bluuebunny/crossref_metadata_2025 huggingface dataset:
Wendbaar wetgeven revisited: de rol van de medewetgever als systeembeheerder
Authors: Lokin M.H.A.F.
Published: September 2023

Wendbaar wetgeven revisited: de rol van de medewetgever als systeembeheerder

In de bijdrage wordt ingegaan op het belang van expliciete en gerichte aandacht voor ICT- en digitaliseringsaspecten van wetgeving in het parlementaire wetgevingsproces. Aan de hand van de (herziene) reglementen van orde wordt geschetst welke mogelijkheden en bevoegdheden de Tweede en Eerste Kamer ten dienste staan om de ICT-component van wetsvoorstellen te beoordelen en daarover het goede gesprek te voeren bij de schriftelijke voorbereiding en mondelinge behandeling. Voor die beoordeling is een concrete vragenlijst uitgewerkt. In de slotbeschouwing wordt ingegaan op de haalbaarheid van de geschetste mogelijkheden.
De rolinvulling van overheidsjuristen
Authors: van Lochem P.J.P.M.
Published: September 2023

De rolinvulling van overheidsjuristen. Bespreking van het proefschrift van Wubbo Wierenga

Wierenga’s proefschrift gaat over de wijze waarop overheidsjuristen hun rol invullen en de verklaring daarvan. Zijn promotieonderzoek bestond uit een drietal empirische deelonderzoeken, gericht op alle overheidsjuristen. Zijn onderzoek heeft geleid tot drie kernbegrippen van de rolinvulling (professioneel handelen, zelf gedefinieerde werksituatie en gekozen beroepsopvatting) en vier ideaaltypische rolinvullingen (maximeren van de juridische kwaliteit, bijdragen aan een bredere opgave, beïnvloeden van beleids- en besluitvorming en laveren tussen rechter en bestuur), waarvan de keuze wordt beïnvloed door omgevingsfactoren zoals de organisatiegrootte en persoonlijke kenmerken zoals het aantal dienstjaren. Zo blijkt dat onervarenheid (weinig dienstjaren, lage schaal) samenhangt met de rolinvulling ‘maximeren van de juridische kwaliteit’.
Decision mining als bijdrage aan kwaliteit van uitvoering
Authors: Leewis S. , Meuwese A.C.M.
Published: September 2023

Decision mining als bijdrage aan kwaliteit van uitvoering

Deze rubriekbijdrage introduceert ‘decision mining’ bij de RegelMaat-lezer. Decision mining is een techniek die vanuit concrete beslisdata de regels die daaraan ten grondslag hebben gelegen reconstrueert. Het promotieonderzoek van Sam Leewis ontwikkelt deze techniek verder in de context van de uitvoering van wetgeving. Uiteindelijk heeft decision mining de potentie om te helpen controleren of de regels die gebruikt worden in digitale beslissystemen van uitvoeringsorganisaties wel in lijn zijn met de daaraan ten grondslag liggende wetgeving.
The Impact of Strategic Vigilance on Entrepreneurship – Field Study at the Baghdad Company for Soft Drinks
Authors: Alawi Jihan
Published: September 2023

يهدف البحث الى تسليط الضوء على تأثير اليقظة الاستراتيجية في ريادة الاعمال، ولليقظة اهمية في الوقت الحاضر بسبب التطورات والتغيرات في البيئة التسويقية والتنافسية والتغيرات الاقتصادية والسياسية التي تحيط بالشركات. تم اختيار شركة بغداد للمشروبات الغازية مجتمع للدراسة، واستخدام استمارة الاستبيان التي وزعت على عينة من المديرين ومسؤولي الشعب في الشركة البالغ عددهم (30) واستخرجت نتائج البحث باستخدام البرنامج الاحصائي الجاهز SPSS واظهرت النتائج ان هناك علاقة ارتباط معنوية واثر بين متغيري البحث(اليقظة الاستراتيجية وريادة الاعمال). ومن اهم التوصيات ضرورة تفادي المخاطرة، واجراء دراسات جدوى للمشاريع ذات الخطورة قبل تنفيذها وتشجيع افرادها على تنفيذها وتحملهم المسؤولية والاستفادة من الاخطاء التي يمكن ان تعزز ريادة الاعمال.
The Role Of Technology In Indonesian Education At Present
Authors: Rabani Salma , Khairat Annisaul , Guilin Xie , Jiao Deng
Published: September 2023

Technology has become increasingly important in education, including in Indonesia. The implementation of technology in education is expected to improve the quality of education and help reduce the gap in education access across regions. However, several factors have hindered the implementation of technology in education in Indonesia, such as limited infrastructure, inadequate training and development for teachers and lecturers, and digital divides between regions. Despite these challenges, the use of technology in education has several benefits, including improving the quality of learning and motivation of students and increasing the efficiency of administrative tasks for teachers and lecturers. To improve the implementation of technology in education in Indonesia, efforts are needed to develop supporting infrastructure, provide training and development for educators, and establish clear policies and regulations. Collaboration between the government, educational institutions, and the private sector is also necessary. This article discusses the role of technology in education in Indonesia and the factors that influence its implementation, drawing on various studies and research.
Development of Media Matching Box to stimulate symbolic thinking skills in children aged 4-5 years
Authors: Hasanah Iis Uswatun , Tabroni Imam , Brunel Benjamin , Alan Milton
Published: September 2023

This study aims to develop Matching Box media to improve symbolic thinking skills in children aged 4-5 years at Hidayatul Islamiyah Kindergarten. The development model used in this study is Borg and Gall which has been simplified into 6 stages consisting of: Needs Analysis, Planning, Initial Product Development, Learning Media Revision, Field Testing, Final Media Revision. The developed media was validated by 1 material expert and 1 media expert before being tested on children. The trial subjects of this study were 11 children. The instruments used to collect data are learning achievement tests, and observations. the results of the learning test and pretest observation obtained a classical percentage of 72.7% Developing According to Expectations (BSH) and 27.3% Starting to Develop (MB) and the results of the study test and posttest observation obtaining a classical percentage of 90.9% could be categorized as 'Very Well Developing (BSB)' and 9.1% of children were categorized as 'Beginning to Develop (MB)'. From these results, it can be concluded that the Matching Box media is appropriate to be used to improve the symbolic thinking skills of children aged 4-5 years
Number Rinner Games To Improve 5-6 Year-Old Counting Ability
Authors: Rahayu Sinta Sri , Tabroni Imam , Martin Jayshree , Fang Wang
Published: September 2023

The purpose of this research is to develop educational game tools for improve children's cognitive. The application of APE (Educative Game Tool) was carried out on village children to be exact at Harapan Pertiwi 2 Kindergarten. The researcher used the R&D research method (Research & Development) which aims to determine the application of game tools educative windmill counting in developing the development of cognitive aspects of children. This study used a child subject, namely 4 children between the ages of 4-5 years. Technique data collection using observation, interviews, trials, expert validation, and documentation. Based on the results of the research on the application of the Counting Rabbit Educative Game Tool it is proven feasible to use and able to improve children's cognitive abilities. Children are very enthusiastic in trying the game. The results of the data obtained from the Material Expert found that the total rating score obtained was 63 out of the expected 80, after being converted in the presentation the result was 143.2% in the 'Very Good' category. In the assessment rubric it is known that there is a significant difference in the ability to recognize the concept of numbers in children aged 5-6 years in playing the Counting Rabbit Windmill. In the pre-test activity, an average score of 30 out of 80 was obtained. Meanwhile, in the post-test activity using developed media, an average score of 50 was obtained from the score of 85. The pre-test and post-test activities experienced an increase in the average score of 125.1. So that with the Counting Rabbit Wheel media it can improve children's cognitive abilities.
Discrimination as a relational matrix of analysis: race, gender, age, social class, immigration, religion, politics, and civil identification: a case study of Rio de Janeiro, Brazil
Authors: Da Conceição Maria Cristina Gomes
Published: September 2023

The general objective of this research is to analyze how and to what extent racist, patriarchal, classist and political arguments are interlocked and mutually reinforced in multiple residual forms today. This article adopts Foucault’s concepts of biopower and normalization to analyze the persistence of racism surrounding unequal and discriminatory power relations and the oppression of racialized, gender, and social inequalities (Foucault 1994; Koopman 2013). A representative survey was applied to 759 urban inhabitants of Rio de  Janeiro, Brazil, who answered a questionnaire asking for their socio-demographic characteristics, perceptions, expectations, attitudes, practices, and intergroup relationships regarding racism, patriarchalism, sexism, homophobia, xenophobia, class discrimination and political-ideological self-identification. The multivariate method of Principal Component Analysis (PCA) was applied, and the results show the predominance of patriarchal values against women, LGBTQ+, Black, youth and poor persons, through explicit racism and the legitimation of the use of violence for both, men and women. Women primarily reject providing sex education at school, agree with their domestic role as wives and with the idea that females’ behavior causes their own rapes, reject LGBTQ marriage, and discriminate against youths, while men rank first the domestic role of women, explicit racism and criminalization of Black people.
Percepções de profissionais de saúde sobre a morte e o morrer durante a pandemia de COVID-19: protocolo de revisão de escopo
Authors: Paula Ney Ronaldy de Oliveira , De Vasconcelos Renata Borges , De Matos Tallys Newton Fernandes , Maciel Nathanael de Souza , Menezes Raila Souto Pinto , Araújo Perpétua Alexsandra , Moreira Thereza Maria Magalhães
Published: September 2023

O objetivo geral foi mapear estudos que revelem percepções de profissionais de saúde sobre a morte e o morrer durante a pandemia de COVID-19. O presente estudo é qualitativo cujo método é o protocolo de scoping review que segue as recomendações do manual do JBI. A elegibilidade envolve a percepção sobre o processo de morte e morrer (conceito) dos profissionais de saúde (População) na pandemia pela covid-19 (Contexto). As bases de dados selecionadas foram: National Library of Medicine (MEDLINE), via PubMed; Literatura Latino-americana e do Caribe em Ciências da Saúde (LILACS), Web of Science, Scopus e PsycINFO. A escolha da literatura cinza foi o site da Organização Mundial da Saúde (OMS), Google Scholar e Banco de Teses e Dissertações. O processo de seleção envolve dois revisores independentes com triagem de títulos, resumos e leitura completa, com treinamento prévio. Após a seleção, os dados serão expostos em quadro e tabelas, e apresentados no formato descritivo com classificações categóricas conceituais fundamentada na Análise de Conteúdo.
Investigating the Adaptive Practices Implemented by Rural Communities in Nigeria to Alleviate the Impacts of Climate Change on Agricultural Sectors
Authors: Adamaagashi Izuchukwu Prince , Adedeji Oluwasayo Badewole , Jephthah Ayodele Omotoso
Published: September 2023

This study investigates the adaptive practices implemented by rural communities in Nigeria to alleviate the impacts of climate change on agricultural sectors. A thorough literature review is conducted to understand the social resilience strategies and adaptive practices employed by these communities. The study highlights the dependence of agriculture on weather and climate factors, and the environmental challenges posed by unsustainable land management practices. It emphasizes the disproportionate impact of climate change on Africa, particularly Nigeria, ranking it as one of the most vulnerable countries. Various climate change adaptation strategies are explored, including crop diversification, early planting, access to climate information, and climate-resilient infrastructure. The study recognizes the importance of education, awareness-raising initiatives, livelihood diversification, and international collaboration in enhancing resilience. Based on the findings, recommendations are provided to strengthen climate change adaptation strategies, such as improving climate information systems, enhancing sustainable agriculture practices, promoting crop diversification, investing in climate-resilient infrastructure, fostering community-based approaches, and strengthening international collaboration.
Small bowel intussusception in an adult, a rare surgical emergency. Case report and literature review
Authors: Montes Lainez Héctor Daniel , Cabrera Espinoza Jean Carlos , Alberca Bonilla Stephanie Susana , Quinteros Morán Manuel Andrés , González Palacios Virginia Andrea , Ramírez Moya Gabriela Mercedes , Calderón Moreano Francisco Adrian , González Yépez Ginger Maite , Arias Quevedo Kely Elvira , Naranjo Tipan Luis Eduardo , Díaz Vega Ruth Alexandra , Chica Lozada Cristhian Xavier , Vega Chanalata Pamela Elizabeth
Published: September 2023

Intussusception or intussusception in the adult corresponds to a rare etiology of intestinal obstruction representing only 0,08 % of abdominal surgeries in the world, unlike its presentation in childhood most of these have an underlying organic cause. We present the case of a 55-year-old middle-aged woman with no underlying pathology who presented with repetitive symptoms of intestinal pseudo-occlusion. With the help of imaging studies, the site of obstruction was visualized and she underwent exploratory laparotomy where small bowel invagination was evidenced due to a tumorous process, resection and anastomosis were performed with a rapid recovery and then small bowel adenocarcinoma was confirmed. In conclusion, we must take into account that this rare pathology could occur in patients with signs of occlusion not so clear in order to offer an effective and timely surgical treatment
A Sensitivity Analysis of a Mathematical Model for the Transmission of Endemic Malaria under Periodic Climatic Conditions
Authors: M. Ndung’u Reuben
Published: September 2023

We perform sensitivity analysis on a periodic mathematical model of endemic malaria transmission to determine the relative importance and impact of model parameters to disease transmission and prevalence. In this analysis, two sets of baseline parameter values are compiled: one for areas that exhibit high transmission rate and another one for areas with low transmission rates. Sensitivity indices for the basic reproductive number and the endemic equilibrium points are computed. The study established that in areas of low transmission, the reproductive number is most sensitive to the mosquito biting rate, but the equilibrium proportion of the infectious humans is most sensitive to the human recovery rate.  Sensitivity analysis on all state variables was conducted. The results indicated that the most influential factors in the transmission and persistence of malaria in the society are those related to vectorial competence. These findings suggests that strategies that target the vector characteristics such as the mosquito biting rate and those that target the human recovery rate can be very successful in controlling malaria. These strategies include the use of insecticide-treated mosquito nets, indoor residual spraying, prompt diagnosis and treatment of infectious individuals. However, a combination of intervention strategies is more effective than application of a single intervention.
Kadınların Hamilelik Sürecinde Ayaklarında Oluşan Ölçü ve Şekil Değişimlerinin Belirlenmesi
Authors: FINDIK SUYABATMAZ Habibe , GÜZEL Selda
Published: September 2023

İnsan yaşamının ilk evresi anne karnında başlar. Bebek doğuma kadar birçok değişime uğrarken, annede de değişimler meydana gelir. Hamileliği kabullenme ve doğuma hazır hissetme süreçlerinde yaşanan duygusal karmaşalar anne adayını psikolojik olarak etkilerken, fiziksel değişimler de hem sağlığını hem de vücut yapısını etkiler. Bu değişimler hamileliğin üç trimester döneminde farklılık göstermektedir. Vücutta oluşan önemli değişimlerden bir tanesi de ayaklarda meydana gelen ölçü ve fiziksel değişimlerdir. Bu çalışmada hamilelik sürecinde ayak yapısında meydana gelen değişimlerin belirlenmesi amaçlanmıştır.
Araştırmanın evrenini Giresun ilinde bulunan hamile kadınlar oluştur-maktadır. Örneklemini ise Giresun ili Şebinkarahisar ilçesinde ikamet eden 10 hamile kadın oluşturmaktadır. Çalışmaya katılan hamilelerin seçilmesinde Basit Olasılıklı Örnekleme yöntemi kullanılmıştır. Kadınların ayakları hamileliklerinin üçüncü ayından itibaren hamileliğin bitimine kadar her ay, ayda bir kez olmak üzere ölçü ve şekil açısından incelenmiştir. Geliştirilen ölçü formuna ayak üzerinden alınan ölçüler yazılarak, yine şekil değişimlerini belirlemek amacıyla hazırlanan form üzerine sağ ayak çizimleri yapılmıştır. 7 ay boyunca alınan baldır çapı, bilek çapı, kontürpiye, bilek- topuk, tarak (milo), ayak numarası ve ayak uzunluğu ölçüleri tablolar halinde verilmiştir. Ayak şekilleri ise bilgisayar ortamına aktarılarak aylık farklılıklar tek form üzerinde gösterilmiştir.
Araştırma sonucunda hamilelerin %40’nın 38 numara ayakkabı giydiği ve aynı oranda (%40) kadının ayak numarasında değişim olmadığı sonucu ortaya çıkmıştır. Ayak şekillerinde en fazla oluşan ölçü değişimleri incelendiğinde iki tane hamile kadının ayak milo ölçüsünün 2,5 cm, birer kişide olmak üzere bilek topuk ölçüsünün 2,2 cm, kontürpiye ölçüsünün 1,8 cm, baldır çapı ölçüsünün 6,8 cm ve ayak uzunluğu ölçüsünün 1,2 cm artış gösterdiği sonucuna ulaşılmıştır.
İbn Bâcce’nin Siyaset ve Yönetim Anlayışı
Authors: OKUMUŞ Ejder
Published: September 2023

Farklı sahalarda önemli eserler veren İbn Bâcce, siyaset felsefesinde mü-tevahhidin tedbiri teorisiyle siyaset ve yönetime dair özgün yaklaşımlar ortaya koyar. İbn Bâcce, öncelikle şehir, siyaset ve yönetimi toplumun vazgeçilmez bir veçhesi olarak ele alır. Mütevahhid insanın yönetimini de toplumun erdemli hale gelmesine temelli bir katkı olarak görür. Siyaset teorisine ait konuları esas itibariyle Tedbîrü’l-Mütevahhid risâlesinde ele alır. Bu makalede İbn Bâcce’nin mezkur eseri ekseninde siyaset ve yönetime yaklaşımı incelenmektedir. Çalışmanın amacı, İbn Bâcce’nin siyaset ve yönetim düşüncesini anlamaya çalışmak, siyasi, idari ve toplumsal boyutlarıyla ortaya koymak ve siyaset ile yönetime dair düşüncesinin ana noktalarının anlaşılmasına katkıda bulunmaktır. İbn Bâcce insanın nihai amacını gerçekleştirmek ve dolayısıyla mutluluğa erişmek için salih, erdemli siyasi topluluğa ve yönetime ihtiyacının olduğu görüşündedir. Bu görüşte erdemli toplum için erdemli yönetim ve devlet gereklidir. Erdemli toplum, devlet ve yönetimin olmadığı yerde erdemli insanlar, siyaset temelinde bir strateji geliştirerek kendini toplumdan ayırmalı ve kendi yönetimini kurmalıdırlar. Kendini yönetme ve toplumu erdemli yapma çabası olarak mütevahhidin yönetimi, insanın içinde yaşadığı bozuk ve erdemsiz toplumda erdemli bir insan olarak kalıp yaşamak için kendini toplumdan uzak tutma ve tek başına kalma stratejisi geliştiren insanın, eylemlerini akıl, düşünme ve hür iradeyle hedefleyip belirlediği bir amaç doğrultusunda düzenlemesi ve organize etmesi, yani yönetmesi anlamına gelir. İbn Bâcce, siyaset biliminin ve yöneticinin, yönetim konusunda doğruya erişmesi ve doğru yönetmesinin yolunun insanı bilmekten geçtiğini ileri sürer. Bu yak-laşımda insanı ve nefs ilmini bilmeden toplumu ve kendini yönetmek müm-kün değildir. Bundan dolayı toplum ve siyaset bilimlerini de içine alan medeni ilim ve medenî hikmetler alanında nefsin durumunu bilmeden doğru bir sonuca varma imkanı yoktur. İbn Bâcce, siyasetle ilgili yaklaşımlarını siyaseti de kapsayan sosyal bir bilim dalı olarak medenî ilim kapsamında ortaya koyma yoluna gider. Bu bağlamda İbn Bâcce siyaset bilimine önemli katkılarda bulunur. Bu katkılardan biri, toplumu yöneten ve yönetilen şeklinde iki tipte ele almasıdır. Buna göre insanlardan bazıları tabiatları gereği yöneten, bazıları ise tabiatları gereği yönetilen olarak konumlanırlar. Dolayısıyla toplumda tabiatı gereği yönetilir insanlarla tabiatı gereği başkan olan insanlar mevcuttur. Bu, iktidar olgusuna ve ilişkilerine dair köklü bir yaklaşımdır. İbn Bâcce’nin siyaset bilimine önemli katkılarından bir diğeri, tevahhüd teorisi olarak özetlenebilecek bir yaklaşım olan erdemsiz toplumda mütevahhid insanın kendini erdemli olarak yönetmesi ve toplum ile devletin erdemli hale gelmesi için gayret etmesiyle ilgili tezidir. Bu teziyle İbn Bâcce, toplumda siyaseti gerçekçi bir bakış açısıyla ele alır ve erdemli birey ve toplulukların toplumda yönetim adına çok önemli görevler ifa edebileceklerini ortaya koyar.
PROJECT BASED LEARNING IMPLEMENTATION TRAINING FOR TEACHERS OF SMPN 44 SURABAYA
Authors: Arbi Anggun Purnomo
Published: September 2023

Project-based learning is one of the learning methods that has 21st century competencies and a scientific approach. Thus, project-based method training activities need to be carried out as an effort to improve the ability of educators. This community service was aimed to train SMPN 44 Surabaya teachers so that they are able to apply project-based learning in the process of implementing Curriculum Merdeka. This community service applied several methods called observation, discussion, and simulation. This activity was held on July 21, 2022, at SMPN 44 Surabaya. The participants of this community service were educators at SMPN 44 Surabaya. Based on the results and discussion, this training activity has been successfully implemented. This can be shown from the enthusiasm of the educators in the training process. Based on the results of discussions and simulations, the educators have succeeded in making sample projects and teaching modules. Therefore, this training activity is followed up with the provision of periodic evaluation activities.
Menumbuhkan Jiwa Kewirausahaan Di Era Digital SMA Masehi 01 Semarang
Authors: Erlitawati Kaharudin  , Hesti Fajarsari
Published: September 2023

The use of technology for entrepreneurship has become a very important factor in driving innovation and business growth in the digital era. Technology has given entrepreneurs powerful tools to design, manage, and expand their ventures in unprecedented ways.

This article delves into various aspects of utilizing technology in entrepreneurship. This includes using AI to find business ideas and leveraging them to make work more efficient. In addition, technology has enabled in-depth data analysis and a better understanding of the market, enabling entrepreneurs to make smarter decisions. This article will discuss various aspects of utilizing technology in entrepreneurship, from opportunities to challenges, as well as the importance of integrating technology with a business vision that is sustainable and has a positive impact on society.
Pressure Transient Analysis for Wellbore Mechanical Formation Damage Control Near No-Flow Boundaries Using an Asymptotic-Perturbation Method
Authors: Fernandes F. B. , Braga A. M. B. , Souza A. L. S. , Soares A. C.
Published: September 2023

Identifying no-flow boundary areas is essential for a successful exploratory and production campaign during the development of an oil field. This work develops a new unsteady two-dimensional (2-D) integro-differential solution for permeability loss monitoring in a well near a sealing fault. The model presented in this study allows for solving the nonlinear hydraulic diffusivity equation (NHDE) with an oil source term. To approach this phenomenon, a new deviation factor is derived and coupled to a first-order series expansion. The proposed solution was calibrated by a finite-difference-based simulator named IMEX® broadly used in reservoir engineering works, and the results were accurate. The results clearly present the instantaneous permeability decay effect by a deviation when compared to the linear solution in a semi-log plot. The main advantages of the proposed solution are the accuracy, availability of a wide table of the GFs, ease of implementation, and computational cost savings. Hence, the modeling developed in this paper becomes a useful and attractive tool for predicting and monitoring permeability loss, oil flow rate specification, reservoir history matching and calibrating new models.

INTRODUCTION

The nonlinear oil flow through porous media near sealed boundaries has a vital role in reservoir damage evaluation and engineering because various oil and gas pressure-sensitive formations are located near sealed zones world-wide (Fernandes, 2022; Fernandes et al., 2022a,b,c). Sealing faults may significantly impact the fluid flow patterns within a petroleum reservoir, (Kuchuk and Kabir, 1988; Kuchuk, 2009). Thereby, the knowledge of fault zones is essential for the economic viability analysis of exploration projects to prevent early depletion during the well-reservoir performance management, (Knipe et al., 1998; Nurafiqah et al., 2020). The mathematical modeling of the permeability pressure-dependent effect through the nonlinear hydraulic diffusivity equation (NHDE) with source term is still challenging in the petroleum industry. Therefore, accurate analytical models for the nonlinear source term have been extensively researched to save computational resources and calibrate new reservoir models. Image data (ID) and pressure transient analysis (PTA) constitute useful, practical tools to identify sealed zones, (Bengtson, 1981, 1982; Goetz, 1993; Adams and Dart, 1998). Therefore, new advances in seismic inversion algorithms and analytical models are sought for no-flow boundary region identification to provide adequate oilfield development, (Schuller and Vogele, 2019).
Numerical Simulation of Hydraulic Fracture Propagation in Coalbed with Cleats
Authors: Fuchun Tian , Yan Jin , Lin Shi , Ziyuan Cong , Yuwei Li
Published: September 2023

Cleats play a crucial role in the propagation of fractures during coalbed hydraulic fracturing. However, current numerical methods still suffer from significant drawbacks in terms of computational efficiency and fracture trajectory prediction. In this study, we used the displacement discontinuity method (DDM) to calculate the stress in the coal body and corrected fluid leakage using the Brinkman equation. We also derived a mechanical criterion for cleat failure under different conditions and proposed a new model for fracture propagation in coalbeds with orthogonal cleats. Our numerical results indicate that simple plane fractures are more likely to form when the horizontal stress difference in the coalbed is greater. When the angle between the cleats and the horizontal principal stress is close to 45°, hydraulic fractures are more likely to activate the cleats. The friction coefficient of the cleats only affects the net pressure within a specific range in the critical crack. As the cohesion of the cleats decreases, the minimum net pressure required for shear failure decreases significantly, making shear failure more likely. We also introduced a reconstruction coefficient, η, to evaluate the effectiveness of coalbed fracturing stimulation. When the cleats are activated, the reconstruction coefficient η increases, indicating that the flow width per unit fracture length improves and is more conducive to production.

INTRODUCTION

Against the backdrop of carbon emission reduction, coalbed methane (CBM) is becoming an increasingly significant clean energy source for future use, playing a crucial role in energy supply and economic development (Wang et al., 2021; Zhang et al., 2018; Li et al., 2020; Fan 2021). Hydraulic fracturing is a well-established technology for CBM production and has proven to be highly effective over decades of application (Ai et al., 2021; Li et al., 2017). The morphology of fracture propagation in coalbeds is complex, with numerous factors affecting the process. Along with coal's low strength, low elastic modulus, and high Poisson's ratio, the presence of cleats also significantly influences fracture propagation. (Li et al., 2019a; Li et al., 2019b; Su et al., 2005; Xu 2020). Cleats within the coalbed develop in an orthogonal network, and their interaction with hydraulic fractures (HF) can alter the HF propagation direction, adding complexity to the fracture system and posing challenges for predicting the trajectory of HF within coalbeds. Despite the significance of cleats on fracture propagation in coalbeds, there is still a lack of theoretical calculation methods capable of accurately simulating and predicting the morphology of fracture propagation.
Investigating Effects of Cryogenic Treatment on Physical and Mechanical Properties of Geothermal Formation Samples – An Experimental Study
Authors: Thiyagarajan Sugan Raj , Emadi Hossein , Altawati Faisal , Soliman Mohamed , Watson Marshall
Published: September 2023

Geothermal formations are generally fractured using water-based fracturing fluid, which has several issues, such as high-water consumption and environmental issues. In this study, a waterless stimulation method was used on granite samples. Studying the optimum injection time of LN2 in HDR formations for efficient fracturing will be beneficial for the future of EGS. Effects of varying LN2 exposure time on heated granite samples and their mechanical and physical properties were studied. Eleven core samples were heated to different temperatures, up to 482°F, and treated with LN2 for different times of 10,20, and 30 minutes. CT scan, porosity, permeability, and ultrasonic velocities tests were conducted both before and after LN2 treatment. Later, unconfined compressive strength and X-Ray Diffraction tests were conducted on the treated samples. The results indicated that the physical and mechanical properties of the core samples were altered after implementing LN2 treatment. The permeability enhancement was more significant than the porosity improvement. The ultrasonic velocities of the samples decreased after the cryogenic treatment owing to the creations of the new fractures inside the samples. Increasing the treatment temperature and treatment time results in an increase in the permeability of samples, which will improve the heat extraction in geothermal formations.

INTRODUCTION

As an abundant and sustainable energy source, geothermal energy, particularly stored in hot dry rocks (HDR), can play a critical role in reducing the fossil fuel consumption and the associated environmental dangers such as carbon dioxide emissions, water pollution, and acid rain (Lu, 2018; Y. Shi et al., 2018; Tester et al., 2006). The amount of heat present in HDR is large, approximately 1.4 × 1025 J in the United States and over 2.52×1025 J in China, and the temperature is higher than in the other geothermal systems, 300°F – 1200°F (Song et al., 2018). The most suitable rock type for HDR is granite or other crystalline basement rock with temperatures from 300°F to 950°F at depths from 3 to 4 miles (Potter et al., 1974). The method of producing energy from hot dry rocks is known as Enhanced Geothermal System (EGS). Even though there are startling numbers regarding the potential of EGS from numerous studies around the world, tapping energy from HDR is still in progression (Breede et al., 2013).
Sub-Core Scale Characterization of Microbial Invasion Impact in Carbonates: Implications for Mechanical Alteration
Authors: Ngoma M. C. , Kolawole O. , Elinski M. B. , Thomas R. , LaGrand R.
Published: September 2023

Biogeomechanics is a novel and resourceful approach to assessing the impact of biological processes on the mechanical properties and behavior of rocks and rock-like materials. However, there is still a lack of knowledge on how far an in-situ bacterial growth can invade a reservoir rock with time and what its long-term impacts at nano- to micro-scale are in the invaded reservoir. This study uses non-destructive methods to investigate time-dependent nano-scale extent of biogeomechanical and morphological alterations in carbonate rocks due to microbial invasion. We conducted a microbial treatment of carbonate rock samples using a distinct microbial solution over a period of 30, 60, 90, and 120 days at a temperature of 42°C. Subsequently, the sub-core scale properties of untreated and post-treatment carbonate rocks were measured using Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) to assess the changes in surface roughness and pore structure. Finally, we compared the untreated and microbially treated samples and assessed the implications for mechanical properties to better understand how microbial invasion could impact carbonate rocks. The results suggest that distinct microbes can continue to invade and alter the formation over time causing dissolution and disintegration of the rock matrix, which may yield a reduction in the mechanical integrity of the microbially impacted carbonate rock.

INTRODUCTION

Interaction between rocks and fluids can have multiple effects on its mechanical and mineralogical properties. Several studies have previously investigated the potential applications of these property changes in various fields such as the control of seepage in underground excavations (Phillips et al., 2013), geological CO2 storage (Kolawole et al., 2021a; Kolawole et al., 2022a), enhanced hydrocarbon recovery (Nikolova & Gutierrez, 2020; Kolawole et al., 2022b), wellbore cement integrity after exposure to corrosive environments (Kirkland et al., 2020; Kolawole et al., 2021b), and many other engineering-related processes. For example, in one study, researchers evaluated the grouting of rock fractures characterized by a fine-scale aperture with calcium carbonate due to microbial activity (Minto et al., 2016). This microbe was used for the treatment of samples over 12 days, and the results showed that the hydraulic aperture was reduced (Minto et al., 2016).
Strain Localization in Jointed Rockmass Analog Laboratory Specimens Under Compression
Authors: West I. G. , Walton G. , Gonzalez-Fernandez M. A. , Alejano L. R.
Published: September 2023

Field-scale rock formations (i.e. rockmasses) are composed of sections of intact rock separated by a preexisting joint network. As rockmass deforms, strain accumulates within the intact rock and slip occurs along the preexisting joints. However, the magnitude of strain within the intact rock sections are not necessarily equal everywhere throughout the rockmass due to the presence of the discontinuities. In general, testing representative rockmass specimens in the laboratory is difficult because of the required size. As an alternative, small-scale rockmass analog laboratory specimens can be used to investigate trends in rockmass behavior. This research evaluates the mechanical behavior of rockmass analog specimens of Carrara marble containing two orthogonal sets of smooth joints. Both intact and the jointed specimens were tested under triaxial compression with 1 and 12 MPa of confinement. Axial and radial deformation within each section of intact rock in the specimens were recorded with separate strain gages, and strain gages in these same positions were also attached to intact specimens for comparison. Notable radial strain heterogeneity was observed in the jointed specimens and this heterogeneity was suppressed under higher confinement levels. Strain was also found to localize in intact rock blocks with higher surface area to volume ratios.

INTRODUCTION

Field-scale rock formations are commonly referred to as rockmasses, which are composed of sections of intact rock separated by a network of preexisting discontinuities (Mendes et al., 1966). Such discontinuities can include joints (i.e. fractures), shear zones, faults, and other structural planes (Cui et al., 2020), which are formed from varying stress fields throughout the rockmass's tectonic history (Mandl, 2005). The presence of discontinuities reduces the strength of the rock and affects other aspects of its mechanical behavior (Hoek and Brown, 1997). Rockmasses are more difficult to test in the laboratory compared to intact rock because representative rockmass specimens are typically on the scale of meters. Large triaxial testing apparati are uncommon and typically allow for a maximum specimen diameter of 1 meter, which is not sufficient for many rockmasses with joint spacing of multiple meters (Muschler and Natau, 1991; Natau, 1977; Singh and Huck, 1972; Vergara et al., 2015).
Polyaxial Failure Criteria in Borehole Breakout Stress Analysis
Authors: Trzeciak M. , Sone H.
Published: September 2023

Analysis of borehole wall failures, breakouts, is the primary method of constraining the maximum horizontal stress in deep wells. To estimate stress using the breakout method, one needs to measure the breakout width from image or caliper logs, and use a failure theory to predict stress that led to the development of the measured breakout. Most commonly, Mohr-Coulomb failure criterion is used which disregards the influence of intermediate stress on strength. Different polyaxial criteria have been proposed to include this effect. Here, we first review selected polyaxial criteria: Drucker-Prager, Mogi and modified Wiebols-Cook, and we conclude that their application in breakout analysis is cumbersome and often unreliable. One reason for these problems is that the criteria are defined using octahedral stresses or invariants, while the breakout analysis is most easily done in the principal stress space. Therefore, the polyaxial criterion can be defined as a simple relation between maximum and intermediate stresses. We propose to define such an empirical criterion as a second order polynomial which fits trends observed in polyaxial laboratory strength data.

INTRODUCTION

Knowledge of in situ stress is essential for many geological engineering applications including: borehole stability, hydraulic stimulation, induced seismicity, and others (e.g. Zoback, 1992, 2007; Jaeger et al., 2007; Heidbach et al., 2018). Among the three principal stresses, the maximum horizontal stress (σH) is the most challenging to constrain (Zoback et al., 2003). The most commonly used method is based on analysis of borehole wall compressive failures, i.e. breakouts. Breakout analysis requires two components: i) the breakout geometry observed from image or caliper logs, and ii) a failure theory to predict stress that led to the development of a breakout with the measured geometry.

Most commonly, the Mohr-Coulomb criterion is used in borehole wall strength analysis and its failure is predicted when the hoop stress reaches a critical value (Barton et al., 1988). However, such approach disregards the influence of the intermediate principal stress (σ2) on rock strength (understood as the maximum principal stress, σ1, at failure) which has been described in numerous experimental studies (e.g. Mogi, 1971; Michelis, 1985, 1987; Haimson and Chang, 2000; Chang and Haimson, 2000; Ingraham et al., 2013; Ma and Haimson, 2016; Lee and Haimson, 2011). Therefore, several polyaxial failure criteria which include the σ2 dependence of strength has been proposed and applied in borehole breakout analyses (Zhou, 1994; Ewy, 1999; Al-Ajmi and Zimmerman, 2005; Chang et al., 2010).
A Case Study of Shale Gas Well Casing Deformation in Longwall Chain Pillars Under Deep Cover
Authors: Zhang Peter , Su Daniel , Van Dyke Mark , Kim Bo Hyun
Published: September 2023

Shale gas wells in longwall chain pillars are subject to longwall-induced overburden movements. Longwall mining on either side of the chain pillars can induce deformations in gas well casings. The casing deformations induced by longwall mining has raised the safety concern that casing integrity might be diminished so that intrusive shale gas could leak into the longwall mine with serious consequences. This study deals with longwall-induced casing deformations of eight shale gas wells in the chain pillars between two adjacent longwall panels in the Pittsburgh coal seam under a cover depth of 314 m and a mining height of 2.1 m. The longwall panels were 457-m wide, and the chain pillars were 66-m wide. The longwall faces passed by the shale gas wells as each adjacent longwall panel was retreated. Gas well casing deformations were measured by a multi-finger caliper after each panel was mined. The first panel mining induced casing deformations less than 1.7 cm above the coal seam horizon. The second panel mining caused an increase of casing deformation up to 20%–30% on average. The casing deformations were also predicted by the FLAC3D modeling technique based on site-specific mining and geological conditions. The study demonstrates that the predicted casing deformations are generally in good agreement with the measurements. The study shows that the casing deformations first occur at the weak/strong rock interfaces after first panel mining and then increase by a small amount at the same locations after second panel mining. The study reveals that longwall-induced casing deformations under deep cover are smaller than those under shallow cover. The study also provides a quantitative method for using numerical modeling to assess the stability of shale gas wells in longwall chain pillars.

INTRODUCTION

Gas wells drilled in longwall pillars are influenced by longwall mining. Due to longwall-induced subsurface ground movements, the gas wells in the vicinity of longwall panels are subject to longwall-induced stresses and deformations. Excessive stresses and deformations induced in gas well casings could lead to a casing breach. More safety concerns have been focused on unconventional shale gas wells in the presumption that the casing breach could allow high-pressure gas to leak into the mine, potentially causing a fire and explosion. Over the past decade, more than 1,500 shale gas wells have been drilled in the current and future reserves of the Pittsburgh coal seam. The impact of longwall mining on these shale gas wells will have to be evaluated as future longwall panels are mined. Therefore, it is important to quantify longwall-induced subsurface movements and casing deformations and to develop reliable models to assess the stability of shale gas wells in longwall pillars.
Advanced Fracturing Modeling Through Combining Fracture Model and Geomechanics
Authors: Gong Yiwen , Fan Meng , Yang Lifeng , Wang Xin , Xie Hongbing , Mao Zhenyu , Liu Chuxi , Yu Wei , Leines Joseph , Miao Jijun
Published: September 2023

Due to the highly uncertain nature of unconventional reservoirs and difficult monitoring of the engineering effectiveness, a reliable, accurate, and efficient fracture propagation model is essential to help operators understand/plan their assets. The fracture modeling sensitivity study is a comprehensive investigation of the key factors that influence the behavior of hydraulic fractures in subsurface rock formations. This study utilizes advanced numerical simulation techniques to model the propagation of hydraulic fractures in various geomechanics conditions and evaluates the sensitivity of fracture behavior to changes in the design parameters and rock properties. Additionally, the study evaluates the sensitivity of fracture behavior to changes in the hydraulic fracturing design parameters, such as injection rate, fluid viscosity, and proppant concentration. The results demonstrate that these parameters can significantly affect fracture geometry and propagation behavior, highlighting the importance of accurate design and optimization of hydraulic fracturing operations. Overall, the fracture modeling sensitivity study provides valuable insights into the mechanics of hydraulic fracture propagation and the key factors that influence it. The findings can inform the design and optimization of hydraulic fracturing operations, ultimately improving the efficiency and effectiveness of hydrocarbon extraction from unconventional reservoirs.

INTRODUCTION

Hydraulic fracturing involves the injection of high-pressure fluid into a wellbore, creating fractures in the rock to allow for the extraction of trapped hydrocarbons. Accurate modeling of hydraulic fractures is crucial for optimizing production and reducing environmental impact. One such modeling approach is the Peudo 3D Displacement Discontinuity Method (P3D DDM), which has gained popularity due to its ability to simulate complex fracture geometries.

The sensitivity study of hydraulic fracture modeling using P3D DDM is an important research topic that aims to understand the effects of various input parameters on fracture behavior. In this study, researchers perform a series of simulations by varying parameters such as fluid viscosity, injection rate, and fracture toughness to investigate their impact on fracture growth and propagation. The results of the study can provide valuable insights into the design and optimization of hydraulic fracturing operations, which can lead to improved efficiency and reduced environmental impact.
Intelligent Lost Circulation Early Warning Method Based on HALSTM Network
Authors: Wang H. T. , Wen X. , Zhang R. , Song X. Z. , Zhu Z. P. , Yao X. Z. , Han L.
Published: September 2023

To further reduce the risk of lost circulation and improve the accuracy and real-time lost circulation warning, this paper proposes a lost circulation warning model based on hybrid attention long short-term memory (HALSTM) network. Firstly, combined with the mechanism of lost circulation occurrence, the characteristic parameters of lost circulation risk and their variation rules were analyzed. Then, the characteristics of the model were screened, and the time of lost circulation occurrence was accurately located by using the drilling activity identification model and the variation rules of the characteristics. Based on the standard LSTM model, the feature and temporal hybrid attention mechanism is proposed to dynamically capture the potential correlation between the risk of lost circulation and the input features. By obtaining the rank importance from both features and temporal, which realizes the interpretability of the model to a certain extent. The results demonstrate that the HALSTM model outperforms the random forest (RF), support vector classification (SVC), artificial neural network (ANN), and LSTM models, exhibiting greater accuracy and enhanced robustness. With a precision of 98%, the HALSTM proves to be a highly practical and effective tool for early warning and decision-making during drilling operations.

INTRODUCTION

Lost circulation is a common downhole risk in the drilling operations (Xu & Li, 2018), which can occur suddenly and is complex to deal with. Typically, lost circulation risks are highly concealed, evolve dynamically, and fluctuate non-linearly, which can lead to other downhole risks such as wellbore instability, pipe sticking, and blow out (Li et al., 2018). Therefore, efficient and accurate diagnosis of lost circulation is of great importance for the safety and economy of drilling operations.

Traditional prediction methods for lost circulation use only one or a few factors, which can cause accident delay, misclassification, and omission. Meanwhile, the comprehensive mudlogging (CML) technique is the most widely used lost circulation diagnosis method, which diagnoses by real-time monitoring whether the logging parameters exceed the threshold value. However, the threshold setting depends on the field experience and is not time-sensitive, resulting in limited accuracy of lost circulation diagnosis.