bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of Hydraulic Fracture Network Propagation in a Naturally Fractured Formation
Authors: Weng X. , Kresse O. , Cohen C. , Wu R. , Gu H. 
Published: January 2011

Abstract
Hydraulic fracturing in shale gas reservoirs has often resulted in complex fracture network growth, as evidenced by microseismic monitoring. The nature and degree of fracture complexity must be clearly understood to optimize stimulation design and completion strategy. Unfortunately, the existing single planar fracture models used in the industry today are not able to simulate complex fracture networks.
A new hydraulic fracture model is developed to simulate complex fracture network propagation in a formation with preexisting natural fractures. The model solves a system of equations governing fracture deformation, height growth, fluid flow, and proppant transport in a complex fracture network with multiple propagating fracture tips. The interaction between a hydraulic fracture and pre-existing natural fractures is taken into account by using an analytical crossing model and is validated against experimental data. The model is able to predict whether a hydraulic fracture front crosses or is arrested by a natural fracture it encounters, which leads to complexity. It also considers the mechanical interaction among the adjacent fractures (i.e., the "stress shadow" effect). An efficient numerical scheme is used in the model so it can simulate the complex problem in a relatively short computation time to allow for day-to-day engineering design use.
Simulation results from the new complex fracture model show that stress anisotropy, natural fractures, and interfacial friction play critical roles in creating fracture network complexity. Decreasing stress anisotropy or interfacial friction can change the induced fracture geometry from a bi-wing fracture to a complex fracture network for the same initial natural fractures. The results presented illustrate the importance of rock fabrics and stresses on fracture complexity in unconventional reservoirs. They have major implications on matching microseismic observations and improving fracture stimulation design.
Characterization of Small Scale Heterogeneity to Predict Acid Fracture Performance
Authors: Oeth C. V. , Hill A. D. , Zhu D. , Sullivan R. B. 
Published: January 2011

Abstract
Recently developed models of the acid fracturing process have shown that the differential etching necessary to create lasting fracture conductivity is caused by the heterogeneous distributions of permeability and mineralogy along the fracture faces. To predict the conductivity that can be created by acid in a particular formation, the models require information about these formation properties and their spatial variation. This research aims to quantify the small scale heterogeneity by using a geostatistical description to ascertain the distribution of permeability in a carbonate formation. Parameters that quantify the directional correlation and variance of the data are developed. The correlation length and variance parameters are a first step in being able to couple acid transport and rock dissolution models at reservoir scale with a model of fracture conductivity based on channels and roughness features caused by small scale heterogeneity. These geostatistical parameters are developed for a well in the Hugoton Field. Data leading to their derivation are obtained from a combination of well logs and cores. The resulting geostatistical parameters and acid etched width are used to predict acid fracture performance. Application of new model conductivity correlations results in a unique prediction for the acid fracture case study that differs from the industry standard.
Application of Multivariate Statistical Analysis to Slickwater Fracturing Parameters in Unconventional Reservoir Systems
Authors: Kazakov Nikita Y. , Miskimins Jennifer L. 
Published: January 2011

Abstract
Hydraulic fracturing is essential for economic production in tight gas and shale gas reservoirs due to their low permeability nature. Slickwater fracturing has been successfully performed in shales and tight gas reservoirs using low viscosity fluid, usually water, with friction reducers. Slickwater fracturing has the advantage of reducing formation damage and generally being less expensive than conventional gel. Predicting which slickwater parameters are important to successful production and which are less important has been an important but unanswered question. This research uses multivariate statistical methods to discover whether production from the Jonah Field, Wyoming, and the Barnett Shale, Texas, can be predicted using slickwater parameters and whether these parameters can provide insight into the design and analysis parameters of the slickwater treatments.
Factor, cluster, and multiple regression analysis show that production data from the sampled Barnett Shale and Jonah Field databases group separately from the slickwater parameters. Multiple regression, used to predict the EUR and the cumulative produced water from the slickwater parameters in the Barnett Shale, yielded best adjusted-R²’s of 34.7% and 25.3%, respectively. Multiple regression was also used to predict the EUR from the slickwater parameters in Jonah Field resulting in the best R² of 22.9%. Multiple regression analysis established a relationship with an adjusted R² of 93.0% between the fluid pumped and the fluid recovered from the Barnett Shale treatments. Multiple regression analysis also established that the amount of proppant used for Jonah Field hydraulic fracturing operations was calculated from the total fluid pumped and the net pay.
This research provides a methodology to use multivariate statistics to analyze stimulation treatments. Additionally, it opens opportunities for the analysis of different fields with more data using multivariate statistics and can aid in improving designs in an operator's current field or in understanding previous designs in a newly acquired field. Finally, it also demonstrates how "no information" can be valuable in cutting costs on commodities purchased to stimulate a well when no benefit is seen from those additional purchases.
Fluid Injection Experiments in Two-dimensional Porous Media
Authors: Huang H. , Zhang F. , Callahan P. , Ayoub J. 
Published: January 2011

Abstract
A series of injection experiments were conducted in a Hele-Shaw cell-like radial flow device filled with fine sands to better understand the fundamental failure/flow mechanisms when dense granular media is invaded and displaced by a fluid. Both aqueous glycerin solutions and polyacrylamide solutionswere used as the invading fluids. The experimental findings suggest that there is a transition from the solid-like (fracturing) to fluid-like (fingering) behavior in the injection process. Based on the gain displacements and fluid flow patterns, four distinct failure/flow regimes can be identified fromthe experiments, namely, 1) the simple radial flow regime, 2) the leakoff-dominated regime, 3) the grain displacement-dominated regime, and 4) the viscosity fingering-dominated regime. These failure/flow patterns emerge as a result of competition among various forms of energy dissipation, i.e., viscousdissipation through flow in porous media, dissipation through mechanical deformation, and viscous dissipation through flow in thin channels.
Hydraulic Fracturing, Microseismic Magnitudes, and Stress Evolution in the Barnett Shale, Texas, USA
Authors: Vermylen John P. , Zoback Mark D. 
Published: January 2011

Abstract
We present new techniques to analyze the effectiveness of hydraulic fracturing for stimulating production in shale gas reservoirs. The case study we have analyzed involves five parallel horizontal wells in the Barnett shale with 51 frac stages. To investigate the numbers, sizes and types of microearthquakes initiated during each frac stage, we created Gutenberg-Richter-type magnitude distribution plots to see if the size of events follows the characteristic scaling relationship found in natural earthquakes. We found that slickwater fracturing does generate a log-linear distribution of microearthquakes, but that it creates proportionally more small events than natural earthquake sources. Finding considerable variability in the generation of microearthquakes, we have used the magnitude analysis as a proxy for the "robustness" of the stimulation of a given stage. We have found that the conventionally fractured well and the two alternately fractured wells ("zipperfracs") were more effective than the simultaneously fractured wells ("simulfracs") in generating microearthquakes.
We also found that the later stages of fracturing a given well were more successful in generating microearthquakes than the early stages. This increase in microearthquake activity in the latter frac stages corresponded with an increase in the instantaneous shut-in pressure (ISIP). The net ISIP increase was most pronounced in the simulfrac wells and least pronounced in the zipperfrac wells. We have attempted to model this increase as a cumulative "stress shadow" using an elastic crack-opening model. However, even the maximum reasonable propped fracture aperture causes a stress increase that is less than what was measured in the wells. Since the fracturing of the simulfrac wells took only half the time of the fracturing of the zipperfrac wells, we believe that poroelastic effects associated with time-dependent leak-off is controlling the rate of ISIP escalation and the increase in microseismic creation. We are incorporating poroelasticity in the model to fully integrate stress evolution and permeable volume creation.
The Use of Sealing Ball Staged Fracturing
Authors: Wang Xingzun , Liu Gangzhi , Wang Da , J. Michael 
Published: January 2011

Abstract
Technologies for horizontal well fracturing in China include multi-staged fracturing and hydraulic jetting. As in many other parts of the world, this type of well stimulation employs mechanical zonal isolation or sand and polymer plugs. All of these technologies are used by us in a number of reservoirs but they depend on the presence of newly targeted and intentionally perforated sections of horizontal wells that are not already perforated. However, because most horizontal wells in the mature Huabei oilfield have been producing for a very long time and the perforations are all along the horizontal sections, it is practically impossible to use the technologies mentioned above.
To prevent multiple fracture initiation in a given section, sealing-ball staged fracturing has been developed and has been used successfully in horizontal wells of the Huabei field. Three kinds of sealing balls, whose densities are &lt;1, 1 and &gt;1 g/cc, are pumped between stages of fracturing and they can seal perforations at 360° around the horizontal well section. Higher- permeability zones are sealed off preferentially. Because staged fracturing can be carried out effectively without stopping the pumps, while running ball sealers downhole, the process can be accomplished in a significantly shorter period of time than other techniques.
In this paper we present field case studies of staged hydraulic fracturing using ball sealers and we demonstrate the success of this form of zonal isolation in both execution and, especially, post-fracture well performance. We also provide guidelines for the effective length of horizontal well section where ball sealers can be used for zonal isolation.
Unconventional Shale Oil and Gas-Condensate Reservoir Production, Impact of Rock, Fluid, and Hydraulic Fractures
Authors: Orangi A. , Nagarajan N. R. , Honarpour M. M. , Rosenzweig J. 
Published: January 2011

Abstract
Development of unconventional oil and gas reservoirs, particularly the shale gas, gas-condensate, and shale oil, has gained tremendous momentum in recent years. Energy companies aggressively are adding unconventional hydrocarbon resources to their portfolios. The unconventional resources usually refer to ultra low permeability reservoirs that cannot be produced at economic rates or volumes without stimulation of near well-bore regions. New technologies of horizontal well coupled with staged hydraulic fracturing have made the development of these reservoirs an economic reality. But often, the initial attractive production rates decline fast and thus making them economically marginal and sometimesoperationally unattractive. In order to efficiently produce these reservoirs, it is important to understand the flow mechanism and the controlling rock and fluid parameters that significantly impact thelong term production performance of these resources.
We have conducted detailed reservoir simulation studies to investigate the impact of rock and fluid properties and the drainage area of hydraulically fractured wells in a standard development pattern. The simulation of horizontal wells with 14-stage hydraulic fractures was conducted in a shale reservoir containing a wide spectrum of rock and fluid types, dry gas to gas-condensate, and oil. An extensive compositional reservoir simulation was conducted using both radial grid and sector model. Short term production data from several horizontal wells and long term production data from one vertical well were used for history matching and model calibration. A number of cases have been run with a wide range of fracture, matrix and fluid properties considering condensate banking, fracture patterns, pore volume compressibility, and relative permeability. The results showed Cumulative oil production is sensitive to fluid properties, particularly to the GORSevere drop in productivity is observed due to matrix and fracture compaction and condensate bankingThe drainage area and the contact area of the fractures with the reservoir are often limited in spite of extensive hydraulic fracturesPerformance is also found to be sensitive to fracture permeability and matrix relative permeabilityFracture interference is limited and may occur in the late life of the reservoir
Channel Fracturing - A Paradigm Shift in Tight Gas Stimulation
Authors: Johnson J. , Turner M. , Weinstock C. , Peña A. , Laggan M. , Rondon J. , Lyapunov K. 
Published: January 2011

Abstract
The hydraulic Channel Fracturing technique relies on the engineered creation of a network of open channels within the proppant pack, which provides for highly conductive paths for the flow of fluids from the reservoir to the wellbore. This paper provides a comprehensive summary of the implementation of this technique in ultra-low permeability, gas-bearing formations.
The Lance formation in the Jonah field near Pinedale, Wyoming was selected for this study. This formation comprises fluvial sand bodies with 0.0005 to 0.05 mD permeability and 35 to 55% gas saturation. The formation requires hydraulic fracturing for economic production. Key historical issues for the stimulation of this formation using gelled fluids and sand as proppant are limited fluid recovery and consequential formation and fracture conductivity impairments. Slick-water treatments have rendered moderate gains in production mainly in low-prospect zones with some occurrence of near-wellbore screen-outs. Moderate increases in production from using ceramic proppants have been gained at the expense of significant increase in stimulation costs.
Hydrocarbon production, treating pressure and fracturing fluid recovery data from a thirteen-well campaign in the Jonah field are summarized in the manuscript. Results indicate that the implementation of the channel fracturing technique increased initial gas production and estimated recovery over conventional fracturing methodologies. Positive features that were also observed during this campaign such as reduced net pressure increase estimates from pre- and post-frac shut-in pressure measurements, reduced tendency for vertical fracture growth and elimination of near-wellbore screen-outs are also reported and discussed.
It is concluded that the Channel Fracturing technique is a viable alternative to conventional fracturing methods for more efficient and effective stimulation of complex tight gas formations.
Experimental Evaluation of Guar Fracture Fluid Filter Cake Behavior
Authors: Xu Ben , Hill A. D. , Zhu Ding , Wang Lei 
Published: January 2011

Abstract
Guar gum and its derivatives have been the most commonly used polymers to increase the viscosity of fracturing fluids. However, the conductivity of many fractures created with guar-based polymers is low because of residual unbroken polymer gel remaining in the fracture. This residue can cause permeability impairment in the proppant pack resulting in low fracture conductivity and decreased effective fracture length. In this study, we experimentally evaluated two important aspects of the gel damage process - the thickness of the polymer gel filter cake that is created as fracture fluid filtrate leaks off into the formation, and the yield stress of the concentrated polymer gel that accumulates in the fracture. The thickness of the filter cake created during the leakoff process was measured as a function of the polymer loading and the volume of leakoff. We created the filter cake following the procedure described by Ayoub et al. (2006), then measured the filter cake thickness with a precise laserprofilometer. We found that the filter cake thickness varied linearly with leakoff volume, meaning that the gel concentration factor is constant for this guar polymer fluid. The concentrated polymer filter cakes created by leakoff behave rheologically as Herschel-Bulkley fluids having a yield stress. The yield stress of this material is a critical parameter influencing whether or not the gel can be removed from the fracture. We measured the yield stress of borate-crosslinked guar polymer fracture fluids at concentrations up to 200 lb/mgals using a unique flat plate device. The yield stresses of th polymer filter cakes were found to depend strongly on the concentration of both polymer and breaker.
Investigation of the underwater noise produced by ships by means of intensity method
Authors: Kozaczka Eugeniusz , Domagalski Jacek , Gloza Ignacy 
Published: January 2011

Investigation of the underwater noise produced by ships by means of intensity method
This paper presents results of research on spectral structure of underwater noise acoustic field radiated into water by selected ships moving in shallow waters. Underwater acoustic field of ships in motion is associated with acoustic activity of ship mechanisms and equipment under work. Vibration energy radiated by the mechanisms and devices is transmitted by ship structural elements to surrounding water where it is propagated in the form of acoustic waves of a wide frequency band. In this paper are presented results of the research on propagation of energy of acoustic waves in the near fiel, obtained from acoustic pressure measurements by means of two sensors located close to each other.
Problems of welding in shipbuilding - an analytic-numerical assessment of the thermal cycle in HAZ with three dimensional heat source models in agreement with modelling rules
Authors: Ranatowski Eugeniusz 
Published: January 2011

Problems of welding in shipbuilding - an analytic-numerical assessment of the thermal cycle in HAZ with three dimensional heat source models in agreement with modelling rules
This part is continuation of PART II. Analytic solutions for the temperature distribution in HAZ - presented in the previous part of this article are transformed for computer calculation with used Mathcad programme. There are established algorithms in moving and stationary systems for thermal cycle calculating. Finally, a few analytical examples with use of C-I-N and D-E models are demonstrated.
Rhetorical Evaluation of Seventeenth Century Prefaces to English Treatises on Midwifery
Authors: Sánchez-Cuervo Margarita 
Published: January 2011

Rhetorical Evaluation of Seventeenth Century Prefaces to English Treatises on Midwifery
This study tries to offer a rhetorical account of the main arguments and figures encountered in 17th c. English prefaces, dealing with the art of midwifery and the delivery of children. I foreground a main causal argument wherein the author states the necessity for a treatise of this delicate nature and proposes the motives for its requirement. In doing so, some other reasonings support the causation and provide the reader with more evidence for a good performance at childbirth. In addition, the arguments are enhanced by the presence of some figures of communion that contribute to the rhetorical organisation, and help to portray the prologue as an expository discourse. The insistence on complying with the author's directions, and the urge not to follow some predecessors' work also suggests the new authority that the early modern English preface writer is acquiring.
On the Relationship Between Grammaticalization and Reanalysis
Authors: Jarad Najib 
Published: January 2011

On the Relationship Between Grammaticalization and Reanalysis
This paper seeks to explain and exemplify the relationship between grammaticalization and reanalysis, two important processes of grammatical change which occur in language. The ultimate goal of this paper is to prove that whilst the two are crucially related, they are not mutually dependent and can extensively occur alone. The paper focuses on the shift of for from the thematic function and/or case realizer to the modern pure complementizer status.
Telling it Straight: A Comparison of Selected English and Polish Idioms From the Semantic Field of Speaking
Authors: Szczepaniak Renata , Adamska-Sałaciak Arleta 
Published: January 2011

Telling it Straight: A Comparison of Selected English and Polish Idioms From the Semantic Field of Speaking
This paper attempts to illustrate one way of achieving greater precision in presenting idiomatic equivalents by implementing the functionally-oriented methodological instrument devised by Dobrovol'skij and Piirainen (2005). A small-scale analysis along the three parameters of semantics, syntax and pragmatics is carried out with a view to identifying and explaining all cross-linguistic contrasts and similarities between selected English and Polish near-equivalent idioms from the semantic field of speaking. The empirical data of this study includes corpus evidence, apart from the available monolingual, bilingual and phraseological dictionaries. The resultant descriptions of the idiomatic expressions attest the validity of a functional approach to contrastive idiom analysis, which, unlike judgments based on the superficial properties of idioms (i.e. their lexical components, structure), reveals that differences in images will not always prevent idioms with similar actual meaning from being regarded as equivalents. On the other hand, closeness of underlying imagery does not guarantee identity with respect to all parameters of comparison (especially pragmatics).
Synchronous Study of Ferroresonance and Inrush Current Phenomena and their Related Reasons in Ground Power Networks
Authors: Akrami Amin , Ghaderi Mohammad , Ghadi Saeed 
Published: January 2011

Synchronous Study of Ferroresonance and Inrush Current Phenomena and their Related Reasons in Ground Power NetworksEnergizing the power transformers usually results in flowing very high inrush currents. This harmful current can be minimized using controlled switching and considering the value of residual flux. But nowadays, developing the ground power networks results in high increment of ferroresonance phenomenon occurrence due to the line' capacitance reactance and nonlinear inductive reactance of power transformer's core. In this study, these transient phenomena and their cause have studied synchronously.