bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing Mechanical Properties and Biological Performances of Injectable Bioactive Glass by Gelatin and Chitosan for Bone Small Defect Repair
Authors: Sohrabi Mehri , Eftekhari Yekta Bijan , Rezaie Hamidreza , Naimi-Jamal Mohammad Reza , Kumar Ajay , Cochis Andrea , Miola Marta , Rimondini Lia
Published: November 2020

Bioactive glass (BG) represents a promising biomaterial for bone healing; here injectable BG pastes biological properties were improved by 25 wt% gelatin or chitosan, as well as mechanical resistance was enhanced by adding 10 or 20 wt% 3-Glycidyloxypropyl trimethoxysilane (GPTMS) cross-linker. Composites exhibited bioactivity as apatite formation was observed by SEM and XRD after 14 days immersion in SBF; moreover, polymers did not enhance degradability as weight loss was >10% after 30 days in physiological conditions. BG-gelatin-20 wt% GPTMS composites demonstrated the highest compressive strength (4.8±0.5 MPa) in comparison with 100% BG control (1.9±0.1 MPa). Cytocompatibility was demonstrated towards human mesenchymal stem cells (hMSC), osteoblasts progenitors and endothelial cells. The presence of 20 wt% GPTMS conferred antibacterial properties thus inhibiting the joint pathogens Staphylococcus aureus and Staphylococcus epidermidis infection. Finally, hMSC osteogenesis was successfully supported in a 3D model as demonstrated by alkaline phosphatase release and osteogenic genes expression.
Convert a Strongly Connected Directed Graph to a Black-and-White 3-SAT Problem by the Balatonboglár Model
Authors: Kusper Gábor , Biró Csaba
Published: November 2020

In a previous paper we defined the Black-and-White SAT problem which has exactly two solutions, where each variable is either true or false. We showed that Black-and-White $2$-SAT problems represent strongly connected directed graphs. We presented also the strong model of communication graphs. In this work we introduce two new models, the weak model, and the Balatonbogl\'{a}r model of communication graphs. A communication graph is a directed graph, where no self loops are allowed. In this work we show that the weak model of a strongly connected communication graph is a Black-and-White SAT problem. We prove a powerful theorem, the so called Transitions Theorem. This theorem states that for any model which is between the strong and the weak model, we have that this model represents strongly connected communication graphs as Blask-and-White SAT problems. We show that the Balatonbogl\'{a}r model is between the strong and the weak model, and it generates $3$-SAT problems, so the Balatonbogl\'{a}r model represents strongly connected communication graphs as Black-and-White $3$-SAT problems. Our motivation to study these models is the following: The strong model generates a $2$-SAT problem from the input directed graph, so it does not give us a deep insight how to convert a general SAT problem into a directed graph. The weak model generates huge models, because it represents all cycles, even non-simple cycles, of the input directed graph. We need something between them to gain more experience. From the Balatonbogl\'{a}r model we learned that it is enough to have a subset of a clause, which represents a cycle in the weak model, to make the Balatonbogl\'{a}r model more compact. We still do not know how to represent a SAT problem as a directed graph, but this work gives a strong link between two prominent fields of formal methods: SAT problem and directed graphs.
Enhanced Anticancer Potency of Hydroxytyrosol and Curcumin by PLGA-PAA Nano-Encapsulation on PANC-1 Pancreatic Cancer Cell Line
Authors: Isazadeh Alireza , Farhoudi Sefidan Jadid Mahdieh , Shadman Behrouz , Chavoshi Reza , Seyyedsani Nasrin , Aghaei Elnaz , Taheri Elham , Goleij Pouya , Hajazimian Saba , Karamad Vahidreza , Baradaran Behzad
Published: November 2020

Background and Aim: Pancreatic cancer (PC) is a highly aggressive malignancy associated with low survival rates. Many chemotherapeutic regimens have been investigated for advanced unresectable and metastatic PC, but with only minimal improvement in survival and prognosis. The present study aimed to investigate the anti-cancer function of free and nano-encapsulated hydroxytyrosol (Hyd) and curcumin (Cur), and its combinations (Hyd-Cur) on the PANC-1 cell line.Methods: The poly lactide-co-glycolide-co-polyacrylic acid (PLGA-co-PAA) nano-encapsulated Hyd and Cur were synthesized, and MTT assay was performed to evaluate cytotoxic effects of free and nano-encapsulated Hyd, Cur, and Hyd-Cur. Moreover, effects of free and nano-encapsulated Hyd, Cur, and Hyd-Cur were evaluated on viability, migration, morphological alterations, colony formation, and apoptosis on PANC-1 cell line. The mRNA expression levels of MMP2, MMP9, BAX, BCL-2, and Cas9 genes were assessed after treated PANC-1 cells with free and nano-encapsulated Hyd, Cur, and Hyd-Cur.Results: The obtained results showed that free and nano-encapsulated Hyd, Cur, and Hyd-Cur treatments significantly decreased the viability, migration, and colony formation in the PANC-1 cells. Furthermore, apoptosis rates in PANC-1 cells were increased in a concentration and time dependent manner in all of the treatment groups. Moreover, anti-proliferative activity of nano-encapsulated Hyd-Cur was significantly more than other treatments.Conclusion: According to our results, Hyd-Cur combination and nano-encapsulation therapy exerts more profound apoptotic and anti-proliferative effects on PANC-1 cell line than free Hyd or Hyd monotherapy.
Diagnosis of Composite Materials in Aircraft Applications–Brief Survey of Recent Literature
Authors: Alhammad Muflih , Zanotti Fragonara Luca , Avdelidis Nicolas P
Published: November 2020

Diagnosis and prognosis of failures for aircrafts’ integrity are some of the most important regular functionalities in complex and safety-critical aircraft structures. Further, development of failure diagnostic tools such as Non-Destructive Testing (NDT) techniques, in particular, for aircraft composite materials, has been seen as a subject of intensive research over the last decades. The need for diagnostic and prognostic tools for composite materials in aircraft applications rises and draws increasing attention. Yet, there is still an ongoing need for developing new failure diagnostic tools to respond to the rapid industrial development and complex machine design. Such tools will ease the early detection and isolation of developing defects and the prediction of damages propagation; thus allowing for early implementation of preventive maintenance and serve as a countermeasure to the potential of catastrophic failure. In this paper, following a short introductory summary and definitions, this paper provides a brief literature review of recent research on failure diagnosis of composite materials with an emphasis on the use of NDT techniques in aerospace industry. In addition to this, within a some of significant NDT application extents, prognosis of composites is also briefly discussed.
Composite Ferroelectric Membranes based on Vinylidene Fluoride-Tetrafluoroethylene Copolymer and Polyvinylpyrrolidone for Wound Healing: A Pilot Study
Authors: Tverdokhlebova Tamara , Antipina Ludmila , Kudryavtseva Valeriya , Stankevich Ksenia , Kolesnik Ilya , Senokosova Evgenia , Velikanova Elena , Antonova Larisa , Vasilchenko Dmitry , Dambaev Georgiy , Buznik Vyacheslav , Bobasov Evgeniy
Published: November 2020

Herein, we report results of the study of the composite ferroelectric scaffolds based on vinylidene fluoride-tetrafluoroethylene copolymer (VDF-TeFE) and polyvinylpyrrolidone (PVP) produced by electrospinning and their application as a wound-healing material. The physicochemical properties of ferroelectric composite polymer scaffolds depending on the content of PVP (in the range from 0 to 50 wt %) including morphology, composition and crystalline structure were studied. The cytotoxicity of materials and the proliferative activity of cells during their cultivation on the surface of formed scaffolds are reported. It has been found that the optimal PVP content in the VDF-TeFE composite scaffolds is 15 wt%. On a model of a full-thickness contaminated wound in vivo, it was shown that piezoelectric scaffolds based on VDF-TeFE copolymer containing 15 wt% PVP provide better wound healing results in comparison with standard gauze dressings impregnated with a solution of an antibacterial agent.
Tree – Open Grassland Structure and Composition Drive Greenhouse Gas Exchange in Holm Oak Meadows of the Iberian Peninsula
Authors: Ibañez Mercedes , Leiva María José , Chocarro Cristina , Aljazairi Salvador , Ribas Àngela , Sebastià Maria Teresa
Published: November 2020

Iberian holm oak meadows are savannah-like ecosystems that result from traditional silvo pastoral practices. However, such traditional uses are declining, driving changes in the typical tree – open grassland structure of these systems. Yet, there are no studies integrating the whole ecosystem — including the arboreal and the herbaceous layer — as drivers of greenhouse gas (GHG: CO2, CH4 and N2O) dynamics. Here we aim at integrating the influence of tree canopies and interactions among plant functional types (PFT: grasses, forbs, and legumes) of the herbaceous layer as GHG exchange drivers. For that purpose, we performed chamber based GHG surveys in plots dominated by representative canopy types of Iberian holm oak meadows, including Quercus species and Pinus pinea stands, the last a common tree plantation replacing traditional stands; and unravelled GHG drivers through a diversity interaction model approach. Our results show that the tree – open grassland structure especially drove CO2 and N2O fluxes, with higher emissions under the canopy than in the open grassland. Emissions under P. pinea canopies being higher than those under Quercus species. In addition, the inclusion of diversity and compositional terms of the herbaceous layer improve the explained variability, legumes enhancing CO2 uptake and N2O emissions. Changes in the tree cover and tree species composition, in combination with changes in the structure and composition of the herbaceous layer, will imply deep changes in the GHG exchange of Iberian holm oak meadows. These results may provide some guidelines to perform better management strategies of this vast but vulnerable ecosystem.
Fostering Appropriate Antibiotic Use in a Complex Intervention: Mixed-Methods Process Evaluation Alongside the Cluster-Randomized Trial ARena
Authors: Poss-Doering Regina , Kühn Lukas , Kamradt Martina , Stürmlinger Anna , Glassen Katharina , Andres Edith , Kaufmann-Kolle Petra , Wambach Veit , Bader Lutz , Szecsenyi Joachim , Wensing Michel
Published: November 2020

The cluster randomized trial ARena (Sustainable reduction of antibiotic-induced antimicrobial resistance, 2017-2020) promoted the appropriate use of antibiotics for acute non-complicated infections in primary care networks (PCNs) in Germany. A process evaluation aimed to provide insights into determinants of practice and explored factors associated with antibiotic prescribing patterns. In a nested mixed-methods approach, a three-waves survey used study-specific questionnaires for participating physicians and medical assistants to assess potential impacts and uptake of the complex intervention program. Stakeholders received a one-time online questionnaire to reflect on network-related aspects. Semi-structured, open-ended interviews with a purposive sample of physicians, medical assistants and stakeholders explored aspects regarding the acceptance of the program components for daily practice and the perceived sustainability of intervention component effects. The intervention components were perceived to be smoothly integrable into practice routines. The highest uptake was reported for the educational components: feedback reports, background information, e-learning modules, and disease specific quality circles. Participation in PCNs was seen as motivational factor for guideline-oriented patient care and the adoption of new routines Future approaches to fostering appropriate use of antibiotics by targeting health literacy competencies and clinician’s therapy decisions should combine evidence-based information sources, audit and feedback reports and QCs.
Sinergi Dosen dan Mahasiswa dalam Pemberdayaan Wanita di Desa Koripan, Kecamatan Matesih, Kabupaten Karanganyar
Authors: Muhammad Dimas Rahadian Aji , Widadie Fanny , Amanto Bambang Sigit
Published: November 2020

Higher education student is known as agent of change that can play a significant role on the transformation of the social life of a society. However, the idealism of students is often hampered by the availability of funds. On the other hand, someone who works as a lecturer at a higher education has a responsibility to do the three pillars of higher education (Tri Dharma Perguruan Tinggi), one of which is to carry out community service activities. To carry out the community service, a lecturer has many opportunities to obtain funds from various funding bodies. This article discusses the community service activity that was done by implementing a synergy between a group of lecturers and students who are the members of the Food Science Technology Student Association (HIMAGHITA) Universitas Sebelas Maret in the Village of Koripan, Matesih Sub-district, Karanganyar Regency. The purpose of the community service activity is to introduce the processing technology of purple sweet potato and corn and to increase the knowledge of food industry management in the group of women farmers in the region. The community service activity included the introduction of flour-making technology, processing technology of purple sweet potato cookies and corn brownies. Based on the results of monitoring and evaluation, it can be concluded that the synergy of lecturers and students can effectively support the community service activity and the introduction of purple sweet potato and corn processing technology can be well-carried out. In addition, the knowledge of farmer women's groups on the management of home-scale food industry increased after this activity was carried out.
Pengembangan Potensi Usaha Abon untuk Meningkatkan Daya Saing Produk di UMKM Ksatria Kelurahan Jagalan, Kecamatan Jebres, Surakarta
Authors: Nuhriawangsa Adi Magna Patriadi , Kartikasari Lilik Retna , Budiharjo Agung , Swastike Winny , Hertanto Bayu Setya
Published: November 2020

Competitiveness in the competitiveness of Micro, Small and Medium Enterprises (MSMEs) is very important to be improved. This is because MSMEs are a force in driving economic development. The purpose of this activity is to improve the competitiveness of MSMEs products Ksatria Jagalan Village, Jebres Sub-district, Surakarta. The methods used are training and mentoring. The results achieved were an increase in the understanding of MSME, actors about marketing which includes aspects: MSME products including quality of product of abon, packaging of abon and labeling related to important information to be conveyed to consumers to increase the skills and existence of MSME. In addition, the factors of promotion of digital marketing era, price, technology-based marketing, branding, innovation and creativity, product competitiveness. The program's achievements are quite satisfactory. This can be seen from the achievements that have been obtained. The improvements made in this activity have made partners produce competitive products. The suggestion for this activity is that mentoring can be carried out continuously under mentoring and evaluation can be carried out periodically.
Inovasi Bisnis : Upaya Adaptasi UKM Werkudoro di Era Adaptasi Kebiasaan Baru
Authors: Kusnandar Kusnandar , Harisudin Mohamad , Setyowati Nuning , Adi Raden Kunto , Qonita Raden Rara Aulia , Khomah Isti
Published: November 2020

The Covid-19 pandemic has a major impact on various sectors of life, including Small and Mid-size Enterprises (SMEs). The government makes various policies, one of which is the implementation of the New Normal. SMEs must adapt to New Normal conditions. SMEs Werkudoro is one of the SMEs in the Sukoharjo Regency. To face this New Normal condition, SMEs Werkudoro has several problems. The problem is that the packaging label is not marketable, product packaging is not marketable, wrap the packaging with stapler and SMEs are less developed. The method used are socialization, introduction, training and accompaniment. Community service activities are improvement marketable packaging labels, introducing marketable packaging with standing pouches, introducing of plastic sealers, repairing of product banner and business innovation training. Community service activities give knowledge for SMEs and benefits for adaptation in the New Normal condition, so they can survive and can develop.
Implementasi Evaluasi Lahan untuk Pengembangan Komoditas Tanaman berdasarkan Kesesuaian Agroklimat
Authors: Mujiyo Mujiyo , Rahayu Rahayu , Sutopo Novi Rahmawati
Published: November 2020

Research activity is a form of expert service by the Research Group (RG) of "Agricultural Development Based on Local Soil-Land Characteristics" to its partner of the Wonoagung Wonogiri Organic Agriculture Association (Perkumpulan Pertanian Organik Wonoagung Wonogiri, PPOWW). The provision of suitable land for plant growth by partner is a required aspect in the development of certain commodities. Expert services by the RG is involving the implementation of land suitability evaluation based on agroclimatic conditions. The objective of the activity is to provide data and information on land suitability levels for certain commodities based on climatic conditions. The area which became the object of this research activity is where the PPOWW partner is located; namely Sidoharjo Sub-district, Wonogiri Regency. The secondary data was obtained from relevant sources in the form of annual rainfall (mm year-1), annual average air temperature (°C) and annual average humidity (%). The method of agroclimate suitability evaluation was carried out by following the procedure from Food and Agriculture Organization (FAO), by matching climatic conditions with plant growth requirements. Plant commodities that were evaluated for their suitability were durian, salak, mangosteen, apples and avocado. The results showed that durian is a suitable commodity (S1) with climatic conditions in Sidoharjo Sub-district. Salak and avocado are quite suitable commodities (S2). Meanwhile, mangosteen is a commodity which is moderately suitable (S3); whereas apple is a commodity that is not suitable (N). Durian, salak and avocado are commodities which have the potential to be developed by PPOWW in Sidoharjo Sub-district. The next stage of the evaluation implementation requires data and information on the suitability of soil conditions.
BAGAIMANA BAGAIMANA KOMPTERENSI TUTOR DAN PELAKSANAAN TUTORIAL MEMPENGARUHI PRESTASI MAHASISWA: TELAAH DARI POKJAR GROBOGAN UPBJJ-UT SURAKARTA
Authors: Rozai Muhrom Ali
Published: November 2020

The research objective was to examine the effect of pedagogic competence, professional competence, personal competence, social competence and tutorial implementation on student achievement. The design / methodology of this research was carried out on 114 non Pendas students at Pokjar Grobogan UPBJJ UT Surakarta which were explored using a questionnaire. The analysis used is multiple regression analysis. The finding of a significant positive influence between pedagogic competence, professional competence, personal competence, social competence and tutorial implementation. The limitation of this research is the difficulty of controlling the respondents, namely that the questionnaire is filled out with other students (discussion) so that the results will risk bias the results
PSYCHOMETRIC PROPERTIES OF FACULTY PERFORMANCE EVALUATION INSTRUMENT OF STATE UNIVERSITIES AND COLLEGES IN THE PHILIPPINE EASTERN VISAYAS REGION
Authors: M. Patimo Donald
Published: November 2020

The main concern of this study was the assessment of the faculty performance evaluation instrument of State Universities and Colleges in the Philippine Eastern Visayas Region. Specifically, the study sought answers to research questions on what are the psychometric properties of the evaluation instrument and what are the problems identified with regards to the faculty performance evaluation instrument. In search of answers to the abovementioned research questions, the researcher made use of the descriptive-assessment research design. The respondents of this study were administrators, faculty members, and students from the main campuses of State Universities and Colleges in Philippine Eastern Visayas Region. As result, the researcher found out that the faculty performance evaluation instrument of the SUCs was valid and administrable, but not yet tested for reliability. The serious problems identified on the faculty performance evaluation system of SUCs in Philippine Eastern Visayas Region were primarily related to the evaluation criteria and procedure such as the lack of involvement of administrators, faculty, and students in the construction of the evaluation system.
Characteristics of Salt-Related Faults in Abu Dhabi, UAE
Authors: Noufal Abdelwahab
Published: November 2020

Kinematically salt-related faults and fault linkage in Abu Dhabi were classified based on the faults geometry, linkage patterns, deformed layers, and associated salt bodies. The outcrops observations and subsurface numerical modelling address fault patterns and styles. The study is based on analysis of cored data, well logs, and seismic and potential field data and linked to the exposures from outcrops.

Salt updoming in the strike slip regions can be formed in the transtensional and in the transpressional regions of the fault segments. Strike slip faults prevailing Abu Dhabi triggered salt movements; as the inherited basement faults reactivation triggered salt in the transpressional regions due to compressional forces. In the transtentional regions, the pull-apart basins is favouring zones for salt updoming. The faults showing asymmetric arrays of tectonic and salt related faults. The tectonic inherited faults are the master segments evolving transtensional/transpressional zones and the diapirs crestal faults are radial in nature linked to the tectonic faults. These faults dip primarily basinward and sole into a subhorizontal salt layer; ramp faults, that extend upward from the landward margin of mushroom salt stocks. The fault segments found triggering salt movement, principally those showing zone of overlap in both transpressional and transtensional regions. In addition, the salt piercements are usually evolved in the transpressional zones and the diapirs not reached the surface formed in the transtensional regions. Therefore, the salt domes are only updoming in these locations answering the question, why not distributed all over Abu Dhabi. Furthermore, the salt mainly allocated in the offshore relative to the onshore, because of the presence of the NE transtenciona shear zone relative to the master NW-fault trends, creating zones of pula-apart basins. The areas of extension between the fault segments are not favoring salt piercement movement and hence forming deep-seated diapirs. Potential field data revealed that the salt is deep seated in the onshore of Abu Dhabi and most of the anticlines forming the giant hydrocarbon fields are rooted by salt diapirs. Understanding the origin of salt movements and their relation to the fault systems of Abu Dhabi help in exploration of the new ventures and development of those fields related to salt tectonics.
Real-Time Fiber-Optic Coiled Tubing Delivered Well Intervention Savings Through Faster Decision-Making Process
Authors: Lerose Marco , Pelusi Luca , Spagnolo Salvatore , Scarso Marco , Colombo Marco , Mittiga Vincenzo , Battaglia Francesco , Cicione Sara , Bartolotto Giuseppina Angela , Riva Simone , Gaeta Massimiliano , Santin Yoann
Published: November 2020

Historically, the preferred method for restoring production on oil producers in a mature field in South Europe (Field A) was bullheading a matrix acid stimulation treatment. Even if successfully implemented, bullheading treatments at matrix rate are not always optimum and, for Well A, it was decided to diagnose the producing interval first to deliver a better selective stimulation treatment through coiled tubing (CT).

This paper presents a novel approach implemented and discusses its associated benefits. Real-time (RT) fiber-optic (FO) CT (RTFOCT) technology was selected to diagnose this well for such benefits. These include accessibility of the producing zone (horizontal section), pumping capabilities, and versatility in executing different well interventions using single equipment. The technology is composed of a FO cable preinstalled into the CT pipe and a modular sensing bottomhole assembly (BHA). In addition to be the telemetry medium for the sensing BHA, the FO can be used as a sensor for distributed temperature and acoustic sensing (DTS and DAS).

Having access to downhole information in RT helped to implement the decision-making process more quickly. DTS and DAS were used to evaluate the reservoir performance before perforating and assessing well performance, post perforation and stimulation. The sensing BHA helped ensure accurate placement of the perforations and stimulation treatment using a RT casing collar locator (CCL) and gamma ray (GR). Monitoring the bottomhole tension and compression allowed the operation to be performed in a safer and more reliable environment. RTFOCT allows interval diagnostics, stimulation treatment, and evaluation in a single CT run. Having the RTFOCT available also allows quick reaction to unexpected well problems, making diagnosis and remediation easier and faster. Moreover, one of the main goals for well monitoring and field management consists of production optimization activities designed to decrease Water Cut (WC). This has been made possible thanks to the detailed downhole dynamic characterization of the specific water flooding zones coming from RTFOCT, which allows Operator to stimulate the matrix in the right zone to enhance well performance, as well as design focused Water Shut-Off (WSO) interventions.

The focus of the paper lies in the capabilities of the Operators to effectively manage this new tool in order to perform downhole analyses in real-time. This enables potentially problematic or complex scenarios to be identified early on, allowing time to react before they fully develop, thus increasing the percentage of success of the planned job, as experienced in the case study presented.
Intelligent Reconciliation of Well Logs – A Pathway Towards 4IR Assisted Log Interpretation
Authors: Katterbauer Klemens , Al-Yousif Ali A , Marsala Alberto
Published: November 2020

Reservoir characterization, well log analysis and interpretation are key enablers for the optimization of field development and the maximization of recovery. Key challenges in well log analysis are that the current interpretation practices could be subjective, discrete and demanding. Additionally, comparing and analyzing well log data from multiple wells requires constraints to the geological setting. Leveraging on big data well log availability in developed areas, we present an innovative fourth industry revolution (4IR) method for the reconciliation of well logs to automatically assist the process of well log interpretation.

The training set of the method consists of reconciled sonic, resistivity and density well logs together with their target set of saturation and porosity. A multi-layer neural network was trained on selected data sets and validated on a synthetic reservoir case as well as on a reservoir box model.

The results are very promising, paving the way towards an innovative approach for the artificial intelligence assisted interpretation of well logs.
Leading Capital Projects to Repeatable Success
Authors: Gachter Rolando , Marton Andras
Published: November 2020

Heavy industry owner companies can deliver large capital projects with repeated success, even during difficult times, by adhering to the fundamentals for delivering projects effectively. As the COVID-19 public health crisis evolves, owners will have to contend with heightened levels of project execution uncertainty. If the capital project industry’s execution performance track record over the last several years is any indication, owners should be concerned. This is especially critical in the Middle East where schedule performance is notably longer and less predictable than in the rest of the world.

Fortunately project fundamentals have not changed: they still drive success. To stay profitable in these leaner times, owners need to (1) regain discipline and re-focus on project fundamentals; (2) address organizational challenges in alignment across functions and competencies; (3) resolve major supply chain issues relating to quality and productivity. With this presentation we describe successful responses to our challenges that have improved CAPEX efficiency by over 30 percent when successfully applied.
Ensure Zonal Isolation Behind Liner Across Multiple Reservoirs with Well on Total Losses
Authors: Ullah Syed Zahoor , Ruzhnikov Alexey , Qasmi Urooj , Subhi Ahmed , Al Fakih Abdulqawi , Al-Mutahr Ammar
Published: November 2020

Loss circulation is encountered frequently while drilling fractured carbonate reservoirs in specific field. The field practice was attempting to cure losses and if incurable, drill blind to total depth (TD) followed by run and cementing of the liner. The interval from loss zone to liner top was covered by the cement squeezed from liner top. The require time to try to cure the lost circulation zone plus squeezing cement job was approximately 15 days. Several optimization initiatives were implemented to reduce this time to less than seven days.

There were at least eight round trips carried out in different ways by different operators to complete the operation of attempting to cure the losses and a liner top squeeze. The engineering team evaluated this for potential optimization, first to identify whether or not losses need to be attempted to be cured to save the time lost on unsuccessful attempts. Second, to analyze the lessons learnt and build on that optimization strategy to reduce the number of trips Lastly to rework the cement slurry design to reduce the number of attempts to squeeze liner top.

As such a detailed strategy was formulated regarding when and how to cure losses followed by an optimized procedure for liner top squeeze which saves three round trips. Further, the liner top squeeze operations previously took multiple attempts of squeeze before a successful pressure test was achieved. Based on the lessons learnt, the slurry design was optimized from several aspects including, slurry density, rheology, thickening time and the pumping and displacement procedure was created which helped to reduce the number attempts from six to only one. Another optimization implemented was enabling the loggers perform pressure pass for cement evaluation by the utilization of tractor instead of conventional (Tough Logging Conditions) TLC which not only saved time but also depicted better the condition of cement behind liner. Finally, a robust risk assessment encompassing all possible contingencies for expected issues was incorporated.

The optimized liner top squeeze strategy has been implemented at five wells with 100% success, reducing the overall operation time from more than two weeks to less than one week while improving cement quality behind liner to ensure zonal isolation as per requirements.

This paper provides details of how the cement slurry, operations sequence and tools selection were enhanced well by well based on continuous improvement. Since cementing liners across loss circulation intervals exists in most of the carbonate reservoirs worldwide, this paper will help to achieve better zonal isolation in losses environment with lower cost and lesser time.
The Concept of Progressive Property Modeling, a Sequential Technique to Enhance the Utilization of Seismic Inversion Products and Lwd Property Measurements from Horizontal Wells into Static Models
Authors: Contreras David , Khalid Bahussain Esra , Susanto Maria Indriaty , Verma Ravi
Published: November 2020

To establish relationships between seismic derived acoustic impedance and LWD porosity measurements from several horizontal wells to be implemented into property modeling. This workflow is a sequential process that integrates property relationships from seismic scale to log scale using log data from a dozen of vertical wells and validate results at field scale with log data from about 50 horizontal wells.

Overall process functions at grid-block scale in a 100x100mx1ft cell size following the four main phases. The first phase, involves exploratory data analysis and quality check. This is followed by a second phase of model building to concatenate all the required modeling steps. Third phase of model optimization explores the effect of all the parameters and data links defined in the process. Finally fourth phase involves validation to assess residual errors from the resulting porosity distributions and quantifying predictability of the model itself.

A comprehensive and robust set of properties is generated by performing a recursive and convergent process of property modeling using lateral coverage from seismic inversion products and vertical resolution near well log scale. Independent analysis of different scales of porosity measurements are reconciled in this systematic approach by defining average distributions and descriptive statistics of reservoir properties at field scale. Variable data types, sample sizes and data resolution evolves across four different phases that integrates a holistic understanding of datasets in different dimensions.

Quantitative analysis of seismic data ultimate correlates to a dense dataset from long horizontal wells. Final predictability of the model reaches a high confidence level (about 80% accuracy) when testing the predicted properties vs real measurements in about 50 horizontal wells. Multiple realizations of properties distribution matching all the available data is final output that provides a better understanding of reservoir property. This workflow allows total utilization of log data from horizontal wells into property distribution with no impact on overall statistics. No complex de-clustering operations are required as all the descriptive statistics are defined from vertical wells calibrated to core and seismic data. This methodology maximizes the value of LWD formation evaluation logs in property distribution, by combining the resolution of the logs along long horizontal wells with the strong lateral coverage of seismic inversion cubes.
The Houta Prospect Hammamet Basin, Offshore Tunisia as an Example of a New Play in an Old Basin
Authors: van Dijk Janpieter , Boulares Achref , De Vincenzi Luca , Gharieni Nawfel , Santoni Stefano
Published: November 2020

A new play concept is presented for the prospectivity of the Miocene of the Gulf of Hammamet (Central Mediterranean Pelagian Basin, offshore Tunisia), built upon three new elements: the role of the Langhian unconformity, the specific type of migration model, and the mechanism of tectonic inversion, based on an extensive subsurface mapping of the area, on vintage 2d and 3d and newly acquired and processed 3d seismic data using available well logs.

The sandstone reservoirs are part of the Oum Douil Group (Serravallian-Tortonian; e.g. Saouaf, Birsa, Zelfa, Somoaa, Beglia Fm’s), and are deposited in the Miocene foreland Basin which developed on the African continental margin, on top of the Langhian unconformity which shows substantial erosion of the Cretaceous-Paleocene sequences, and angular relationships as evident in seismic. We interpret this as related to a foreland bulge connected to the Early Miocene approaching of the Maghrebian (Atlas) mountain front from the North which culminated in the Late Burdigalian shortening pulse and Langhian transgression, a front that moved to the South during the Mio-Pliocene up to the Present position (Sicily-Tunisian Atlas).

Our analyses showed that important thickness variations occur in the Miocene deposits; Most of the discovered fields are related to older structural highs showing relatively thin reservoirs. Major burial occurred during the Pliocene deposition in the Jirba trough. All traps (fault bounded structures with sealing faults that in many cases reach the seafloor) are related to the Late Plio–Pleistocene tectonic pulse which inverted the thicker portion of the Miocene sediments which have become structurally higher and constitute the new prospects we identified (e.g. the Houta Prospect).

Source rocks are the Fahdene shales (Albian), deposited upon the Mesozoic rifted continental margin, and subcropping below the Langhian unconformity. Important reservoirs and regional seals exist between Fadhene Fm and Birsa Fm, making direct vertical hydrocarbon charge unlikely. Moreover, several fields show an effective regional vertical seal (Paleocene El Haria shale) between Birsa Fm and in the underlying producing Abiod limestones Fm (Upper Cretaceous). We postulate that hydrocarbons migrated through sub-cropping windows in the Langhian unconformity within the Ain Grab bioclastic limestones (deposited on top of it) as carrier beds, and that further migration occurred through juxtapositions on existing fault surfaces. This concept, new for the Miocene play in the Pelagian Basin, explains in a satisfactory way the hydrocarbon occurrences in the discovered fields.

The new play concept, which has been overlooked previously because the main exploration objectives were the deeper Mesozoic and Paleogene sequences in the structural highs, is a typical example of a New Play in an Old basin, which opens-up new hydrocarbon exploration opportunities in the Tunisian offshore area.
A Unique Approach of Numerical Simulation with Multistage Hydraulic Fractures Modeling of a Complex Regional Scale Unconventional Biogenic Gas Reservoir. A Case Study of Miocene Gachsaran Formation, Abu Dhabi, United Arab Emirates
Authors: Gueddoud Abdelghani , Al Hanaee Ahmed , Khan Riaz , Abdelaal Atef , Kurniawan Redy , Al Ameri Abdulla
Published: November 2020

Recently unconventional gas resources including the shallow biogenic gas reservoirs have received great attention around the world due to technical advances in the field development and corresponding large in-place resources. However, the technologies needed for the effective development of unconventional reservoirs are still behind the industry needs, for example the gas recovery rates from these unconventional resources are still very low.

The Miocene Gachsaran Formation across Onshore Abu Dhabi and Dubai possesses high potential of generating shallow biogenic gas. To understand and evaluate its capability for a promising gas resources a dynamic model and field development plan were generated based on a detail G&G analysis. The Gachsaran biogenic gas potential falls under the category of unconventional resources due to the existence of adsorbed gas within the organic matter and clay.

The paper provides a detailed numerical simulation approach from a modified commercial simulators to simplify analytical solutions for adsorbed gas in-place calculation and full field development plan. The construction of dynamic model to tackle the growing advances in drilling and stimulation technologies for such complex tight reservoirs have become possible. These reservoirs are still challenging to produce due to their complex geology, tightness and requirements of advance production technologies such as hydraulic fracturing to achieve economical production rates.

The gas flow mechanisms in nano-pores cannot be simply described by Darcy flow equation. In addition, due to large-scale fracturing, the conventional single porosity model is not enough to simulate the characteristics of these source rock type reservoirs. Furthermore, advanced simulation methods such as molecular dynamic simulation are computationally challenging and very time consuming.

To mitigate these challenges, two alternative unique approaches were considered to model these reservoirs: (1) application of analytical methods to characterize the primary characteristics of nano-pores, and (2) extending the conventional simulator to effectively model flow from the nano-pores gas reservoirs. The study describes the theory and application utilized to modify and enhance the capability of conventional simulator. Consequently, to properly estimate the adsorbed gas in-place and integrate the effects of Langmuir gas desorption and gas diffusion effects. Therefore, the dual-porosity model was built and coupled with local grid refinement to capture the associated hydraulic fracture design and properties. This robust modeling approach has provided an enhancement in the field development planning of such a complex regional scale unconventional reservoir.
A New, Data-Driven Methodology for the Integration of Seismic and Well Data Into Geological Model - Case Study Block 4, Offshore Angola, Lower Congo Basin
Authors: de Sá Mario , Ferreira Lidia. J , José Manuel. N , Simào Joào , Sonibare Wasiu Adedayo , Oyeleke Kehinde Zaid , Bouchet Francois D. , Darous Christophe , Fadipe Oluwaseun , Kolivand Hassan , Hasan Hesham , Chidundo Maximiano , Khan Waqar Ali
Published: November 2020

The acquisition of high-resolution and high-fidelity seismic data opens the possibility of precision reservoir characterization, particularly for those formations that do display a very pronounced Amplitude Versus Offset (AVO) response. In a traditional approach, the integration of seismic and well data information is driven by the ideas and view of the geologist, whose ideas and views might introduce bias in reservoir representation. It is undeniable that the guidance of the model construction by the geologist is an absolute requirement where seismic data limitations (quality, fidelity or accuracy) does not allow extracting a high-resolution reservoir description as an input to the static model construction.

This is evolving: Where AVO effects at reservoir level are significant, the grade of both seismic data and petrophysical measurements now available allow a very precise description of the reservoir, in terms of reservoir geometry and reservoir property distribution. In the study area, AVO response in the Upper Miocene turbiditic deposits, offshore Angola are suitable for detail reservoir characterization.

In this paper, we shall demonstrate through a real case how the results of seismic inversion and attribute analysis have been used for the characterization of depositional elements and the modeling of reservoirs. We shall present first how seismic inversion results have been integrated with facies defined from logs, and how this was used to confirm and identify fluid type and contacts verified at wells, as well as for the delineation of structural and stratigraphic reservoir boundaries. A systematic approach to constructing the 3D static model was applied. The top reservoir was picked in detail, allowing for the channel geometries to be sculpted out using seismic inversion results. The integration of qualitatively and quantitatively delineated sand-body architecture, geometry and orientation from seismic data. Sequential Indicator Simulation method, using well data, allows the facies to be modeled hierarchically through a combination of deterministic and stochastic approaches.

The advantages of this methodology are: (i) integrating fully facies characterization and geological concepts with seismic response, (ii) reducing uncertainty on reservoir distribution and extent and, (iii) constructing of a coherent reservoir description fit for dynamic model even with limited number of wells.
Redevelopment of a Supergiant Southern Iraqi Oil Field with Horizontal Wells
Authors: Khan Sameer A. , Hassan Fadhel A. , Wang Junwen , Gan Junqi , Liu Yang , Patz Joseph F. , Abdulshbeb Saeb K. , Al Lawe Erfan M.
Published: November 2020

This work encompasses redevelopment of a supergiant southern Iraqi oil field from fully vertical to primarily horizontal wells. The subject reservoir is a massive world-class carbonate limestone reservoir containing 23 °API oil and is the dominant reservoir in a set of vertically stacked reservoirs. This reservoir is a part of a large anticline which is oriented north-northwest. The formation is Middle Cretaceous and has a subsea depth of 2100–2600 m. The reservoir was initially developed on a 200 acre inverted 9-spot pattern, and was on primary oil production until reservoir pressure dropped and production declined. Later, water injection started at centers of the 9-spot pattern. Development drilling was projected with future addition of vertical infills at 100 and then 50 acre patterns.

During pressure drop due to primary production, water encroachment from flanks occurred, particularly, in the thin super-high permeability (vuggy) layers present in the reservoir; however, this was not clearly evident at early stages. By the time of starting pattern water injection with comingled injection and production in vertical wells, there was clear evidence of rapid water movement in the vuggy layers. As water injection progressed, the severity of watercut evolution in vertical wells rapidly progressed, necessitating change of the depletion plan. Continued development of the field with vertical infills would result in unsustainable water production and injection requirements, and lower oil recovery.

A redevelopment effort was initiated to overcome these challenges. Geologic and simulation models were modified to reflect the evolved understanding of geology. Appropriate distribution of high permeability layers was introduced and calibrated to production data, in particular, water breakthrough timing and watercut evolution. The main change in the redevelopment plan has been to shift emphasis from drilling vertical infill wells to a fewer horizontal wells targeting low permeability zones which comprise most of the reserves. Reservoir development of the massive lower section is planned with 2 km long horizontal wells with injectors located in lower part of the reservoir and producers higher arranged in a line drive. Upper reservoir development is planned by working over existing comingled vertical wells to upper reservoir only thus decoupling upper and lower comingled production.

The redevelopment plan achieves the business target rate with a much longer plateau duration at lower cost. The plan effectively utilizes existing vertical wells in addition to drilling new horizontal wells for recovering oil from lower, tighter reservoir. Initial performance of horizontal wells have shown very promising results with boosted dry oil production. This updated development plan is now in full execution phase and can provide redevelopment ideas for other brown fields with similar issues.