An array of cortical and subcortical structures have been implicated in the recognition of emotion from facial expressions. It remains unknown how these regions communicate as parts of a system to achieve recognition, but white matter tracts are likely critical to this process. We hypothesized that (1) damage to white matter tracts would be associated with recognition impairment and (2) the degree of disconnection of association fiber tracts [inferior longitudinal fasciculus (ILF) and/or inferior fronto-occipital fasciculus (IFOF)] connecting the visual cortex with emotion-related regions would negatively correlate with recognition performance. One hundred three patients with focal, stable brain lesions mapped onto a reference brain were tested on their recognition of six basic emotional facial expressions. Association fiber tracts from a probabilistic atlas were coregistered to the reference brain. Parameters estimating disconnection were entered in a general linear model to predict emotion recognition impairments, accounting for lesion size and cortical damage. Damage associated with the right IFOF significantly predicted an overall facial emotion recognition impairment and specific impairments for sadness, anger, and fear. One subject had a pure white matter lesion in the location of the right IFOF and ILF. He presented specific, unequivocal emotion recognition impairments. Additional analysis suggested that impairment in fear recognition can result from damage to the IFOF and not the amygdala. Our findings demonstrate the key role of white matter association tracts in the recognition of the facial expression of emotion and identify specific tracts that may be most critical.

Air injection-based enhanced oil recovery processes are receiving increased interest because of their high recovery potentials and applicability to a wide range of reservoirs. However, most operators require a certain level of confidence in the potential recoveries from these (or any) processes prior to committing resources. This paper addresses the challenges of predicting field performance of air injection projects using laboratory and numerical modelling. Laboratory testing, including combustion tube tests, ramped temperature oxidation and accelerating rate calorimeters can supply data for simple analytical models, as well as providing important insights into potential recovery-related behaviours. These tests are less suited to providing detailed kinetic data for direct and reliable use in numerical simulators. Indeed, the oxidation reactions are sufficiently complex that, regardless of how powerful the thermal reservoir simulator is, its predicting capability will strongly depend on the engineer's understanding of the process and ability to model the most relevant oxidation behaviours of the particular oil reservoir under study. It is proposed that the optimum design cycle for air injection-based processes is to perform laboratory testing that would aid in the understanding of the process and in the design and monitoring of a pilot-scale field operation. Analytical models and simplified, semi-quantitative reservoir simulation models would be employed at this stage. If this evaluation stage is successful, a pilot operation would be initiated and the data gathered during the pilot, as well as laboratory oil property and compositional data, would then be used to history match and tune a model for predictions of the full field operation. Introduction This paper has been written in response to questions which many reservoir engineers express when evaluating the feasibility of air injection as an enhanced oil recovery process for their fields. Questions such as, "What laboratory tests are available? What type of data is provided by each test? How do we use the lab results to predict field performance?" are not uncommon, and, although there are not straightforward answers, a discussion on the usefulness of different lab tests is presented to clarify some of the related concepts. This document has also been written in response to the concerns and comments expressed by many reservoir simulation practitioners when matching combustion tube tests and other supporting oxidation experiments, and trying to predict field performance of an air injection project based on kinetic parameters obtained from such tests. Questions such as, "How do we use the lab data in the reservoir simulator? What are the limitations of thermal reservoir simulation when predicting field performance of air injection projects?" are addressed to provide additional feedback and promote further discussion. Additionally, this manuscript describes some of the combustion behaviours which have been observed by the In Situ Combustion Research Group (ISCRG) at the University of Calgary while performing combustion tube tests and supporting cracking/oxidation experiments, and gives some recommendations to improve the modelling of the combustion process using thermal reservoir simulators.

We develop a simple and efficient method for soft shadows from planar area light sources, based on explicit occlusion calculation by raytracing, followed by adaptive image-space filtering. Since the method is based on Monte Carlo sampling, it is accurate. Since the filtering is in image-space, it adds minimal overhead and can be performed at real-time frame rates. We obtain interactive speeds, using the Optix GPU raytracing framework. Our technical approach derives from recent work on frequency analysis and sheared pixellight filtering for offline soft shadows. While sample counts can be reduced dramatically, the sheared filtering step is slow, adding minutes of overhead. We develop the theoretical analysis to instead consider axis-aligned filtering, deriving the sampling rates and filter sizes. We also show how the filter size can be reduced as the number of samples increases, ensuring a consistent result that converges to ground truth as in standard Monte Carlo rendering.

In recent years, high pressure air injection (HPAI) has proven to be a valuable IOR process, especially in deep, high pressure, low permeability fields where other recovery processes are uneconomic. This paper will provide engineers and engineering managers with a wide-ranging look at the key factors that should be addressed when considering a high pressure air injection (HPAI) based IOR process in a light oil reservoir. The paper is based on many years of involvement of the authors both in the laboratory and the field, as well as drawing on published literature. The main focus is on key design and operating criteria that must be considered, including reservoir screening, air injection design, ignition, and monitoring. The benefits and potential risks of HPAI are also discussed. Along with the discussion of design and operating criteria, the paper contributes significantly in the comparison of oxidation/combustion kinetics for light oils versus heavy oils (HPAI versus in situ combustion), as well as in a discussion of the oil mobilizing effects of a gas flood compared to an advancing thermal (combustion) front. Introduction In recent years, High Pressure Air Injection (HPAI) has received considerable attention as an effective IOR process, based primarily on the success of several projects located within the Williston Basin, and the vision and initiative by Amoco Production Company (now BP) in forming an industrial consortium to develop a state-of-the-art HPAI laboratory. This has led to increased interest from companies in exploring the suitability of the HPAI process for application in their onshore and offshore reservoir holdings. The intent of this paper is to provide managers as well as engineers with a reference that discusses several design and operational issues that are important to consider. It is based on the authors' nearly thirty years of research and consulting in the area of in situ combustion and HPAI. While the paper was not intended as a review of the large body of existing HPAI literature, there are several useful references that serve as a starting point for understanding the process. The papers by Erickson, et al.1 and Kumar, et al.2 provide good summaries of the HPAI projects that were started by Koch Exploration Company in the Buffalo Red River Units and the Medicine Pole Hills Unit located in the Williston Basin; these projects continue to be operated, currently by Continental Resources, Inc. Watts, et al.3 describe a newer project started in the nearby Horse Creek Field by Total Minatome Corporation, and a paper by Fassihi, et al.4 discusses the light oil air injection process and addresses various recovery mechanisms based on field and laboratory data. Fassihi, et al.5 discuss the economics associated with two separate air injection projects at West Hackberry, Louisana, and the Medicine Pole Hills Unit, N. Dakota. Moore, et al.6,7 describe strategies for design and operation of successful air injection-based processes, and highlight the significant differences between air injection in light and heavy oil reservoirs. Yannimaras and Tiffin8 and Tiffin and Yannimaras9 describe laboratory testing of the HPAI process at the Amoco Production Company laboratory using the combustion tube and the accelerating rate calorimeter, while Greaves, et al.10 describe light oil recovery by air injection, based on laboratory work at the University of Bath, U.K. Field-specific numerical simulations of the HPAI process have been described by Kumar11, Glandt, et al.12, and Kuhlman13. Finally, two classical air injection design papers by Nelson and McNeil14 and Gates and Ramey15 are important reading for anyone involved in the design of air injection-based IOR processes. As stated previously, this list does not represent the complete literature on HPAI, but represents an excellent starting point in learning about the process.

A series of experiments to measure the water solubility in supercritical nitrogen and carbon dioxide have been conducted at experimental conditions up to 483 K and 134 MPa. The accuracy of the experimental procedure is verified by comparing the water content data of methane in the literature and our experimental data for the methane−water system. In addition, a fugacity−fugacity approach including the cubic-plus-association equation of state (CPA EoS) and a fugacity−activity approach based on the Peng−Robinson EoS and the Henry’s law model are incorporated to predict the water content data of methane, nitrogen, and carbon dioxide. A comparison between our experimental data, literature data, and the results of the fugacity−activity approach shows the reliability of the PR-Henry’s law model for the phase behavior studies of the nitrogen−water system over a wide range of pressure and temperature conditions. However, the CPA equation is not capable of reproducing the high pressure vapor and liquid phase compositions of the water−nitrogen system. The concept of cross-association satisfactorily improves the performance of the CPA equation of state in predicting the water content data of supercritical methane. On the basis of the literature and new measured data in this study, it has been found that the CPA equation better represents the phase behavior of the water−carbon dioxide system if carbon dioxide is considered as a self- and cross-associating molecule.

During in-situ combustion (ISC) processes, different chemical reactions occur depending on the temperature level. In heavy oils and bitumens, low temperature oxidation (LTO) reactions dominate below 300ºC, increasing the density and viscosity and producing coke which could prevent the success of ISC. Above 350ºC, combustion reactions dominate, known as high temperature oxidation (HTO), producing carbon oxides and water. Numerical models tend to include only thermal cracking and HTO reactions, as LTO reactions are not well understood. In the present work, ISC experiments operated under LTO were simulated, using Saturates, Aromatics, Resins and Asphaltenes (SARA) fractions to characterize the Athabasca bitumen. Concentration profiles and coke deposition for individual temperatures were matched for isothermal experiments from 60ºC to 150ºC. Based on these results, ramped temperature oxidation (RTO) experiments were then modelled, incorporating the heat of reaction at LTO. Different reaction models were studied to match temperature profiles along the reactor, oxygen consumption, coke formation and fluids production. This research will greatly increase the understanding of LTO reactions occurring in Athabasca bitumen during ISC and contribute to the creation of a reliable numerical model that predicts ISC performance under ideal (HTO) and, importantly, non-ideal (LTO) temperature conditions. Introduction ISC is a promising but complex oil recovery process in which thermal energy is generated inside the reservoir owing to combustion reactions between the heaviest fractions of the oil and an injected oxygen containing gas. For heavy oils and bitumens, ignition temperatures above 350°C are required to promote the combustion reactions (HTO). At lower temperatures, other types of reactions predominate, involving the addition of oxygen to the bitumen, producing heavier oxidized compounds. The LTO reactions are detrimental to oil production; hence, ISC processes are designed to operate under the high temperature combustion regime (HTO). However, LTO reactions occur if the air flux becomes too low to sustain the combustion reactions, leading to lower-than-estimated production yields. It has been proven in laboratory experiments that oil recovery is considerably reduced when LTO reactions occur to some extent, compromising the success of the ISC.

High Pressure Air Injection (HPAI) is an Improved Oil Recovery (IOR) technique in which compressed air is injected into light oil, high-pressure reservoirs. The objective of this process is the oxygen from the injected air reacts with a small fraction of the reservoir oil at an elevated temperature to produce a mixture of carbon dioxide and nitrogen. The produced gas flowing from the reaction region mobilizes the oil downstream of the reaction zone towards the production wells. Knowledge of the oil's oxidation behaviour is a key to the successful implementation of this process. However, information on oxidation behaviour of oils based on their compositions is limited, especially for light oils. An experimental study was designed to examine the oxidation behaviour of three crude oils (a light oil, a medium oil, and an Athabasca bitumen) by using the Pressurized Differential Scanning Calorimeter (PDSC) at pressures from 110 to 6,894 kPa. Pure hydrocarbon aromatics and paraffin samples were also selected for the current study. The study shows an increase of pressure results in an increase in the rate of oxidation reactions and heat released from the oxidation reactions. The PDSC heat flow curves also clearly demonstrate the effect of chemical structure of the samples on their oxidation behaviour. The extent of oxidation of hydrocarbon samples is strongly dependent on the nature of the hydrocarbon. Introduction Air injection continues to be an important oil recovery process, used to increase both the amount and the rate of oil recovered from a petroleum reservoir(1,2). When air is injected into a light oil reservoir, exothermic chemical reactions occur between the reservoir oil and the oxygen contained in the injected air. The reactions are mainly oxidation reactions resulting in heat generation and the production of carbon dioxide, carbon monoxide, and water corresponding to the consumption of oxygen. The heat of reactions results in a temperature elevation leading to vapourization of some lighter components and a decrease of viscosity of the oil, even though the heat effect is not very important for light or medium oil compared to heavy oil. Therefore, the driving gas, which can sweep the oil to production wells, is not the injected air but an in situ-generated flue gas, composed of CO, CO2, N2, and vapourized light hydrocarbon components. Air injection is a complex process involving simultaneous heat and mass transfer in a multiphase environment coupled with oxidation chemical reactions. Oxidation reactions play an important role in this process. In order to improve the efficiency of the air injection process, it is necessary to have additional knowledge of the factors influencing the process and how they affect the oxidation of oil. In recent years, the application of thermal analysis techniques, thermogravimetry (TG/DTG), and differential scanning calorimetry (DSC) have obtained wide acceptance in the study of combustion behaviour of oil. Attempts to use thermal analysis techniques to study crude oil combustion began with Tadema(3).

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