bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Vertical Permeability and Its Influence on CO2 EOR and Storage in a Carbonate Reservoir
Authors: Ren Bo , Jensen Jerry , Lake Larry , Duncan Ian , Male Frank 
Published: September 2021

Abstract
The objective of this study is to improve understanding of the geostatistics of vertical (bed-normal) permeability (kz) and its influence on reservoir performance during CO2 enhanced oil recovery (EOR) and storage. kz is scrutinized far less often than horizontal permeability (kx, ky) in most geological and reservoir modeling. However, our work indicates that it is equally important to understand kz characteristics to better evaluate their influence on CO2 EOR and storage performance prediction.
We conducted this study on about 9,000 whole-core triaxial permeability (kx, ky, kz) measurements from 42 wells in a San Andres carbonate reservoir. We analyzed kz data, including heterogeneity, correlation, and sample sufficiency measures. We analyzed wells with the largest and smallest fractions of points with kz &gt; kmax = max(kx, ky), to explore geological factors that coincided with large kz. We quantified these geological effects through conditional probabilities on potential permeability barriers (e.g., stylolites).
Every well had at least some whole-cores where kz &gt; kmax. This is a statistically justifiable result; only where Prob(kz &gt; kmax) is statistically different from 1/3 are core samples non-isotropic. In conventional core data interpretation, however, modelers usually assume kz is less than kmax. For the well with the smallest fraction (11%) of cores where kz &gt; kmax, the cumulative distribution functions differ and coincides with the presence of stylolites. We found that kz is about twice as variable as kx in many wells. This makes kz more difficult to interpret because it was (and usually is) heavily undersampled.
To understand the influence of kz heterogeneity on CO2 flow, we built a series of flow simulation models that captured these geostatistical characteristics of permeability, while considering kz realizations, flow regimes (e.g., buoyant flow), CO2 injection strategies, and reservoir heterogeneity. CO2 flow simulations showed that, for viscous flow, assuming variable kx similar to the reservoir along with a constant kz/kx = 0.1 yields a close (within 0.5%) cumulative oil production to the simulation case with both kx and kz as uncorrelated variables. However, for buoyant flow, oil production differs by 10% (at 2.0 hydrocarbon pore volume HCPV of CO2 injected) between the two cases. Such flows could occur for small CO2 injection rates and long injection times, in interwell regions, and/or with vertically permeable conduits.
Our geostatistical characterization demonstrates the controls on kz in a carbonate reservoir and how to improve conventional interpretation practices. This study can help CO2 EOR and storage operators refine injection development programs, particularly for reservoirs where buoyant flow exists. More broadly, the findings potentially apply to other similar subsurface buoyancy-driven flow displacements, including hydrogen storage, geothermal production, and aquifer CO2 sequestration.
Improved Prediction of Sand Erosion by Accurate Particle Shape Representation in CFD-DEM Modelling
Authors: Agrawal Madhusuden , Haghnegahdar Ahmadreza , Bharadwaj Rahul 
Published: September 2021

Abstract
Predicting accurate erosion rate due to sand particles in oil and gas production is important for maintaining safe and reliable operations while maximizing output efficiency. Computational Fluid Dynamic (CFD) is a powerful tool for erosion prediction as it provides detailed erosion pattern in complex geometry. In an effort to improve accuracy of erosion prediction, this paper proposes an algorithm to accurately represent particle shape in CFD erosion simulation through coupling with Discrete Element Method (DEM) for non-spherical shape particles. The fluid motions are predicted by CFD and the particle movements (including particle-particle and particle-wall collisions) and fluid-particle interaction are calculated using DEM.
It is widely known that sand particles are of finite volume with a non-spherical shape, accurate representation of sand particles is important in CFD modelling for accurate prediction of erosion rate. Traditional CFD approach usages lagrangian tracking of sand particles through Discrete Phase Model (DPM), where a particle is assumed as a point mass for the calculation of trajectory and particle-wall interaction. Particle impact velocity and impact angle are important parameter in determining erosion. Assumption of point mass in DPM approach, will not capture particle-wall interaction accurately especially when particles are of non-spherical in shape. In additional, DPM approach ignores particle-particle interactions. This can adversary affect the accuracy of erosion predictions. Integrating non-spherical DEM collision algorithm with CFD erosion simulation, will overcome these limitations and improve erosion predictions.
Benefits of this CFD-DEM erosion modelling was demonstrated for gas-solid flow in a 2" pipework which consists of out-of-plane elbows in series and blind-tees. Experimental dataset [1] for erosion pattern on each elbow was used to validate CFD predictions. Three different erosion CFD simulations were performed, traditional DPM based CFD simulation, CFD-DEM simulation for spherical shape particles and CFD-DEM simulation for non-spherical shape particles. CFD-DEM coupled simulations clearly show an improvement on erosion predictions compared to DPM based CFD simulation. Effect of non-spherical shape on rebound angle during particle-wall collision is captured accurately in CFD-DEM simulation. CFD-DEM simulation using non-spherical particle, was able to predict erosion pattern closer to experimental observations.
This paper will demonstrate an increase in accuracy of sand erosion prediction by integrating DEM collision algorithm in CFD modelling. The prediction results of elbow erosion subject to a condition of dilute gas-particle flow are validated against experimental data. Improved prediction of erosion risk will increase the safety and reliability of oil & gas operations, while maximizing output efficiency.
Development of a Mentoring Program as a Strategy for the Empowerment of Young Professionals in the Strengthening of Their Soft Skills
Authors: Ovalle Oscar , Estepa Claribeth , Hoyos Maria , Diaz Claudia , Jaramillo Sandra , Rada Angelica , Pastor Paola 
Published: September 2021

Abstract

Objectives/Scope
Contribute to the development of the profile of young professionals based on a balance between personal and work life, strengthening the self-confidence of the individual and leaving aside the influence of personal aspects in the professional field. Provide a deeper vision of their personal objectives from the discovery of the personality and the strengthening of soft skills by implementing an innovative methodology

Methods, Procedures, Process
The program implements a structured, simplified and staggered methodology for the identified needs, attracting qualified young people and matching them with the most appropriate mentors, ensuring that throughout the mentoring process, a different focus and objective with the necessary durability is worked session by session. With the development of three books, SPE Colombia Section provides all the necessary tools to work on different aspects, objectives and evaluate the learning that takes place in each session, which are:
Mentor-Mentee connection Strengthening your profile Leadership and decision making Breaking paradigms and overcoming obstacles Evaluating learning.
In its two versions, the program has had the participation of 92 young professionals and 92 Seniors in total. It has managed to obtain a satisfaction level of 92% and has met the goals of the young people by 88%. More than 300 sessions and 500 hours of mentoring have been carried out. 10 training talks have been held for mentors and mentees. 3 guide books for mentor and mentee with all activities and minimum requirements per session. The Mentoring program works for different purposes, especially based on the age and needs of the individual". It is a unique relationship between individuals. There is no equal mentoring, different interpersonal exchanges and patterns of idiosyncratic interactions define and shape the relationship. However, two main contributions emerge for the mentee: 1) As a space in itself for the exploration of ideas and to receive support of different kinds, and 2) As an indirect learning alliance by the acquisition of valuable information through the experience.
DFIT: An Interdisciplinary Validation of Fracture Closure Pressure Interpretation Across Multiple Basins
Authors: Buijs Hernán 
Published: September 2021

Abstract
Recent papers on pre-frac tests have proposed fracture closure pressure interpretation methodologies that lead to an earlier, higher stress estimation than the ones estimated from well-established practices. These early time estimations based on the fracture compliance method lead the practitioner to utilize unrealistic permeability, stress, and fracture pressure models. This, in turn, has a severe impact on the modeled fracture geometries which hinders the hydraulic fracture optimization process. A multi-basin analysis of pre-frac tests from the North Sea, Europe, Russia, North Africa and South America is presented to support traditional closure estimation techniques. The validity of traditional minimum stress interpretation techniques will be reinforced through multiple case histories by comparing permeability estimates from the time required for the fracture to achieve closure during diagnostic injections, after-closure analysis, core, pressure build up and rate transient analysis. Results will be supported further by fiber optics and production logging tool (PLT) driven flow allocation, fracture geometry assessment through micro seismic and sonic anisotropy, and diagnostic injections numerical inversions.
Simulation of Subsea and Platform Production Schemes to Quantify Flow Assurance Risks under Transient and Steady State Conditions in Offshore Kuwait
Authors: Al-Safran Eissa 
Published: September 2021

Abstract
In offshore production, the type of field development scheme is crucial aspect due to its associated flow assurance risks, which affect project economic, safety, and sustainability. The objective of this study is to simulate and evaluate two offshore field development schemes, namely subsea and platform in offshore Kuwait. Further objective is to carry out detailed transient simulation study on the subsea scheme to investigate flow assurance risks related to terrain slugging, and hydrates formation during shut-in and re-start transient events. The evaluation of the two schemes is based on the associated flow assurance risks, and project economics. Steady state simulations are used to identify the feasible production scheme, which is further simulated under transient shut-in/restart events to investigate flow assurance risks related to terrain slugging and hydrates formation. The steady state simulation results of this study showed that flow assurance risks such as hydrates and pipeline corrosion are significant in both production schemes. To mitigate these risks, sixteen different field development designs of both production schemes were simulated and economically evaluated. Results revealed that the subsea multiphase development scheme with 10-in. ID carbon steel multiphase flowline and 0.3-in. thick polypropylene thermal insulation is the optimum design. Consequently, the optimum design is further analyzed under transient conditions, resulting in appreciable risk of terrain slugging due to hilly-terrain pipeline configuration, especially for the low production rate cases. The transient shut-in/restart simulation results revealed a risk of hydrates formation due to cooling effect during shut-in, which is mitigated by MEG injection. In conclusion, the subsea multiphase flow scheme is selected over platform scheme due to manageable flow assurance risks, low capital investment cost, and minimum environmental impact. This study would enable Kuwait Oil Company to evaluate different offshore development schemes to ensure sustainable production with safe operation and protected environment.
Prediction of High Viscosity Liquid/Gas Two-Phase Slug Length in Horizontal and Slightly Inclined Pipelines
Authors: Shaaban Omar , Al-Safran Eissa 
Published: September 2021

Abstract
The production and transportation of high viscosity liquid/gas two-phase along petroleum production system is a challenging operation due to the lack of understanding the flow behavior and characteristics. In particular, accurate prediction of two-phase slug length in pipes is crucial to efficiently operate and safely design oil well and separation facilities. The objective of this study is to develop a mechanistic model to predict high viscosity liquid slug length in pipelines and to optimize the proper set of closure relationships required to ensure high accuracy prediction. A large high viscosity liquid slug length database is collected and presented in this study, against which the proposed model is validated and compared with other models. A mechanistic slug length model is derived based on the first principles of mass and momentum balances over a two-phase slug unit, which requires a set of closure relationships of other slug characteristics. To select the proper set of closure relationships, a numerical optimization is carried out using a large slug length dataset to minimize the prediction error. Thousands of combinations of various slug flow closure relationships were evaluated to identify the most appropriate relationships for the proposed slug length model under high viscosity slug length condition. Results show that the proposed slug length mechanistic model is applicable for a wide range of liquid viscosities and is sensitive to the selected closure relationships. Results revealed that the optimum closure relationships combination is Archibong-Eso et al. (2018) for slug frequency, Malnes (1983) for slug liquid holdup, Jeyachandra et al. (2012) for drift velocity, and Nicklin et al. (1962) for the distribution coefficient. Using the above set of closure relationships, model validation yields 37.8% absolute average percent error, outperforming all existing slug length models.
Experimental Study and History Match of Near-Miscible WAG Coreflood Experiments on Mixed-Wet Carbonate Rocks
Authors: El Faidouzi Mohamed Mehdi 
Published: September 2021

Abstract
Water-alternating-gas (WAG) injection, both miscible and immiscible, is a widely used enhanced oil recovery method with over 80 field cases. Despite its prevalence, the numerical modeling of the physical processes involved remains poorly understood, and existing models often lack predictability. Part of the complexity stems from the component exchange between gas and oil and the hysteretic relative permeability effects. Thus, improving the reliability of numerical models requires the calibration of the equation of state (EOS) against phase behavior data from swelling/extraction and slim-tube tests, and the calibration of the three-phase relative permeability model against WAG coreflood experiments.
This paper presents the results and interpretation of a complete set of two-phase and thee-phase displacement experiments on mixed-wet carbonate rocks. The three-phase WAG experiments were conducted on the same composite core at near-miscible reservoir condition; experiments differ in the injection order and length of their injection cycles.
First, the two-phase water/oil and gas/oil displacement experiments and first cycles of WAG were used to estimate the two-phase relative permeabilities. Then, a history matching procedure over the full set of WAG cycles was carried out to tune the Larsen and Skauge WAG hysteresis model—namely the Land gas trapping parameter, the gas reduction exponent, the residual oil reduction factor and three-phase water relative permeability.
The second part of this paper is dedicated to the value of information (VOI) analysis of the coreflood work program to assist the decision to proceed with a capital intensive WAG pilot at an offshore oilfield. Stochastic simulation of WAG injection using a fine scale sector model allowed to quantify the reduction in the range of uncertainty of key metrics—such as oil recovery, peak gas production and injectivity—linked with the additional SCAL information.
The current study highlights the impact of the WAG injection sequence on the oil recovery and trapping mechanism. In addition, it is shown that the relative permeabilities and hysteresis model calibrated on one particular set of injection cycles fail to capture the WAG performance when the injection cycles are altered. Finally, the VOI methodology demonstrated the value enhancement from the coreflood work program.
Efficacy And Safety Of EUS-Guided Multimode Ablation Compared With Conventional Chemotherapy In Unresectable Pancreatic Cancer Patients
Authors: Ruan Xixian , Zhang Zinan , Long Xiuyan , Fang Ning , Yu Xiaoyu , Qiu Jianing , Long Yu , Tian Li , Wang Xiaoyan 
Published: September 2021

Abstract
Background & Aims: To compare the feasibility and safety between multimode endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) and conventional chemotherapy in unresectable pancreatic ductal adenocarcinoma (PDAC).Methods: All the pathologically confirmed unresectable PDAC located in the head of the pancreas patients who underwent multimode EUS-RFA or conventional chemotherapy were retrospectively enrolled from June 2018 and April 2019. Patients who underwent multimode EUS-RFA (Group A) was performed through HybridTherm probe(HTP). Patients in Group B accepted nab-Paclitaxel plus Gemcitabine or S-1 plus Gemcitabine. The comparison between efficacy and safety of multimode EUS-RFA and conventional chemotherapy were analyzed by T test and MannWhitney test. A multivariate analysis was performed for each prognostic factor using the Cox proportional hazards model.Results: A total of 10 unresectable PDAC patients were retrospectively enrolled in Group A (mean size 9.46±5.94 cm3, range 2.00-21.09 cm3) and 9 patients in Group B (mean size 14.02±5.81cm3, range 4.60–24.62 cm3). The tumor size was significantly reduced before and after undergoing multimode EUS-RFA (P = 0.005), with an average tumor volume reduction of 38.1%.The tumor size was not significantly changed in Group B (P = 0.452). Statistically significant difference was observed in tumor size between Group A and Group B after treatment (P = 0.033). All patients died because of the progress of the tumor. The median lifetime from Group A&B was 9 months ranged 3-18 months VS 7 months ranged 1-7 months (P = 0.001). Overall no severe adverse events occurred in both groups.Conclusion: EUS-guided multimode ablation has the more feasibility in the treatment of unresectable pancreatic cancer than conventional chemotherapy. In this article, the limited data seems to show the trend of tumor shrinkage, pain relief, lifetime prolongation. Further studies are needed, such as expanding the sample size of patients and comparing the feasibility and safety among all the treatment.
Hydrolysis of the Kitchen Waste through Dry Anaerobic Digestion - A Sustainable Environmental Practice for its Effective Management
Authors: Agrawal Akanksha , Chaudhari Parmesh Kumar , Ghosh Prabir 
Published: September 2021

Abstract
Population explosion coupled with rapid industrialization and urbanization has led to accumulation of food waste. Nearly, 1.3 billion tons of food waste has been encountered annually which poses a serious threat to the environment and human beings. Therefore, it has become imperative to look for the sustainable environmental practices to manage huge quantum of the waste. Anaerobic Digestion (AD) has emerged as techno economical viable solution with the aim of resource as well as energy recovery to combat the global energy crisis. In this study, an attempt has been made to study the hydrolysis of kitchen waste through dry anaerobic digestion being a suitable technology for treating organic wastes with varying composition and its superiority over the wet digestion. Laboratory scale batch studies were conducted on kitchen waste using three different dry fermenters of total volume 4-litre operating under mesophilic regime for duration of 32 days. The reactors were simultaneously operated with the retention time of 1 day, 2 day and 4 days, respectively. Comparative performance of leachate generation during hydrolysis reveals that reactor with 1-day retention time generates maximum leachate with high COD of 244 g/l and VFA of 12.99 g/l. The specific rate constants for hydrolysis of kitchen waste through dry fermentation with retention time of 1 day, 2 days, 4 days were found to be 0.063, 0.054 and 0.027 day− 1, respectively.
Who Wants To Improve Collaboration in Services for Individuals with Chronic Conditions? Specialists and Rural General Practitioners Taking Action in a Fragmented Health Care System
Authors: Tomaschek Rebecca , Gemperli Armin , Essig Stefan 
Published: September 2021

Abstract
Introduction

Strategies to improve fragmented care for individuals with chronic conditions can be futile if those health care professionals who would have benefited are not engaged. We aimed to explore motivation and previous collaboration quality of general practitioners (GPs) and specialists who participate in an intervention study to improve their collaboration, and GPs who do not participate.
Methods

Explorative survey among rural GPs and specialists for spinal cord injury (SCI) participating in an intervention to improve collaboration, and non-participating GPs, from August to October 2020, in Switzerland.
Results

Eight GPs and 13 specialists of the intervention study and 23 non-participating GPs took part. Specialists were from various medical disciplines. Participating GPs were located farther away from a hospital and consulted a higher number of patients. Overall, the collaboration quality at the primary-secondary care interface was good. Whereas specialists and participating GPs were mostly satisfied with their collaboration, non-participating GPs’ reported a lower quality regarding some aspects of collaboration. Furthermore, differences in collaboration quality between general chronic care and SCI specific care could be observed.
Conclusion

The collaboration quality was rather high in participating physicians. The benefit of the intervention would have been higher in non-participating than participating GPs. When participation is optional, interventions to improve collaboration likely do not achieve the effect that would actually be possible.