bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Classification Plot for Naturally Fractured Reservoirs
Authors: Gilman James R. , Wang Huabing , Fadaei Sepehr , Uland Michael J. 
Published: November 2011

Abstract
The classic Nelson plot (Nelson, 2001) has been widely used to illustrate the geologic characteristics of various NFR types ranging from matrix dominated flow with some fracture enhancement to purely fracture dominated systems (e.g. basement reservoirs). However, for many reservoirs, there is significant overlap in model types and different parts of the reservoirs may fit into different classifications. In fact, the choice of characterization and modeling approaches depends on other considerations such as the fluid system, matrix geologic characteristics, and recovery processes. For example, for gas-oil gravity drainage processes, the rate of vertical oil drainage in the matrix may dominate oil recovery and dual-permeability may be the desired modeling approach even in a highly fractured reservoir. Alternatively in pure depletion processes, we might be able to model a highly fractured system with an effective single-porosity representation because of rapid matrix-fracture pressure equilibration. However, in all fractured reservoirs, of special concern is the rate of matrix-fracture fluid transfer which is directly related to the fracture intensity of the open connected fractures.
In this paper we present a new classification plot that highlights the importance of fracture-matrix fluid transfer. This consideration is not directly incorporated in the Nelson plot. Our new classification concept can be used to understand differences in dynamic performance of NFR for purposes of analogue selection or screening of potential recovery processes. In this paper, several characterized NFR reservoirs (including unconventional systems) are compared via the new classification plot and their differences and performance are discussed. Additionally we provide some discussion of naturally fractured reservoir (NFR) characteristics for the purpose of illustrating the controls on matrix-fracture fluid transfer.
Pseudo-Component, Thermal, Reservoir Simulation Study of a Proposed, Low Pressure, Steam-Assisted Gravity Drainage Pilot Project In Northeast Alberta
Authors: Uwiera-Gartner M. M. , Carlson M. R. , Palmgren C. T. 
Published: November 2011

Abstract
Bitumen production from the Athabasca Oil Sands in northeast Alberta, Canada typically uses steam-assisted gravity drainage (SAGD) techniques. For shallow bitumen resources, low pressure, SAGD (LP-SAGD) and expanding solvent, LP-SAGD (SLP-SAGD) techniques are viable options for such developments as these methods maximize bitumen production and control steam-oil ratios (SORs), while maintaining asset integrity throughout the life of the project.
In Alberta, applications requesting approval for pilot-scale, thermal exploitation of bitumen resources are submitted to the Energy Resources Conservation Board for review. As part of the application process, thermal reservoir simulation studies are often conducted, forecasting 10 years of asset development using SAGD.
The authors recently completed a 3D, pseudo-component, thermal, reservoir simulation study of the proposed Clearwater West, Phase 1 Pilot Project located southeast of Fort McMurray, Alberta. The simulation program, STARS™, was used for this investigation. Three potential development strategies for the Pilot Project were evaluated. These strategies included LP-SAGD, where 100% coldwater equivalent (CWE) steam is continuously injected into the reservoir for 10 years. The other cases were SLP-SAGD, where the injection stream consists of 75% CWE steam and 25% solvent is continuously injected into the reservoir for either 10 years or for 7 years, followed by wellpair blowdown and the termination of solvent injection. Comparisons of key modelling parameter results, such as steam chamber development, bitumen production and recovery, SORs and solvent loss, were completed for all development strategies. A sensitivity study was also conducted.
Why Not to Base Economic Evaluations on Initial Production Alone
Authors: Taylor Robert S. , Barree Robert , Aguilera Roberto , Hoch Ottmar , Storozhenko Ken 
Published: November 2011

Abstract
If one is repeatedly conducting the exact same completion in the same lithology of the same reservoir, then initial production (IP) rates might be a good indicator of relative long-term well performance or estimated ultimate recovery (EUR). This technique is tempting to use because it is quick and simple, and allows for easy comparison. However, use of this method alone assumes the shape of production decline curves will remain consistent from one well to the next. This method can especially be fallible when different numbers of fractures are placed along a lateral with possibly variable length. In this case, the relation between IP and EUR becomes much less defined.
Basing key economic decisions on IP alone can be misleading. This paper examines situations in which IP is not only a poor indicator of ultimate well performance, but in fact shows a reverse correlation. Sizing and spacing of fracturing treatments along a horizontal wellbore as well as vertical placement of the lateral in the zone can all be key variables. In many cases, one can choose high IP or optimized economic return, but not always both. Assuming that high IP equates to greater economic return can be a critical error. It is therefore essential to those involved in well-completion design as well as financial analysts to understand the variables involved as well as their impact. A lack of understanding could lead to poor completion and/or stimulation decisions that could severely impact the return on investment (ROI).
Shale Gas Modeling Workflow: From Microseismic to Simulation -- A Horn River Case Study
Authors: Novlesky Alex , Kumar Anjani , Merkle Stefan 
Published: November 2011

Abstract
Recent success of commercial shale gas developments in a number of basins throughout North America can be attributed to the application of advanced technologies used to drill horizontal wellbores, stimulate the shale reservoir, and optimize productivity of shale-bearing formations. Many of the drilling and completion techniques learned from the thousands of wells drilled and stimulated in more mature shale basins, such as the Barnett, have been applied to newer shale discoveries such as the Marcellus and Haynesville in the United States, and both the Montney and the remarkable Horn River Basin in Canada. The unique properties of each shale, however, preclude a "cookie-cutter" development approach from being applied. Each play must be optimized as a unique reservoir.
In order to utilize numerical simulation as a tool in optimizing well design, one needs to develop a model that appropriately represents the complex process of gas flow from the native reservoir to the hydraulic fractures and subsequently to the wellbore. This is challenging due to poor understanding of variables such as pressure dependent permeability variation, fluid cleanup, relative permeability effects, non-Darcy flow, methane desorption in a nano-Darcy shale matrix, and fracture conductivity variations from the dominant hydraulic fractures to the secondary induced and natural fractures. Another challenge is accurate representation of the hydraulic fracture. Is the fracture planar or complex? What is the fracture geometry? What is the fracture intensity within the stimulated volume? What is effectively propped? What is the proppant distribution within the fracture system? How does this tie to effective conductivity and does it vary with distance from the wellbore (three dimensionally)?
Finding a unique match to historical production is very challenging. Shale gas operators collect a large amount of data including cores and logs (specialized for nano-Darcy rock), micro seismic, diagnostic fracture injection testing (DFIT), fluid and proppant tracers and more. This data is used to better characterize the reservoir and the natural and hydraulic fractures and can help to constrain model inputs.
This paper discusses a workflow used in developing a numerical shale gas model for Nexen’s Horn River shale gas reservoir. Presented is a practical and systematic approach to using surveillance data; specifically microseismic data in construction of the stimulated reservoir volume (SRV) and the network of hydraulic fractures in the model. Discussions will also focus on accurately modeling complexities such as non-Darcy flow in the hydraulic fractures, pressure-permeability dependencies, variations in hydraulic fracture conductivity and fluid cleanup. The objective is to gain understanding and insight into the uncertainties that have the greatest impact on well performance.
SAGD Pair Performance Optimization: A Field Case of Recovery Enhancement
Authors: Jorshari Kamran R. , O’Hara Brendan , Jones Ramsey W. 
Published: November 2011

Abstract
Performance of fields under thermal recovery processes has been considerably improved by experimenting with new techniques and innovative operational solutions in heavy-oil and extra heavy-oil fields. By far, steam-assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) methods have been the most compelling and have proven a successful history in these oil fields. At the Celtic heavy-oil field, Husky Energy experienced three phases of optimization over the course of ten years of recovery. The Celtic field consists of 28 SAGD pairs located in the Lloydminster heavy-oil region that have been in service since 2001. Among these pairs, there are three SAGD pairs (F-pad east) with early productivity challenges in addition to down-time caused by sand production. Following new geological realization and reservoir studies, the injector wells were converted to production wells performing horizontal CSS process. In 2008, and in an effort to maintain production, a detailed numerical simulation study was conducted to compare different steam support configurations and the result was justified for field execution. The outcome resulted in four directional steam-injection wells (G-Pad) permanently started to support the current horizontal producers.
In 2009, the new configuration commenced and is still in operation today. Communication with horizontal wells has been completed on one side of the pattern and it has been gradually extending to other side. Recently acquired field data suggest that the process is exceeding the expected oil profile and its steam consumption is less than that was anticipated. The geological review, history of the F-Pad East pairs, results of numerical simulation study, and recommendations are presented in this paper.
Analysis of Production Data Using the Beta-Derivative
Authors: Idorenyin E. , Okouma V. , Mattar L. 
Published: November 2011

Abstract
This paper presents a new insight into rate transient analysis using the beta-derivative function (β-derivative). Production rates and flowing pressures from tight gas and shale gas wells were analyzed using various implementations of the betaderivative to emphasize different features of the data and, as a result, reveal characteristic information about flow regimes and the extent to which the reservoir has been drained. The beta-derivative was applied to rate, pressure and normalized rate, and the effect of skin on the β-derivative was also investigated. The intent was to determine which format is the most useful for diagnosing the dominant flow regimes or the sequence of flow regimes that have occurred while producing from an unconventional hydrocarbon reservoirs (tight gas, shale gas and light tight oil).
It was found that the classic signature of the β-derivative is altered by the presence of skin. Also, the derivative based on constant rate is different from that based on constant pressure. The beta-derivative's diagnostic value was compared to that of the Bourdet Derivative and the Primary Derivative
The β-derivative has significant diagnostic value for identifying power-law type of flow regimes (such as wellbore storage, linear flow, bilinear flow, boundary-dominated flow, etc) because it possesses a recognizable unique character for each of these flow regimes. For instance, the β-derivative is 0.5 for linear flow, 0.25 for bilinear flow and 1.0 for boundary dominated flow. In addition, since the β-derivative is dimensionless, it can be used to differentiate the performance of wells producing from the same field or from different resource plays. The new plotting functions presented in this paper are not intended to replace existing diagnostic functions but can be used in conjunction with them to enhance production data analysis.
New Type Curves for Shale Gas Wells with Dual Porosity Model
Authors: Abdulal Haider J. , Samandarli Orkhan , Wattenbarger Robert A. 
Published: November 2011

Abstract
As interest in exploiting shale gas/oil reservoirs with multiple stage fractured horizontal wells increased, complexity of production analysis and reservoir description have also increased. The main objective of this paper is to present and demonstrate type curves for production data analysis of shale gas/oil wells using a Dual Porosity model.
Dual Porosity model is based on Bello and Wattenbarger’s (2010) mathematical model where hydraulic fractures act as a secondary porosity system where matrix is the primary porosity system. Samandarli et al. (2011) showed application of this model on history matching and forecasting of shale gas wells with multiple fractures by doing regression on effective fracture and matrix permeability and half length. This type of regression is as rigorous as simulation, however much faster than it. On the other hand for "quick look interpretation" having type curves will make the production analysis even more convenient for practical purposes.
With this method production of shale gas/oil well can be matched with developed type curves which vary with effective permeability. Once the production data is matched with one of the type curves, effective permeability and match points are recorded. By using dimensionless equations developed for Dual Porosity model fracture half-length can be determined. In order to use type curves, good estimate for effective porosity and matrix permeability should be predetermined.
Type curves developed in this paper were applied to synthetic and field data examples. Early results show that method works well in determining effective fracture half-length which is the most important parameter in evaluation of stimulated reservoir volume (SRV).
New Type Curves for Analyzing Horizontal Well With Multiple Fractures in Shale Gas Reservoirs
Authors: Nobakht M. , Clarkson C. R. , Kaviani D. 
Published: November 2011

Abstract
To produce economically from most shale gas plays, horizontal wells (cased or open hole) with multiple fractures are the most popular choice for completing the wells. A number of well-performance behaviors can be seen for these wells depending on reservoir behavior and induced hydraulic-fracture geometry. In this paper, conceptual models for well/reservoir/hydraulic fracture combinations are first presented. Next, we discuss the impact of various reservoir types/induced hydraulic-fracture geometries upon the sequence of flow-regimes that could be encountered for shale gas reservoirs. In addition, we develop and present new sets of dimensionless type-curves for one of the conceptual models. The newly developed type curves in this study yield more unique results than those presented previously. With these dimensionless type curves, the early linear flow (early-time half slope) and boundary-dominated flow (late-time unit slope) fall on top of each other and the transition between these two regimes depends on the geometry of the reservoir and completion. Using the type curves as a guide, we then present the flow regimes that are expected for different values of horizontal well length, number of fractures, length of the fractures and spacing between horizontal wells. We also present a new method for evaluating the contribution from the outer reservoir (beyond the fracture length). Finally, using the characteristics of new dimensionless parameters and the new type-curve set, we present a simple and practical procedure for long-term forecasting in multi-fractured horizontal wells.
Organic Maturity, Hydrous Pyrolysis and Elastic Property in Shales
Authors: Zargari Saeed , Prasad Manika , Mba Kenechukwu C. , Mattson Earl D. 
Published: November 2011

Abstract
Organic-rich shales (ORS) are common source rocks for most clastic reservoirs. More recently, they have gained importance as reservoirs. However, the processes of kerogen maturation, hydrocarbon storage, and hydrocarbon transport are still poorly understood. Empirical relations have been developed to relate the increase in acoustic velocity and elastic modulus with increasing maturity. The reason for this increase in velocity also remains poorly understood.
We conducted experiments on ORS samples with a range of maturities from the Bakken formation. Our study focuses on investigating methods of predicting maturity of ORS by evaluation of their impedance micro-structure. Our Young’s modulus measurements on a nanometer scale help understand variations of Young’s modulus of minerals, clay particles, and kerogen matter in naturally matured shales. The samples were re-measured after subjecting them to hydrous pyrolysis. This step helped us investigate the cause for change in modulus with maturity and the mobility of the pyrolysed organic matter.
In the naturally matured samples, we find direct qualitative relationships between the Young’s modulus of shale samples and its maturity indicators, such as TOC and Transformation Ratio. After hydrous pyrolysis, there is a significant lowering of the Young’s modulus in some immature samples. We will present results of elastic property changes before and after hydrous pyrolysis in shales of various maturities.
This study improves our current understanding of maturity-related variations by using analysis from nanoindentation. We integrate these measurements with geochemical analysis, and observations from downhole sonic measurements to develop relationships of elastic impedance to shale maturity. These results are critical to help us understand how shales evolve with burial and maturation and how hydrocarbons are stored and transported to sustain large storage even at high overburden stresses.
A Review and Model of Auditor Judgments in Fraud-Related Planning Tasks
Authors: Hammersley Jacqueline S. 
Published: November 2011

SUMMARY
In this paper, I develop a model that describes auditor and fraud risk factor characteristics that I expect to affect auditor performance in fraud-related planning tasks (i.e., fraud hypothesis generation, risk assessment, and audit program modification). I expect that auditor knowledge, especially fraud knowledge, will significantly affect auditor performance in audit program modification tasks through its effects on fraud risk factor identification and hypothesis generation. Further, due to fraud's rarity, I expect that this knowledge is acquired primarily through indirect experience such as training rather than from direct experience and is enhanced when auditors have better problem solving skills and higher epistemic motivation. This is a significant departure from knowledge acquisition in other audit settings, and there is currently no evidence in the literature examining these relationships. I also propose that the diagnosticity of fraud risk factors and, specifically, the degree to which they support generation of specific testable fraud hypotheses affect auditors' ability to plan effective changes to audit programs. Finally, I review and summarize the extant fraud-related, audit planning literature and identify opportunities for future research.
JEL Classifications: M40; M41; M42.
The Effect of Auditing Standard No. 5 on Audit Fees
Authors: Krishnan Jagan , Krishnan Jayanthi , Song Hakjoon 
Published: November 2011

SUMMARY
In June 2007, the PCAOB issued Auditing Standard No. 5 (AS5), superseding Auditing Standard No. 2 (AS2). AS5 significantly changed the rules relating to audits of internal control over financial reporting (ICFR). Policymakers expected AS5 to lead to improvements in audit efficiency and thus a general reduction in audit costs, and specifically a reduction in fees for smaller and less complex companies that were disproportionately affected by AS2. We investigate the impact of the change from AS2 to AS5 on audit fees. We restrict our analysis to stable client-auditor combinations to ensure that auditors had prior AS2 experience with the client before the transition to AS5. We find that, after controlling for other factors, audit fees were lower in the first two years of implementation of AS5 relative to the last year of AS2. The decrease in fees was the highest for companies that had remediated material weaknesses in their internal control and thus moved from an adverse opinion under AS2 to a clean opinion under AS5. Further, firms that received first-time adverse opinions on their internal control in the AS5 period paid lower fee premiums (relative to firms with clean opinions) than did firms with adverse reports in the last AS2 year. Finally, in contrast to policymakers' expectations that AS5 would generate cost savings by allowing the ICFR audits to be “scaled” for small and less complex firms, there is no evidence that the smallest firms benefited. Specifically, audit fee savings were found only for relatively more complex firms (measured by multiple segments and international operations).
Non-Periodontal Oral Manifestations of Diabetes: A Framework for Medical Care Providers
Authors: Gandara Beatrice K. , Morton Thomas H. 
Published: November 2011

In Brief
In addition to periodontitis and dental caries, other oral conditions commonly occur commonly in patients with diabetes. These include fungal infections, salivary gland dysfunction, neuropathy, and mucosal disorders. Many of these lesions can be easily examined and documented by non-dental providers.
A note on regularity and positive definiteness of interval matrices
Authors: Farhadsefat Raena , Lotfi Taher , Rohn Jiri 
Published: November 2011

Abstract
We present a sufficient regularity condition for interval matrices which generalizes two previously known ones. It is formulated in terms of positive definiteness of a certain point matrix, and can also be used for checking positive definiteness of interval matrices. Comparing it with Beeck’s strong regularity condition, we show by counterexamples that none of the two conditions is more general than the other one.
Influence of dendrimers on red blood cells
Authors: Ziemba Barbara , Matuszko Gabriela , Bryszewska Maria , Klajnert Barbara 
Published: November 2011

AbstractDendrimers, highly branched macromolecules with a specific size and shape, provide many exciting opportunities for biomedical applications. However, most dendrimers demonstrate toxic and haemolytic activity because of their positively charged surface. Masking the peripheral cationic groups by coating them with biocompatible molecules is a method to reduce it. It was proven that modified dendrimers can even diminish haemolytic activity of encapsulated drugs. Experiments confirmed that anionic dendrimers are less haemotoxic than cationic ones. Due to the high affinity of dendrimers for serum proteins, presence of these components in an incubation buffer might also influence red blood cell (RBC)-dendrimer interactions and decrease the haemolysis level. Generally, haemotoxicity of dendrimers is concentration-, generation-, and time-dependent. Various changes in the RBCs’ shape in response to interactions with dendrimers have been observed, from echinocytic transformations through cell aggregation to cluster formation, depending on the dendrimer’s type and concentration. Understanding the physical and chemical origins of dendrimers’ influences on RBCs might advance scientists’ ability to construct dendrimers more suitable for medical applications.