IZLJEV NAFTE U MORSKOME OKOLIŠU: ZAHTJEVI NAKON ODOBALNOGA IZLJEVA NAFTE

The global lifestyle of this modern world has become more dependent on petroleum-based products, whose applications are involved almost everywhere. Since a large quantity of oil is being used on a daily basis, the spilling of oil by various means during its storage and transportation has become inevitable. This work focuses on the spilling of oil in a marine environment, generally referred to as an offshore oil spill, in contrast to an onshore oil spill associated with a terrestrial environment. These oil spills not only devastate the natural resources and unsettle the economy, they also jeopardize marine life, as well as human health. The remediation of an oil spill remains very challenging, when the disaster is associated with a large aerial extent. In this context, a sound understanding is required on the origin, seeping, composition and properties of the spilled oil in order to better monitor the spreading of the oil spill. In this manuscript, a detailed list of fundamental queries, which will be required to be addressed at the instance of an oil spill has been deduced, which will be extremely useful for the oil spill respondents as there are no previous studies that exclusively provide the type and nature of data required to be collected, immediately following an oil spill. Furthermore, this manuscript has deduced a list of sensitive and essential plots that will be required in order to analyse and forecast the spreading of an oil spill. An essence of weathering and its associated movement of oil spill has been included.Globalni stil života modernoga svijeta postao je sve ovisniji o proizvodima na osnovi nafte, koji se gotovo svugdje primjenjuju. Budući da je u svakodnevnoj upotrebi velika količina nafte, izljevi nafte u okoliš tijekom njezina transporta i skladištenja neizbježni su. Ovaj rad usmjeren je na izljeve nafte u morski okoliš, koji se razlikuju od izljeva nafte u terestrički okoliš. Izljevi nafte u morski okoliš devastiraju prirodne resurse i utječu na gospodarstvo, ali i ugrožavaju morske ekosustave, kao i zdravlje ljudi. Kod velikih onečišćenih područja sanacija izljeva nafte dodatan je izazov. U tome kontekstu, a kako bi se bolje pratilo širenje nafte u okolišu, potrebno je dobro razumijevanje izljeva nafte, njegova izvora te sastava i svojstava izlivene nafte. S obzirom na nedostatak sustavno prikazanih podataka u literaturi, u ovome je radu izrađen detaljan popis temeljnih pitanja na koja je potrebno odgovoriti u slučaju izljeva nafte, kao pomoć odgovornim osobama u definiranju tipa i prirode podataka koje moraju prikupiti odmah nakon što se izljev nafte dogodi. Nadalje, izveden je popis temeljnih grafičkih dijagrama koji su nužni za analizu i predviđanje širenja izlivene nafte. Uzeto je u obzir i djelovanje vremenskih prilika i s njima povezano kretanje izlivene nafte

NUMERIČKO MODELIRANJE UTJECAJA POČETNE DISTRIBUCIJE ZASIĆENJA VODOM NA IZVEDBU ZAVODNJAVANJA TOPLOM VODOM U NEIZOTERMNIM UVJETIMA

The heterogeneity in the spatial distribution of initial water saturation influences the performance of hot water flooding. The prospect of a reduction in oil recovery arises from the development of viscous instability. In the present study, a numerical simulation model has been developed by coupling heat transport, and multiphase flow in porous media integrated with the non-isothermal flow, and the numerical model has been verified with the existing analytical solution by Buckley and Leverett. The formation of a wavy temperature profile at the condensation front was found with a decreased depth of temperature penetration. The average rise of temperature is drastically affected by the spatial distribution of initial water saturation. The formation of viscous fingering was highly dominating in the reservoir, with initial water saturation randomly distributed and causing the front to move in an irregular pattern from the initial stage of the flooding. The heterogeneous reservoir with initial water distribution showed the earlier formation of viscous fingering than the homogeneous reservoir. The heterogeneity in the spatial distribution of initial water saturation had caused viscous instability, lower viscosity reduction, lower displacement sweeps efficiency, and higher residual oil saturation. The present study is limited to spatial distribution in initial water saturation to a certain degree of heterogeneity. The heterogeneity in the spatial distribution of initial water saturation highly impacted the production performance of hot water flooding. The present study provides an idea for the implementation and future development of hot water flooding in a randomly initial water saturation distributed environment.Heterogenost u prostornoj distribuciji početog zasićenja vodom utječe na izvedbu zavodnjavanja toplom vodom. Smanjenje iscrpka nafte proizlazi iz povećanja nestabilnosti viskoznosti. U ovom je istraživanju razvijen numerički simulacijski model, koji uključuje prijenos topline i višefazni protok u poroznoj sredini integriran s neizotermnim protokom, pri čemu je navedeni numerički model potvrđen postojećim analitičkim rješenjem Buckleya i Leveretta. Sa smanjenem dubine prodiranja topline utvrđeno je stvaranje valovitog temperaturnog profila na fronti kondenzacije. Na prosječni porast temperature drastično utječe prostorna raspodjela početnog zasićenja vodom. U ležištu s nasumično raspoređenim početnim zasićenjem vodom domininantno je bilo prstoliko prodiranje vode (engl. fingering) koje je od početne faze zavodnjavanje uzrokovalo pomicanje fronte u nepravilnom obrascu. Heterogeno ležište s početnom raspodjelom vode pokazalo je raniju pojavu prstolikog prodiranja utisnute tople vode od homogenog ležišta. Heterogenost u prostornoj distribuciji početnog zasićenja vodom uzrokovala je nestabilnost viskoznosti, manje smanjenje viskoznosti, niži koeficijent istiskivanja fluida i veću zasićenost zaostalom naftom. Ovo istraživanje je ograničeno na prostornu distribuciju početnog zasićenja vodom do određenog stupnja heterogenosti. Heterogenost u prostornoj distribuciji početnog zasićenja vodom uvelike je utjecala na proizvodni učinak zavodnjavanja toplom vodom. Ovo istraživanje daje ideju za implementaciju i budući razvoj zavodnjavanja toplom vodom u poroznoj sredini s nasumično raspodijeljenim početnim zasićenjem vodom

KOMPARATIVNA ANALIZA UTJECAJA ZASIĆENJA VODOM NA IZGARANJE NAFTE U LEŽIŠTU

The amount of oil together with the water Originally in Place (OIP), makes up the liquid phase in heavy oil reservoir systems. This amount of liquid present in the pores of the reservoir system is known as liquid saturation, plays a vital role in improving oil recovery through In-Situ Combustion (ISC) process. The oil phase acts as fuel in generating thermal energy required for viscosity reduction and the water phase supports in the formation of an enlarged condensation zone that aids in higher mobility of the low viscous oil. A numerical investigation is carried out to study the role of water saturation on the performance of in-situ combustion in a heavy oil reservoir. A finite-difference based numerical model is developed and validated for water recovery. The model is then used to carry out the impact of liquid saturation on the performance of the ISC, as it plays a vital role in screening criteria for the selection of ISC. The numerical results projected a significant effect on the thermal and production profile during the process. A comparison between the effect of variation in water and oil saturations projected a significant increase in reservoir temperatures with increased water saturation than the oil saturation. The highest reservoir temperatures are observed at the maximum liquid (oil and water together) saturation. Further, the additional water drive provided by increased water saturation is observed to contribute to early production rates.Količina nafte zajedno s ukupnim rezervama vode (engl. originally in place, OIP) čini tekuću fazu ležišta teške nafte. Ova količina tekućine prisutna u porama ležišta poznata je kao zasićenje tekućom fazom, a ima vitalnu ulogu u povećanju iscrpka nafte pomoću procesa izgaranja nafte u ležištu (engl. in situ combustion, ISC). Naftna faza djeluje kao gorivo i stvara toplinsku energiju potrebnu za smanjenje viskoznosti, a vodena faza potiče stvaranje proširene kondenzacijske zone, koja doprinosi većoj mobilnosti nisko viskozne nafte. Provedeno je numeričko istraživanje utjecaja zasićenja vodom na in situ izgaranje u ležištu teške nafte. U sklopu istraživanja razvijen je i vrednovan numerički model za iscrpak vode temeljen na metodi konačnih razlika. Model je korišten za provođenje utjecaja zasićenja tekućinom na izvedbu ISC-a, s obzirom na to da ima vitalnu ulogu u odabiru kriterija za odabir odgovarajućega ISC-a. Dobiveni numerički rezultati upućuju na znatan učinak na toplinski i proizvodni profil tijekom procesa. Usporedba učinka varijacija u zasićenosti vodom i naftom pokazuje znatno povećanje temperature ležišta s povećanjem zasićenosti vodom u odnosu na vodu u slučaju povećanja zasićenosti naftom. Najviše temperature ležišta opažene su pri maksimalnoj zasićenosti tekućinom (nafta i voda zajedno). Nadalje, uočen je dodatni vodonaporni (hidraulični) režim, koji se, zbog povećanja zasićenosti vodom, javlja u ranoj fazi proizvodnje

Twelve-month observational study of children with cancer in 41 countries during the COVID-19 pandemic

Introduction Childhood cancer is a leading cause of death. It is unclear whether the COVID-19 pandemic has impacted childhood cancer mortality. In this study, we aimed to establish all-cause mortality rates for childhood cancers during the COVID-19 pandemic and determine the factors associated with mortality. Methods Prospective cohort study in 109 institutions in 41 countries. Inclusion criteria: children <18 years who were newly diagnosed with or undergoing active treatment for acute lymphoblastic leukaemia, non-Hodgkin's lymphoma, Hodgkin lymphoma, retinoblastoma, Wilms tumour, glioma, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, medulloblastoma and neuroblastoma. Of 2327 cases, 2118 patients were included in the study. The primary outcome measure was all-cause mortality at 30 days, 90 days and 12 months. Results All-cause mortality was 3.4% (n=71/2084) at 30-day follow-up, 5.7% (n=113/1969) at 90-day follow-up and 13.0% (n=206/1581) at 12-month follow-up. The median time from diagnosis to multidisciplinary team (MDT) plan was longest in low-income countries (7 days, IQR 3-11). Multivariable analysis revealed several factors associated with 12-month mortality, including low-income (OR 6.99 (95% CI 2.49 to 19.68); p<0.001), lower middle income (OR 3.32 (95% CI 1.96 to 5.61); p<0.001) and upper middle income (OR 3.49 (95% CI 2.02 to 6.03); p<0.001) country status and chemotherapy (OR 0.55 (95% CI 0.36 to 0.86); p=0.008) and immunotherapy (OR 0.27 (95% CI 0.08 to 0.91); p=0.035) within 30 days from MDT plan. Multivariable analysis revealed laboratory-confirmed SARS-CoV-2 infection (OR 5.33 (95% CI 1.19 to 23.84); p=0.029) was associated with 30-day mortality. Conclusions Children with cancer are more likely to die within 30 days if infected with SARS-CoV-2. However, timely treatment reduced odds of death. This report provides crucial information to balance the benefits of providing anticancer therapy against the risks of SARS-CoV-2 infection in children with cancer

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Application of integrated petroleum reservoir study for intervention and field development program in western onshore field, India

In this research, an integrated reservoir study is performed in the J#Field (J-Oil Field) of western onshore, India to evaluate its additional reserves expectations and implement field developments plan using waterflood pilot program. The target strata includes two formations of Paleogene, which is about 3600 ft, namely G#Fm (G-Formation) of the Eocene and T#Fm (T-Formation) of Oligocene, subdivided into 11 zones. Based on these results, an attempt was made to construct of an optimization plan to exploit it, taking into account that the field is producing since 1947, with a cumulative production of 183.5 MMbbl and an overall recovery factor of 28% until January 2016. On the basis of the potential evaluation and geological modeling, blocks J48 and J45 were simulated, and the remaining oil distribution characteristics in two blocks were studied after history match. The work includes the stratigraphic studies, seismic study, logging interpretation, sedimentary facies modeling, three dimensional geological modeling, simulations for waterflooding, and future field development plans

Вплив наночастинок у технології підвищення вилучення нафти на основі полімерів

Хімічні методи підвищення вилучення нафти на основі полімерів, хоч і усувають недоліки звичайного заводнення, такі як в'язке пальцеподібне нагрівання, мають проблеми з ефективністю в умовах соляного розчину та високих температур, які можна вирішити за рахунок застосування нанотехнологій. У роботі досліджується нанорідина, виготовлена з оксиду міді (PHPA), щоб підвищити ефективність вилучення нафти. Підготовлену нанорідину аналізують на її реологічні характеристики при різних концентраціях добавок, солоності та температурах від 25 до 100 °C. Аналіз передбачає, що нанорідина продемонструє значне покращення своїх реологічних властивостей із стійкістю до сольових та температурних умов.Polymer-based chemical enhanced oil recovery methods, while overcoming the disadvantages of conventional waterflooding such as viscous fingering, have performance issues in saline and high temperature conditions that can be addressed through the application of nanotechnology. In the present work, a nanofluid prepared from copper oxide (PHPA) is explored in order to improve the oil recovery efficiency. The prepared nanofluid is analyzed for its rheological performance at various additive concentrations, salinities and for temperatures ranging from 25 to 100 °C. The analysis predicts the nanofluid to exhibit a significant improvement in its rheological properties with resistance to saline and temperature conditions

Design and optimization of a throttle body assembly by CFD analysis

350-360Throttle body assembly plays a vital role in metering the airflow. It mainly consists of a butterfly valve to vary the flow area to control air flow rate through it. There is hardy any established procedure to design a throttle body assembly based on the engine specifications. In order to bridge the gap, this study, design and optimization of a throttle body assembly for a single-cylinder engine used in two-wheeler application has been analyzed along with the investigation of critical flow through various sub systems using computational fluid dynamics (CFD). To start with, the throttle bore and bypass passage diameters are calculated from the basic flow equations. Using CFD, best possible throttle shaft profile is arrived at, which will enhance airflow to the engine. The airflow rate for different throttle openings is predicted taking into account the distribution of main and bypass flow. It is observed that the airflow through main and the bypass passage are almost same around 12% throttle opening and the airflow through main passage takes over beyond 25% opening. The novelty of this study is that airflow through the bypass is also predicted for different screw positions. From the analysis of results, it is found that with around two turns of bypass screw opening, the required amount of air flow rate could be achieved through the bypass passage to run the accessories of the engine at idling and also to meet the required performance and emissions levels as per the design target. In addition, there is a good agreement of CFD predictions with experimental results with an error of about 6%. Finally, it is concluded that the procedure adopted in this study to design the throttle body as per engine specifications will be very useful for the engine designers and in this aspect, CFD plays an important role