bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuances and Frequently Asked Questions in Field-Scale Hydraulic Fracture Modeling
Authors: McClure Mark , Picone Matteo , Fowler Garrett , Ratcliff Dave , Kang Charles , Medam Soma , Frantz Joe 
Published: January 2020

Abstract
Hydraulic fracturing and reservoir simulation are used by operators in shale to optimize design parameters such as well spacing, cluster spacing, and injection schedule. In this paper, we address ‘freqently asked questions’ that we encounter when working on hydraulic fracture modeling projects with operators. First, we discuss three high-level topics: (1) data-driven and physics-based models, (2) the modeling workflow, and (3) planar-fracture modeling versus ‘complex fracture network’ modeling. Next, we address specific technical topics related to modeling and the overall physics of hydraulic fracturing: (1) interrelationships between cluster spacing and other design parameters, (2) processes affecting fracture size, (3) fracture symmetry/asymmetry, (4) proppant settling versus trapping, (5) applications of Rate-Transient Analysis (RTA), (6) net pressure matching, (7) Initial Shut-In Pressure (ISIP) trends along the wellbore, and (8) the effect of understressed/underpressured layers. We discuss practical modeling decisions in the context of field observations.
High Viscosity Friction Reducers - Potential for Fracture Damage and Impact of Brines on Proppant Transport Capability
Authors: Hlidek Barry , Duenckel Robert 
Published: January 2020

Abstract
High viscosity friction reducer (HVFR) fracturing fluids are widely implemented for unconventional reservoir development. HVFR's are easy to apply and reduce chemical costs. The research objective of this paper is to measure polymer cleanup in both propped and unpropped fractures utilizing multiple methods. Additionally, the study will compare rheological measurements to proppant transport observations in brines using a large-scale slot flow device.
API conductivity cells determined pack damage over a range of proppant sizes, HVFR's, and temperatures. An extended length conductivity (ELC) apparatus was utilized for comparison with the API cell. Cleanup in unpropped fractures employed a core holder using fractured core plugs. HVFR rheological property measurements include low and high steady shear measurements, and oscillatory measurements used to determine elastic properties. Mix waters include fresh water, salt solutions, and a simulated field brine. Proppant transport in fresh and simulated field brine is evaluated in a 1 × 8 foot slot flow device. Proppant deposition rates are recorded using video cameras.
Propped fracture cleanup in the API cell and ELC apparatus is a function of proppant mesh size and HVFR type. As mesh size decreased, the potential for damage increased. Tests with 50/140 mesh proppants in the API cell in some cases showed significantly impaired regain conductivities as low as 65%. When compared to the ELC, API cell cleanups were in some cases significantly optimistic. Cleanup also varied greatly with HVFR product. Even with a low loading of HVFR of 1 gallon per thousand gallons of fluid (gpt) significant damage was sometimes noted. The tests of the unpropped fractures showed that very severe damage to unpropped fractures may occur. The presence of salts significantly and negatively affects HVFR rheological properties for most of the materials selected for this study. Viscosity at higher shear rates (10-511/sec) do not necessarily reflect HVFR performance at lower shear rates. In all tests, the rheological performance between different products exhibited a wide variation in properties, likely reflecting the potentially wide variation in chemical composition. Proppant transport testing validates the rheology measurements. The slot flow evaluations showed a significant loss of transport capability in brines. Commercial HVFR's are not equivalent and require laboratory performance evaluations.
The study demonstrated that the potential for significant damage to the proppant pack and reservoir is present with HVFR fluid systems. Even low salt concentrations significantly influence the HVFR rheological performance. Mix water compatibility must be a primary concern when selecting HVFR's. The results of this study provide useful information to engineers for selecting HVFR's and describes a methodology for evaluating damage potential, and proppant transport.
Using Automation While Pumping to Improve Stimulation Uniformity and Consistency: A Series of Case Studies
Authors: Holley Eric , Martysevich Vladimir , Cook Katie , Gale Scott 
Published: January 2020

Abstract
Within the hydraulic fracturing domain, automation has begun to play a substantial role in logistics, supply chain, and manufacturing. A review of automation opportunities generally focuses on cost reduction arising from throughput improvements for service delivery. Although cost reduction efforts are important and are delivered in many ways, the automation efforts discussed in this paper take a different approach. Automation now plays a larger role in how stimulation operations are performed from the subsurface perspective.
The automation processes reviewed in these studies focus on making more consistent decisions while breaking down the formation to promote an even distribution of fracture fluid placement for all stages. The metric for success is not necessarily focused on cost or time reduction; although these outcomes are occurring, the success metrics focus on the concept that more effective fracturing treatments can be consistently delivered by removing human inconsistency through automation during stimulation operations. This is accomplished is by automatically controlling the pump rate, based on the pressure response from the formation in real time.
This paper highlights a series of cases in North American shale basins that include wells that are instrumented with fiber optics and downhole pressure gauges, as well as non-instrumented wells with wellhead pressure and flowrate measurements only. It reviews how automation improves placement consistency in stimulation operations, eliminating some of the risks associated with traditional approaches that can lead to inconsistent outcomes. All of the results communicated are based on the capability to place fracturing fluid and proppant with more uniformity and consistency across the target interval while making real-time automated rate adjustments during pumping operations. The studies include work conducted in all major North American plays. The major findings include a discernable capacity to treat more clusters within a given stage, using automated rate controls, and achieving more even distribution of proppant to the target clusters within a given stage.
Perforating Trends, Technology and Evaluation in North America
Authors: Squires Christopher , Ramos Claudio , Clay Matthew 
Published: January 2020

Abstract
Perforating cemented casing is a staple for completing wells in every major basin in North America. The objective is to provide a highly conductive pathway between the wellbore and the target formation for both the stimulation and production fluids. New technology, statistical analysis, experimentation and trial-and-error are all used to find the optimal method for creating this pathway. Diagnostics like proppant tracers, downhole cameras, distributed temperature sensing (DTS), distributed acoustic sensing (DAS) and perforation friction pressure analysis can also be used to help evaluate the successes associated with the different methods for perforating.
New technology in creating consistent hole perforations in a horizontal wellbore, without the need for mechanical centralization or positioning systems, has recently been developed. This method of perforating employs a specialty shaped charge that allows for more control in the distribution of entry hole diameter (EHD) across a given cluster. This provides operators a more predictable and consistent pathway from the wellbore to the formation.
Not only is a consistent hole desirable in a standard multi-cluster stage treatment, but other recent completions trends can also benefit from increased precision in perforating. High density perforating (HDP) is being used in order to create more transverse fractures along the length of the well. A consistent hole allows for more precise estimations of pressure drop across each cluster in these mostly limited-entry or extreme limited entry (XLE) completions. Additionally, near-wellbore (NWB) perf sealing pods are being used to divert treatments from initially open clusters to bypassed or partially open clusters in an attempt to force perf cluster efficiencies higher and distribute stimulation fluids and proppant more evenly. Having a consistent hole for every perforation is ideal in attempting to seal the perforations in the NWB region with a fixed diameter pod. SPE 189900 (Senters, et al 2018) provides more detail on diversion optimization. Engineered completions design is employed in an attempt to selectively perforate rock within a stage with similar mechanical properties to drive stimulated cluster efficiencies higher. Perforating similar rock with a consistent hole shaped charge only stands to improve the chances of distributing the treatment more evenly throughout the clusters.
This paper will provide insight into the recent trends in perforating which show an increase in the amount of consistent hole shaped charges versus conventional shaped charges like deep penetrating and large hole. Diagnostic data accompanies entry hole diameter statistics and friction pressure calculations for the consistent hole shaped charges in order to demonstrate how they differ from conventional shaped charges. Finally, proppant tracer diagnostics will highlight several case studies where consistent hole shaped charges or other recent perforating methods were employed.
Delineating Far Field Prropped Fracture Geometry Using Electromagnetic Geophysics and its Potential Impact on Well Planning and Reservoir Modeling
Authors: Palisch Terry , Mukherjee Souvik , Al-Tailji Wadhah 
Published: January 2020

Abstract
Several field trials since 2016 have showcased the early development of a novel borehole to surface geophysical technique to characterize propped fractures in the far field of the well bore. Recent advancements have been made with the technique with regards to the processing and inversion algorithms, that have improved the confidence level and extent of the proppant imaged. These advancements will be presented in detail, along with field examples of its application.
The imaging technique is broadly classified into three phases: (a) survey design, (b) data acquisition and processing, and (c) inversion to provide propped fracture dimensions and location. The survey design phase includes acquisition of geophysical noise data and synthetic data generation using a realistic simulation of the target and its ambience. This helps determine source receiver locations to maximize response from the propped fracture. Acquired data is digitally processed to remove potential sources of noise arising out of cultural debris, acquisition anomolies, etc. Geophysical inversion of processed data utilizing known geological, engineering, and other constraints then provides the propped fracture image.
The novel electromagnetic method for determining propped fracture location and geometry has been developed and deployed safely and successfully in multiple field trials. The recent advancements in modelling and processing have been successfully used to analyze recent field applications, providing key insights on depletion effects of parent wells on bi-wing fracture growth in child wells, as well as proppant settling and stress shadowing impacts. Additional learnings on proppant/fracture fluid interactions, well landing location, and other important issues have demonstrated the potential to impact the planning of future wells in this area. This paper will present the current full-physics methods for processing, modelling and imaging the proppant location. It will include confidence levels and probability functions of the mapped proppant. The paper will also show field examples of the various insights gained from the results (mentioned above), which can be used for future development objectives.
The latest advancements in modeling, processing and inversion will be of interest to those who are knowledgeable with forward modeling and inversion theory. In addition, the field results will be useful to development engineers who are interested in optimizing well/lateral spacing, both areally and vertically, as well as understanding the impact of parent-child depletion, stress shadowing and cluster efficiency.
Proppant Flowback: Can We Mitigate the Risk?
Authors: Chuprakov Dimitry , Belyakova Ludmila , Iuldasheva Aliia , Alekseev Alexey , Syresin Denis , Chertov Maxim , Spesivtsev Pavel , Salazar Suarez Franck Ivan , Velikanov Ivan , Semin Leonid , Bannikov Denis 
Published: January 2020

Abstract
We propose a new model and workflow to predict, quantify and mitigate undesired flowback of proppant from created hydraulic fractures. We demonstrate several field cases in which we predict significant proppant flowback and propose options for mitigation. Mitigation of proppant flowback is based on case- specific changes in the fracturing treatment design and modifications in the well startup schedule that preserve near-wellbore conductivity. The presented workflow integrates four key components of proppant flowback study: (A) simulation of the fracturing job with a high-resolution model of proppant placement inside a fracture; (B) subsequent simulation of flowback from the created fractures equipped by a validated proppant flowback model; (C) a series of laboratory experiments, which quantify the proppant flowback for a wide range of commercial proppants; and (D) an accurate mathematical model, which is validated by the results of laboratory experiments and integrated into a flowback simulator to predict the behavior of injected proppant. Each component is presented with sufficient details to demonstrate its necessity for accurate modeling of a coupled solid-and-fluid flow inside a fracture. The presented theory of proppant pack mobilization is based on the concept of a proppant pack erosion process evolving from free boundaries of proppant packs. The theory confirms that proppant flowback critically depends on flow rate, proppant, fracture, and reservoir parameters. Laboratory experiments on proppant flowback in a cell support these theoretical predictions. The theoretical model of proppant flowback is integrated into the numerical simulator of early-time production from a fractured reservoir and predicts flowback of both injected solids and fluids from a fracture. We show that the combination of the proppant flowback model, laboratory experiments, hydraulic fracturing design tool, and early-time production simulator result in a useful workflow for prediction and mitigation of issues with proppant flowback and production decline.
The entire workflow was validated using field cases where proppant flowback was observed. Modeled amounts of flowed back proppant are in good agreement with amounts of proppant observed in the field. Hydraulic fracturing design optimization was performed to minimize or eliminate proppant flowback. The novelty of the proposed study is related to the model of proppant flowback, which accounts for erosion of the proppant pack and is calibrated against unique laboratory experiments. The presented model and proppant flowback mitigation workflow can assist in understanding and mitigating proppant flowback events that can occur during wide range of oilfield operations.
Fighting the Fear: Overcoming Preconceived Notions of Low Polymer Cross-Linked Gels and High Viscosity Polyacrylamides in Unconventional Fracturing
Authors: Poppel Benjamin 
Published: January 2020

Abstract
The objective of this paper is to highlight the preconceived notions that both ultra-low polymer cross-linked gels and high viscosity polyacrylamide fluid systems are difficult to work with or damaging to formations. The paper discusses when such systems are beneficial as well as define some design restrictions. Historically these types of fluid systems have fallen into a gray area of technology that have now become accepted by some operators in the current low-cost market.
The fluids technology discussed in this paper have blossomed not solely because of their technological advancement, but also due to the market. Industry downturns have forced operators and service companies to find more cost-effective means to stimulate the reservoirs in question. This paper examines the use of these new systems in two regions (Williston and DJ Basins), where hundreds of wells have been pumped with these new systems as well as regained conductivity tests performed in 3rd party labs. We also compare production results of thousands of stages pumped with these new systems versus a more traditional approach.
Over the past decade the DJ Basin has be primarily been stimulated with high-priced low pH zirconate CMHPG fluid systems, as a result of the notion that they leave less residue in the fractures. However, with the very cost sensitive market and the new ultra-low polymer systems testing with higher regained conductivity than the incumbent system, change was inevitable.
In the Williston Basin high rate slickwater jobs have become more commonplace. Hybrid designs have been used to increase proppant loadings. However, a new trend to use significantly higher FR concentrations to achieve a system capable of placing higher proppant concentrations is gaining market share.
This leads to the current obstacles for both systems’ further use in the field. These obstacles are threefold: The notion that the system is contaminating the proppant pack with residue. Lab testing shows this not to be the case.Reconditioning field personnel to run the new systems as designed.Ensure that these systems are not used in designs that do not fit the operational criteria without understanding the limitations.
The success of all of these items remain attached to the final product, a well producing as much as, or more, for a lower total cost than the more traditional method.
This paper uses data from the lab and field to challenge many of the preconceived notions about what it takes to successfully place a solid stimulation package. Also, it will address how some of the largest barriers to new technology are predominantly mental, while the new products are technically sound and economically superior.
High Frequency Pressure Monitoring and Data Analytics for Stimulation Efficiency Determination: New Perspectives or Potential Limits
Authors: Korkin Roman , Parkhonyuk Sergey , Fedorov Andrey , Badazhkov Dmitry , Kabannik Artem 
Published: January 2020

Abstract
A method of nonintrusive hydraulic fracturing monitoring based on high frequency pressure measurements has been known since 1985. Since that time, multiple attempts of its implementation into a commercial product have been tried. A new method using a wellhead pressure sensor during well stimulation was developed in 2017. The method discussed here is a continuation and improvement of this method. It is based on an advanced signal processing algorithm used for detection and analysis of tube waves in a wellbore and on the data science approaches for further processing of tube wave parameters and providing the answers of fluid entry point depth, plug failure probability, and casing leak detection. Use of the wellhead pressure sensor with a data acquisition box eliminates the need for sophisticated hardware. This enables cost-effective and timely decisions at the wellsite. The technique was validated in the field in several fracturing and refracturing jobs.
Weight Development Between Age 5 And 10 Years And Its Associations With Dietary Patterns At Age 5 In The Abcd Cohort
Authors: Rashid Viyan , Streppel Martinette T , Engberink Marielle F. , Weijs Peter J.M. , Nicolaou Mary , Verhoeff Arnoud P. 
Published: January 2020

Abstract
Background: Social inequalities in bodyweight start early in life and track into adulthood. Dietary patterns are an important determinant of weight development in children, towards both overweight and underweight. T herefore, w e aimed to examine weight development between age 5 and 10 years by ethnicity, SES and thereafter by BMI category at age 5, to explore its association with dietary patterns at age 5.

Methods: Participants were 1 765 children from the Amsterdam Born Children and their Development (ABCD) cohort that had valid data on BMI at age 5 and 10 and diet at age 5. Linear mixed model analysis was used to examine weight development between age 5 and 10 years and to assess if four previously identified dietary patterns at age 5 (snacking, full-fat, meat and healthy) were associated with weight development. Analyses were adjusted for relevant confounders, stratified by ethnicity and SES and thereafter stratified per BMI category at age 5.

Results: Overall, weight decreased in Dutch and high SES children and increased in non-Dutch and low/middle SES children. Across the range of bodyweight categories at age 5, we observed a conversion to normal weight, which was stronger in Dutch and high SES children but less pronounced in non-Dutch and low/middle SES children. Overall, the observed associations between weight development and dietary patterns were mixed with some unexpected findings: a healthy dietary pattern was positively associated with weight development in most groups, regardless of ethnicity and SES (e.g. Dutch B 0.084, 95% CI 0.038;0.130 and high SES B 0.096, 95% CI 0.047;0.143) whereas the full-fat pattern was negatively associated with weight development (e.g. Dutch B -0.069, 95% CI -0.114;-0.024 and high SES B -0.072, 95% CI -0.119;-0.026).

Conclusions: We observed differential weight development per ethnic and SES group. Our results indicate that each ethnic and SES group follows its own path of weight development. Associations between dietary patterns and weight development showed some unexpected findings; follow-up research is needed to understand the association between dietary patterns and weight development.

Keywords: BMI, body mass index, thinness, normal weight, overweight, obesity, socio-economic position, ethnicity, children, young children.