bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linking Flowback Recovery to Completion Efficiency: Niobrara-DJ Basin Case Study
Authors: Moussa Tamer , Barhaug Jessica , Witt Darby , Hawkes Robert , Dehghanpour Hassan 
Published: January 2022

Abstract
Near wellbore complexity is a current topic of discussion among geoscience and engineering disciplines across North America. Asset teams are constantly investing money and resources into the variety of near- and far-field wellbore diagnostic techniques to ascertain completion efficiency. These range from high-cost microseismic for far-field fracture placement to higher risk technologies such as fiber optics, cameras, and production logging tools. These techniques are generally used for parameter constraints for rate-transient-analysis (RTA) that requires months (and sometimes years) of production after post-frac flowback. Therefore, in this study we utilize flowback water-oil-ratio (WOR) as a diagnostic tool to provide early-time feedback for completion-efficiency evaluation.
We analyze flowback, post-flowback and completion-design data of 19 multi-fractured horizontal wells (MFHWs) completed in Niobrara and Codell formations that are classified into parent and child groups. Child wells are then sub-clustered into Zipper-1 and -2 completed with more and less intense completion strategy, respectively. First, we analyze the flowback rate and pressure profiles of the 19 wells to estimate initial pressure in the stimulated area around wellbore and validate it against the outcomes of diagnostic fracture injection test (DFIT). Second, we apply rate-normalized-pressure (RNP) diagnostic analysis to a) investigate flow regimes during flowback and post-flowback periods; and b) assess interference between parent and child wells. Third, we use WOR diagnostic plots to estimate ultimate load recovery (ULR) and calculate initial effective fracture volume as two indicators for completion efficiency. We also cross-check the estimated effective fracture volume with microseismic dimensions. Finally, we apply rate-decline analysis on oil production data to predict ultimate oil recovery (UQo), assuming a critical oil rate of 1 stbd, and use it as a third performance indicator to evaluate the completion-design efficiency of each group.
Child wells show 32% more load recovery compared with the parent wells. However, the parent wells show 38% and 50% more 9-months cumulative oil production (Qo) and UQo, respectively. For both the parent and child wells, more than 50% of the predicted ULR is produced back within the first three months of production. Although the intense completion-design strategy for Zipper-1 wells led to 35% larger effective fracture volume compared to Zipper-2 wells, both groups show similar oil recovery performance. Generally, Niobrara wells show less load recovery and effective fracture volume compared to Codell wells in each completion group.
Multi-Pronged Diagnostics with Modeling to Improve Development Decisions-An Operator Case Study
Authors: Kerr Erich , Haustveit Kyle , Scofield Reid , Estrada Erick , Johnson Andrew , Galuska Scott , Haffener Jackson , Landry Miles 
Published: January 2022

Abstract
The drive for capital efficiency in unconventionals has encouraged operators to understand subsurface interactions as effectively as possible. Combining multiple types of new and proven field technology systematically with advanced fracture modeling tools has led to continued improvements in field testing, understanding, and acreage development. Careful selection and application of these tools and technologies to understand subsurface characteristics and responses is a high priority when determining how to improve the net asset value. Diagnostic and modeling results will be integrated together to show how these learnings, when combined appropriately, equate to a sum greater than their parts.
Several field case studies will be provided to illustrate the benefits of the multi-pronged diagnostics with modeling approach. Fiber optic strain monitoring and Sealed Wellbore Pressure Monitoring (SWPM) tests will be combined and performed across multiple wellbore distances with multiple fracture design tests. Results will then be analyzed to understand fracture growth characteristics by using a hydraulic fracture simulator capable of convective particle transport, multi-fracture stress and strain shadowing, and complex fluid rheology. Select results will then be coupled with concurrent diagnostics that include microseismic, formation imaging, and casing caliper data to show how hydraulic fracturing interactions occur dynamically in the subsurface.
The geomechanics models will then be used to inform stage and cluster level details derived from field diagnostics that include stimulation and production performance behaviors, which incorporate combined non-Darcy and multi-phase flow impacts. Technologies will include erosion imaging diagnostics and permanent fiber optic warmback results.
Finally, a cluster-level analysis with downhole fiber optics strain data will be analyzed in conjunction with SWPM to inform subsurface dynamics and show how fracture treatment design optimization may be achieved by combining field learnings with the modeling.
These case studies are summarized to show how proper geomechanics modeling, application of field data, collection of the necessary diagnostics, and testing methods are used together to effectively improve completion designs, well spacing configurations, field diagnostics, and real-time stimulation and post-stimulation production analyses.
A Computational Model to Simulate Proppant Transport and Placement in Rough Fractures
Authors: Gong Facheng , Huang Hai , Babadagli Tayfun , Li Huazhou 
Published: January 2022

Abstract
Hydraulic fracturing creates rough fracture surfaces, instead of smooth ones, in subsurface formations. It is challenging to simulate the complex proppant transport phenomena in rough fractures due to the roughness effect as well as the complex nature of the coupled particle-fluid two-phase flow. This study first establishes realistic rough fracture models using digital scanning images of real fracture surfaces, and then conducts numerical simulations on the proppant transport and placement dynamics occurring on those rough surfaces. The digital scanning images of the artificially created tensile fractures are used to establish the geometry models of the rough fractures. The Computational Fluid Dynamic (CFD) method is adopted to describe the fluid flow, while the Discrete Element Method (DEM) is adopted to describe the particle motion. A resolved CFD-DEM coupling approach is established to simulate the fluid-granular interactions by properly modeling the momentum exchange between fluid flow and particle motion. We obtain the following preliminary simulation results: the proppant transport and settlement characteristics in rough fractures appear to be drastically different from those in smooth fractures, and the roughness feature tends to increase particle-wall and particle-particle contact. We observe an attenuated particle velocity in rough fractures compared to what occurs in smooth fractures. Additionally, the roughness increases the possibility of proppant settling when particles encounter a location with a large roughness height. Through comparison of the proppant transport phenomena in flat and rough fractures, it is observed that there is a great chance for the rough fractures to create tree-like proppant dunes, which would be beneficial for forming a proppant-filled flow channel with a higher and more sustainable conductivity.
Modelling of Parent Child Well Interactions
Authors: Ratcliff Dave , McClure Mark , Fowler Garrett , Elliot Brendan , Qualls Austin 
Published: January 2022

Abstract
We performed a modeling study calibrating a coupled "true" hydraulic fracturing and reservoir simulator to a complex set of observations from a parent-child well pad in the STACK play located in the Anadarko Basin area of Oklahoma. The model was constrained by sealed wellbore pressure monitoring, interference testing, pressure responses during frac hits, production data, and responses to chemical treatment. It was possible to match the full set of observations in a single, continuous simulation by calibrating the fracture toughness and leakoff, the permeability and relative permeability, a parameter related to proppant transport, and parameters related to a ‘fracture conductivity damage’ mechanism built into the simulator. The ‘fracture damage’ calculations mimic the reaction of frac fluid with the formation fluid as they mix in a hydraulic fracture during and after a frac hit. The interpretation of ‘fracture conductivity damage’ is corroborated by production impacts after frac hits, positive response to chemical mitigation treatments, and direct sampling of material from the wellbore. Because of the volume and quality of calibration data available, it is possible to constrain the key uncertainties of the model. It can now be used to design strategies to mitigate negative impacts from parent/child interactions.
Determination of the Perforation Hole Erosion Characteristics on Single and Dual Casing for Hydraulic Fracturing, in a Laboratory Test Setup Under Realistic Downhole Conditions
Authors: Loehken Joern , Fricke Bernd , McNelis Liam , Yosefnejad Davood 
Published: January 2022

Abstract
Numerous papers have dealt with the description and measurements of the erosion of perforation holes during a hydraulic fracturing treatment in single casing completions, but not much is known about the erosion of perforations in dual casing setups. This study addresses this topic and compares it to the erosion rate of single casing scenarios and how this is influenced by the backpressure, which is created by the fracture closure pressure.
The API 19B norm provides a guideline on how to test perforators under the most realistic downhole conditions. All casings used in our experiments were perforated in such a Section IV test set-up and subsequently installed in a specially designed high pressure flow apparatus. The casing holes were carefully measured, their hydraulic resistance was determined by a flow test and successively eroded by a slurry using high pressure pumping equipment. After each test, the holes were again geometrically measured, and their flow resistance was tested. In addition, the sand grain sizes were analyzed before and after the tests.
Our tests revealed a significant difference in the erosion characteristic of dual casing compared to single casing setups. Especially the diameter of the hole in the inner casing is critical for the progress of the erosion and the final hole diameters. Equal holes on both casings provide a better control of the treating pressures, especially after the first minutes of the treatment. The back pressure, which is created by the fluid in the fractures, influences mainly the flow rate through the perforation. For identical flow rates, the pressure differential becomes less with back pressure, however the erosion rate as a function of the cumulative energy pumped through the perforation, remains similar. Finally, the application and design of a bigger test cell was evaluated and will be discussed as well.
Although many perforating companies have started testing the charge performance for multiple casing completions, not much is known about the flow and erosion of two radially aligned holes in dual cemented casings during the fracture treatment and the influence of the back pressure created by the reservoir. The results will enhance the completion design and provide a better understanding of fracturing or refracturing through double-casings for hydraulic fracturing specialists and both operation and services companies.
Parent-Child Well Relationships Across US Unconventional Basins: Learnings from a Data Analytics Study
Authors: Cozby Joe , Sharma Mukul 
Published: January 2022

Abstract
Parent-child wells are horizontal wells drilled in close proximity to each other in unconventional basins. Simulation work in the technical literature demonstrates how depletion and fracture communication between parent and child wells can lead to child well underperformance. High-level, basin-wide data analysis of unconventional basins confirms this effect. However, as completion designs evolve and more state-of-the-art horizontal wells are completed in these basins, it is necessary to revisit this analysis and make adjustments and additions to the previous body of work. Specifically, initial production differences between parent and child wells need to be correlated to cumulative production differences, and more analysis regarding the effect of timing and spacing are needed. In this study, parent-child well pairs for wells completed within the last seven years in nine different unconventional basins are identified using a Python code applied to Enverus public data obtained in November 2020. These basins include the Bakken, Delaware, Eagle Ford, Haynesville, Marcellus/Utica, Midland, Niobrara, Powder River, and Scoop/Stack Basins. Our Python code also performs calculations to create the necessary comparative metrics for analysis. Four cumulative production proxies are created and First 12 Months BOE (barrel of oil equivalent) is chosen as the appropriate metric for analysis. Basin-to-basin comparisons are conducted, and the effects of well spacing and infill timing are investigated. The study finds that as stated in the technical literature, child well performance increases with spacing and decreases with infill timing. We show that parent cumulative production (BOE) at child well completion is a better indicator of child well performance. Overall, these assessments can help operators manage child well underperformance and can help them understand the effects of differing well spacing and infill timing on child well performance in different US unconventional basins.
A Rigorous Coupled Flow-Geomechanics Semianalytical Approach for Analyzing Early Flowback Data from Multifractured Horizontal Wells with Complex Fracture Geometry
Authors: Lamidi Abdul-Latif Benson , Clarkson Christopher R. 
Published: January 2022

Abstract
In this study, a rigorous coupled flow-geomechanics semianalytical approach is presented to analyze flowback data and forecast production performance in multifractured horizontal wells. Hydraulic fracture characterization using post-stimulation flowback data is of critical importance to the quantification of early-time well performance and for efficient development of unconventional reservoirs. However, conventional reservoir (flow) simulators can be challenging to setup for flowback analysis. Further, flow simulators usually approximate stress-dependence of fracture and reservoir parameters, the former of which is particularly important to capture for both the flowback and forward modeling problem, using porosity and transmissibility multipliers. However, in order to apply this approach, transmissibility multipliers must be estimated from laboratory experiments, or used as a history-match parameter, possibly resulting in large errors in performance predictions. The goal of this study is to provide a rigorous, coupled semianalytical workflow for hydraulic fracture characterization from flowback data, that utilizes a 3D coupled flow-geomechanics semi-analytical model as its basis.
A 3D semi-analytical coupled flow-geomechanical model is developed to capture the complexities of stress-dependence in order to forecast production performance from multifractured horizontal wells. The model can also be used to derive hydraulic fracture properties from early post-stimulation flowback data. An enhanced fracture region (EFR) conceptual model is applied for approximating complex fracture geometries. The fully-analytical fluid flow and semi-analytical geomechanical models are coupled for both the fracture and reservoir regions. The proposed approach requires simultaneous solutions of the fluid flow model (reservoir simulation) and geomechanics model, the latter capturing the stress and deformation behavior of the fracture and reservoir. Coupling between fluid flow and geomechanics is achieved by updating the pressure and stress-dependent properties through a porosity function (coupling parameter) in the flow model for each region (hydraulic fracture and reservoir) at each iteration step.
The coupled flow-geomechanics EFR model is validated with fully-numerical simulation. Fracture properties are estimated by using the proposed inverse model for analyzing flowback (water) data. The new flowback analysis approach is applied to synthetic field data and the results compared with the inputs of the synthetic model.
With this model, combined with the semi-analytical coupled flow-geomechanics workflow, a more confident estimate of hydraulic fracture properties is obtained.
Reservoir and Completion Characterization Leads to Improved Well and Field Economics in South Texas Eagle Ford Field
Authors: Schubarth Stephen , Gates Bruce , Spies Blaine , Lestz Robert 
Published: January 2022

Abstract
The capital investment required when completing horizontal, unconventional reservoir wells is significant. This capital pays for materials and services which help to improve the productivity and recovery from the well. The goal of our work is to identify the primary drivers in this capital spending that effects productivity and recovery and then optimize the spending to get the most revenue for the least amount of dollars. We will show how through the characterization of reservoir properties and completion effectiveness that we can maximize the profitability of a well and field development without sacrificing recovery or productivity. A case history from beginning evaluation to final results will be presented. Improving oil recovery and economic performance.
Our process begins by estimating key reservoir parameters such as Net Pay, Porosity and Water Saturation. We include the description of reservoir fluid properties. We then analyze the producing history from existing wells and determine formation average permeability, the average effective length of the fractures created along with the number of fractures producing along the lateral. The solution for this becomes unique if we have sufficient producing history. However, engineering judgement can be used to narrow down the potential range of values when sufficient production data is not available. From the results of our production analyses, we can determine the effect of treatment size on resulting effective length of fractures and then using physical based analytical reservoir models we can predict the producing life for wells completed in a wide variety of completion designs. Economics scenarios are then calculated, and the outcome plotted to form a "road map" for the direction of change in completion design that will result in improved economics.
Comparative results are complete from five wells drilled 1000 feet apart. Four were completed using past designs and one with the recommended design to improve economics. The results indicate that the optimized design is performing much like predicted and should produce over 20% more oil over its life while total well cost was reduced. The productivity of all of the wells is very similar. The results seen here agree with other projects where this process has been implemented. We conclude that through accurate reservoir and completion characterization, capital spending can be targeted to enable profitability to be improved significantly.
The methods presented in this work can be applied to every unconventional play to optimize completion capital spending, reducing the capital needed to develop a field by hundreds of millions of dollars, where applicable. This work has been performed in other areas with similar results.
Risk factors for acute brucellosis in patients on the day of admission at selected hospitals of Abbottabad, Pakistan
Authors: Hassan Laiba , Ali Shahzad 
Published: January 2022

Abstract
Brucellosis is a neglected zoonotic disease of ruminants. It causes severe health problems in humans and significant economic loss. Only a limited number of studies have been conducted in Pakistan to determine the prevalence of human brucellosis and related risk factors. The objectives of the current cross-sectional study were to determine the prevalence of anti-Brucella antibodies in sera collected from symptomatic patients at three hospitals of Abbottabad using a commercial slide agglutination test (SAT) and to determine risk factors for brucellosis for these patients. Five hundred blood samples were collected. A questionnaire was filled in for each patient to obtain information on age, gender, living area, brucellosis associated symptoms, pregnancy and abortion history. A total of 13.6% (n=68) patients were found to be SAT positive and in 83.3% (n=57) of these samples Brucella DNA was detected by genus specific BCSP-31 gene using real time PCR. Statistical analysis was performed to determine odd ratios, risk ratios, 95% confidence intervals and P-values. The prevalence of anti-Brucella antibodies was reported to be higher in women (14.6%, n=44) than in man (12.1%, n=24). The age group of 25-50 years was found to be at higher risk for brucellosis (14.5%, n=50). Animal contact was reported as the main risk associated factor followed by consumption of raw animal products. Thirteen pregnant women (9.9%) were found brucellosis positive. Of these, 23.8% (n=5) had an abortion history. The present study reports a striking prevalence of brucellosis among patients including pregnant women at three hospitals of Abbottabad. These findings may foster strategies for controlling human brucellosis at household level, raising of awareness about brucellosis in hospital and family doctors and finally in setting up an eradication program in the dairy industry.
Retina-Inspired Narrowband Perovskite Sensor Array for Panchromatic Imaging
Authors: Wang Kai , Hou Yuchen , Li Junde , Yoon Jungjin , Knoepfel Abbey , Yang Dong , Zheng Luyao , Ye Tao , Ghosh Swaroop , Priya Shashank 
Published: January 2022

Abstract
Retina, a thin layer of tissue, is the essential part of the human visual system that receives light, converts it to neural signal, and transmits it to the brain for visual recognition. The red, green, and blue (R/G/B) cone retina cells are natural narrowband photodetectors (PDs) sensitive to R/G/B lights. Connecting with these R/G/B cone cells, a multilayer neuro-network in the retina provides neuromorphic pre-processing for R/G/B signals before transmitting them to the brain. Inspired by this sophistication, in this study we develop the narrowband (NB) PD imaging sensor that combines the R/G/B perovskite NB sensor array (mimicking the R/G/B cone cells) with a neuromorphic algorithm (mimicking the intermediate network of the retinal system) for high-fidelity panchromatic imaging. Compared to commercial image sensors, we utilize perovskite intrinsic NB PD to exempt the complex optical filter array and thus avoiding issues such as color aliasing, limited quantum efficiency and demosaicing processing. Furthermore, we utilize an asymmetric device configuration to spontaneously collect photocurrent under zero external bias, enabling a power-free photodetection feature. Results of the novel perovskite image sensor along with the machine learning algorithm assisted image information correction, demonstrate a promising device for efficient and intelligent panchromatic imaging.