bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of long-term constant irradiation on retinal glia
Authors: Potapov A. V. , Varakuta E. Yu. , Solonsky A. V. , Logvinov S. V. , Gerasimov A. V. , Svetlik M. V. , Zhdankina A. A. , Gereng E. A. , Petrov I. A. 
Published: January 2024

Aim. To study the response of retinal glial cells to constant irradiation of various intensity and to develop a mathematical model allowing to evaluate the dynamics of damage to radial glial cells and predict their photodamage depending on the duration and intensity of irradiation.Materials and methods. Outbred sexually mature white rats (n = 50) weighing 180–200 g were exposed to constant round-the-clock light (200, 3,500 lux, days 1, 2, 7, 14, 30). The control group consisted of 25 non-irradiated animals. Using semi-thin sections stained with toluidine blue, we counted the number of pycnomorphic cells in the radial glial cells. Ultrastructural changes in the glial cells were studied using the JEM-100 CX-II electron microscope.Results. The study showed that after photodamage, oligodendrocytes and astrocytes were mainly characterized by mitochondrial swelling and expansion of endoplasmic reticulum cisterns. Microglial cells at the late stage of the experiment (day 30) were localized in the inner layers of the retina; their density depended on the intensity of irradiation. The earliest (days 1, 2) changes in the radial glial cells were noted in the subretinal space and were manifested by proliferation of scleral processes and phagocytosis of dead sensorineural cell fragments. The intensification of destructive changes in the radial glial cells led to disturbances in neuron – glia interactions in the retina and a decrease in regeneration of retinal neurons (day 7–14). The developed mathematical model allowed to assess the dynamics of damage to the radial glial cells in the retina and to predict photodamage depending on the duration and intensity of irradiation.Conclusion. Glial responses in the retina after photodamage depend on the intensity and duration of light exposure. As the duration of irradiation increases, degenerative changes in glial cells intensify and are more pronounced after high (3,500 lux) irradiation intensity.
Experimental Investigation Using Low-Frequency Distributed Acoustic Sensing for Two Parallel Propagating Fractures
Authors: Reid T. , Li G. , Zhu D. , Hill A. D. 
Published: January 2024

Abstract
Low-frequency distributed acoustic sensing (LF-DAS) is a diagnostic tool for hydraulic fracture propagation in the far-field using measured values of strain. To understand subsurface conditions with multiple propagating fractures, a laboratory-scale hydraulic fracture experiment was performed to simulate the LF-DAS response to fracture propagation with embedded distributed optical fiber strain sensors under these conditions. The objectives of this research are to generate two hydraulic fractures of known geometry, measure the strain response along distributed fiber sensors embedded in the sample, and use the results to improve interpretations of field LF-DAS data when multiple fractures are approaching an observation well.
The experiment was performed using a transparent 8-inch cube of epoxy with two-parallel radial initial flaws centered in the cube 2.6-inches apart. Fluid was injected into the sample to generate fractures along the initial flaws. The experiment used distributed high-definition fiber optic strain sensors with tight spatial resolutions. The sensors were embedded at two different locations on opposite sides of the initial flaws, serving as observation/monitoring locations. Pressure and fracture propagation were also recorded. This paper presents a workflow to model fracture geometries, and simulate the resulting strain along a fiber optic sensor. We employed finite element modeling to numerically solve the linear elastic equations of equilibrium continuity and stress-strain relationships. The simulation domain includes one-half of the 8-inch epoxy cube with two radial fractures. The measured strains from the experiment were compared to simulation results from the finite element model.
The experimentally derived strain and strain-rate waterfall plots from this experiment show responses to both fractures propagating, while the fracture below took most of the fluid during the experiment. Interestingly, a fracture first began propagating from the upper of the two flaws, but once the lower fracture was initiated, it grew much more than the upper fracture. Both fibers were intercepted by the lower fracture, further verifying the strain signature as a fracture is approaching and intersecting an offset fiber.
The zero-strain-rate method was applied to both fibers to dynamically estimate the propagation of the fracture fronts as they approached the fibers. The fracture growth behavior interpreted with the zero-strain-rate method compared well to the evolving fracture dimensions obtained from video-recording of the fracture geometries. The results from this work can be used in the field to reveal stress shadowing effects of two fractures and further increase our understanding of how LF-DAS can be used in the field to diagnose fracture propagation when multiple fractures are approaching an observation well.
Practical Optimization of Perforation Design with a General Correlation for Proppant and Slurry Transport from the Wellbore
Authors: Dontsov Egor , Ponners Christopher , Torbert Kevin , McClure Mark 
Published: January 2024

Abstract
During plug and perf completion, perforation pressure drop is used to encourage a uniform distribution of flow between clusters by overcoming stress shadowing, stress variability, and nonuniform breakdown pressure. However, proppant inertia, gravitational settling, and perforation erosion contribute to nonuniformity, even with an aggressive limited-entry design. In prior work, Dontsov (2023) developed a correlation for predicting proppant outflow from the wellbore as a function of slurry velocity, perforation phasing, and other parameters. In the present study, the Dontsov (2023) correlation is integrated into a wellbore dynamics simulator capturing key physical processes that control slurry and proppant outflow from the wellbore, such as erosion, stress shadowing, and near-wellbore tortuosity. The simulator is fast running and incorporated into a tool for Monte Carlo uncertainty quantification and design optimization. First, we run a series of sensitivity analysis simulations to evaluate the effect of key model inputs. The simulations demonstrate processes that can cause heel bias, toe bias, or heel/toe bias in the erosion distribution. Next, we apply the tool to analyze field datasets from the Eagle Ford and the Montney. Downhole imaging of erosion data enables model calibration. Calibration is necessary because differences in casing, cement, and formation properties cause differences in erosion behavior and flow distribution. Parameters controlling the magnitude of erosion and stress shadow are modified to match the trends observed from the downhole imaging. After calibration is performed, the model is applied to maximize the uniformity of proppant placement by optimizing perforation phasing, diameter, count, and cluster spacing.
Cementing: The Good, the Bad, and the Isolated - Techniques to Measure Cement Quality and its Impact on Well Performance
Authors: Haustveit Kyle , Haffener Jackson , Young Steven , Dwyer John , Glaze Garrett , Green Brett , Ketter Chris , Williams Tyler , Brinkley Kourtney , Elliott Brendan 
Published: January 2024

Abstract
Cement isolation is considered by some a critical component of effective well completions in horizontal, multi-stage, hydraulically stimulated oil and gas wells. Virtually every new unconventional well includes multiple cement jobs which cost tens to hundreds of thousands of dollars each. As cluster spacing gets tighter, the importance of high-quality cementing becomes even more pronounced, or does it? This paper explores the various diagnostic techniques used to measure cement isolation, including ultrasonic imaging, optical fiber, radioactive tracer, and downhole pressure gauges on sleeve completion assemblies. The paper ties these diagnostic techniques back to well performance for both new completions and refracs.
The study examines multiple US basins and reveals that the necessity of high-quality cement isolation is potentially related to the size of the annulus being cemented. Smaller annuli are more difficult to cement due to higher Equivalent Circulating Densities (ECDs) caused by friction, but well performance may be less impacted by poor cement in these scenarios because the large pressure drop in the annulus during stimulation contains much of the stimulation in and around the intended interval. However, this does not mean that poor cementing in smaller annuli can be overlooked, as it can still have an impact on well performance.
The paper presents case studies that evaluate the importance of cement isolation in both new completions and refracs with various annulus sizes and well spacings. The findings are applicable to cemented laterals completed with multi-stage stimulations in oil and gas reservoirs as well as in enhanced geothermal applications, where effective fracture uniformity is one key to performance.
Overall, this paper provides valuable insights into the importance of cement isolation in horizontal, multi-stage, hydraulically stimulated oil and gas wells. It emphasizes the need for accurate diagnostic techniques to measure cement isolation and the importance of high-quality cementing to ensure optimal well performance.
Time-Dependent Integration of Fiber Optic Results with Post-Treatment Rate Transient Analysis
Authors: Bourdon N. M. , Miskimins J. L. , Rich J. P. 
Published: January 2024

Summary
A long-term monitoring project included collection of fiber-optic data in one well of a multi-well development for the first few years of production. We demonstrate a benefit to including the fiber data in rate transient analysis (RTA). The fiber data also reveals communication between stages along the monitored well and communication with the offset wells. We use a calibrated hydraulic fracture model to simulate fracture stimulation of wells in the development. Fiber data gathered at the time of stimulation included both distributed acoustic sensing (DAS) and distributed temperature sensing (DTS). Additionally, DTS was acquired over two years of production and used to help calibrate the model and associated RTA. For comparison purposes, RTA was performed on the wells with and without consideration of the DTS data to quantify the benefit of including the fiber data. We conclude that the fiber data was highly beneficial in both the fracture propagation modeling and the resulting RTA process. The time-lapse data allowed for visual interpretation of how the flow behavior of different stimulation stages along the lateral are not constant. Early time heel or toe dominance can, and likely will, disappear over time. The data also indicates that the child wells were in communication with each other at varying levels during treatment and post-production. We provide a workflow for incorporating these varied data to provide a long-term overview of multi-well production and interference behavior. Additionally, we provide insight on the use of years of DTS datasets for unconventional wells, which are still relatively rare in the literature.
Optimizing Stage Lengths by Leveraging Fracture Interference
Authors: Rodgers Evan , Williams Tony , Rittenburg Dylan , Lawrence Matthew 
Published: January 2024

Objectives/Scope
This paper covers a case study in the Denver-Julesburg (DJ) Basin that reveals stage lengths can be dynamically varied when wells are tightly spaced to optimize pad drainage and completion cost in homogeneous rock strata. Alternating stage designs in offset wells can support increased stage lengths up to 6x standard (exceeding 1,000 ft) and still treat and produce as uniformly as smaller stages, due to the cooperative effect of the overlapping fracture network created by neighboring infill wells. These findings were corroborated by fiber optic data acquired during frac (cross-well strain) and post-flowback production monitoring and interference testing. We also observed Formations within damage zones altered from faults can affect drainage results.

Methods, Procedures, Process
Differing stage lengths (X, 2X, 3X and 6X) were trialed in three wells in a six well section. Fiber optic diagnostics were acquired during frac for cross-well strain evaluation and 60 days post-flowback for production monitoring and interference testing. Locations and extent of fracture interactions were observed during the fracturing process, and later compared to the production and interference testing results after flowback.

Results, Observations, Conclusions
The post-completion diagnostics corroborated the during frac cross-well strain data. Interference testing reveals communication as well as unique geological features in the areas identified by the cross-well strain data. There is little if any difference in cross-well strain or production behavior of standard-length X stages offset by X stage lengths and X offset by 2X or 3X stage lengths. Performance of the 3X and 6X stages is nearly identical to the X stage lengths, in both production and interference from a uniformity and production volume.

Novel/Additive Information
When wells are known to interfere or communicate, completion designs can be modified dynamically to work with overlapping stage designs, optimizing completion costs without sacrificing treatment uniformity nor production. Stage lengths of offset wells, depending on the play and geologic structure, may be dramatically larger than previously thought when offset against smaller stages, while still allowing for sufficient reservoir access and drainage, leading to reduced pad development time.
Validation of Conductive Fracture Imaging with Cross Well Strain and Permanent Fiber Optic Flow Profiling
Authors: Reshetnikov A. , Taylor S. , Nazarova A. , Haffener J. 
Published: January 2024

Abstract
The study applies Conductive Fracture Imaging (CFI) on Hydraulic Fracturing Test Site-2 in the Delaware Basin, USA, acquired in 2019. The CFI results are independently delivered and compared with strain data recorded by permanent distributed fiber optic sensor arrays in a vertical data well (the Boxwood 5PH) and two horizontal wells (Boxwood 3H and Boxwood 4H). Boxwood 4H's permanent fiber provides Distributed Acoustic Sensing (DAS) cluster flow and proppant allocation analytics, as well as distributed strain sensing (DSS) for cluster level shut-in pressure build-up tests.
The objective of this study is to directly compare CFI results with in-well DAS and DSS fiber optic measurements. CFI utilizes microseismic events as active sources for reflection imaging of the conductive portion of hydraulic fractures, offering high-resolution images of the seismically active zone for precise description of cluster level fluid allocation and conductivity.
CFI has been benchmarked successfully against established fiber optic diagnostics, providing insights into conductive fracture geometries, cluster efficiencies, and in-well production flow profiling. Key advantages of CFI include imaging fluid and proppant allocation at the cluster level, offering a four-dimensional view of dynamic transport, estimating fracture height, and providing valuable data on hydraulic and conductive fracture geometries.
The study reveals strong correlations between CFI and cross-well strain intensity measured by fiber monitors, as well as good agreement with in-well DAS stimulation fluid allocation. Furthermore, CFI shows clear correlations with cluster level DSS strain changes during the production phase, accurately resolving cluster positions along the wellbore. Cluster level reflectivity values from CFI demonstrate a robust agreement with DSS strain change peak values observed on the same clusters.
Hydraulic Fracturing Design Considerations for Carbon Capture, Utilization, and Storage (CCUS)
Authors: Sierra Leopoldo , Lovingfoss Connor 
Published: January 2024

Abstract
Hydraulic fracturing, a well-established technique in the oil and gas industry, has gained significant attention as a potential method to improve the short- and long-term efficiency of the Carbon Capture, Utilization, and Storage (CCUS) process. Most of the scoping studies on CCUS have centered on the reservoir aspects, such as storage and CO2 movement. Very little has been done evaluating what the fracture designs might look like in this process.
This paper presents a review of the application of hydraulic fracturing in CCUS projects, examining its technical feasibility, fluids, sustaining agents, wellbore orientation, and fracture orientation considerations required to assure its technical and economic success. It will consider rock properties, depleted oil or gas reservoirs conditions, or deep saline aquifers horizons and compressed CO2 supply at the storage site; simulations have been performed using primarily super critical CO2 (scCO2) and conventional fluids to perform the hydraulic fracturing. In addition to the sCO2 usage and proppants required to tail the generated fractures; the wellbore orientation effect in reference to the stress plane is also considered in the paper.
Finally the short- and long-term benefit of the hydraulic fracturing will be evaluated by simulating the CO2 injection behavior.
The review encompasses an analysis of the various key stages involved in CCUS hydraulic fracturing process, starting from the review of rock properties, wellbore orientation, perforation strategy, selection of suitable fluid and propping agents for efficient and safe stimulation of a well candidate. The potential benefits of the proper hydraulic fracturing process implementation will be translated in an enhanced storage capacity and improved injectivity.
The extensive simulations considering the sCO2 as the primary fluid system for fracturing purposes, combined with the wellbore orientation and other parameters will show the direct benefit of the combinations of the hydraulic fracturing and the CCUS processes, including: The use of sCO2 and proppants for hydraulic fracturing purposes in CCUSThe influence of the wellbore and hydraulic fracture orientation in the success of the CCUS process
The paper aims to explore the potential of CCUS in conjunction with hydraulic fracturing to increase the efficiency of CO2 disposal and analyze methods to maximize its effectiveness. It will be beneficial for those contemplating CCUS, complementing other CCUS evaluations to provide a more complete picture of the feasibility as well as technical hurdles that must be overcome to implement this concept.
Evaluation of a Rapid Diagnostic Tool to Estimate Geometry Evolution of Multiple Simultaneously Propagating Fractures from Cross-Well Fiber Optic Strain Measurements
Authors: Leggett Smith , Chen Ming 
Published: January 2024

Abstract
Cross-well low-frequency distributed acoustic sensing (LF-DAS) strain rate measurements generate data useful for hydraulic fracture diagnostics. These data contain information about hydraulic fracture geometry; however, interpreting the data has relied on time-consuming and computationally expensive numerical interpretation methods. This study aims to evaluate the applicability of a rapid diagnostic tool, known as the "zero strain rate location method" (ZSRLM), for characterizing the geometry of multiple fractures propagating simultaneously.
Simulations of multiple fracture propagation are conducted using a planar 3D multi-fracture simulator that incorporates 3D rock deformation, fluid flow in the wellbore, fluid leak-off, and multi-scale fracture propagation regimes. A super-time-stepping algorithm is employed to solve the nonlinear parabolic equations governing fluid-driven fractures. The far-field strain profile induced by multiple propagating fractures along a cross-well fiber optic cable is computed using the displacement discontinuity method. Various scenarios are simulated by adjusting key completion parameters, including the number of clusters, cluster spacing, in-situ stress states, and geomechanical properties. The ZSRLM is then applied to the computed strain field to estimate fracture extents and propagation rates. The accuracy of the ZSRLM is assessed by comparing the estimated fracture geometry parameters with the known simulated values.
Our observations indicate that the ZSRLM is not effective when two or more fractures approach the observation well at similar times, as it becomes challenging to discern unique strain-rate converging patterns on waterfall plots for each fracture. However, when fracture arrivals at the monitor well are offset, distinct strain rate patterns emerge, enabling the application of the ZSRLM. Errors between simulated and estimated fracture extent propagation rates are quantified. Finally, the ZSRLM is applied to a field case involving multi-cluster fracture propagation, and the interpretation of the results is discussed in light of these findings.
This research demonstrates the applicability of the ZSRLM for diagnosing the velocities and final extents of multiple fractures propagating simultaneously. The method offers a rapid means of characterizing stimulations using cross-well LF-DAS measurements, which can inform decisions regarding completion design, well spacing, and landing zone. The study contributes to the advancement of efficient fracture diagnostics in the industry, reducing the reliance numerical interpretation methods.
Hybrid Long Short-Term Memory and Convolutional Neural Network Architecture for Electric Submersible Pump Condition Prediction and Diagnosis
Authors: Liu DongJiang , Feng Guoqiang , Feng Guoyong , Xie Lijie 
Published: January 2024

Summary
Electric submersible pump (ESP) is one of the common artificial lift technologies in offshore production systems. ESP failures are the main cause of the decline in the production efficiency of oil wells. Early warning and diagnosis of ESP failures are crucial to improve well production efficiency. In this study, a hybrid model of long short-term memory neural network and convolutional neural network (LSTM-CNN) for accurate early warning and diagnosis of ESP faults is proposed, based on electrical data as the basis of analysis. Using hyper-parameters to optimize the LSTM neural network structure and highly fit the field electrical data so that it can be applied to anomaly prediction before ESP faults, the results show that the optimized LSTM model with R2 (test set) = 0.79, root mean square error (RMSE) (test set) = 0.89, which can predict the future electrical data more accurately, and the predicted data are plotted in the polar coordinate system to simulate the ammeter card as the validation set. The ammeter card data set is simulated by collecting electrical data from different working conditions, which is expanded using data expansion, and different CNN models are trained to fine-tune the parameters using transfer learning. The results show that the GoogLeNet model has a significant diagnostic accuracy of 97%, which is 2% and 18% better than VGG16 and ResNet34, respectively. The model evaluation shows that the GoogLeNet model has good recall, F1-Score, and confusion matrix. The trained GoogLeNet model was applied to the validation set, and the hybrid LSTM-GoogLeNet model was found to be well-suited for ESP warning and diagnosis.