bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Multi-Well and Stage-by-Stage Flowback from Multi-Fractured Horizontal Wells
Authors: Williams-Kovacs J. D. , Clarkson C. R. 
Published: September 2014

Abstract
As a result of low gas prices and recent reductions in natural gas liquids prices, unconventional light oil reservoirs remain a primary target for exploration and development in North America. Due to the low permeability of such reservoirs, well-life tends to be dominated by transient linear flow from the matrix to the fractures which may last several years. This flow period is affected by hydraulic fracture properties, therefore operators are looking for new methods to characterize hydraulic fractures, particularly early in the well life. In previous studies by the authors it has been shown that high-frequency flowback flow rates and flowing pressures can be modeled to obtain key hydraulic fracture parameters (i.e. half-length and conductivity). Although commingled data is commonly gathered, technology exists to collect individual stage data.
In this work, we advance the analytical procedure presented by Clarkson and Williams-Kovacs (2013b) and Williams-Kovacs and Clarkson (2013c) for analyzing pre- and post-breakthrough of formation fluid during flowback of light tight oil wells by investigating multi-well and stage-by-stage flowback. Studies have shown that there may be significant communication both between stages and between wells on a given pad (or beyond) during the flowback period but not during long-term production. In order to accurately model the flowback period this communication must be accounted for in order to properly assess individual well hydraulic fracture properties. Building upon the analytical models developed previously for single well flowback from unconventional light tight oil wells, we employ the "communicating tanks" concept to account for stage (or inter-well) interaction. Proper allocation and transfer of fluids between stages, if they are communicating, is necessary to ensure that the fracture volume assigned to each stage/well is correct. Our work demonstrates that if individual stage/well flowback data is analyzed without accounting for communication, derived reservoir properties (i.e. fracture halflength) are in significant error. As a result, future well performance predictions, and attempts to optimize fracture stimulations, will also be in error.
Our new methods are tested against both simulated and field examples. Stage-by-stage flowback is demonstrated using simulated data, while multi-well flowback will be demonstrated using field data from a multi-well pad.
Quantification of Proppant Distribution Effect on Well Productivity and Recovery Factor of Hydraulically Fractured Unconventional Reservoirs
Authors: Sierra Leopoldo , Sahai Rakshit (Raki) , Mayerhofer Michael 
Published: September 2014

Abstract
The most common completion methodology the industry uses to help maximize productivity and fluid recovery in unconventional reservoirs consists of placing multiple, optimally spaced transverse fractures in horizontal wells, navigating along the direction of minimum principle horizontal stress. In this type of completion, well productivity and fluid recovery can be maximized when the following conditions are met:
Horizontal wellbore navigates optimally in the reservoir. Generated fracture connects the entire productive pay zone. Transverse fractures are optimally spaced. Proppant is well-distributed throughout the created fracture.
With respect to the actual completion strategy, the first two conditions are met using proper geological interpretation and measurements of fracture height growth (e.g., microseismic); the third condition depends on economics and cluster efficiency. However, the distribution of proppant within the hydraulic fractures is usually ignored, particularly for cases in which low-viscosity fracturing fluids are used for stimulation.
By performing extensive simulations for gas-producing reservoirs with a wide range of unconventional reservoir permeabilities, this paper quantifies the impact of proppant distribution on well productivity and the recovery factor (RF). For cases in which proppant distribution is not optimized, previously published extensive simulations demonstrate that the RF and productivity are significantly affected.
Experimental and Numerical Study on Spontaneous Imbibition of Fracturing Fluids in Shale Gas Formation
Authors: Zhou Z. , Hoffman B. , Bearinger D. , Li X. 
Published: September 2014

Abstract
During some hydraulic fracturing processes, it is found that only 10% to 50% of fracturing fluids is recovered. This paper investigates how much of the remaining fracturing fluids are imbibed by shale rocks as a function of time, and also investigates the influence of various parameters on the imbibition process including: lithology, reservoir characteristics, and fluid properties. In addition, based on the experimental results, a numerical model is developed to estimate the amount and rate of spontaneous imbibition during fracturing over the entire fracture face.
The rock samples are from the Horn River formation. The fracturing fluids used in the experiments include 2% KCL, 0.07% friction reducer and 2% KCL substitute. Distilled water is also used in experiments as control groups. Through spontaneous imbibition experiments, the relationships between imbibed weight of fluid and time show that the content of clay is the most important factor which affects the total amount imbibed. Shale matrix with high clay content can imbibe volume of fluid greater than its measured porous space because of the clay's strong ability to expand and hold water. Small porosity with less total organic carbon (TOC) results in the highest imbibed rate. Contact angle results show the stronger water wet shale samples have a faster imbibed rate. Temperature also influence amount of imbibition. The total imbibed volume decreases as the environment temperature rises.
From this paper, it can help optimally design fracturing fluid for different conditions of shale formation to reduce fluid loss. We find that 2% KCL and 2% KCL substitute fracturing fluid are imbibed 10% to 40% less than 0.07% friction reducer in shale formation with high clay content; while in shale formation with low clay content, the opposite occurs. 0.07% friction reducer is imbibed 10% to 30% less than 2% KCL, but has similar imbibed amount with 2% KCL substitute.
The numerical model results are matched with the experiment results in order to estimate relative permeability and initial water saturation in the model which can represent the properties of rocks. This model can use to estimate the total imbibed volume along fracture faces through spontaneous imbibition.
Linking Rock Mechanic Petrophysics to Proppant Selection in the Wolfcamp: Capitalizing on Log Based Value of Information
Authors: Prochnow S. , Brown R. L. , Rexilius J. P. , Fields M. J. 
Published: September 2014

ABSTRACT
Value of information for petrophysical data in unconventional plays can be extended far beyond perforation placement, but can also be used to develop strategic plans for the selection of costly proppants. Proppant is the single most expensive feature of Midland Basin Wolfcamp completions, especially in deeper (&gt;10,000 ft. TVD) zones that are under high stress. Wire line petrophysical data has recently been adopted as a critical element in proppant capital stewardship.In particular, dipole sonic logs in the Wolfcamp play now provide critical closure stress information for the decision to attempt hydraulic fracturing of a zone and the selection of appropriate proppant for those zones. New proppant selection criteria relate zone stress to required hydraulic fracture conductivity given the expected formation permeability and production capacity. Before this study, frac stages and proppants were chosen on a paucity of available completion records. This resulted in a strategy to use ceramic proppants in all zones below 10,000 ft., or roughly &gt; 6,500 psi closure stress. The incorporation of petrophysical log analysis has refined the process by which the prescription of expensive proppants and frac stages are made and ultimately reduces cost. Dipole sonic data is now collected every square mile of the active development area. The sonic data is converted into estimates of fracture gradient (psi*ft−1), minimum horizontal stress (psi), and closure pressure (psi). Average porosity of pay ranges from 6.3% (P10) to 9.5% (P90) in the mudstone prone Cline formation, while the ramp carbonates constituting the Strawn and Bend formations ranges from 3.2% (P10) to 12.8% (P90). Core analysis suggests the corresponding permeability are around 0.19 MD (P10) to 0.71 MD (P90) for the Cline while the Strawn and Bend range from 0.02 MD to 8.06 MD (P90). Log based, average P90 minimum horizontal stress in deep Pennsylvanian zones ranges from 7,743 psi (Cline Fm), 7,389 (Strawn Fm), to 9,783 (Atoka Fm). These relationships suggest that white sand provides adequate frac conductivity for 35% to 45% wells completing in the Upper Atoka and Atoka-Bend zones, or when average porosity is less than 7.5%. Likewise, the Strawn can be completed with white sand 80% of the time instead of ceramic because the zone has lower permeability and closure stress. The Cline formation should ceramic proppant only about 10% of the time. This method of prescribing the ideal proppant considering both sonic-based stress and formation permeability is projected to save around $96,000 per well. This translates to 6.4 million dollars for 67 wells to be drilled in Queen Anne's Field from the 2nd through 4th quarter 2014. This is a huge incremental value enabled by adding sonic logs and petrophysical analysis to the completion design paradigms.
Integrated Reservoir Characterization and 3D Modeling of the Monteith Formation: Tight Gas Sandstones in the Western Canada Sedimentary Basin, Alberta, Canada
Authors: Zambrano Liliana , Ramirez John Freddy , Pedersen Per Kent , Aguilera Roberto 
Published: September 2014

Abstract
The Monteith Formation is an important tight gas reservoir in the Deep Basin, Alberta, and consists of a progradational succession of shallow marine sediments, non-marine carbonaceous and coaly, coastal plain facies, and coarse-grained fluvial deposits, from base to top, respectively. This study compares rock properties and production performance of the uppermost lithostratigraphic unit ("Monteith A") and the lowermost portion ("Monteith C") of the Monteith Formation in the Western Canada Sedimentary Basin (WCSB) in Alberta.
The study is based on multi-scale description and characterization techniques using cores and drill cuttings, including multiple laboratory measurements of key reservoir parameters such as porosity and permeability. A second stage of the study involves the use of laboratory measurements obtained from cores and drill cuttings and their integration with well logs to produce a numerical 3D model of the study area. The 3D model is used to history match gas production, and forecast performance of new wells in those areas where the geologic model indicates potential for gas production. The ultimate goal is to provide a better understanding of the distribution of reservoir properties in the study area, for developing drilling prospects and their production potential. In addition to that, the reservoir modeling stage is carried out by implementing a recently developed methodology that integrates a Variable Shape Distribution (VSD) model, capable of capturing different reservoir properties through the whole scale spectrum without any data truncation. This new methodology introduces an extension of the VSD approach for reservoir simulation purposes.
The results are showing that the Monteith A unit has better rock quality than the shallow marine sandstones of the Monteith C interval. This is most likey due to larger pore throat apertures ranging between 0.5 and 1 microns, relatively higher proportion of preserved intergranular pore space within these coarser-grained framework grains. Furthermore, the best production performance is found from wells that are actually producing from the uppermost interval. The resulting 3D reservoir model will allow to improve field development strategies for this and other similar unconventional gas reservoir in the Deep Basin of Alberta.
Rate-Decline Analysis For Fracture-Dominated Shale Reservoirs: Part 2
Authors: Duong Anh N. 
Published: September 2014

Abstract
When it comes to forecasting production from shale plays that are subject to multistage hydraulic fracturing, most modeling approaches do not apply throughout the life of a well. The Duong decline method, introduced in 2010, is no exception. When a well reaches the stage of boundary-dominated flow (BDF), the method's limitations become clear.
Part 2 of the Duong method proposes to extend the approach in order to apply it to the long-term performance of wells that are influenced by various fracture fabrics, well spacing, and fluid types such as gas and saturated and unsaturated oil production. In addition to overcoming its own limitations, the extended method is also intended to rectify limitations associated with other commonly used production forecasting methods. The outcome of this work should generate a model that accounts for the physical processes of flow regimes in horizontal wells with multistage hydraulic fracturing.
This extension employs empirical, analytical, and numerical solutions to represent a depletion model that consists of multiple realistic flow regimes. The method uses the Duong diagnostic plot, log(q/Gp) versus log(t), to normalize the constant rate and constant pressure analytical solutions during both linear flow and BDF. This forms an equivalent Fetkovich-type curve for unconventionals and serves as the base curve for identifying the start time of fracture interference among the fractures and in connection with the Arps' b values. Results from numerical simulation modeling are used to fill in long-term production estimates affected by various fracture geometries, well drilling spacing units, and fluid types. Type-curve parameters include start fracture interference time and fluid influx ratio for each depletion system. The fluid influx ratio based on permeabilities, fracture distance and half-length, and well spacing ranges from zero to one, where zero represents an isolated system and one represents transient conditions.
The outcome of this work should help the industry not only to forecast rate production more accurately, but to better understand decline prediction in tight oil and shale gas reservoirs. The paper also discusses methods to estimate input parameters for forecasting, using factors such as permeabilities, fracture interference time, stimulated-rock volume (SRV), and fracture half-length from production history and completion data. The paper applies field and simulation data to demonstrate the use of the new extension.
Abiotic Effects on Effluent Dissolved Organic Nitrogen Along an Estuarine Transect
Authors: Funkey Carolina P. , Latour Robert J. , Bronk Deborah A. 
Published: September 2014

ABSTRACT: Biological nutrient removal is a process commonly used in water resource recovery facilities to reduce dissolved inorganic nitrogen (DIN) concentrations in effluent; this process is less effective at removing all of the effluent dissolved organic nitrogen (EDON). The goal of this study was to investigate the fate of EDON after it undergoes the disinfection process and enters receiving waters. The authors quantified the abiotic effects of effluent exposure to sunlight, increased salinity, and a combination of the two factors. Effluent dissolved organic nitrogen showed significant breakdown during the disinfection process (UV and chlorine) and when exposed to sunlight and increasing salinity. Approximately 7% of the EDON was transformed to DIN and dissolved primary amines after exposure to 9 hours of sunlight and a salinity increase from 0 to 33. The production of DIN and primary amines should be taken into account when considering sources of labile nitrogen to aquatic ecosystems.
Debris and friction of self-ligating and conventional orthodontic brackets after clinical use
Authors: Araújo Raíssa Costa , Bichara Lívia Monteiro , de Araujo Adriana Monteiro , Normando David 
Published: September 2014

ABSTRACT

Objective:
To compare the degree of debris and friction of conventional and self-ligating orthodontic brackets before and after clinical use.

Materials and Methods:
Two sets of three conventional and self-ligating brackets were bonded from the first molar to the first premolar in eight individuals, for a total of 16 sets per type of brackets. A passive segment of 0.019 × 0.025-inch stainless steel archwire was inserted into each group of brackets. Frictional force and debris level were evaluated as received and after 8 weeks of intraoral exposure. Two-way analysis of variance and Wilcoxon signed-rank test were applied at P &lt; .05.

Results:
After the intraoral exposure, there was a significant increase of debris accumulation in both systems of brackets (P &lt; .05). However, the self-ligating brackets showed a higher amount of debris compared with the conventional brackets. The frictional force in conventional brackets was significantly higher when compared with self-ligating brackets before clinical use (P &lt; .001). Clinical exposure for 8 weeks provided a significant increase of friction (P &lt; .001) on both systems. In the self-ligating system, the mean of friction increase was 0.21 N (191%), while 0.52 N (47.2%) was observed for the conventional system.

Conclusion:
Self-ligating and conventional brackets, when exposed to the intraoral environment, showed a significant increase in frictional force during the sliding mechanics. Debris accumulation was higher for the self-ligating system.
Improve 3D laser scanner measurements accuracy using a FFBP neural network with Widrow-Hoff weight/bias learning function
Authors: Rodríguez-Quiñonez J. , Sergiyenko O. , Hernandez-Balbuena D. , Rivas-Lopez M. , Flores-Fuentes W. , Basaca-Preciado L. 
Published: September 2014

AbstractMany laser scanners depend on their mechanical construction to guarantee their measurements accuracy, however, the current computational technologies allow us to improve these measurements by mathematical methods implemented in neural networks. In this article we are going to introduce the current laser scanner technologies, give a description of our 3D laser scanner and adjust their measurement error by a previously trained feed forward back propagation (FFBP) neural network with a Widrow-Hoff weight/bias learning function. A comparative analysis with other learning functions such as the Kohonen algorithm and gradient descendent with momentum algorithm is presented. Finally, computational simulations are conducted to verify the performance and method uncertainty in the proposed system.
What Predicts the Effectiveness of Foreign-Language Pronunciation Instruction? Investigating the Role of Perception and Other Individual Differences
Authors: Kissling Elizabeth M. 
Published: September 2014

Abstract: This study investigated second language (L2) learners’ perception of L2 sounds as an individual difference that predicted their improvement in pronunciation after receiving instruction. Learners were given explicit pronunciation instruction in a series of modules added to their Spanish as a foreign language curriculum and were then tested on their pronunciation accuracy. Their perception of the target sounds was measured with an AX discrimination task. Though the best predictor of pronunciation post-test score was pre-test score, perception made a unique and significant contribution. The other factors associated with better pronunciation of some L2 sounds were age, attitude, and time spent using Spanish outside the classroom. The results suggest that instructors should give adequate time for learners to hone their perception of target sounds at the outset of pronunciation instruction, because their initial ability to perceive the target sounds will, in part, determine how much they learn from such instruction. The results support models of L2 speech acquisition that claim that target-like perception is a precursor to target-like production, in this case in a formal learning context.
Early evidence of xeromorphy in angiosperms: Stomatal encryption in a new eocene species ofBanksia(Proteaceae) from Western Australia
Authors: Carpenter Raymond J. , McLoughlin Stephen , Hill Robert S. , McNamara Kenneth J. , Jordan Gregory John 
Published: September 2014

•Premise of the study:Globally, the origins of xeromorphic traits in modern angiosperm lineages are obscure but are thought to be linked to the early Neogene onset of seasonally arid climates. Stomatal encryption is a xeromorphic trait that is prominent inBanksia, an archetypal genus centered in one of the world's most diverse ecosystems, the ancient infertile landscape of Mediterranean‐climate southwestern Australia.•Methods:We describeBanksia paleocrypta, a sclerophyllous species with encrypted stomata from silcretes of the Walebing and Kojonup regions of southwestern Australia dated as Late Eocene.•Key results: Banksia paleocryptashows evidence of foliar xeromorphy ∼20 Ma before the widely accepted timing for the onset of aridity in Australia. Species ofBanksiasubgenusBanksiawith very similar leaves are extant in southwestern Australia. The conditions required for silcrete formation infer fluctuating water tables and climatic seasonality in southwestern Australia in the Eocene, and seasonality is supported by the paucity of angiosperm closed‐forest elements among the fossil taxa preserved withB. paleocrypta. However, climates in the region during the Eocene are unlikely to have experienced seasons as hot and dry as present‐day summers.•Conclusions:The presence ofB. paleocryptawithin the center of diversity of subgenusBanksiain edaphically ancient southwestern Australia is consistent with the continuous presence of this lineage in the region for ≥40 Ma, a testament to the success of increasingly xeromorphic traits inBanksiaover an interval in which numerous other lineages became extinct.
Current interpretations and scientific rationale of the ozone usage in dentistry: A systematic review of literature
Authors: Kumar Anil , Bhagawati Sharnamma , Tyagi Prashant , Kumar Prince 
Published: September 2014

AbstractIn the era of antibiotic resistance, a naturally occurring substance is needed to completely cure the infection without any toxic side-effects; a responsibility that “O3 or Ozone” seems to implement sincerely. Ozone gas has a high-oxidation potential and has the capacity to stimulate blood circulation and the immune response. It is a great supplement to conventional therapeutic dental modalities. Treatment may be achieved by increasing the resistance of the tooth against the microbial activity and reducing the extent of microbial activity. In addition to the recent materials and techniques, the therapeutic actions of ozone may provide beneficial results by reducing the demineralization of the tooth. Its bactericide, virucide and fungicide effects are based on its strong oxidation effect with the formation of free radicals as well as its direct destruction of almost all microorganisms. This potentially beneficial agent has been used in dentistry also. Ozone has a wide application in dentistry which includes treatment of carious lesions, root canal disinfection, wound healing impairments after surgical interventions, plaque control, disinfection of dentures, etc., The purpose of this article is to summarize the mechanism of action and different modalities of ozone therapy in the practice of dentistry.