Passive Margin evolution and control on natural gas leakage in the Orange Basin South Africa

Throughout exploration Block 2 of the Orange Basin offshore the South African continental margin, different natural gas leakage features and the relationship between natural gas leakage with structural and stratigraphic elements were studied. This study also quantifies liquid/gas hydrocarbon generation, migration and seepage dynamics through the post-rift history of the basin. The interpretation of seismic data reveals two mega-sequences: Cretaceous and Cenozoic that are subdivided by major stratigraphic unconformities into 5 and 2 sub-units, respectively. The basin is also divided into 2 structural domains: 1. an extensional domain characterized by basinward dipping listric normal faults rooted at the Cenomanian/Turonian level identified between 500 to 1500 m of present-day depth, 2. a compressional domain that accommodates the up-dip extension on the lower slope, and which is characterized by landward dipping thrust faults. One hundred and thirteen observed gas chimneys are identified and classified into .stratigraphically-controlled (sa-c) and structurally-controlled (s-c) chimneys. The ratio of s-c versus s-ac chimneys is estimated as 2:5, which suggest a strong stratigraphic control on natural gas leakage. The chimneys either terminate at the seafloor where active leaking gas is manifested by pockmarks, or are sealed within the Miocene (14 Ma) sequence as paleo-pockmarks. The s-c chimneys are located along the normal faults in the extensional domain, and terminate as seafloor mounds up to 1500 m in diameter and with heights between 10 to 50 m. The sa-c pockmarks range between 100 to 400 m in diameter, and are linked to stratigraphic onlaps and pinch-outs within the Aptian sequence. Several giant chimneys, with diameters of more than 7 km, are also identified. At least one of these displays apparent internal gravitational collap.se structures. Bright spots indicative of gas presence within these large chimneys were identified, but there is no evidence of acoustic turbidity or seismic pull-downs within these large structures. This suggests the giant chimneys are inactive paleo-gas-escape structures. Modelling suggests that gas from the lower Aptian and the Barremian source rocks migrates laterally-updip to the proximal parts of the basin where it accumulates beneath the Cenomanian/Turonian sequence that acts as a regional seal. Across the shelf-break and the upper slope, chimneys and pockmarks are fed from younger Cenomanian/Turonian source rocks. The migration model also indicates that fluids are about 24 times more likely to flow out of the study area than to be preserved within it. Since methane gas escaping across the sea floor into the exosphere (combined hydrosphere and atmosphere) may contribute to Earth s climate fluctuations, and because escaping gas must have been cut off when at least half of identified s-c chimneys were sealed within the Mioeene .sequenee, deerease of gas escape along the southern African continental margin may have to be factored into global Neogene cooling models

Distribution and origin of natural gas leakage in the Colorado Basin, offshore Argentina 2 Margin, South America: seismic interpretation and 3D basin modelling

The detailed analysis of a dense 2D seismic reflection dataset and data from 8 exploration wells, allowed us to identify, map out and characterize possible indications of past and present-day hydrocarbon leakage (i.e. gas chimneys, gas pockets, and seafloor mounds and pockmarks) on the continental shelf and slope of the Colorado Basin, offshore Argentina, where Permian, Jurassic and Early Cretaceous source rocks are potentially present and may be currently mature. Identified gas leakage features, developed both in the syn-rift and post-rift successions, were also analysed in relation to the structural the stratigraphic elements of the basin. A family of seabed pockmarks, located close to an array of submarine channels, was identified on the distal slope of the basin. These pockmarks are overlying a series of sub-vertical to vertical seismic chimneys in the subsurface. A calibrated basin-wide 3D petroleum system model comprising generation and migration of hydrocarbons was carried out and compared with the observations from the seismic analysis. Preliminary results from this model indicate that although synrift and early Cretaceous source rock (SR) intervals may be depleted in the central areas of the basin, an active kitchen from the Aptian SR may be present below the slope areas. Hydrocarbon migration pathways predicted by the 3D model (Hybrid method) coincide with the interpreted seismic chimneys underlying the observed seabed slope pockmarks. Hence, our results indicate that thermogenic gas may be currently generated in the distal slope of the basin from mature early post-rift source rocks within the Early Cretaceous (Aptian) sequences and migrates vertically, due to seal failure, through the stratigraphic column. This migrating thermogenic gas is feeding the seafloor pockmarks identified in the distal slope of the basin, although up-dip lateral migration along stratigraphic layers to the more proximal slope areas cannot be ruled out. The present work represents the first published study integrating detailed seismic analysis and 3D basin modelling linking observed gas-leakage indicators and associated seepage pathways, to their relative abundance, distribution and feeding systems offshore Argentina’s continental margin

Varijabilnost i povezanost osnovnih parametara kvaliteta sirovog kravljeg mleka

In this paper the results of the analysis of the milk somatic cell count are presented, as well as correlation between the somatic cell count and content of certain chemical parameters in milk (milk proteins, fat, lactose and dry matter without fat) determined in collective samples of milk obtained from cows reared in intensive rearing system, during two production years. The research was carried out by control of collective milk samples from cows reared on family holdings. Somatic cell count, as well as the chemical quality of milk, were controlled daily in the laboratory for raw milk in dairy plant AD 'Mlekara' - Subotica using the apparatus CombiFoss 6200 FC. In this investigation, statistically significant correlation (P lt 0,001) between all observed milk parameters was determined. Positive, weak and statistically highly significant correlation between the content of milk fat and proteins in milk and somatic cell count was established. It was also established that the variability of chemical parameters of milk and somatic cell count is also under the influence of different factors, such as: month of control, year of the research and farm.U radu prikazani su godišnji rezultati ispitivanja broja somatskih ćelija u mleku, mlečne masti, proteina, laktoze i suve materije bez masti, u zbirnim uzorcima mleka krava u intenzivnoj proizvodnji u toku dve proizvodne godine. Ispitivanja su izvršena kontrolom zbirnih uzoraka mleka od približno 3000 krava sa porodičnih farmi. Prosečni broj somatskih ćelija je bio 462x103 u 1 ml zbirnog mleka (uz variranje od 410,43 do 536,06 x 103 u 1 ml), prosečni sadržaj proteina je bio 3,21%, mlečne masti 3,76%, laktoze 4,54% i suve materije bez masti 8,46%. Utvrđene su statistički značajne razlike u broju somatskih ćelija utvrđenih na zbirnom uzorku mleka u odnosu na mesec kontrole. U ovom radu je utvrđena pozitivna i statistički signifikantna korelacija (P lt 0,001) između sadržaja mlečne masti i proteina u mleku i broja somatskih ćelija, i negativna i statistički signifikantna (P lt 0,001) korelacija između broja somatskih ćelija i sadržaja laktoze i suve materije bez masti u zbirnom uzorku mleka. Utvrđivanje odn. merenj broja somatskih ćelija u zbrinom mleku je ključni faktor u oceni kvaliteta mleka zapata, i koristi se i u određivanju cene otkupljenog mleka, i ukazuje na zdravlje vimena mlečnih grla u zapatu i omogućava farmi da prati uspeh programa za kotnrolu mastitisa u zapatu

Distribution and origin of natural gas leakage in the Colorado Basin, offshore Argentina Margin, South America : seismic interpretation and 3D basin modelling

The detailed analysis of a dense 2D seismic reflection dataset and data from 8 exploration wells, allowed us to identify, map out and characterize possible indications of past and present-day hydrocarbon leakage (i.e. gas chimneys, gas pockets, and seafloor mounds and pockmarks) on the continental shelf and slope of the Colorado Basin, offshore Argentina, where Permian, Jurassic and Early Cretaceous source rocks are potentially present and may be currently mature. Identified gas leakage features, developed both in the syn-rift and post-rift successions, were also analysed in relation to the structural the stratigraphic elements of the basin. A family of seabed pockmarks, located close to an array of submarine channels, was identified on the distal slope of the basin. These pockmarks are overlying a series of sub-vertical to vertical seismic chimneys in the subsurface. A calibrated basin-wide 3D petroleum system model comprising generation and migration of hydrocarbons was carried out and compared with the observations from the seismic analysis. Preliminary results from this model indicate that although synrift and early Cretaceous source rock (SR) intervals may be depleted in the central areas of the basin, an active kitchen from the Aptian SR may be present below the slope areas. Hydrocarbon migration pathways predicted by the 3D model (Hybrid method) coincide with the interpreted seismic chimneys underlying the observed seabed slope pockmarks. Hence, our results indicate that thermogenic gas may be currently generated in the distal slope of the basin from mature early post-rift source rocks within the Early Cretaceous (Aptian) sequences and migrates vertically, due to seal failure, through the stratigraphic column. This migrating thermogenic gas is feeding the seafloor pockmarks identified in the distal slope of the basin, although up-dip lateral migration along stratigraphic layers to the more proximal slope areas cannot be ruled out. The present work represents the first published study integrating detailed seismic analysis and 3D basin modelling linking observed gas-leakage indicators and associated seepage pathways, to their relative abundance, distribution and feeding systems offshore Argentina's continental margin

Tectonic evolution of the Colorado Basin, offshore Argentina, inferred from seismo-stratigraphy and depositional rates analysis

International audienceBased on a dense 2D seismic reflection dataset and information from 8 exploration wells, we reinterpreted the stratigraphic evolution of the Colorado Basin. The basin is located on the continental shelf and slope within 50 to 2250 m of bathymetry. The total sediment fill can be up to 16,000 m. Seismic-to-well log correlations provide a chrono-stratigraphic framework for the interpreted seismic sequences. We show that the Colorado Basin records the development of a Permian pre-rift period, a Triassic/Jurassic to Early Cretaceous rift phase and a Lower Cretaceous to Tertiary drift phase. This passive margin represents the evolution of lithospheric extension from active rifting to the thermal subsidence/drift stage. Several Cretaceous to Cenozoic slumping episodes were identified and related to progradation of the sequences and sediment build-up in the slope, as well as to the development of seaward dipping extensional faults

Risk Factors for Intraoperative Hypertension during Surgery for Primary Hyperparathyroidism

Objective: To investigate the incidence and identify risk factors for the occurrence of intraoperative hypertension (IOH) during surgery for primary hyperparathyroidism (pHPT). Subjects and Methods: The study included 269 patients surgically treated between January 2008 and January 2012 for pHPT. IOH was defined as an increase in systolic blood pressure >= 20% compared to baseline values which lasted for 15min. The investigated influence were demographic characteristics, surgical risk score related to physical status (based on the American Society of Anesthesiologists [ASA] classification), comorbidities, type and duration of surgery, and duration of anesthesia on IOH occurrence. The investigated factors were obtained from the patients' medical history, anesthesia charts, and the daily practice database. Logistic regression analysis was done to determine the predictors of IOH. Results: Of the 269 patients, 153 (56.9%) had IOH. Based on the univariate analysis, age, body mass index, ASA status, duration of anesthesia, and preoperative hypertension were risk factors for the occurrence of IOH. Multivariate analysis showed that independent predictors of IOH were a history of hypertension (OR = 2.080, 95% CI: 1.102-3.925, p = 0.024) and age (OR = 0.569, 95% CI: 0.360-0.901, p = 0.016). Conclusion: In this study, a high percentage (56%) of the patients developed IOH during surgery for pHPT, which indicates that special attention should be paid to these patients, especially to the high-risk groups: older patients and those with a history of hypertension. Further, this study showed that advanced age and hypertension as a coexisting disease prior to parathyroid surgery were independent risk factors for the occurrence of IOH

Summertime PAH assembly in Mediterranean air: the Herceg Novi sampling station as an example

The results of an analysis of the total suspended particles (TSP), total solvent organic extracts (TSOE), and polycyclic aromatic hydrocarbons (PAHs) in aerosol samples collected from the atmosphere of Herceg Novi from 17th June to 15th September in 1998 and 1999 are presented. The TSP and TSOE concentrations were determined by the standard gravimetric method, whereas the PAHs from the organic part of the aerosol were analysed by the GC-MS method. The difference found in the TSP and TSOE contents between the two consecutive years (before and after the bombing of Yugoslavia) was attributed to changes in the intensity and origin of emissions from dominant sources, specific to the summer period of this region. The content and nature of the PAHs identified in the samples of 1998 and 1999 were also different, indicating the significance of traffic as the source of PAHs, which was of significantly lower intensity in 1999 (immediately after the war) due to the lower influx of tourists. Factor analysis showed that the PAH distribution at the measuring site in 1999 was largely determined by meteorological parameters, mainly by the average daily temperature and wind direction. In 1998, the dominant impact on the PAH distribution was attributed to traffic, both local and from a wider region, without an explicit impact of meteorological parameters

Impact of Teacher Demonstration Video On Polytechnic Students’ Achievement in Shorthand in Zamfara State

The study examined the effect of teacher demonstration video on Polytechnic students’ achievement in Shorthand in Zamfara State. A pretest-posttest quasi-experimental and control group design was used in the study. A sample size of 185 students was obtained from the two intact classes of the two polytechnics that were used for this study. The polytechnics were assigned to treatment and control groups through simple random selection. The instrument for data collection was Shorthand Achievement Test (SHAT). It was validated by 3 educational technology experts and 5 Shorthand lecturers. The instrument was later subjected to reliability test and the data was computed using Pearson product Moment Correlation. A coefficient value of (r) .75 was obtained indicating that the instrument is reliable for the study. Data gathered from the field was computed and used to answer the research questions using mean and standard deviation while hypotheses were tested using t-test. All the analyses were conducted using SPSS version 23. The findings of the study revealed that significant difference exists in the Shorthand achievement scores of polytechnic students exposed to teacher demonstration video and those in the control group. It also revealed that significant difference exists in the Shorthand achievement scores of male and female polytechnic students exposed to teacher demonstration video. Based on these outcomes, the researchers recommended amongst others that Shorthand lecturers should critically examine the need, suitability in use, easy in operation and the possible benefits which is attainable in the use of video instruction in his shorthand class before deciding to apply it in order to avoid futile efforts at the end of the lesson