bluuebunny/crossref_metadata_2025 huggingface dataset:
A Longitudinal Study of Ice Hockey Helmet Shelf Life
Authors: Pearsall David J. , Dowler Patrick M.
Published: March 2010

After manufacture and before retail, ice hockey helmets must pass safety standard tests based primarily on multiple impacts at several global sites to receive certification. Unknown is the effective “shelf life” of these products; that is, do material and construction properties deteriorate with aging to a point below the impact criteria for certification? To address this question, a prospective 6 year study has been completed to investigate the effects of aging on hockey helmet impact attenuation. A longitudinal study (2001–2007) was performed on five models of ice hockey helmet to investigate the effects of aging on these helmets' impact attenuation characteristics. Helmets were tested on the date of manufacture and years two and six (Y0, Y2, and Y6). The five brands (Nike-Bauer-3000, Nike-Bauer-4000, Nike-Bauer-5000, CCM-HT500, and Jofa-690) were evaluated according to ASTM 1045-99 protocol, impacting four sites: the crown, front, rear, and side. All helmets were stored at ambient temperatures 20±4°C and relative humidity between 10 and 50%. Helmets in Y2 and Y6 did not have prior impacts before testing. Peak acceleration (PA, g) and severity index (SI) were calculated for third impacts and compared between years. In general, PA and SI measures remained within safety criteria levels for all helmets and sites during all testing intervals (that is, all met certification standards). Though some specific helmet∕site differences were noted, no substantial change in impact attenuation was observed. Visual inspection of helmets postimpact showed no conspicuous damage to liner or shell, though in several instances the binding glue had disintegrated allowing liners to shift or fall away from the shell. From these results, contemporary ice hockey helmets retain their robust impact attenuation characteristics even after several years of storage, though adhesive embrittlement needs to be addressed. Further testing should evaluate the viability of used helmets in a similar prospective manner to ensure safe helmet function.
Development of a New Methodology Capable of Characterizing the Contribution of a Controlled Venting System to Impact Attenuation in Chamber Structures for Head Protection
Authors: Lamb L. , Post A. , Hoshizaki T. B.
Published: March 2010

Currently, ice hockey helmet technologies are based mainly around foam energy absorbers. There is a need in the head protection industry for improved designs, capable of protecting the brain under a wide range of impact conditions. Air chambers are new, thin-walled collapsible energy absorber structures which have the potential to replace or to be used in conjunction with current helmet technology. The chambers consist of several engineering parameters, each of which needs to be examined to understand its mechanical response under impacts. This study was designed to investigate a new methodology capable of investigating the air venting system. This research thereby analyzed the role the chamber's controlled air release device plays in managing impact energy. The results demonstrated that, as the air chamber approaches the critical failure region, the air released though the controlled vent can prevent larger peak forces. This research identified that an engineered thin-walled collapsible chamber does use air as a mechanism to absorb impacting force.
Experimental Characterization of Ice Hockey Pucks and Sticks
Authors: Bigford Rosanna L. , Smith Lloyd V.
Published: March 2010

In spite of the broad popularity of ice hockey, little has been done to characterize the performance of pucks or sticks used in play. Data representative of play conditions is particularly lacking. A high speed impact test was developed to measure the puck impact force and coefficient of restitution. Puck brand, temperature, and speed were all shown to have a measurable effect on the relative puck response. The high speed puck test was modified to measure the performance of hockey sticks. The performance of six wood and 11 composite sticks (including different shaft tapers for each group) were compared to evaluate the effect of modern materials on the game. Stick performance was expressed in terms of the maximum puck speed from an idealized slap shot model. In spite of the popularity of the relatively expensive composite sticks, on average the performance of the wood sticks was 10 % higher than the composite sticks. Shaft loading was found to increase the puck speed but did not significantly change the relative performance of the sticks. In contrast to balls in golf and baseball, puck hardness was shown to have a negligible effect on stick performance.
When Metal Meets Ice: Potential for Performance or Injury
Authors: Lockwood K. , Frost G.
Published: March 2010

Physical conditioning, technical ability, contact, and protective equipment have been identified through research as factors that can potentially contribute to the incidence of injuries in ice hockey players. One safety-related factor often overlooked is the interaction between the skate blade and the ice. Skating is one of the fundamental skills of a successful hockey player, but the effect of skate sharpening on blade characteristics and performance has received limited research attention. The point of contact with the ice is essentially what allows the transition of human motion to skating mechanics, and it may affect both the quality of skating performance and the potential for on-ice injuries. The purpose of this paper is to address the influence of skate blade sharpening characteristics on performance. Experiments performed to examine skate blade sharpening characteristics have identified radius of hollow (ROH), radius of contour (ROC), pitch and level-ness of edges as variables that can be manipulated, quantified, and controlled when analyzing blade-ice interaction and the effect of skate sharpening on skating performance. Optimum values for each may produce more effective skating performances. Less than optimum values can result in slower speeds, longer stopping times, instability, body malalignment, greater fatigue, and potentially, greater chance of injury. Being able to define blade characteristics and determine the best combination of ROH, ROC, and pitch for a specific player allows some degree of control in an environment which can often be unpredictable. Furthermore, although there are standards for acceptable ice in professional hockey leagues, very often players must skate on a surface which is not only less than ideal, but which can also change over the course of a game or practice. Careful sharpening to accommodate for less than ideal ice conditions and the unpredictable nature of the play may also help to prevent fatigue, and injuries.
An Analysis of Head Impact Profiles and Safe Hockey Behaviors in Youth Hockey Players
Authors: McPherson Moira N. , Montelpare William J. , Keightley Michelle , Reed Nicholas , Sutherland Malcolm , Taha Tim , McAuliffe Jim , Baker Joseph R. , Cubos Jeff , Faught Brent
Published: March 2010

Although injury risk factors can be described in biomechanical terms, previous research has not described the relationship between style of play and the frequency and magnitude of head impacts. This paper is focused on the analysis of head impact profiles and safe hockey behaviors demonstrated during contact situations in a cohort of 13 Bantam-aged minor hockey players. Head impacts sustained at 27 home games during the 2006–2007 season were measured using the Head Impact Telemetry System (HITS). Hockey helmets (Canadian Standards Association approved) were equipped with six linear accelerometers and a wireless system that transmitted data to a receiver interfaced with a computer. Nine games were recorded using a field videography system to capture player collisions. A HITS profile was determined, which included the number of impacts (>10 g) (“g”=m∕sec2) by player, the total number of impacts, the average number of impacts per game, and the mean linear acceleration value for all impacts per player. Based on these results, ten taped trials for the players sustaining greater than 180 total impacts over the season were qualitatively analyzed using a checklist to examine the safe hockey behaviors associated with body contacts. We captured 2753 head impacts over the season, with the average number of impacts per player per game ranging from 3 to 16 with a mean linear acceleration of 15.8 g (standard deviation=13.76). The checklist of safe hockey behaviors was used to analyze skating performance for a group of five players who experienced more than 180 impacts, with some impact magnitudes exceeding 98 g. In general, differences in indicators of skating skill, body position prior to check∕contact, and actions during the contact were observed. While specific players may be predisposed to head impacts of a greater frequency and magnitude because of their style of play, these characteristics can be changed to reduce risk of potential injury.
Relationships among Risk Factors for Concussion in Minor Ice Hockey
Authors: Cubos Jeff , Baker Joseph , Faught Brent , McAuliffe Jim , Keightley Michelle L. , McPherson Moira , Macpherson Alison , Reed Nick , Duggan Catrin , Taha Tim , Montelpare William J.
Published: March 2010

There is increasing concern among parents, coaches, and officials about injury risk in youth ice hockey, particularly in light of recent evidence suggesting that incidence of serious injury is considerably under reported. However, an adequate method for ascertaining injury risk for concussion does not yet exist. The purpose of this study was to examine the relationships among variables measuring exposure and head impact forces in a group of representative level bantam aged hockey players. Across an entire hockey season, trained research assistants attended games and recorded the duration of time spent on the ice for each player (i.e., exposure time) and total number of body contacts using time-on-task software designed specifically for this study. A body contact included any intentional or incidental contact between two players. Collectively, these variables provide a simple, easily administered measure of head injury risk for researchers collecting data in this area. However, their relationship to actual brain trauma is unknown. To this end, head acceleration data were also collected using helmet-based accelerometers that provide measures of linear accelerations experienced by each player. These data were collected by telemetry methods and represent data that are likely very useful for injury researchers but not without sufficient costs. Results demonstrated low associations among the data sources. A method based on combining data sources (through an examination of their potential relationships) is proposed to maximize the potential to identify at-risk youth in minor hockey.
Hockey Education Program (HEP): A Statewide Measure of Fair Play, Skill Development, and Coaching Excellence
Authors: Smith Aynsley M. , Jorgenson Mark , Sorenson Matthew C. , Margenau David , Link Andrew A. , MacMillan Michael , Stuart Michael J.
Published: March 2010

Following the death of a youth hockey coach in a fight with a parent in 2000, the Mayo Clinic Sports Medicine Center and Minnesota Hockey collaborated to implement a three-component Hockey Education Program (HEP). HEP was initiated in 2003 to ensure youth players develop sportsmanship, skills, and a Fair Play approach to the game. Another goal was to decrease attrition of players, coaches, and officials. Coaching Excellence, a component of HEP, is based on 25 years of youth sport research. The HEP manuals Coaches Who Never Lose and Sports and Your Child contain the philosophy, objectives, and guidelines to ensure implementation of HEP components across players, coaches, and parents. The Skill Development component emphasizes learning age-appropriate hockey skills though skill progression. Increasing the practice-to-game ratio to 3–4 practices per game greatly increases the maximum time players skate with the puck during developmental years. Pre- and post-season Skills Challenges allow coaches, players, and parents to gauge improvement, and structure practices to address identified skill deficits. The Fair Play (FP) component emphasizes sportsmanship. Teams earn a FP point each game if they incur less than a preset number of penalty minutes. A coach receiving a game misconduct or a parent∕spectator asked to leave the game will cause the team to forfeit their FP point. FP points are factored into league standings across the state. This past season, 17 678 records of game data were obtained and 25 % (4420) were randomly selected for analysis. The data analysis permits comparison across seasons and changes are made accordingly. Based on four years of data, most Minnesota youth hockey games are played in a sportsmanlike manner. Checking from behind and head contact penalties have decreased since the penalty minutes for these dangerous infractions were increased.
Ice Hockey Facility Safety: Litigated Case Studies Involving Ice Hockey Injuries
Authors: Lucenko Leonard K.
Published: March 2010

This paper will discuss the duties facility owners and operators owe participants and spectators in the ice skating and ice hockey environment. These duties have been established by case law, standards in the industry, and the safety and risk management literature in sports and recreation. There will also be a discussion of court cases that illustrate the importance of incorporating risk management principles and industry standards into operating procedures. The consequences, when these principles are not followed, will also be addressed based on results of litigated cases.
Luigi Nono's Canti di vita e d'amore: Musical Dialectics and the Opposition of Present and Future
Authors: Durazzi Bruce
Published: March 2010

Luigi Nono's Canti di vita e d'amore represents a moment of stylistic shift in the composer's output, and also a change in his political commitments. As Nono's political commitments shifted from a kind of Left idealism to more immediate forms of social activism, so his composition turned from abstract integral serialism to more immediately perceptible constructive strategies. Canti di vita e d'amore not only exhibits these new developments in compositional technique, but also deploys those techniques to support the work's long-range narrative of emergence from present-day crisis into a future of light and hope.
The Presence of Hindemith in Nono's Sketches: A New Context for Nono's Music
Authors: Guerrero Jeannie Ma.
Published: March 2010

Approximately two hundred leaves of Luigi Nono's sketches from 1946 to 1951 demonstrate that he was well schooled in the teachings of Paul Hindemith, a theorist and composer whose outlook and musical inclinations would seem to be altogether different from those of the younger musician. To be sure, Nono never pointed to Hindemith as a direct influence; and the aesthetic climate at Darmstadt would surely have encouraged Nono to remain quiet on this subject. Furthermore, commentators on Nono's earliest music have tended to focus on comparisons with Webern's twelve-tone technique. While such comparisons reveal much about the reception of Webern, they obscure Nono's antipointillist concern for expression and musical tension. The sketches suggest a means to reassess Nono's music by showing how Hindemith's building stones furnished a foundation for Nono's artistic diversity. In Nono's sketches, Hindemith emerges as a progressive theorist to whose teachings the younger composer would return for many years.
Blurred Borders for Some but Not “Others”: Racialization, “Flexible Ethnicity,” Gender, and Third-Generation Mexican American Identity
Authors: Vasquez Jessica M.
Published: March 2010

How are the lives of middle-class third-generation Mexican Americans both racialized and gendered? Third-generation Mexican Americans in California experience a racialization process continuum that extends from “flexible ethnicity,” the ability to be considered an “insider” in different racial/ ethnic communities, to racialization as nonwhite that is enforced through the deployment of negative stereotypes. Using interview data, the author finds that women are afforded more “flexible ethnicity” than men. Accordingly, men are more rigorously racialized than women. Women are racialized through exoticization, whereas men are racialized as threats to safety. Lighter-skinned individuals escaped consistent racialization. These findings have consequences for the incorporation possibilities of later-generation Mexican Americans, as women and light-skinned (often multiracial) individuals are more frequently granted “flexible ethnicity” and less strongly racialized than men and dark-skinned (often monoracial) individuals. Even among the structurally assimilated, contemporary racial and gender hierarchies limit the voluntary quality of ethnicity among third-generation Mexican Americans.
Race, Gender, and the Social Construction of Mental Illness in the Criminal Justice System
Authors: Thompson Melissa
Published: March 2010

This article tests whether perceptions of “normal” defendants influence the use of psychiatric evaluations in the criminal justice system. The author theorizes that typifications–or taken-for-granted assumptions–of African Americans as “criminals” and women as “mentally ill” will influence court actors' perceptions of the rationality of a defendant's criminal actions. Using case-control sampling methods, the author compiled data from a large Midwestern county to examine the demographic, familial, legal, and psychiatric predictors of which felony defendants receive a psychiatric evaluation; these psychiatric evaluations are indications that the defendant may be considered exempt from criminal responsibility. Using logistic regression, the author finds that mental health status is the best predictor of psychiatric evaluations but that criminal justice decision-makers' attributions of criminal responsibility are also influenced by typifications of defendants based on race and gender.
Silvestre Revueltas’s Redes
Authors: Kolb-Neuhaus Roberto
Published: March 2010

On May 12, 1936 at the Palacio de Bellas Artes in Mexico City, Silvestre Revueltas directed the Orquesta Sinfónica Nacional in a concert version of the music he had recently composed for the film Redes which would premiere just two months later, on July 9 at Mexico City’s Cine Principal. Of nine film scores composed by Revueltas, two—Redes (1934– 1935) and Música para charlar (1938)1— were also conceived as concert music in the form of symphonic poems. Of the two, Redes is of greater interest, not only due to its musical qualities, but also because of its historic significance within the particular confluence of aesthetic and political references of the time, which were highly significant in the history of art in Mexico
Against All Odds
Authors: Mitchell Helen
Published: March 2010

With the birth of sound film, the symphonic film score would begin a journey which would firmly entrench the symphonic score in Hollywood practice and parlance. On route, the symphonic film score would experience many highs and lows, reflecting changes within the film and music industries and also within society at large; changes compounded by the impact of new technologies. This article draws together a number of sources and presents an overview of the main factors involved in the decline and subsequent resurgence of the symphonic film score in Hollywood.
High Noon
Authors: Khannanov Ildar
Published: March 2010

Legendary Hollywood composer Dimitri Tiomkin (1894-1979) represents a golden era of film, arguably an apex of the role music has played in cinematic art. His presence in films was as strong as that of the film director: for example, the font size of Tiomkin’s name in the screen credits for Red River (1948) is the same as that of director Howard Hawks. This paper explores the Russian sources of Tiomkin's High Noon.
Film Studies in Musicology
Authors: Rosar William H.
Published: March 2010

Since the turn of the 21st century the term “film musicology” has gradually come into use in Anglophone scholarship, though apparently without there being any published definition of its disciplinary scope and methodology in relationship to musicology and film studies, respectively. For example in reviewing the 2004 critical study Hollywood Theory, Non-Hollywood Practice by Annette Davison, Leslie Andersen comments that “Davison describes [her] research early on as ‘film musicology’ (p. 1) without a definition as to what this is. Is ‘film musicology’ the musicology of film or the study of film music? Davison assumes that the reader understands what this term means without documenting its origin.” A clue can be found on the dust jacket of Davison’s book that quotes praise for the book from Robynn Stilwell: “Annette Davison offers a second-generation approach to film musicology that stands in relationship to the first generation (Gorbman, Kalinak, et al) much as her subject stands to Hollywood cinema—building on, reacting against, making us think about the most basic issues with new critical facilities.” Inasmuch as neither Gorbman nor Kalinak are musicologists, but are film scholars by virtue of academic training and professional discipline, and the et alia to whom Stilwell alludes are disciplinarily anonymous, how did film musicology come to be constituted as a field of scholarly inquiry, if not by musicologists?
Representations of eating and of a nutrition program among female caregivers of children under 5 years old in Tizimin, Yucatan, Mexico
Authors: Uicab-Pool Gloria de los Ángeles , Ferriani Maria das Graças Carvalho , Gomes Romeu , Pelcastre-Villafuerte Blanca
Published: March 2010

This study was carried out between January and April 2008 with 14 caregivers of children younger than 5 years residing in Tizimín city, Mexico. It aimed to understand the social representations of eating and the Programa Oportunidades [Opportunity Program] held by caregivers taking into account their social and cultural context. This qualitative investigation with an ethnographic approach was based on participant observation and semi-structured interviews. Two empirical categories emerged: 1) feeding and 2) an aid. The first refers to the caregivers' representation of eating patterns of children younger than 5 years and the second reveals that the program is considered an aid, which favors and helps caregivers to meet part of their needs. The study achieved the proposed objectives since it enabled us to understand caregivers in the complex task of feeding these children and also to propose strategies in several spheres to improve infant nutrition.
Enhanced Oil Recovery - What We Have Learned
Authors: Ali S.M. Farouq , Thomas Sara
Published: March 2010

After thousands of field tests of EOR processes, we have learned that Enhanced Oil Recovery, or EOR, is difficult, expensive, and more likely to be a commercial failure than a success. At the same time, we have little choice but to strive to make EOR work, because the oil remaining in the reservoirs after primary recovery and waterflooding (secondary) can range from 50 - 60﹪ of the original oil in place (OOIP) in the case of a light oil (30 - 35 ° API), to 90﹪ in the case of a Saskatchewan/California type heavy oil (∼15 ° API). The volume of such "unrecoverable" oil in existing reservoirs is about 5 ? 109m3 (30 billion bbls) in Canada, and about 10 times as much in U.S.A. Worldwide, it could be something like two trillion bbls.

Speaking of oil sands, where primary recovery is nil, EOR yields all of the production. Clearly EOR will play an ever increasing role in Canada and other countries with unconventional hydrocarbon resources.

We shall briefly discuss status of EOR, the processes, and what lies ahead. Our purpose is to show that EOR has an important place in oil production, but one must be clear about the objective: is it to test a process or is it to make money?

FIGURE 1: Production life of a typical oil reservoir (Available in full paper)

EOR and IOR

Figure 1 depicts the life of a typical oil reservoir. After discovery, oil production rate increases in the development stage, reaching a plateau. This can be because of regulation, demand, oil prices, or the field size. At some point the decline stage starts, and if something is not done, the field eventually reaches economic limit, and is abandoned. Good reservoir engineering practice calls for pressure maintenance, followed by (or simultaneously) waterflooding, this being the least expensive option. But even after that over one-half of the oil is left in the reservoir. (Table 1 shows typical recovery factors for a light and a heavy oil, as well as the oil saturations at different stages).

If the reservoir is a candidate for EOR, the selected process should be developed early, as shown in Figure 1, because the "lead time" for developing a known recovery method from conception to commercial production can be 10 to 20 years. Examples abound: Cold Lake CSS (Cyclic Steam Stimulation) 20 years, Peace River In Situ Project 18 years, Gregoire Lake In Situ Combustion Project 20 years (unsuccessful), SAGD 15 years, etc. Most miscible carbon dioxide projects have taken 10 - 15 years to reach commercial stage.

When the oilfield is offshore, the time window for improving oil production is very narrow because of limited platform life, and the choice of a recovery process is limited by platform space and logistics. The aim is to improve oil production during the primary stage, rather than waiting until after a gas/waterflood. This is true even for onshore fields, but may be less critical. IOR or Improved Oil Recovery refers to this type of approach. In this discussion we shall speak of EOR only.
Modelling Wormhole Flow in Cold Production
Authors: Yuan J.Y. , Babchin A. , Tremblay B.
Published: March 2010

Wormholes are believed to be generated during the initial phase of cold production and are responsible for enhanced production rates when sand cuts are reduced to their minimum. In this work, we present a theoretical model describing sand and fluids flow within a wormhole uniformly filled with sand. This model is based on the Darcy-Brinkman equations for fluids in mobile sand, a rheological equation for sand motion, and conservation laws. Velocity profiles of sand and fluid are calculated and used to establish the relation between the pressure drop and the flow rates. An estimation of wormhole size is also provided. This model provides understanding of the basic flow behavior in a wormhole during the massive sand production stage of cold production. It also provides some key parameters for field scale numerical simulations of cold production.

Viscous Drag and Critical Radii

The detailed mechanism of sand erosion is a complicated subject. It involves the geomechanical properties of the sand, the rheological properties of fluids, and the nature of sand-fluid and fluid-fluid interactions. However complicated, the key to flux erosion is that it happens when the drag force overcomes the resistance of the sand matrix. The drag force should be mainly the viscous body force due to flow of fluids through the sand matrix (Darcy flow). The resistance of the sand matrix is mostly a surface force. It is due to cohesion, adhesion and contact forces. It holds a chunk in place against the body force. The thickness of this chunk, ?, can be as small as the averaged grain size or orders of magnitude larger, depending on the sand properties and the viscous body force. In the former limiting case, "raining" of sand grains into a cavity occurs. In the latter limiting case, microcracks in the sand matrix may be observed just before the erosion. Assuming fluid flow into a cavity of radius R, the above-stated criterion can be expressed as:

Equation (1) (Available In Full Paper)

where σ is the surface strength of the sand, and P the fluid pressure. The geometry of the wormhole is assumed to be comprised of a straight cylindrical tube, with a hemispherical cap at the end, as illustrated in Figure 1. Computed tomography images(1) of the wormhole tip show that it is more pointed in reality, as shown by the dashed line in Figure 1. The assumption of hemispherical flow at the tip, however, seems reasonable. For a spherical geometry,

FIGURE 1: Influx of fluid into a wormhole. The dashed line represents the actual shape of a wormhole tip (Available In Full Paper)

the pressure gradient is inversely proportional to the square of the radius if the fluid is incompressible. Therefore, we can integrate the right-hand side of the inequality (1). Denoting the reservoir pressure as Pre, the pressure at the wall of the cavity as P, and the radius of the drainage zone beyond which the reservoir retains its original reservoir pressure as Rs, we find:

Equation (2) (Available In Full Paper)
The Steam and Gas Push (SAGP)-2:Mechanism Analysis and Physical Model Testing
Authors: Jiang Q. , Butler R. , Yee C.T.
Published: March 2010

At the 48th Annual Technical Meeting of the Petroleum Society, one of us presented a paper that showed that there was a possibility of making the SAGD process more efficient by adding a small concentration of a non-condensible gas such as methane to steam(1). For this to be effective the steam injection well should be located slightly above the production well. With this configuration, and with a small continuous production of gas with the produced oil and condensate, the non-condensible gas becomes concentrated in the upper part of the chamber and the heat loss to the overburden, and for the heating of the chamber, is greatly reduced; the steam oil ratio is much lower.

Another configuration involves the continuous injection of a small stream of non-condensible gas from a well or wells near the top of the chamber with steam injection from a lower well or even into the production well. The heat is confined to the near wellbore region and again there is a considerable economy.

The present paper discusses further analysis of these configurations and also results from physical model tests that are being carried out at the University of Calgary. The results of these experiments have been very positive and it appears that the concept may be even more effective than was predicted originally. The reason for this appears to be that the introduction of gas with steam invokes a new mechanism as the gas flows counter currently to the falling liquids; this mechanism involves the creation of a large surface area for mass transfer. As a result, the steam chamber is not only much lower in temperature, particularly at the top, but it also rises more slowly and spreads laterally more quickly. A larger volume is draining at a much lower temperature. Measurements made in our model show large improvements in the steam/oil ratio.

The observation of the new mechanism suggests that this approach may have economic applications in fields having top water such as Surmont as well as in more normal type reservoirs. In general, the improved performance should broaden the range of reservoirs that can be produced economically.

Introduction

It is estimated that there are 273 billion m3 heavy oil and bitumen in place in Canada. They are deposited mainly in the Athabasca, Cold Lake, Lloydminster, and Peace River areas. Conventional heavy oil (10 to 20 ° API), which is partially recoverable by conventional in situ methods, is less than 2﹪ of the total resources. Most of the bitumen has a viscosity ranging from 100,000 to over 1.0 million mPa ⋅s at reservoir temperature. It is present in a solid or semi-solid state in the porous media and there is almost no mobility at the initial reservoir conditions. The effective recovery of bitumen by in situ methods is difficult.

The current production of bitumen is over 400,000 barrels a day, which constitutes about 70﹪ of the total heavy oil and bitumen production(2) in Canada.
A Procedure for Modelling Gas Gathering Systems
Authors: McNeil Ralph
Published: March 2010

It is not uncommon to hear gas producers complain that the success they had finding gas with the drill bit never seems to be fully translated to sales. Often they will use historical references such as, "sales volumes are expected to increase by only 70﹪, 50﹪, or even 20﹪ of the total gas volume added by new wells into the gathering system." In severe cases, new high pressure wells can cause older wells, especially those with liquid production problems, to shutdown. Operators quickly learn to avoid this situation by choking the new wells. In many situations, this is the best they can do, but it raises a big flag for anyone monitoring daily field logs. Inevitably, the question is asked, "Why are these wells choked?" Unfortunately, the operator can only say thatthis is what he has to do to avoid killing other wells, whereas, thosemonitoring the field's production cannot reconcile why all the new gas added to the system doesn't show up in the sales reports.

This is a classic case of the confusion that often exists between office and field personnel. It is also a case that could be simulated using a gas gathering system model. A model could be used to demonstrate why new wells may need to be choked but more importantly, it can be used to test ideas for optimizing system production rates.

FIGURE 1: Back pressure plot. Available in Full Paper.

A gas gathering system model can be an important tool for testing the impact of various ideas proposed for optimizing a gathering system. The relationship, as shown, between deliverability (lower pressure to increase production) and the gathering system (increase pressure to increase capacity) is non-linear and opposing. This relationship can lead to the counter-intuitive situation where additional compression is installed to lower well back-pressures with the expectation of increased production, but the lower pipeline operating pressures reduce pipeline capacity and so the well back-pressures are only reduced minimally or worse, increased! Modelling offers the opportunity to test many ideas, virtually, before making expensive capital expenditures to lay pipeline or install compression that may not increase gas volumes appreciably. Consequently, proposals can be put to the test and can be quantified in terms of incremental gas rates and incremental recovery of reserves.

When attempting to build a model to replicate an existing gathering system's behaviour, it is extremely important to first "tune" the model. Tuning requires that, at a minimum, a systematic approach be used to match pipeline pressure losses, each well's deliverability relationship and each compressor's capacity relationship to current operating conditions. The five most common mistakes made after building a model arenot tune the model,assume all the data is representative of true conditions,assume that all pressure losses are frictional pipeline losses,not confirm that well deliverability relationships match current operating conditions, anduse compressor design curves without confirming their validity with current operating conditions.
Effect of Viscosity and Diffusion Coefficient on the Kinetics of Bubble Growth in Solution-Gas Drive in Heavy Oil
Authors: Kumar R. , Pooladi-Darvish M.O.
Published: March 2010

Some of the heavy oil reservoirs in Alberta and Western Saskatchewan show anomalously high primary recovery and high flow rate under solution gas drive. Several theories have been proposed for the anomalous behaviour. However, only a few theories look at the basic physics of the problem and find out the reason for this favourable behaviour.

The process of solution gas drive involves nucleation of gas bubbles followed by bubble growth and finally flow of gas. In his work, the aspect of bubble growth is studied in heavy oil and in light oil. A numerical model is developed, including the hydrodynamic and mass transfer effects to investigate the effect of viscous and diffusional forces on bubble growth.

An objective of the paper is to show that the effect of oil viscosity on bubble growth might be insignificant, even for heavy oils. A secondary objective is to examine the validity of the popular rowth model of R(t) = atb, when both diffusional and hydrodynamic forces are acting. The case of a gradual decline in pressure is studied, which more closely simulates the reservoir condition, and is compared with a step decline in pressure. It is found that the constants a and b in the above model need to be found for the conditions of interest; they depend on oil-type, rate of pressure drop, mass transfer boundary condition, etc. In another part of the paper, the gas phase growth during the solution gas drive experiment is modelled and the effect of various parameters, such as viscosity, depletion rate and diffusion coefficient, on the process is studied.

It is found that, in a constant volumetric rate of depletion process, the system compressibility might remain unchanged for some time, even after bubbles have nucleated and while they are growing. Hence, the maximum supersaturation observed does not have to correspond with the nucleation pressure.

Introduction

The process of solution gas drive involves nucleation of bubbles in oil as the pressure falls below the bubblepoint pressure, following which the bubbles grow. During growth, the bubbles come in contact with each other and, with the breaking of the lamella, coalesce to form interconnected gas bubbles, often with multiple branches.

The process of solution gas drive in heavy oil reservoirs shows a number of anomalies when compared to that in a light oil reservoir. A number of theories(1-7) have been proposed to explain this behaviour of the heavy oil reservoir. However, only a few look at the basic physics of the problem. In this paper, an attempt has been made to study bubble growth with specific application to the solution gas drive process by looking at the physics of bubble growth and study the effect of viscosity and other parameters. As a first step, a single bubble growth in bulk is considered and the effect of the porous medium is not included. The bubble growth in light oil, is compared with that in heavy oil, and the reason for the differences sought.
Reservoir Paraffin Precipitation: The Oil Recovery Challenge in Dom Jo?o Field?
Authors: Mezzomo R.F. , Rabinovitz A.
Published: March 2010

Dom Joao Field, located at Reconcavo Basin in northeastern Brazil, has been under production for more than 50 years. From the very beginning in 1947, exploitation has been plagued with problems that standard geology and reservoir engineering practices were not able to cope with. With an OOIP of 113 MMm3 of 38 °CDATA[API paraffinic crude, the current recovery factor stands at only 15%, in spite of the early implementation of waterflooding. Three major reservoir studies by different organizations, Petrobras included, were conducted over the years with significant impact on the geological model and appraisal of the original volumes, together with recommendations as to the variation in the injection and production patterns. They were implemented accordingly but with limited success and, other than the heterogeneity of the reservoirs in the main Sergi Formation, no suitable explanation was found for the poor recovery performance, not to mention a solution to the problem. The size of the target oil and the constant threat of field abandonment, led to the approval of a research project in late 1993 as part of the portfolio of PRAVAP, Petrobras Strategic Advanced Oil Recovery Program. Its goal was twofold: verify the assumption of paraffin precipitation in the reservoir as the cause of the low recovery factor, and eventually put to the test recovery strategies that would ensure the economical exploitation of the shalloweposits of paraffinic crude in Reconcavo Basin. This paper summarizes the major accomplishments of this project throughout the 3 1/2 years of research and development and the corresponding IOR field implementations.

Introduction

As reported by Leite(1), Dom Joao Field, the second oldest commercial accumulation in Brazil, was discovered in March 1947. Situated in the southwestern part of Reconcavo Basin in Bahia State, Brazil, it is 23.5 km long and 0.6 - 3.5 km wide for an area of 47.3 km(2) (Figure1). Structurally, it is a slightly dipping (1 - 5 °CDATA[) horst, limited by a major fault zone with 400 to 500 m of displacement in the West, and smaller ones in the East. Two thirds of the field are located offshore in Todos os Santos Bay, at an average water depth of 3 m. It produces from the 8 zone (C-J) Sergi formation at depths between 146 m and 376 m. C zone, with an average net pay of 10 m, is the major producer. For management purposes only, the field is divided into Dom Joao Onshore and Dom Joao Offshore. Also, due to a series of normal faults across the structure, the offshore part of the field is further divided into Northern Dom Joao Offshore and Southern Dom Joao Offshore. General data on Dom Joao Field is given in Table 1. Over the years, a total of 828 wells were drilled in Dom Joao Field to tap an original volume of oil in place of 113 MMm3. Yet, after more than 50 years of exploitation, the recovery factor stands at barely 15﹪ OOIP.
Upgrading Athabasca Tar Sand Using Toe-to-Heel Air Injection
Authors: Xia T.X. , Greaves M.
Published: March 2010

The unique operation of the THAI (Toe-to-Heel Air Injection) process, enables very high oil recovery and substantial in situ upgrading. Both thermal upgrading (non-catalytic) and also catalytic upgrading, in which a catalyst is emplaced along the horizontal producer well, were investigated. 3D physical model experiments were conducted on virgin Athabasca tar sand bitumen to investigate dry and wet combustion performance. These results were compared against those from a steamflood test, which was subsequently followed by air injection. Excellent ignition, very stable combustion propagation and thermal upgrading of nearly 10 ° API were achieved using Athabasca tar sand. Additional upgrading was achieved using an in situ catalyst. THAI has the extra advantage that some hydrogen is generated in situ, providing further significant upgrading via hydroconversion. There are also substantial environmental benefits because of the large reductions in sulphur and heavy metals in the produced oil. Furthermore, oil is produced without "displacement delay," immediately ahead of the combustion front. The oil recovery using THAI was greater than 75% OOIP.

Introduction

The world's conventional crude oil production is expected to reach its peak in the second decade of this century and enter a permanent decline phase(1). The composition of the oil barrel is getting heavier, and diluent blending "stop-gaps," assisted by very limited coker upgrading capacity will, eventually, be insufficient to cope with the increasing demand for light oil. Historically, heavy oil trades at a substantial discount to that of premium light crude oil. Therefore, it has lower economic value and also market potential, unless new technology is developed to upgrade it to lighter oil, in an economic manner.

The Athabasca Tar Sand deposit of northeastern Alberta, Canada, is one of the largest reserves of bitumen in the world. These are estimated to be 212.9 ??109 m3 (1,339 ?109 bbl)(2). Although about 10% of the bitumen reserves are mineable, the rest of the Athabasca Tar Sands have to be exploited by in situ recovery technology. A number of in situ oil recovery methods, such as steam assisted gravity drainage (SAGD)(3) and in situ combustion (ISC)(4, 5), have been extensively studied, both in the laboratory and in field tests.

In situ combustion (ISC) is a thermal EOR method, in which a small fraction of the oil (or coke) in the oil layer is burned in order to mobilize the unburned fraction. Due to the strong exothermic oxidation reactions between hydrocarbon (or coke) and oxygen, the temperature of the oil-bearing matrix in the combustion zone is 500 to 700 °C, which is much higher than in steam flood processes (150 to 250 °C). High temperatures are very favourable for tar sands and heavy oil reservoirs, because not only is the oil viscosity reduced by several orders of magnitude, but the heavy residue is also thermally cracked to lighter compounds.
Strategic Upstream R&D Collaboration
Authors: Dingle Howie
Published: March 2010

The Canadian upstream oil and gas industry-like any other non-renewable resource industry-is ultimately a "sunset" industry. But not yet!

Renewal Through R&D

Our traditional mechanism for renewal (Figure 1) has been to explore for and to develop new reserves. Estimated undiscovered conventional liquid in the Western Canada Basin is one-eighth the unrecoverable volume remaining in discovered pools. Estimated undiscovered conventional liquids in the frontiers may be large but has prohibitive development costs which have kept existing discoveries from production. The undiscovered natural gas resources in both the Western Canada Basin and the frontiers face supply cost vs price hurdles at least through the balance of the decade.

Our known heavy oil and oil sands bitumen in place are a worldclass hydrocarbon resource with prohibitive supply cost hurdles for the foreseeable future.

This is a challenging, but not an impossible scenario. Canada has the hydrocarbon resources-discovered and potential-to sustain a domestic production industry well into the 21st Century. We also have the economic and scientific will to fulfill that potential. R&D is crucial for renewal for several reasons. First, it will enable us to control and reduce ever-increasing unit operating costs in our existing operations. Secondly, it will enable us to maintain our aging infrastructure-even in the face of ever more stringent environmental and safety requirements. R&D is also necessary to extend the life of our existing pools by facilitating the enhancement existing recovery processes. It is a critical tool, moreover, in renewing hydrocarbon reserves through the development of new recovery processes, and through the development of technologies to enable the development of the inherently high supply cost frontier and oil sands resources. Finally, R&D is necessary to add value to our commodity products in order to retain our existing markets in the face of international competition.

Changing the R&D Paradigm

Historically, with real growth in energy prices and with reserves additions exceeding production, upstream research and technology development has been fragmented and duplicated. It has been aimed at obtaining competitive advantage with the local industry, in an effort to capture the largest possible piece of a prize which has failed to materialize. The industry as a whole has spent a great deal of money on R&D - AOSTRA estimates that over a billion dollars has been spent on oil sands R&D alone. Thus, the level of R&D effort is not the problem so much as the way in which it has been conducted.

Collaborative research and technology development must now be the major mechanism for renewal of our domestic upstream industry. Today, our principal competition is global-low supply cost crude from overseas. Our domestic industry is not competitive in the world marketplace, as is evident from our returns on investment through the 1980s.