bluuebunny/crossref_metadata_2025_split huggingface dataset:
Well Productivity Improvement Using Radial Jet Drilling
Authors: Ashena Rahman , Mehrara Reza , Ghalambor Ali 
Published: February 2020

Abstract
Radial Jet Drilling (RJD) is an unconventional drilling technique using the jet energy of high velocity fluids to drill laterals into the reservoir formation as an alternative to the traditional stimulation technique. In this subject case study, the productivity index in a Middle Eastern well had dramatically declined due to the excessive observed bottomhole pressures. In order to improve the production conditions, a workover operation was recommended using the state-of-the-art RJD technique. The paper explains the stepwise job procedure in the drilling well plan and operations. The production conditions were compared prior to and following the RJD. Finally, the reasons for the limited success of the operation and the lessons learned for guarantying future jobs success are provided.
For the RJD perforation in the well, two assembly runs were required: 1) running the RJD assembly consisting of 5/8-in drill bit, the mud motor and the coiled tubing pipe through the drill pipe, in order to open the window in the casing, and 2) running the jet nozzle assembly (no rotation) below the coiled tubing pipe in order to drill into the formation and extend the laterals to the projected lateral depth. Following the review of these procedures and operations, the paper makes a comparison between the plan and the real experience and provides the reasons for the discrepancies.
The number of 14 lateral holes (six holes of 131 ft(40 m) lateral depth and eight holes of 65 ft(20 m) lateral depth) with the aperture size of 0.25 inch, were planned to be drilled by RJD. In practice, the number of only eight laterals of different length ranging 34–65 ft(9–20 m), were drilled due to improper design and operational challenges. Comparing the production conditions following the workover with the previous production conditions, a productivity enhancement of 50% was observed with RJD drilling. However, the operation had several drawbacks: the number of the drilled laterals was less than planned, their penetrated length of the laterals was lower than the planned, and the duration of the well drilling was also greater than the planned rig time. Therefore, the operations was a limited success overall. This is attributed to the smaller coiled-tubing size selected, the performance of the jet nozzle used, and the inexperience of the personnel, among other factors.
The paper provides the dos and don'ts of RJD, as the first application of RJD in this field and the lessons learned from the field practice, future wells can be drilled with great enough number of laterals, their penetration length and lower cost. Therefore, the planned well productivity would be further enhanced, thereby, full success from the application of the RJD technique can be achieved.
Lessons Learned to Avoid Formation Damage Development During Waste Slurry Injection Operations
Authors: Panchal Yashesh , Sameh Omar , Mounir Nihal , Shams Mahmoud , Mohamed Ibrahim , Abou-Sayed Omar , Abou-Sayed Ahmed 
Published: February 2020

Abstract
The injection of oil and gas wastes produced during the exploration and production phases have been proven to be an effective technique toward achieving zero discharge. However, several challenges are associated with the injection of slurry into an underground formation. The most common challenge during waste slurry injection (WSI) is the continuous loss of well injectivity due to poor engineering design of the injection parameters for most of the current existing WSI wells.
For the WSI operation, near wellbore formation damage (including the fracture damage) will be formed by the injected solids. The real time injection monitoring of the ongoing operations is important to correct any operational mistake and adjust the injection parameters in order to ensure the well longevity.
The paper discusses the importance of injection monitoring and steps necessary to maintain the injectivity and perform a healthy WSI operation. Three different case studies are presented to highlight the operational mistakes that caused a significant formation damage development in injectors in Eagle Ford, Haynesville, and Permian Basin shale plays. Certain guidelines depending on the monitoring results are provided in modifying the slurry rheology, pressure, injection strategy etc. that are helpful in maintaining the injectivity. The presented case studies show that the wells with good monitoring program maintained its injectivity during the course of its operation compared to the other wells that lost its injectivity sooner.
The results from different case studies are used to prepare a set of guidelines that can be used to maintain the well injectivity and extend the well life. This paper discusses the techniques that will help in eliminating and avoiding the problems leading to formation damage and well plugging during the WSI operation.
Removing Scale Damage with Fast-Acting Anhydrite CaSO4 Removal System
Authors: Reyes-Garcia Enrique , Holan Kristina 
Published: February 2020

Abstract
The development of a highly efficient calcium sulfate (CaSO4) scale removal fluid containing a first-of-its class dissolver system is presented. Common CaSO4 scale dissolvers require chelant(s) along with scale converters. A drawback of this type of dissolver is that removal of anhydrite represents a problem if extended shut-in periods are necessary. To help minimize the nonproductive time (NPT) necessary to dissolve CaSO4, a solution has been identified that can restore production within two hours or less and is field-proven.
Mineral anhydrite and gypsum samples were exposed to dissolver formulations at 200°F under static conditions, from one hour up to 24 hours. Dissolution kinetics investigation indicates that the limiting step is a substitution surface process that catalyzes the reaction. The formulation was generated based on the discrete chemical activities of individual components with respect to anhydrite, and then refined against a performance-based design of experiments (DoE). Various chemical agents were tested for activity as a function of the chemical functionality (i.e., carboxylate, halide, etc.). Combining the results from multiple design spaces allowed determination of the most desirable formulation.
A customized performance methodology was implemented to rapidly identify formulations having a dissolution efficiency exceeding 70% within one hour, followed by a targeted design space aiming for 90% dissolution of actual wellbore anhydrite scale. All tests were conducted with low surface area samples cut from mined substrates for the purpose of experimental designs while wellbore scale was used to validate the formulation efficacy. Elemental analysis of gypsum and anhydrite dissolution products over time was conducted to elucidate kinetic parameters at 150 and 200°F from 1 to 24 hours. The dissolution of anhydrite as a function of time, at 150 and 200°F, showed limiting effect dependency as a function of scale converter concentration. Mass of scale to volume of dissolver fluid effects indicate a dependence on the converter concentration while temperature had the most significant effect. Formulations showed 60-80% dissolution in one hour using anhydrite. This signifies that wellbore and equipment clean out can be accomplished with a simple, non-corrosive treatment fluid when the mineral is of the CaSO4 type. Field trials have been conducted, demonstrating the efficacy of the fluid.
The anhydrite dissolver formulation provides mineral dissolution within one hour under conditions representative of a wellbore, such as static fluid column and temperatures of 200°F. The treatment is delivered as a one-fluid system, or single treatment design, whereas a majority of existing treatments require multiple fluids providing protection to downhole equipment such as electro submersible pumps (ESP). The new system functions without the need for prolonged well shut-ins or the use of complicated treatment fluid designs.
The Impact of Contractional Flow on the Extensional Viscosity of Polyacrylamide Polymers in Fracturing Applications
Authors: Fischer Christine , Constien Vernon , Cage Brad 
Published: February 2020

Abstract
High molecular weight polyacrylamide polymers have been used for many years in water floods for enhanced oil recovery (EOR) and as friction reducers in hydraulic fracturing. More recently, so called "high viscosity" versions of these polymers are being used in fracturing operations for friction reduction and also for fracture creation and proppant transport (Hu, 2018). These polymers have more complex viscous properties than materials such as guar gum or cellulose. In addition to the typical shear thinning behavior (shear viscosity), they also may have extensional viscosity thickening in convergent geometries. Separating and quantifying these properties for polyacrylamide polymers is difficult but is needed to predict their behavior not only for flow in porous media but for slot flow in hydraulic fracturing applications.
Extensional viscosity in polyacrylamide polymers may be generated in a flow field that experiences a sudden change in geometry such as a contraction. The elongational flow triggers a transition in the conformation of the molecule from a coiled to a stretched state. This conformation change can result in a sudden change in resistance to flow of several magnitudes. Screen-factor measurement used in determining the resistance factor for polymers in EOR applications have been shown to have components of both shear thinning viscosity and extensional viscosity (Lim, 1986).
A technique has been developed using contraction flow which can separate shear viscosity from apparent extensional viscosity. The contraction flow technique is useful in determining the effect on the extensional viscosity as a result of changes in molecular weight, copolymer composition, salt effects and shear degradation of polyacrylamide polymers. Examples are given which illustrate how the results are quite useful in the selection of appropriate polymers for fracturing or water flood operations.
While the extensional properties are known and the effects of the change in extensional viscosity have been better defined for flow in porous media, the definition and change in these properties have not previously been well defined for fracturing applications. Particularly, the duration of the extensional viscosity change and the effect of extensional viscosity on proppant transport and fracture geometry have not been determined.
New High Viscosity Friction Reducers for Proppant Transport in Hydraulic Fracturing
Authors: Song Jingshe , Navarrete Reinaldo , Asadi Mahmoud , Jin Bryan 
Published: February 2020

Abstract
The use of high viscosity friction reducers (HVFRs) has increased rapidly as replacements for linear and even crosslinked guar-based fluids for proppant transport in hydraulic fracturing. HVFRs at high loadings have significantly higher fluid viscosities than conventional friction reducers (FRs). However, the efficiency of current HVFRs is still limited. The primary objective of this study is to compare proppant transport performance of newly developed HVFRs with commercial HVFRs and guar-based systems.
Several test protocols were performed for investigating the proppant transport efficiency of HVFR systems. Five HVFRs with different structures were prepared using the inverse emulsion polymerization technique. The viscosity of these five HVFRs and a commercial HVFR were measured and compared across a wide range of concentrations under various shear rates using a rheometer with a concentric cylinder geometry. Proppant transport performance was assessed using static proppant settling tests. A conventional linear guar-based gel was also tested and compared as a reference.
Several HVFRs were tested in the laboratory. The results show that using only high shear viscosity as an indicator of proppant transport performance is not appropriate. Low shear rate viscosity is a better indicator of proppant transport. Static settling tests are a good testing method to compare the proppant transport performance of different HVFRs. The structure of HVFRs was found to be critical to the viscosity and proppant transport performance. The chemical structures of HVFRs were optimized in the laboratory. The testing results show that the newly developed HVFRs have higher viscosity and better proppant transport performance than the commercial HVFR and linear guar-based gel systems tested.
This paper provides a comprehensive study of HVFRs as replacements for linear and crosslinked guar-based systems. This study shows the effects of polymer structural features, such as charge, size and water salinity on proppant transport performance.
A Novel Relative Permeability Modifier Polymer
Authors: Yang Chao , Navarrete Reinaldo , Asadi Mahmoud 
Published: February 2020

Abstract
A novel branched synthetic polymer capable of changing the relative permeability of water and oil in a formation was developed. The new polymer has the capacity to anchor to the sandstone formation, allowing it to endure production fluid flow.
Thermal aging tests were conducted to evaluate the thermal stability. Gravity column tests were established as a screening method to evaluate the polymer's capacity to impair water flow and to anchor to the formation. Laboratory core flow tests were conducted using sandstone cores plugs with an air permeability of 0.8 to 5 Darcies at 200°F. The polymer was evaluated as a near wellbore treatment and as a far field treatment by altering the injection direction of the polymer slug.
Results indicate that the polymer can reduce the permeability to water without significantly impairing the permeability to oil. The regain relative water permeability was less than 20% after the injection of a relative permeability modifier (RPM) polymer. The subsequent regain relative oil permeability was above 75% and the regain relative water permeability was less than 30% after the oil injection. Results also showed that the RPM polymer had similar performance regardless of the injection direction used. Moreover, pre-flushing the core with mutual solvent and surfactants before the polymer treatment did not have a significant effect on the performance of the polymer.
The capacity to selectively modify the water permeability makes it feasible to use this polymer in a near wellbore or in a far field treatment to reduce excessive water production. Moreover, the polymer can be applied without the use of a mutual solvent and surfactants, thereby reducing treatment costs.
Non-Monotonic Retention Profiles of Suspended Particles Under Water Injection
Authors: Khazali Nastaran , Malgaresi Gabriel , Bedrikovetsky Pavel 
Published: February 2020

Abstract
Injection of water with particles distributed by various features (size, shape, density, surface charge, Z-potential) can highly affect the retention profile (RP) of suspended particles. The main objective of this study is to investigate non-monotonic retention profiles (NRPs) during the axi-symmetric flow of size-distributed colloids and accordingly, predict injectivity decline reliably. For this target to be achieved, coreflooding is performed by water with particles that are distributed by sizes. The results obtained by implementing derived exact upscaled equations of colloidal transport for multi-component particle population closely match by the experimental data monitored during the flood provided that the model coefficients are determined from the tuning. Altogether, four tests are conducted from which breakthrough curves (BTCs) and retention profiles in three moments can be observed. The observed close match proves the accurate representation of the mathematical model in all tests due to the higher number of degrees of freedom of the experimental data array compared to the number of tuned model parameters.
Application of Standardised Effect Sizes to Hospital Discharge Outcomes for People with Diabetes
Authors: Robbins Tim David , Keung Sarah N. Lim Choi , Sankar Sailesh , Randeva Harpal , Arvanitis Theodoros N. 
Published: February 2020

Abstract
Background: Patients with diabetes are at an increased risk of readmission and mortality when discharged from hospital. Existing research identifies statistically significant risk factors that are thought to underpin these outcomes. Increasingly, these risk factors are being used to create risk prediction models, and target risk modifying interventions. These risk factors are typically reported in the literature accompanied by unstandardized effect sizes, which makes comparisons difficult. We demonstrate an assessment of variation between standardised effect sizes for such risk factors across care outcomes and patient cohorts. Such an approach will support development of more rigorous risk stratification tools and better targeting of intervention measures.
Methods: Data was extracted from the electronic health record of a major tertiary referral centre, over a 3-year period, for all patients discharged from hospital with a concurrent diagnosis of diabetes mellitus. Risk factors selected for extraction were pre-specified according to a systematic review of the research literature. Standardised effect sizes were calculated for all statistically significant risk factors, and compared across patient cohorts and both readmission & mortality outcome measures.
Results: Data was extracted for 46,357 distinct admissions patients, creating a large dataset of approximately 10,281,400 data points. The calculation of standardized effect size measures allowed direct comparison. Effect sizes were noted to be larger for mortality compared to readmission, as well as for being larger for surgical and type 1 diabetes cohorts of patients.
Conclusions: The calculation of standardised effect sizes is an important step in evaluating risk factors for healthcare events. This will improve our understanding of risk and support the development of more effective risk stratification tools to support patients to make better informed decisions at discharge from hospital.
neoANT-HILL: an integrated tool for identification of potential neoantigens
Authors: Coelho Ana Carolina , Fonseca Andre , Martins Danilo , Lins Paulo , Cunha Lucas da , de Souza Sandro 
Published: February 2020

Abstract
Background: Cancer neoantigens have attracted great interest in immunotherapy due to their capacity to elicit antitumoral responses. These molecules arise from somatic mutations in cancer cells, resulting in alterations on the original protein. Neoantigens identification remains a challenging task due largely to a high rate of false-positives. Results: We have developed an efficient and automated pipeline for the identification of potential neoantigens. neoANT-HILL integrates several immunogenomic analyses to improve neoantigen detection from Next Generation Sequence (NGS) data. The pipeline has been compiled in a pre-built Docker image such that minimal computational background is required for download and setup. NeoANT-HILL was applied in The Cancer Genome Atlas (TCGA) melanoma dataset and found several putative neoantigens including ones derived from the recurrent RAC1:P29S and SERPINB3:E250K mutations. neoANT-HILL was also used to identify potential neoantigens in RNA-Seq data with a high sensitivity and specificity.Conclusion: neoANT-HILL is a user-friendly tool with a graphical interface that performs neoantigens prediction efficiently. neoANT-HILL is able to process multiple samples, provides several binding predictors, enables quantification of tumor-infiltrating immune cells and considers RNA-Seq data for identifying potential neoantigens. The software is available through github at https://github.com/neoanthill/neoANT-HILL.
DNA methylation regulates glioma cell cycle through down-regulating MiR-133a expression
Authors: Liu Liang , Zhu Zhengquan , Li Xu , Zheng Yong 
Published: February 2020

Abstract
Background: MiRNAs plays a key role in regulating gene expression networks of various biological processes in many cancers.
Results: Here, we analyzed miRNA expression profiles by miRNA microarray and verified by RT-PCR. It was shown that the expression difference of miR-133a was most significantly and consistently downregulated. The proliferative capacity and cell cycle profile of cells transfected with miR-133a mimic were assessed by colony forming assay and PI staining, respectively. The target gene of miR-133a was predicted using TargetScan and verified by dual luciferase gene reporter assay. Western blotting and RT-PCR were used to analyze the expression levels of relevant factors. Methylation-specific quantitative PCR (MSP) was used to detect miR-133a methylation levels. Epigenetic regulation of miR-133a was assessed by treating the cells with the DNA methyltransferase inhibitor AZA or the histone deacetylase inhibitor TSA. We found that overexpression of miR-133a inhibited cell proliferation, induced a cell cycle arrest and downregulated the expression of Cyclin D1, Cyclin D2, and cycling-dependent killdeer 4 (CdK4). Peroxisome proliferator-activated receptor γ (PPARγ) was verified as a target gene of miR-133a. PPARγ protein levels were significantly higher in the glioma tissues, and overexpression of miR-133a markedly reduced its levels. Furthermore, forced expression of PPARγ partly abrogated the anti-proliferative effects of miR-133a. miR-133a was hypermethylated in glioma cells, and AZA treatment significantly up-regulated its levels.
Conclusions: MiR-133a is downregulated in glioma cells through promoter hypermethylation, and its forced expression inhibits glioma cell proliferation and induces G1 phase arrest by targeting PPARγ.
A simple monochromatic flow cytometric assay for assessment of intraerythrocytic development of Plasmodium falciparum
Authors: Kulkeaw Kasem , Ketprasit Nutpakal , Tungtrongchitr Anchalee , Palasuwan Duangdao 
Published: February 2020

Abstract
Background Gold standard microscopic examination of Plasmodium falciparum intraerythrocytic stage remains an important process for staging and enumerating parasitized erythrocytes in culture; however, microscopy is laborious and its accuracy is dependent upon the skill of the examiner. Methods In this study, ViSafe Green (VSG), which is a nucleic acid-binding fluorescent dye, was used for assessing in vitro development of P. falciparum using flow cytometry. Results Fluorescence intensity of VSG was found to depend on the developmental stage of parasites. Specifically, multiple-nuclei-containing schizonts were observed in the VSGhigh population, and growing trophozoites and ring-shaped forms were observed in the VSGintermediate and VSGlow populations. The efficacy of VSG-based assay was found to be comparable to the microscopic examination method, and it demonstrated an ability to detect as low as 0.001% of the parasitaemia estimated by Giemsa staining. Moreover, when applying VSG for anti-malarial drug test, it was able to observe the growth inhibitory effect of dihydroartemisinin, the front-line drug for malaria therapy. Conclusions Taken together, the results of this study suggest the VSG-based flow cytometric assay to be a simple and reliable assay for assessing P. falciparum malaria development in vitro.