Reduciendo la incertidumbre en la ejecución de un piloto de combustión in situ en un campo de crudo extra pesado colombiano mediante la realización de una prueba de conectividad con nitrógeno

Prior to start any Enhanced Oil Recovery (EOR) process, it is desirable to characterize the flow pattern within the affected reservoir volume. This becomes of critical importance for in situ combustion in heavy oil reservoirs, where the mobility ratio is highly unfavorable, oftentimes resulting in channeling or early breakthrough. An inter-well connectivity test through immiscible gas injection aids improving the characterization of the flow distribution, in addition to: 1) calibrating estimates for sweep efficiency; 2) evidencing geological features that may lead to preferential flow towards a particular well or group of them, or lack of connection amongst them; 3) creating a gas path between the injector and producer wells to enable a safe progression of the combustion front; and 4) evaluating the performance of artificial lift and well control systems under high gas-liquid ratio conditions. A connectivity test using nitrogen was designed, implemented and evaluated at the Chichimene field, prior to the ignition of the in situ combustion pilot. This process is summarized and described in this paper. This will be the first in situ combustion trial in a deep (≈ 8000 ft.), extra-heavy oil reservoir, and will serve as a data source to evaluate the development of resources under similar conditions in the eastern plains basin of Colombia. This set of reservoirs bears a significant fraction of the hydrocarbon resources in the country and under Ecopetrol operation. The importance of this pilot makes this connectivity test of even larger relevance to reduce the subsurface and operational uncertainty, identifying potential risks, and increase the probability of success of the combustion process as an option to economically produce these resources.Antes de comenzar cualquier proceso de recuperación mejorada de petróleo (EOR), es deseable caracterizar el patrón de flujo dentro del volumen del yacimiento afectado. Esto se vuelve de importancia crítica para la combustión in situ en yacimientos de petróleo pesado, donde la relación de movilidad es altamente desfavorable, a menudo dando como resultado una canalización o un avance temprano del frente de inyección o combustión. Una prueba de conectividad entre pozos a través de inyecciones de gas inmiscible contribuye a mejorar la caracterización de la distribución de flujo de gas, además de: 1) Estimar eficiencias de barrido, 2) evidenciar características geológicas que pueden conducir a un flujo preferencial hacia un pozo o grupo particular de ellos, o falta de conexión entre ellos, 3) creación de una ruta de gas entre el inyector y los pozos productores para permitir una progresión segura del frente de combustión, y 4) evaluación del rendimiento de los sistemas de levantamiento artificial y sistemas de control de pozos en condiciones de alta relación gas-líquido. Se diseñó, implementó y evaluó una prueba de conectividad usando nitrógeno en el campo Chichimene, antes del inicio del piloto de combustión in situ. Este proceso se resume y describe en este documento. Esta será la primera prueba de combustión in situ en un yacimiento de petróleo extra-pesado profundo (≈ 8000 pies) a nivel mundial y servirá como una fuente de datos para evaluar el desarrollo de recursos en condiciones similares en la cuenca de los llanos orientales de Colombia. Este conjunto de yacimientos tiene una fracción significativa de los recursos de hidrocarburos en el país y están bajo la operación de Ecopetrol. La importancia de este piloto hace que esta prueba de conectividad tenga una relevancia aún mayor para reducir las incertidumbres de subsuelo y operativas, identificar riesgos y aumentar la probabilidad de éxito del proceso de combustión como una opción para producir estos recursos de manera económicamente rentable

"Fire burns matter: A case-control study of severe accidental burns in pediatric patients"

"Objective: We aimed to identify factors associated with severe accidental burns in patients ≤12 years old. Materials and methods: We conducted a matched case-control study, in which we retrospectively reviewed the medical records of children treated in a single institution from 2014-2016. We classified the cases (patients with severe burns) and controls (patients with non-severe burns) according to the criteria of the American Burn Association. We used multivariate conditional logistic regression analysis to identify the relationship between the etiology of burns and their severity. Results: We reviewed 180 cases and 90 controls. The most common etiology of burns was boiling water in both cases (65.6%) and controls (83.3%). Most burns occurred inside the home (84.1%) and in the afternoon (37.4%). Multivariate analysis identified that severe burns were mainly due to exposure to fire (odds ratio [OR]: 3.22, 95% confidence interval [CI]: 1.53-6.81). Similarly, these patients were more likely to live in a rural area (OR: 2.96, 95% CI: 1.17-6.19). Conclusions: In pediatric patients ≤12 years of age severe accidental burns are more likely to be caused by fire compared to boiling water. Public health interventions should focus on populations located in rural areas.

Sustainable sugarcane vinasse biorefinement for trans-aconitic acid-based biopolymer synthesis and bioenergy generation

This study aimed at developing a multiproduct biorefinery scheme for vinase valorization. It involved the extraction of trans-aconitic acid, its transformation into biopolymers using microwave irradiation and the use of the raffinated-vinasse for biogas production. Each technology was assessed individually, followed by a process integration at bench scale, from which a mass balance was calculated, supporting the feasibility of the approach. As a renewable source derived from a residue, these bioproducts can replace crude-oil-based materials in various chemical industrial processes; however, a detailed techno-economic and life-cycle analysis are required to defined the sustainability of the process

Thermal Imaging to Assess the Health Status in Wildlife Animals under Human Care: Limitations and Perspectives

Ensuring the welfare of wildlife under human care requires tools to monitor their health and well-being. Infrared thermography is a non-invasive technique for assessing thermal states that measure the radiation emitted from the skin in distinct anatomical areas, known as thermal windows—anatomical regions with abundant capillaries and arteriovenous anastomosis that facilitate heat exchange with the environment. However, thermal windows for wildlife species have not yet been established due to the different characteristics of their skin, coats, fur, or coloring. This review discusses published information on the usefulness of the ocular, nasal, thoracic, abdominal, and podal anatomical regions as thermal windows for evaluating these animals’ thermal responses and health status and monitoring habitat design. Another aspect that must be considered for wildlife under human care is the limitations of distinct species due to differences between animals and critical factors. Future studies should focus on establishing a precise application for each thermal window according to the specific characteristics of distinct animal species

Geographical ecology of dry forest tree communities in the West Indies

© 2018 The Authors. Journal of Biogeography Published by John Wiley & Sons Ltd Aim: Seasonally dry tropical forest (SDTF) of the Caribbean Islands (primarily West Indies) is floristically distinct from Neotropical SDTF in Central and South America. We evaluate whether tree species composition was associated with climatic gradients or geographical distance. Turnover (dissimilarity) in species composition of different islands or among more distant sites would suggest communities structured by speciation and dispersal limitations. A nested pattern would be consistent with a steep resource gradient. Correlation of species composition with climatic variation would suggest communities structured by broad-scale environmental filtering. Location: The West Indies (The Bahamas, Cuba, Hispaniola, Jamaica, Puerto Rico, US Virgin Islands, Guadeloupe, Martinique, St. Lucia), Providencia (Colombia), south Florida (USA) and Florida Keys (USA). Taxon: Seed plants—woody taxa (primarily trees). Methods: We compiled 572 plots from 23 surveys conducted between 1969 and 2016. Hierarchical clustering of species in plots, and indicator species analysis for the resulting groups of sites, identified geographical patterns of turnover in species composition. Nonparametric analysis of variance, applied to principal components of bioclimatic variables, determined the degree of covariation in climate with location. Nestedness versus turnover in species composition was evaluated using beta diversity partitioning. Generalized dissimilarity modelling partitioned the effect of climate versus geographical distance on species composition. Results: Despite a set of commonly occurring species, SDTF tree community composition was distinct among islands and was characterized by spatial turnover on climatic gradients that covaried with geographical gradients. Greater Antillean islands were characterized by endemic indicator species. Northern subtropical areas supported distinct, rather than nested, SDTF communities in spite of low levels of endemism. Main conclusions: The SDTF species composition was correlated with climatic variation. SDTF on large Greater Antillean islands (Hispaniola, Jamaica and Cuba) was characterized by endemic species, consistent with their geological history and the biogeography of plant lineages. These results suggest that both environmental filtering and speciation shape Caribbean SDTF tree communities

Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC

We present results from daily monitoring of gamma rays in the energy range $\sim0.5$ to $\sim100$ TeV with the first 17 months of data from the High Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2 steradians and duty cycle of $>95$% are unique features compared to other TeV observatories that allow us to observe every source that transits over HAWC for up to $\sim6$ hours each sidereal day. This regular sampling yields unprecedented light curves from unbiased measurements that are independent of seasons or weather conditions. For the Crab Nebula as a reference source we find no variability in the TeV band. Our main focus is the study of the TeV blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a power law index $\Gamma=2.21 \pm0.14_{\mathrm{stat}}\pm0.20_{\mathrm{sys}}$ and an exponential cut-off $E_0=5.4 \pm 1.1_{\mathrm{stat}}\pm 1.0_{\mathrm{sys}}$ TeV. For Mrk 501, we find an index $\Gamma=1.60\pm 0.30_{\mathrm{stat}} \pm 0.20_{\mathrm{sys}}$ and exponential cut-off $E_0=5.7\pm 1.6_{\mathrm{stat}} \pm 1.0_{\mathrm{sys}}$ TeV. The light curves for both sources show clear variability and a Bayesian analysis is applied to identify changes between flux states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab Nebula flux by a factor of approximately five. For Mrk 501, several transits show fluxes in excess of three times the Crab Nebula flux. In a comparison to lower energy gamma-ray and X-ray monitoring data with comparable sampling we cannot identify clear counterparts for the most significant flaring features observed by HAWC.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical Journa

All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV

We report on the measurement of the all-particle cosmic ray energy spectrum with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range 10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to gamma rays and cosmic rays at TeV energies. The data used in this work were taken from 234 days between June 2016 to February 2017. The primary cosmic-ray energy is determined with a maximum likelihood approach using the particle density as a function of distance to the shower core. Introducing quality cuts to isolate events with shower cores landing on the array, the reconstructed energy distribution is unfolded iteratively. The measured all-particle spectrum is consistent with a broken power law with an index of $-2.49\pm0.01$ prior to a break at $(45.7\pm0.1$) TeV, followed by an index of $-2.71\pm0.01$. The spectrum also respresents a single measurement that spans the energy range between direct detection and ground based experiments. As a verification of the detector response, the energy scale and angular resolution are validated by observation of the cosmic ray Moon shadow's dependence on energy.Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review