Search

La Inyección de gas es usada ampliamente en campos de explotación de petróleo como un método de recobro mejorado. Sin embargo, este método puede resultar ineficiente si la formación productora favorece la canalización del gas debido a heterogeneidades. Fluidos divergentes, como las espumas, han sido inyectados a este tipo de yacimientos para aumentar la eficiencia de barrido, ya sea por reducción de la movilidad del gas o por bloqueo de su flujo a través de canales preferenciales, que bien pueden ser fracturas o sistemas de fracturas naturales. Este estudio tiene como fin evaluar la eficiencia de una espuma para reducir la canalización del gas y aumentar el recobro de aceite al interior de medios porosos naturalmente fracturados. Se diseña una metodología en laboratorio que involucra la evaluación de la estabilidad de la espuma a alta temperatura, la compatibilidad de la solución espumante con los fluidos de formación, restringir la canalización del gas a través de la(s) fractura(s) y la obtención de parámetros para el óptimo desarrollo de las pruebas de desplazamiento a condiciones cercanas a las de yacimiento. Tomando el recobro de aceite como el parámetro con el cual se mide la eficiencia de los métodos, se encontró que el recobro adicional de aceite se incrementa en promedio en un 10%, cuando se cierran las fracturas con la solución espumante, en comparación con el cierre de fractura por aumento de la presión de sobrecarga. Se pudo verificar que la espuma actúa de manera eficiente como fluido divergente para bloquear fracturas y barrer fluidos que en general se encuentran en la matriz.

Background: Emphysematous cholecystitis (EC) is a rare but life-threatening complication of acute cholecystitis, and an early diagnosis is required to prevent delay in patient management. Because sonography (US) is the first choice for diagnosing gallbladder diseases, US findings of EC should be understood more precisely.Methods: We reviewed US findings of 11 surgically proven cases of EC (with small amounts of gas in three cases and large amounts in eight cases) and compared those with patients' clinical data.Results: (1) In cases with small amounts of gas, US showed an echogenic line with a distinct ring-down artifact or a "powder snow-like" speckled posterior echo. (2) In cases with large amounts of gas, US showed a wide spiculated echogenic band with a powder snow-like speckled posterior echo or a speckled acoustic shadowing. In all cases, the presence of gas prevented visualization of the gallbladder wall. (3) US did not differentiate gas localized to the gallbladder wall and gas extending to the surrounding hepatic tissue. (4) Two diabetic cases showed gas throughout the intrahepatic bile ducts. In those cases, the time from diagnosis to recovery was relatively long.Conclusion: Our series showed some characteristic US patterns of EC. A good understanding of its US findings and appropriate emergent management will reduce the serious morbidity and mortality rates caused by EC. [ABSTRACT FROM AUTHOR]

Air pollution control is one of the most important issues in the cities of the developing countries. Based on an analysis of the local economic and technological development the paper puts forward 9 air pollution control schemes. They are 4 briquette schemes, 2 coal gas schemes, 1 centralized heating system and 2 comprehensive schemes. A comprehensive diffusion model combined with a 3-D advection-diffusion equation and the Gaussian puff model is developed and verified. According to the calculation of potential reduction of pollutant discharge and the corresponding air quality improvement made by each air pollution control scheme, the paper then works out a feasible and comprehensive air pollution control scheme, which is characterized by low investment and better environmental benefits. When the scheme is efficiently carried out, 19.3% SO2 and 24.4% soot discharge is to be reduced annually in the city. There is a clear descent of air pollution concentration. The daily mean concentration of SO2 and TSP declines 24.6–75.4% and 10.4–45.4%, respectively. SO2 concentation of the whole city does not exceed the second grade of the Ambient Air Quality Standard of China except at a few grid points. [ABSTRACT FROM AUTHOR]

We describe a case of fatal fulminant hepatic infection with gas replacement of the hepatic parenchyma and no evidence of a liquified abscess in a diabetic patient: a case of "emphysematous hepatitis," the hepatic equivalent of emphysematous pyelonephritis. Computed tomography and clinical findings are described. [ABSTRACT FROM AUTHOR]