Petrological and Biostratigraphic Characteristics of Pre-Cenozoic Carbonate Rocks in the Northern Song Hong Basin, Vietnam

Pre-Cenozoic carbonate rocks in the northern Song Hong basin, Vietnam that are being considered and studied by oil companies in exploration and exploitation. The hydrocarbon accumulations in these rocks have been discovered and have significantly commercial reserves, in which the porosity plays an important role in estimating the capacity of hydrocarbon. The carbonate rocks are composed mainly of crystalline limestone, packstone, wackestone and mudstone, which have been experienced dolomitization, compaction and dissolution. The main carbonate pore systems include fracture, vuggy and intercrystalline porosity. The predominance of larger benthic foraminiferal assemblages indicates that the carbonate sediments were formed during the late Paleozoic (Carboniferous-Permian) and were deposited in shallow marine environment. Furthermore, the obtained petrological and biostratigraphic characteristics are well-correlated with the carbonate formations exposed in adjacent Cat Ba island area. The results of this study are either used in petroleum exploration or used in a local stratigraphic correlation in northern Vietnam

Pore and Grain Geometry Analysis of Sandstone Reservoir Rocks from a Well of a Northern German Basin

Pore space and grain geometry are important physical properties distinguished in reservoir rocks, particularly in sandstones, due to their influence on oil and gas reservoir quality. Therefore, a detailed study of pore space morphology and grain surface roughness in sandstone reservoir rocks is a key element in petroleum geology. It is eminent in understanding of the adhesion of hydrocarbons in rocks and coupled fluid flows in pores and along grain surfaces. In this work, sandstone samples taken from a well of a Northern German basin deposit have been analysed by thin section petrography, Confocal Raman Microscopy and Confocal Laser Scanning Microscopy (CLSM). The roughness of grain surfaces is analysed and the pore geometries of sandstone rocks are verified. Roughness and pore geometry have a significant impact on the wetting behaviour and adhesion properties of hydrocarbon fluids, water or carbon dioxide (CO2) to the pore walls. The results show the relationship between the composition of sandstones and their pore geometry and the grain surface roughness. The geometry of the pore morphology and the grain surface shows a range from very rough to flat smooth crystal facets, from few hundreds to sub-micron, depending on the scale of observation. The 50x and 100x magnifications were applied in this study. The findings offer a detailed insight into the relationship of pore space morphology and the grain surface roughness. The results add important parameters to the calculation models for hydrocarbon exploitation and to enhancement of the amount of oil recovery

Recurrence of tuberculosis among patients following treatment completion in eight provinces of Vietnam: A nested case-control study

Background: Patients completing treatment for tuberculosis (TB) in high-prevalence settings face a risk of developing recurrent disease. This has important consequences for public health, given its association with drug resistance and a poor prognosis. Previous research has implicated individual factors such as smoking, alcohol use, HIV, poor treatment adherence, and drug resistant disease as risk factors for recurrence. However, little is known about how these factors co-act to produce recurrent disease. Furthermore, perhaps factors related to the index disease means higher burden/low resource settings may be more prone to recurrent disease that could be preventable. Methods: We conducted a case-control study nested within a cohort of consecutively enrolled adults who were being treated for smear positive pulmonary TB in 70 randomly selected district clinics in Vietnam. Cases were patients with recurrent TB, identified by follow-up from the parent cohort study. Controls were selected from the cohort by random sampling. Information on demographic, clinical and disease-related characteristics was obtained by interview. Treatment information was extracted from clinic registries. Logistic regression, with stepwise selection, was used to develop a fully adjusted model for the odds of recurrence of TB. Results: We recruited 10,964 patients between October 2010 and July 2013. Median follow-up was 988 days. At the end of follow-up, 505 patients (4.7%) with recurrence were identified as cases and 630 other patients were randomly selected as controls. Predictors of recurrence included multidrug-resistant (MDR)-TB (adjusted odds ratio 79.6; 95% CI: 25.1-252.0), self-reported prior TB therapy (aOR = 2.5; 95% CI: 1.7-3.5), and incomplete adherence (aOR = 1.9; 95% CI 1.1-3.1). Conclusions: Index disease treatment history is a leading determinant of relapse among patients with TB in Vietnam. Further research is required to identify interventions that will reduce the risk of recurrent disease and enhance its early detection within high-risk populations. Keywords: Contact investigation, Tuberculosis, Active tuberculosis, Tuberculosis epidemiology, Relapse, Risk factors, Screenin