bluuebunny/crossref_metadata_2025_split huggingface dataset:
World Journal on Educational Technology (WJET)
Authors: Index Referees 
Published: January 2016

The academicians listed below have acted as referees since December 2015 for manuscripts in which the review process of which have been completed, as well as for those paper submissions which have been cancelled by the authors for some reason and for those that have been rejected. The editorial board members are grateful to all referees who have contributed to World Journal on Educational Technology.Abdullah KuzuAnadolu University, TurkeyAntonella CarbonaroUniversity of Bologna, ItalyBirikim OzgurNear East University, CyprusChristine HarmesJames Madison University, United StatesCigdem HursenNear East University, CyprusHafize KeserAnkara University, TurkeyHuseyin UzunboyluNear East University, CyprusMurat TezerNear East University, CyprusRay WebsterMurdoch University, AustraliaSirin KaradenizBahcesehir University, TurkeySonia Maria Suaez-GaraboaUniversity of A Coruña, SpainSteven RossJohn Hopkins University, United StatesThirusellvan VandeyarUniversity of Pretoria, South AfricaTse-Kian NeoMultimedia University, Malaysia
Variable Pump Rate Fracturing Leads to Improved Production in the Marcellus Shale
Authors: Ciezobka Jordan , Maity Debotyam , Salehi Iraj 
Published: January 2016

Abstract
Typical hydraulic fracturing designs in shale utilize a predetermined fluid pump rate, which once achieved is held constant throughout the treatment, excluding situations when surface pressure limitations or other conditions disallow. We propose a method of pumping hydraulic fracture stages where the fluid pump rate is rapidly changed from the predetermined maximum rate, to some significantly lower rate, and then rapidly increased back to original maximum rate. This rapid change in the flow rate produces a pressure pulse that travels up and down the wellbore and has the capacity, together with the pump rate change, to open previously unopened perforations, while increasing fracture complexity through fluid diversion.
We observed increased microseismicity during hydraulic fracturing in stages with frequent pump rate changes. Regardless of their type and nature, seismic signals are indicative of fragmentation of the treated zone. This could be from shear shattering or dilatational opening. One can also assume that high signal density is a good measure of fracturing efficiency. To further investigate these observations, we implemented a variable pump rate fracture design in a Marcellus shale well. More specifically, we implemented the variable pump rate frac design in every odd stage, while implementing a constant rate design in every even stage. This was done in order to account for changes in the reservoir along the horizontal lateral.
Production log results showed on average a 19% increase in production for the variable pump rate stages versus the constant pump rate stages. A lower treating pressure was often encountered after the rapid rate changes, leading to the conclusion that unopened perforations were opened with the aid of the induced pressure pulses. Total well production decline was much slower for test well that included variable pump rate changes versus the offset horizontal well which did not include the variable pump rate frac design.
And finally water hammer frequency decay analysis shows a predictable trend in well with variable pump rate stages. Throughout the variable pump rate stages, no proppant transport issues were encountered and the frac stages were completed without any major issues.
Rapid rate changes applied throughout the fracture treatment enhance microseismicity, which could be interpreted as additional fracture complexity. Surface fracturing pressure data shows that rapid pump rate changes open additional perforations without physical flow diverters such as ball sealers or frac balls, while production log data shows higher production. Implementation of the Variable Rate hydraulic fracturing method results in no additional costs while it increases stimulation efficiency.
The Search for Optimized Stimulation in Horizontal Wells: Coiled Tubing Fracturing, Lessons Learned from Bottomhole Gauges and Diagnostic Data
Authors: Stolyarov S. , Hurt R. S. , Thacker C. W. , Sookprasong P. A. 
Published: January 2016

Abstract
The struggle to define an optimized completion strategy remains a significant challenge in unconventional multistage horizontal wells. Stage and cluster spacing is a design decision that often requires significant experimentation to determine what is the optimized spacing of propped fractures that efficiently drains the reservoir yet can be reliably pumped to completion. This paper illustrates the importance of bottomhole (BH) gauge data for evaluation of stage and cluster spacing and general completion quality. The knowledge derived through careful analysis of this valuable data source, can significantly reduce the amount of experimentation typically required in other completion techniques. Consequently optimized field scale completion strategies can be refined with efficiency and reduced overall costs.
Coiled tubing (CT) assisted hydraulic fracturing (HF) is a good alternative to the standard plug and perf completion in multistage horizontal well stimulation. During a CT HF operation, fracturing is initiated via pre-installed frac sleeves or sand-jetted perforations. One of the advantages of CT fracturing is improved target fracturing, where a single-entry fracture initiation point can be placed at the desired depth to target the best rock for stimulation. Another benefit of CT fracturing is the ability to gather BH treating pressure via BH gauges (BHG) mounted on the CT bottomhole assembly (BHA). Bottomhole pressure and temperature gauges, installed above and below the isolation packer, provide valuable information about fracture communication between stages, cement integrity and stress shadowing.
This paper will review dozens of CT frac jobs performed across various basins in North America. Information obtained from BHG is merged with surface treating pressure and other diagnostic data sources and subsequently analyzed. One key area of analysis is to examine stage communication data for stress shadowing effects. The primary takeaways from this paper are to illustrate the importance of BHG data, how it compares to other diagnostic data, and how it can be analyzed to effectively drive the stimulation design process.
The Good, the Bad and the Ugly: A Case History of a Multi Stage Hydraulic Fracturing Horizontal Well Tight-Gas Development in Oman
Authors: Nicolaysen A. , Casero A. , Roy A. , Rylance M. , Kurniadi S. , Batmaz T. 
Published: January 2016

Abstract
One often overlooked aspect of hydraulic fracturing is that the majority of reasonable permeability reservoirs (0.1 mD and above), on the North American continent, were in fact originally completed with straightforward hydraulically fractured vertical wells. However, as the average permeability of formations being developed deteriorated, this triggered a transition to multi-stage fractured horizontal wells and not unreasonably the fracture design and techniques that were developed to move from stage to stage were designed to be fit for purpose in these much lower permeability environments. These approaches, while suitable for lower permeability and unconventional formations, are not necessarily appropriate for higher permeabilities and conventional reservoirs.
The Khazzan development in the Sultanate of Oman Block 61 includes a multi-layered, reasonable permeability, gas reservoir, which may be categorized as a tight gas reservoir. In such tight gas developments, fractured vertical wells have historically been the preferred completion design, due to favourable economics. Following an extensive appraisal programme, the development of the Barik reservoir in Block 61 was approved in February 2014, and while successful appraisal had taken place with fractured vertical wells, not unexpectedly multi-stage fractured horizontal wells were subsequently proposed as an additional incremental improvement option for development. In order to successfully achieve this, a number of standard operational practices and assumptions associated with North American unconventional horizontals needed to be challenged, adapted and in some cases stopped.
The technical journey to deliver an effective multistage well design included an assessment of the impact of assumptions and considerations that drive unconventional practice, eventually leading to the road map to success that was developed. The learning includes three key pilot horizontal wells and clearly demonstrates incremental progression that was achieved, including technical obstacles faced, engagement with a complex stress-regime and how unconventional technology has to be adapted to be fit for purpose for the formation at hand. Not a static solution, the Khazzan development continues in the initial phase with fractured vertical wells achieving a rapid learning-curve and multi-stage fractured horizontal wells being optimized further.
The experiences and outcomes from the suite of wells in this project demonstrated that multistage fracturing of horizontal wells requires careful consideration, particularly in the selection of technologies and their application. The approach adopted in this project has led to developing the field with a healthy suite of competing completion techniques that offer best-fit solutions under different scenarios, and this set of complementary options will ensure that the development economics are maximised.
A Validation Assessment of Microseismic Monitoring
Authors: Warpinski N. R. , Wolhart Steve 
Published: January 2016

Abstract
Microseismic monitoring of hydraulic fracturing in unconventional reservoirs is a valuable tool for delineating the effectiveness of stimulations, completions, and overall field development. Important information, such as fracture azimuth, fracture length, height growth, staging effectiveness, and many other geometric parameters, can typically be determined from good quality data sets. In addition, there are parameters now being extracted from microseismic data sets, or correlated with microseismic data, to infer other properties of the stimulation/completion system, such as stimulated reservoir volume (SRV), discrete fracture networks (DFNs), structural effects, proppant placement, permeability, fracture opening and closure, geohazards, and others. Much of the information obtained in this way is based on solid geomechanical or seismological principles, but some of it is speculative as well.
This paper reviews published data where microseismic results have been validated by experiments using some type of ground-truth or alternative measurement procedure, discusses the geomechanics and seismological mechanisms that can be reasonably considered in evaluating the likelihood of inferring given properties, and appraises the uncertainties associated with monitoring and the effect on any inferences about fracture behavior. Considerable data now exist from tiltmeters, fiber-optic sensing, tracers, pressure sensors, multi-well-pad experiments, and production interference that can be used to aid the validation assessment.
Relatively limited microseismic results have actually been validated in any consistent manner. Fracture azimuth from microseismic has been verified across a wide range of reservoir types using multiple techniques. Good validation of fracture length and height were performed in sandstones for planar fractures; fracture length and height in typical horizontal completions with multiple fractures or complexity have a lesser degree of verification. Other parameters, such as complexity, discrete fracture networks, source parameters, and SRV, have little supporting evidence to provide validation, even though they might have sound physical principles underlying their application. It is clear that microseismic monitoring would benefit from more attention to validation testing. In many cases, the data might be available but have not been used for validation purposes, or such results have not been published.
Completion Optimization in the Fayetteville Shale Utilizing Rate Transient Analysis for Candidate Selection
Authors: McDonald B. , Wright T. H. 
Published: January 2016

Abstract
Areas of Southwestern Energy's Fayetteville Shale asset were identified as candidates for optimized completions by analyzing the y-axis intercept of the Rate Transient Analysis (RTA) square root time plot, an indicator of skin, and looking for those wells with values above the field average. It is hypothesized that the increase in the y-intercept from the typical average across the asset is due to proppant embedment in the formation and through optimized completions a reduction in the y-intercept, or skin, can be achieved.
The initial test program started in Q4 2014 and the area of interest (AOI) was established by conducting rate transient analysis on all Southwestern Energy Fayetteville Shale wells and then mapping the variable across the play. The initial test pads were located in areas where y-intercept values exceeded average and included 6 pads, 19 wells, with completion designs using 30 - 50% more sand/stage and 7 pads, 24 wells, with 30 - 50% reduction in fluid volume/stage versus the standard Southwestern Energy Fayetteville Shale completion. Success or failure was determined by comparing normalized pressure and well performance to the 9-section area of the test pad.
The wells with 30 - 50% more sand/stage have an average EUR/CLAT improvement of 4% and exhibit a reduction of 24% in the y-intercept. The wells with 30 - 50% reduction in fluid volume have an average EUR/CLAT improvement of 6% and exhibit a reduction of 68% in the y-intercept and the economics are more favorable due to the reduced costs of the completion.
Given the success of the initial test program in the AOI, more pads are being evaluated to have optimized completions. As the program progresses, the y-intercept will be used in conjunction with data analysis of the more than 3,500 wells currently in the Fayetteville Shale to further optimize completions in specific areas.
Sinuosity of the Hydraulic Fractured Horizontal Well Impact on Production Flow Assurance: An Eagle Ford Case
Authors: Qiu Fangda , Yuan Ge , Marongiu-Porcu Matteo , Xu Jian , Pope Timothy 
Published: January 2016

Abstract
Shale operators are finding it increasingly critical to find a reservoirs' sweet spot, choose the optimum landing point, geo-steer the well within the best rock, and run the optimal completion hardware in order to exceed investor expectations. Due to geological structures that vary across the field or geo-steering quality issues, many wells suffer severe sinuosity which potentially impairs completions and inhibits productivity.
This study presents a comprehensive evaluation of hydraulically-fractured wellbore productivity compared with relatively smooth and highly-sinuous wells of similar reservoir quality. The sharp contrast leads to the engineering investigation by coupling a reservoir model which imbeds a representative complex fracture network with a transient multiphase wellbore simulator. The integrated model provides insight behind the flow instability in horizontal wells that produce hydrocarbons from unconventional reservoirs and the remedy completion and production strategy by considering reservoir and wellbore coupled performance.
Hydraulically-fractured horizontal wells in shale reservoirs have unstable flow dynamics because of low effective productivity index, small fluid velocity (due to large production string), and multiphase flow under bubble-point pressure, etc. We found that all these reasons lead to vigorous terrain slugging for any toe-up or toe-down wellbore geometries. Furthermore, this flow assurance issue determines more serious problems while encountering a certain level of wellbore sinuosity. In fact, we observed how the stagnation of fluid may isolate entire sections of the lateral and lead to a huge impairment of well deliverability.
This study couples for the first time an unconventional fracture model with an unstructured grid reservoir simulator and a transient multiphase wellbore deliverability model, evaluating the hydraulic fracture networks productivity and irregular or sinuous wellbores.
Understanding Completion Performance in Niobrara-Codell Reservoirs Through the Use of Innovative Software-Guided Workflows and Models
Authors: Wallace K. J. , Aguirre P. Reyes , Jinks E. , Yotter T. H. , Malpani Raj , Silva Felipe 
Published: January 2016

Abstract
This paper describes a comprehensive field study of eight horizontal wells deployed in the stacked Niobrara and Codell reservoirs in the Wattenberg oilfield (Denver-Julesburg basin). The overall goal was to understand the geometry of the hydraulic fractures (propped), producing volume with respect to completions design, target reservoirs, and well spacing. Through this understanding we are able to develop the asset more effectively and economically.
In this study, an unconventional hydraulic fracture model was developed and calibrated against surface and downhole microseismic recordings, "frac hits" in offset vertical wells, chemical tracers, pressure interference testing, diagnostic fracture injection tests (DFITs), and treatment pressure/instantaneous shut-in pressure (ISIP) history matching. The hydraulic fracture geometry and conductivity were simulated using unconventional models populated with a natural discrete fracture network (DFN) defined through outcrop and image log observations along with a rigorous mechanical earth model.
A special unstructured grid that conforms to the shape of the calibrated hydraulic fracture model planes was constructed. This unstructured, fractured reservoir grid was fed into a compositional reservoir simulator that was tuned using pressure dependent permeability, offset vertical well pressure depletion, and relative permeability (among others) to match the production history available to date.
This workflow allowed for complete integration of geological, geomechanical, and production models in a single platform to produce a consistent set of results. This study concludes that 1) Increasing the hydraulic fracture treatment volume beyond a certain point does not significantly enhance the fracture geometry or improve early time well performance; 2) additional wells are needed to access undrained reservoir; 3) existing vertical-well depletion has a significant impact on early time well performance, and; 4) hydraulic fracture height extension allows initial communication between the Niobrara and Codell reservoirs, however this connectivity dissipates during production likely due to the loss of fracture connectivity vertically.
Expanding Interpretation of Interwell Connectivity and Reservoir Complexity through Pressure Hit Analysis and Microseismic Integration
Authors: Lehmann Jurgen , Budge Jessica , Palghat Abhinav , Petr Christopher , Pyecroft James 
Published: January 2016

Abstract
This paper presents a multi-disciplinary workflow for analyzing interwell hydraulic fracturing pressure interactions on multi-well horizontal pads in unconventional reservoirs. Over twenty wells in multiple fields with varied spacing across multiple landed zones are evaluated. The workflow provides a method for determining the degree of connectivity between the wells to assess the extent and complexity of the stimulated network. The analysis method provides a cost efficient, timely means of understanding the stimulated network in order to impact decisions regarding well spacing, injection rate, perforation design and frac order.
Prescriptive completions programs enable observation of pressure interactions between wells during multi-stage hydraulic fracturing. Wellhead pressures are continuously recorded during all completion and flowback operations. In the observation pads studied, wells experience varying degrees of pressure communication across the fracture network. Pressure hits are grouped by according to identifying characteristics and correlated to microseismic data where available.
Characterization of the stimulation network gained from analysis of pressure interactions closely aligns with available high resolution microseismic data. Networks are shown to have significant vertical and lateral growth establishing a highly complex network. Additional insights on the degree of connectivity and the definition of effective fracture network are gained. Results are fundamental to understanding well spacing and zonal placement.
Synergy between Hematopoietic and Radioresistant Stromal Cells Is Required for Autoimmune Manifestations of DNase II−/−IFNaR−/− Mice
Authors: Baum Rebecca , Nündel Kerstin , Pawaria Sudesh , Sharma Shruti , Busto Patricia , Fitzgerald Katherine A. , Gravallese Ellen M. , Marshak-Rothstein Ann 
Published: January 2016

Abstract
Detection of endogenous nucleic acids by cytosolic receptors, dependent on STING, and endosomal sensors, dependent on Unc93b1, can provoke inflammatory responses that contribute to a variety of autoimmune and autoinflammatory diseases. In DNase II–deficient mice, the excessive accrual of undegraded DNA leads to both a STING-dependent inflammatory arthritis and additional Unc93b1-dependent autoimmune manifestations, including splenomegaly, extramedullary hematopoiesis, and autoantibody production. In this study, we use bone marrow chimeras to show that clinical and histological inflammation in the joint depends upon DNase II deficiency in both donor hematopoietic cells and host radioresistant cells. Additional features of autoimmunity in these mice, known to depend on Unc93b1 and therefore endosomal TLRs, also require DNase II deficiency in both donor and host compartments, but only require functional TLRs in the hematopoietic cells. Collectively, our data demonstrate a major role of both stromal and hematopoietic cells in all aspects of DNA-driven autoimmunity. These findings further point to the importance of cytosolic nucleic acid sensors in creating an inflammatory environment that facilitates the development of Unc93b1-dependent autoimmunity.
A prospective comparison of perioperative morbidity in advanced epithelial ovarian cancer: Primary versus interval cytoreduction - experience from India
Authors: Ahmad Sheikh Zahoor , Rajanbabu Anupama , Vijaykumar D. K. , Haji Altaf Gauhar , Pavithran K. 
Published: January 2016

Abstract
Objectives: The objective was to compare perioperative morbidity and mortality of patients with advanced epithelial ovarian cancer (EOC) treated with either of the two treatment approaches; neoadjuvant chemotherapy (NACT) followed by interval debulking versus upfront surgery. Design: Prospective comparative observational study. Participants: In total, 51 patients were included in the study. All patients with diagnosed advanced EOC (International Federation of Gynecology and Obstetrics IIIC and IV) presenting for the 1st time were included in the study. Interventions: Patients were either operated upfront (n = 19) if deemed operable or were subjected to NACT followed by interval debulking (n = 32). Primary and Secondary Outcomes: Intra- and postoperative morbidity and mortality were the primary outcome measures. Results: Patients with interval cytoreduction were noted to have significantly lesser operative time, blood loss, and extent of surgery. Their discharge time was also significantly earlier. However, they did not differ from the other group vis. a vis. postoperative complications or mortality. Conclusions: Neoadjuvant chemotherapy although has a positive impact on various intraoperative adverse events, fails to show any impact on immediate postoperative negative outcomes.