Geology, Geophysics & Environment
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ISSN 2299-8004
e-ISSN: 2353-0790
Issue Date
2021
Volume
Vol. 47
Number
No 3
Description
Journal Volume
Geology, Geophysics & Environment
Vol. 47 (2021)
Projects
Pages
Articles
Significance of real-time petro-physical data for an optimal remote geosteering operation in complex geological reservoirs
(Wydawnictwa AGH, 2021) Amer, Muhammad Attique; Ehsan, Muhsan; Akhtar, Muhammad Javid
In the last decade, the oil industry has transitioned from primarily drilling vertical wells to a majority of extended reach complex horizontal wells with help of geosteering techniques for better reservoir and production efficiencies. The overall objective of geosteering and well placement has helped to maximize reservoir contact by the keeping well trajectory in the pay zone with the help of quality real-time data, especially in these uncertain times of pandemic due to COVID-19. This paper illustrates the immense impact of real-time data feeds (special logging tools/images) at operation centers with the full remote expert support of multidisciplinary teams. The proper data communication mechanism is also helpful to share the information across asset teams in a timely manner to drill complex wells remotely. To achieve the desired geosteering objectives, experts monitor and evaluate the real-time data in a landing well accurately in the pay horizon by designing the well path which considers geological variables like (reservoir architecture, permeability and porosity distribution, and fluid contacts) which further helps update the reservoir models in real-time based on the latest subsurface information for better reservoir management and timely decision making.
Satellite data based abundance mapping of mafic and ultramafic rocks in Mettupalayam, Tamil Nadu, India
(Wydawnictwa AGH, 2021) Libeesh, Nharakkat Kalarikkal; Arivazhagan, Sundaram
The mafic and ultramafic rocks of Mettupalayam belong to the southern granulite terrain of India, which is concomitant with vital economic resources. The advantage of Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) data for mapping the litho units are exploited well here for differentiating the rock units with the aid of band combination (1, 3, 6), principal component analysis (5, 1, 6) and band ratioed band combination (2/3, 3/2, 1/5 and (9–8)/1, (8–6)/2, and (9–6)/3). As part of the field study, the collection of samples and ground control points were carried out and in addition to that, the generation of laboratory reflectance spectra for samples was achieved. The Spectral Angle Mapper (SAM) and Support Vector Machine (SVM) were performed using ASTER data with the aid of spectra obtained from the laboratory conditions to demarcate the abundance of mafic and ultramafic rocks of the area. The XRF method was used to retrieve the major oxides of the field-collected samples and the spectral absorption characters are validated with it. The results show a vibrant interpretation of the litho units.
Sulfur and lead isotope geochemical characteristics of Pb-Zn deposits in the Khau Loc zone, northeastern Vietnam, and their significance
(Wydawnictwa AGH, 2021) Khương, Thế Hưng; Ta, Dinh Tung; Do, Quoc Binh; Sang, Pham Nhu; Nguyẽ̂n, Thị Cúc; Nguyẽ̂n, Thi Hoang Linh; Quach, Duc Tin
In northeastern Vietnam, the Khau Loc zone is considered to have high potential for lead-zinc mineralization. The lead isotope data for 18 galena samples and 18 ones of $\delta^{34}S$ isotope data (including galena and pyrite samples) were collected from lead-zinc ore deposits in some areas in the Khau Loc zone, including Phia Dam, Khuoi Man, Ban Lin, Lung Dam, and Ta Pan. These were employed to investigate the sulfur and lead isotope geochemical characteristics of Pb-Zn deposits and their significance in this study. The samples were analyzed using the LA-ICP-MS to show that the Pb isotopic ratios of $^{206}$Pb/$^{204}$Pb, $^{207}$Pb/$^{204}$Pb, and $^{208}$Pb/$^{204}$Pb in the galena samples range from 17.8908 to 18.6012, 15.5794 to 16.1025, 38.4420 to 39.2118, with the average values of 18.296, 15.749, and 38.812, respectively. The pyrite and galena samples had the $\delta^{34}S$ isotope, ranging from 9.0 to 15.106. The sulfur isotope systematics implies that most of the lead-zinc ore formations originated from marine sedimentary evaporation deposits and magmatic intrusion-volcanic eruption sources rich in silica. The distribution of lead isotopic ratios had a well-defined cluster for each deposit, indicating the formation of lead-zinc deposits and lower crust and orogen trends. In addition, these findings of lead isotopic ratios and $\delta^{34}S$ isotopes proved that the Khau Loc zone is an activated structure with continuous growth in continental crust thickness during the early Proterozoic and Cenozoic periods. Furthermore, the study results also presented the evolution of material sources involved in the formation of lead-zinc ores in the Khau Loc zone.
Hydrothermal ore mineralization from the Polish part of the Tatra Mts., Central Western Carpathians
(Wydawnictwa AGH, 2021) Sitarz, Magdalena; Gołębiowska, Bożena; Nejbert, Krzysztof; Dimitrova, Dimitrina; Milovský, Ratislav
Several areas with hydrothermal ore mineralization are present in the Polish part of the Western Tatra Mts. Massive and disseminated sulfides, mainly minerals from the tetrahedrite group and chalcopyrite, fill quartz veins accompanied by siderite, dolomite and baryte - many of these were mined between the 16$^{th}$ and 18$^{th}$ century. This paper presents information on the mineralogy of the common sulfides and the preliminary studies of both the isotopic composition of sulfur in tetrahedrite as well as the origin of hydrothermal fluids. The most common primary sulfide minerals in the ores are tetrahedrite-(Zn) and tetrahedrite-(Fe) corresponding to Zn ranges from 1.83 to 5.87 wt.% (0.47–1.44 apfu), and Fe from 1.63 to 5.05 wt.% (0.48–1.52 apfu). The substitution of As for Sb shows maximum As content of 7.25 wt.% (1.588 apfu) which corresponds to the Sb/(Sb+As) = 0.60. Both varieties show substitutions of Bi and Hg, up 0.6 wt.% (0.049 apfu) and 0.96 wt.% (0.081 apfu), respectively, and content of trace elements: Co (max. 976 ppm), Cd (max. 735 ppm), In (max. 14 ppm). Chalcopyrite, pyrite, and galena show compositions close to the ideal formula. Differences in the content of trace elements in the studied tetrahedrite and chalcopyrite were explained by element partitioning between these minerals. The distributions of In, Ga and Sn in the studied minerals indicate that the mineralization was formed at low temperature and pressure. The homogenization temperature of the primary inclusions in quartz in the range of 120–174°C indicate the origin of mineralization in low temperature stage from low salinity fluids (up to 17.92 wt.% NaCl eq.). Stable $\delta^{34}S$ isotopes in minerals of the tetrahedrite group suggest that the igneous fluids might be one of the sources from which ores were crystallized.