bluuebunny/crossref_metadata_2025_split huggingface dataset:
Logistics of Marcellus Shale Stimulation: Changing the Face of Completions in Appalachia
Authors: Perkins C. K. 
Published: October 2008

Abstract
The Appalachian Basin has long been known for its relatively shallow and associatively economical wells. However, in the fairly recent past the Marcellus Shale has caused a buzz in the industry reaching from the small independents of West Virginia to the established majors of Texas and beyond. This creates a two-fold problem for those parties interested in exploring this play. Firstly, how can the independents justify breaking into a tier of spending not typical of Appalachian Basin operations, and secondly, how can the majors create economical situations in an unfamiliar and challenging environment.
Although uniquely different, the path to each solution is similar, both attempting to create an economical and successful project. This begins with careful planning, and a realistic approach. For those familiar with the terrain and environmental challenges, a focus upon fiscal planning and careful economic research is necessary to walk the fine line between feasibility and cutting yourself short. Others may be familiar to large-scale projects, but inexperienced in the challenge that is Appalachia terrain.
All of this plays a direct impact on what may arguably be the most crucial aspect of the entire project – the stimulation design. Without proper planning and execution of site and approach construction, the majority of designs are moot. The facts are that Marcellus Shale wells demand large volumes of materials, delivered at a high rate.
This paper will explore the logistic challenges that any operator could expect to encounter in the Marcellus Shale, and will discuss stimulation design options shown by field experience in over 150 stimulations.
Investigation of Mud-Filtrate Invasion Using Computational Fluid Dynamics
Authors: Won S. , Bilgesu H. I. , Ameri S. 
Published: October 2008

Abstract
In spite of continued improvements in logging technology, mud-filtrate invasion and related formation damage due to drilling fluids can result in the misinterpreted values of rock and fluid properties in the reservoir. Well planning with accurate information of target reservoir would not only optimize drilling operation and completion but also maximizes production of oil and gas.
To produce hydrocarbons effectively, the wellbore must communicate with formations beyond the altered zone and this can be accomplished by using proper perforation penetration or creating fractures. Thus the prediction of invaded zone is critical and a numerical model can be used for preplanning purposes.
In this study, the dynamic filtration process and the related penetration into the gas and oil bearing reservoirs are studied in a vertical openhole system using a Computational Fluid Dynamics (CFD) software package. The radius of filtrate invasion is determined by the unsteady-state three-dimensional multiphase fluid flow model. This study investigates the communication between fluids and formations during drilling with special emphasis on the effects of formation porosity and permeability, time, and overbalanced pressure. As drilling fluids Non-Newtonians such as Bingham plastic, Power-law, and Herschel-Bulkley fluids also considered in addition to Newtonian fluids. Mud filtrate invasion in multi-layer reservoirs model and effect of hydraulic fracturing operations are also investigated in this study.
The results provided an insight in the formation damage around wellbore and related reduction in the hydrocarbon flow due to altered fluid saturations. Accurate prediction of damaged zone around the wellbore will benefit different operations such as drilling fluids design, log interpretation, hydraulic fracturing and well completion.
Design, Execution, and Evaluation of a "Typical" Marcellus Shale Slickwater Stimulation: A Case History
Authors: Fontaine J. , Johnson N. , Schoen D. 
Published: October 2008

Abstract
In 2004 the first Appalachian Basin Marcellus Shale gas well stimulation utilizing a large slickwater treatment was performed in southwestern Pennsylvania. Since that time, based upon various publically reported results, it has become the most widely discussed play in the basin with numerous operators drilling and completing Marcellus wells in Pennsylvania, West Virginia, Ohio, and New York. This wide geographic range has led to numerous different completion schemes being utilized as with geographic variation comes geologic variability within the formation itself. A primary topic of discussion has been determining the optimal size and type of stimulation treatment for a given area. This paper will discuss the stimulation treatment designed and performed on a Marcellus well operated by Guardian Exploration LLC.
A Look Into Casing Deformation Due to Plastic Behavior of Formations
Authors: Sunal O. , Bilgesu H. I. , Heasley K. A. , Tulu I. B. 
Published: October 2008

Abstract
A successful drilling operation at a location depends on the selection of proper hardware and optimum operating conditions. An important part of the hardware design is the selection of the casing based on estimated downhole conditions of pressure forces. Reliable information about the downhole conditions at a drilling site is available during drilling that helps the design of casing strings. However, the conditions of the hardware later in the life of the well due to plastic behavior of formations are not well understood. Casing damage may occur due to overburden shear damage on localized horizontal planes or compaction of the reservoir.
In this study, we investigated the behavior of plastic formations and the related impact of horizontal stresses on the casing in a wellbore. In an effort to understand the casing buckling due to plastic behavior of formations, a numerical model is used to study the forces on casing. Our approach uses a finite difference program to investigate the effect of horizontal stress on the casing for different formation characteristics, cement thicknesses, off-center casing configuration and anisotropic stress conditions.
The simulation shows rock behavior under vertical loading, including stress propagation inside the rock, deformation and damage evolvement as well as how cemented casing behaves under these conditions.
Compositional Simulation and Optimization of Secondary and Tertiary Recovery Strategies in Monument Butte Field, Utah
Authors: Wang J. , McVay D. A. , Ayers W. B. 
Published: October 2008

Abstract
Monument Butte field produces oil from low-permeability, lacustrine fluvial-deltaic sandstones of the Green River formation. Reservoir sands are heterogeneous, lenticular, and have limited aerial extent and vertical communication, resulting in poor inter-well connectivity. Cumulative recovery to date (primary and secondary) is about 2% of the estimated 2 billion barrels of original oil in place (OOIP). Current water flooding successfully maintains reservoir pressure, but it provides very poor sweep efficiency. The objectives of this study were to assess secondary and tertiary recovery methods and to recommend a reservoir management approach that would increase oil recovery efficiency. To accomplish these objectives, we conducted detailed compositional simulation studies in a pilot area of the field.
The reservoir model was calibrated using manual and assisted history matching methods. To reduce simulation time, we grouped fluid components into 10 pseudo-components. The 3-parameter, Peng-Robinson equation of state (EOS) was used to match PVT experimental data. Primary-then-water-flood and water-flood-only strategies were simulated using different water-flood timings. Infill drilling potential was evaluated by simulating downspacing from the original 40-ac to 20-ac well spacing. Immiscible and miscible flooding with CO2, water alternating with gas (WAG), N2, and CH4 were simulated with reservoir pressures below and above minimum miscibility pressure (MMP).
Simulation results indicate that water flooding should be started within 6 months of production. A water-flood-only strategy provides more oil recovery than a primary-then-water-flood strategy. Infill drilling may effectively produce unswept oil and double oil recovery. Immiscible gas injection suffers early gas breakthrough and is not an effective way to increase ultimate oil recovery. CO2 injection is much more efficient than N2 and CH4 injection, because it has a lower MMP (2500 psia) and later gas breakthrough. Water-alternating-CO2 injection is superior to continuous CO2 injection in oil recovery, because it makes the gas-oil mobility ratio more favorable, controls early CO2 breakthrough and maintains reservoir pressure. The study results can be used to optimize oil production from other parts of the large Monument Butte field.
Fracture Conductivity Loss Due to Geochemical Interactions Between Man-Made Proppants and Formations
Authors: Weaver Jim , Rickman Richard , Luo Hongyu 
Published: October 2008

Abstract
The selection of proppant to provide highly conductive pathways in hydraulically generated fractures is typically based on the proppant crush strength, permeability, availability, and cost. Extensive libraries of laboratory determined conductivity values, obtained using API standardized methods at a variety of simulated well conditions, are available for most proppants. However, post-fracture stimulation well testing indicates that these values are often one to two orders of magnitude too high. In many fields, the productivity of fractures declines rapidly, requiring frequent re-stimulation treatments to remain economically viable.
Proppant crushing and embedment, fracturing fluid damage, and fines invasion are proppant-pack permeability damage mechanisms that have been used to explain this loss of productivity. This paper reports on recent studies that have determined that aluminum-based proppant materials may promote geochemical reactions that can occur at a surprisingly rapid rate, even at moderate temperatures, resulting in the loss of porosity and permeability and the creation of fines in the proppant pack.
The compatibilities of several man-made proppants ranging from lightweight ceramics to high-strength bauxites with a variety of formations are presented. These findings indicate that the formation mineralogy plays a heretofore unrecognized role in determining proppant suitability. Most proppants were found to lose 50–60% permeability before stabilizing, while others were shown to lose up to 90% in only a few days.
This paper describes the specialized methods that were developed to study these geochemical reactions and reports quantitative changes in permeability, proppant composition, and fluid changes. Surface analysis using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) provides dramatic visual confirmation of this damage mechanism.
Results of this study have a great potential economic significance, suggesting new, important fracture design parameters that need to be determined to enable choosing the appropriate proppant for maximized stimulation longevity.
Gas or Oil Producer? Layered? Laminated?—Basic Guiding Principles We Should Understand for Effective Fracture Stimulation
Authors: McDaniel B. W. 
Published: October 2008

Abstract
Sometimes we dive too quickly into the smallest of details when trying to plan for fracture stimulation applications in our industry. It has been too often that a frac design engineer will gloss over the importance of unknown or missing reservoir data but spend many hours chasing the "exact-best" value to use for the treating fluid viscosity in the frac design simulator. Some reservoirs we frac routinely and understand how fracturing is best applied, and a few where we can choose the full scientific approach and monitor with microseismic listening. When there is just no chance to know accurate reservoir data, we may have few design options. However, it seems more often the case that the "frac design world" simply does not search out important data available within the geologist-geophysicist realm. The available pseudo-3D and numerical 3D frac design simulator software available to us can be used as a crutch instead of a useful tool.
We can be a novice in frac design from our lack of experience, or because we do not understand how to use our experience in a new or different reservoir setting. In very recent years, we have witnessed many highly experienced "frac gurus" fail to understand how to apply their experience when moving to horizontal wellbore applications. This paper will offer guidance to the less experienced frac design personnel as to some of the more important basic concepts of integrating hydraulic fracturing applications to reservoirs or well completion plans where little experience currently exists. Some reservoirs have been evaluated and reported in our literature to near "overkill" proportions for vertical completions and then struggled to understand frac stimulation of horizontal completions. Within the large body of technical papers and texts, most have slighted the importance of two factors: Rock hardness and formation pore pressure of gas reservoirs. This paper will stress the importance of including these factors.
With record high oil prices, and in some markets, good gas prices, we are seeing the extension of hydraulic fracturing to areas and reservoirs where little or no "frac" experience exists. Additionally, our need to fracture stimulate when our wellbore is significantly deviated is starting to multiply in number and importance, both offshore and onshore. This paper will be a valuable aid to this transition.
Using Reservoir Architecture To Maximize Co2 Storage Capacity
Authors: Riestenberg D. E. , Koperna G. J. , Kuuskraa V. A. , Esposito R. 
Published: October 2008

Abstract
This work explores, using reservoir simulation, the impact of reservoir architecture on CO2 plume movement and the reservoir's storage capacity. Subsurface flow of CO2 in the presence of shale "baffles", or lack thereof, will be reviewed in conjunction with other reservoir characteristics that influence flow such as formation dip, capillary pressure, pore volume trapping, and the rate of CO2 dissolution. Recent geologic and reservoir data collected from the Tuscaloosa Formation at the Mississippi Test Site (a Southeastern Regional Carbon Sequestration Partnership CO2 sequestration pilot test) will be used as the case study for evaluating alternative CO2 storage engineering concepts for maximizing CO2 storage capacity. The Tuscaloosa Formation is a thick, porous, permeable, regionally extensive saline reservoir occurring throughout the Gulf Coast and is considered a promising target for large-scale CO2 storage.
Evaluation of Skin Factor from Single-Rate Gas-Well Test
Authors: Aminian K. , Ameri S. , Almutairi F. , Brannon A. 
Published: October 2008

Abstract
Skin factor is commonly used as well flow efficiency indicator and the criterion for performing stimulation treatment to enhance well productivity. Skin factor, which is generally determined from interpretation of pressure transient well tests, is a composite factor and must be broken down into its various components in order to estimate near-wellbore damage. This is particularly important in the gas wells because they experience additional pressure drop near the wellbore due to high gas velocity. This additional pressure drop near the wellbore is generally referred to as non-Darcy effect and can be approximated by a rate-dependent skin factor. Therefore, the total skin factor obtained from a gas well pressure transient test has two primary components, rate-independent and rate-dependent skins. The rate-independent skin is primarily a function of formation damage, well deviation, completion, and perforation. Rate-dependent skin accounts for the non-Darcy effects. Both of these skins can be determined directly from the interpretation of pressure transient well tests if several transient tests at different rates were conducted. The multi-rate tests are however cumbersome to conduct and it is advantageous to estimate the rate-independent skin factor from a single rate test. In order to obtain a reliable value for the rate-independent skin from a single-rate test, the rate-dependent skin must be evaluated independently. The rate-dependent skin depends, among other parameters, on the coefficient of inertial resistance, β. A number of correlations relating β to permeability are available in the literature. These published correlations are derived from limited set of laboratory measurements on various porous media. Our previous investigations have revealed that these correlations do not provide consistent results. Alternatively, β can be determined from the results of the multi-rate well tests. The calculated β values from such tests reflect the actual field conditions that cannot be replicated in the laboratory. However, the complex dependency of β on the properties of the porous media precludes development of a single β -k correlation that can provide accurate and consistent results in all reservoirs. A more realistic approach would be to develop a relation between permeability and β for a specific porous media. To develop a correlation for β, a database of multi-rate gas well tests was established which contained data from over 100 well tests obtained from a number of operators in the Appalacian Basin. The well tests from several wells in the same reservoir were available and several field-specific correlations for β were developed. The comparison of skin factor determined from these correlations against the skin factors determined from the well test data indicated that reservoir-specific correlations for β provide accurate and consistent results.
Formation Evaluation Logging While Drilling (LWD) in Unconventional Reservoirs for Production Optimization
Authors: Quinn T. H. , Dwyer J. , Wolfe C. , Morris S. , Coope D. 
Published: October 2008

Abstract
Formation evaluation (FE) while drilling is an established technique in horizontal well orientations for unconventional reservoirs such as the Barnett Shale. Due to constrained well economics, special care is taken to acquire cost-effective information quickly to maximize lateral wellbore effectiveness. Real-time data and rapid analysis provide rock parameters impacting completion decisions. New technologies are discussed that further benefit our understanding of the reserve potential and improve asset economics. In particular we will discuss innovative applications of LWD imaging, LWD magnetic resonance (MR), and full-bore coring.
One key evaluation technology to optimize stimulation design is imaging-while-drilling to determine natural fracture system orientation and density and to distinguish J1 and J2 fracture sets and fractures that are potentially open. Images also provide input into geomechanical models that are used to plan stable wellbores and optimize stimulation treatments.
Innovation in LWD NMR applications allows quantification of porosity, irreducible and clay bound water in real-time. When combined with LWD bulk density, the total organic carbon content and static rock mechanical properties can also be computed optimizing well placement and completion design. It is shown that the integration of LWD imaging, MR and other LWD logs can improve the understanding of unconventional reservoirs.
Use of Outcome Measures in Physiotherapy Practice in Ireland from 1998 to 2003 and Comparison to Canadian Trends
Authors: Stokes Emma K. , O’Neill Desmond 
Published: October 2008

Purpose: The purposes of this study were to examine changes in the use of standardized outcome measures by practising physiotherapists in Ireland and to compare those trends to the results of a similar survey conducted previously in Canada. Method: A survey methodology was employed. The review of practice occurred at two points in time. Senior clinical physiotherapists working with older people participated. Questions were asked about the use of standardized outcome measures, the nature and pattern of their use, and the level of confidence the respondents had in using such measures. Results: The results chart the changes in practice over a 5-year period. Although there was an increase in the use of standardized outcome measures, the respondents acknowledged barriers to their systematic use in routine practice (e.g., lack of time, resources/administrative support). There was a lack of professional consensus on what instruments to use in general, as well as which to use for particular client groups. Concern was expressed that none of the available instruments met their clients’ needs. Where possible and appropriate, comparison was made between the data from the 2003 Irish study and a survey of Canadian physiotherapists conducted in 1998. Conclusion: This review of practice illustrates that changes that have occurred in Ireland in the use of standardized outcome measures are similar to those that have occurred in Canada, but barriers remain to their complete integration into clinical practice and clinical decision making.
Self-Assessment: The Disconnect between Research and Rhetoric
Authors: Miller Patricia A. 
Published: October 2008

Purpose: Physical therapists are expected to engage in self-assessment in order to ensure competent practice and to identify appropriate professional development activities. Summary of Key Points: This paper reviews the current literature on the accuracy and role of self-assessment in physical therapy. Current literature indicating that self-assessment cannot be conducted with any degree of accuracy is discussed, and a proposed reformulation of the concept of self-assessment is presented. Recommendations: Practical strategies are offered for clinicians to improve the potential for obtaining reliable and valid information about their own clinical performance to guide the selection of appropriate professional development activities and to promote the provision of competent patient care.
Effects of Exercise Interventions on Stereotypic Behaviours in Children with Autism Spectrum Disorder
Authors: Petrus Christopher , Adamson Sarah R. , Block Laurie , Einarson Sarah J. , Sharifnejad Maryam , Harris Susan R. 
Published: October 2008

Purpose: The purpose of this systematic review was to synthesize evidence from studies examining the effect of exercise interventions on stereotypic behaviours in children with autism spectrum disorder (ASD). Methods: Only exercise-related physical therapy (PT) interventions were included. A multifaceted search strategy identified studies published between 1980 and 2007. Quality was assessed using the American Academy of Cerebral Palsy and Developmental Medicine (AACPDM) Study Quality Scale, the Clinical Relevance Tool for Case Studies, and the Quality, Rigour or Evaluative Criteria tool. Results: Seven studies (1982–2003) met our inclusion criteria; four of these used single-subject research designs, two were group studies, and one was a case study. Ages and behavioural characteristics of the children (N = 25) varied among the studies. Levels of evidence ranged from II to V (of a possible I–V). Study quality scores ranged from 2 to 5 (range: 0 to 7); mean = 3.9, mode = 5. Few studies in this area of PT practice have been published, and those identified scored low levels of rigour on the AACPDM criteria. Conclusions: Research suggests that exercise provides short-term reductions of stereotypic behaviours in children with ASD. Future research with stronger evidence levels, greater rigour, and longer-term outcome assessment is required to determine specific exercise parameters.