover versus scintigraphy for detection of bone fragility syndrome in horses
Authors: Arens Amanda M. , Puchalski Sarah M. , Whitcomb Mary Beth , Bell Robin , Gardner Ian A. , Stover Susan M.
Published: December 2012

Objective—To define scintigraphic, physical examination, and scapular ultrasonographic findings consistent with bone fragility syndrome (BFS) in horses; develop indices of BFS severity; and assess accuracy of physical examination, scapular ultrasonography, and serum biomarkers for BFS diagnosis.

Design—Prospective case-control study.

Animals—48 horses (20 horses with BFS and 28 control horses).

Procedures—Horses underwent forelimb scintigraphic evaluation, physical examination, scapular ultrasonography, and serum collection. Scintigraphy was used as a reference standard to which physical examination, scapular ultrasonography, and concentrations of serum biomarkers (carboxy-terminal telopeptide of collagen crosslinks and bone-specific alkaline phosphatase activity) were compared for assessing accuracy in BFS diagnosis.

Results—A diagnosis of BFS was strongly supported on scintigraphy by ≥ 2 regions of increased radiopharmaceutical uptake, including 1 region in the scapular spine and 1 region in the scapular body or ribs; on physical examination by lateral bowing of the scapulae; and on ultrasonography by widening of the scapular spine. None of the tests evaluated were accurate enough to replace scintigraphy for mild disease; however, physical examination and scapular ultrasonography were accurate in horses with moderate to severe BFS. Serum biomarkers were not accurate for BFS diagnosis.

Conclusions and Clinical Relevance—Scintigraphy remained the most informative diagnostic modality for BFS, providing insight into disease severity and distribution; however, physical examination and scapular ultrasonographic abnormalities were diagnostic in horses with moderate to severe disease. Proposed severity indices classified the spectrum of disease manifestations. Clearly defined criteria for interpretation of diagnostic tests aid in the detection of BFS. Severity indices may be useful for assessing disease progression and response to treatment.