Geology, Geophysics & Environment
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ISSN 2299-8004
e-ISSN: 2353-0790
Issue Date
2020
Volume
Vol. 46
Number
No 4
Description
Journal Volume
Geology, Geophysics & Environment
Vol. 46 (2020)
Projects
Pages
Articles
Seismic stratigraphic analysis for hydrocarbon exploration in the Beta Field, Coastal Swamp Depobelt, Niger Delta
(Wydawnictwa AGH, 2020) Adeleye, Mutiu A.; Yekeen, Kazeem O.; Amidu, Sikiru A.
Hydrocarbon exploration analysis from a seismic stratigraphic approach was carried out within the Beta Field, Coastal Swamp Depobelt, Niger Delta, to identify system tracts and sequence boundaries that could be associated with potential hydrocarbon accumulation. 3D seismic volume and data from four wells were analyzed. Depositional sequences, system tracts, sequence boundaries, and candidate maximum flooding surfaces were picked from logs, while reflection patterns and terminations were interpreted from seismic sections. Log shapes from gamma rays in combination with seismic facies analysis were interpreted in order to delineate lithology, depositional environments and depositional sequences. Seismic attributes were extracted and were draped on gridded surfaces from the interpreted seismic horizons. These were integrated with structure maps to obtain structural and stratigraphic trends, and possible presence of reservoir sand. Five depositional sequences and nine seismic facies were identified within the field. The depositional sequences were designated Sequences S1 to S5 based on the depth of the occurrences and stacking patterns. This study reveals a progression from fluvial depositional settings to the shelf. The main reservoirs identified are the sand units of the highstand and lowstand within three depositional sequences (S1, S4 and S5) although interbedded sands within the TST of S4 and S5 are also suspected of being potential reservoirs. The channel sand deposits within the study area are suspected to be hydrocarbon bearing as they occurred within the complex fault trapping system popular in the Niger Delta. The application of seismic stratigraphy, as shown in this study, serves to encourage exploration in the Niger Delta where it could be effectively employed for reducing risk in hydrocarbon exploration.
A determination of areas of biocorrosion development on the route of a main gas pipeline in the Western region of Ukraine
(Wydawnictwa AGH, 2020) Polutrenko, Myroslava; Kryzhanivs'kyy, Yevstakhiy; Federovych, Yaroslav
A determination of soil corrosivity on three sections of a main gas pipeline in the Western region of Ukraine has been carried out. We have distinguished areas of development of biocorrosive processes with the participation of sulphate-reducing bacteria (SRB). Soil evaluation by the degree of corrosivity has been conducted. We used weight, titrimetric, gravimetric methods, pH-metry, ten-fold limit dilution method and Postgate nutrient medium B for culturing SRB. It has been established that the soil in the first area selected along the lower generatrix of the main gas pipeline has a high degree of corrosivity. It was ascertained that corrosive metal damage increases in the »ferrozone« with the growth of metal exposition time from 24 to 72 hours. The soil selected in the middle part and from above the pipeline refers to soils with a normal degree of corrosive activity. Innovative biostable insulating coatings based on bituminous-polymerous mastic MBPID-1 have been developed, modified with organic inhibitors from the class of quaternary ammonium salts and amines. Regularities of influence of nature of nitrogen-containing corrosion inhibitors of industrial production M, N, L, H and K on the corrosion rate of 17G1S steel for 180 days have been established. It was found that the corrosion rate of steel specimens remained unchanged throughout the study in variants with the presence of inhibitors H and K in the test systems, which indicated their bioresistance to the effect of SRB bacteria.
Statistical evaluation of the geochemical data for prospecting polymetallic mineralization in the Suoi Thau–Sang Than region, Northeast Vietnam
(Wydawnictwa AGH, 2020) Khương, Thế Hưng; Sang, Pham Nhu; Nguyễn, Phuong; Vũ, Thái Linh; Sang, Bui Viet
In Northeast Vietnam, Suoi Thau-Sang Than is considered as a high potential area of polymetallic deposits. 1,720 geochemical samples were used to investigate polymetallic mineralization, thereby polymetallic ore occurrences in this study region were discovered and the statistical and multivariate analysis helps to define geochemical anomalies in some northeastern regions, namely Suoi Thau, Sang Than, and Ban Kep. The statistical method and cluster analysis of geochemical data indicate that the Cu, Pb, and Zn elements are good indicators, and most of them comply with the lognormal or gamma distribution. Based on the third-order threshold, the geochemical anomalies of the content of the Cu, Pb, and Zn elements reflect the concentration of copper forming ore bodies in the mineralized zone, and clearly show the concentration in three distinct zones. The trend surface analysis which was employed to determine spatial variations and relationships among these good indicator elements and anomalous areas revealed relative changes in the content of the indicator elements, and they can be considered as regular. Moreover, the goodness of fit obtained trend functions of Pb and Zn, and Cu elements is a third-degree trend surface model. These results indicate that the models can be useful in studying geochemical anomalies and analyzing the tendency of the concentration of indicator elements in the Suoi Thau-Sang Than region. Additionally, it is suggested that the statistical analysis shows a remarkable potential to use the bottom river sediments in the region to investigate polymetallic mineralization. Moreover, geochemical data can help to evaluate geochemical anomalies of the pathfinder elements and potential mineral mapping of the Suoi Thau-Sang Than region in Northeast Vietnam.
The application of volume texture extraction to three-dimensional seismic data - lithofacial structures exploration within the Miocene deposits of the Carpathian Foredeep
(Wydawnictwa AGH, 2020) Łukaszewski, Mariusz
There are numerous conventional fields of natural gas in the Carpathian Foredeep, and there is also evidence to suggest that unconventional gas accumulations may occur in this region. The different seismic signatures of these geological forms, the small scale of amplitude variation, and the large amount of data make the process of geological interpretation extremely time consuming. Moreover, the dispersed nature of information in a large block of seismic data increasingly requires automatic, self-learning cognitive processes. Recent developments with Machine Learning have added new capabilities to seismic interpretation, especially to multi-attribute seismic analysis. Each case requires a proper selection of attributes. In this paper, the Grey Level Co-occurrence Matrix method is presented and its two texture attributes: <i>Energy</i> and <i>Entropy</i>. Haralick's two texture parameters were applied to an advanced interpretation of the interval of Miocene deposits in order to discover the subtle geological features hidden between the seismic traces. As a result, a submarine-slope channel system was delineated leading to the discovery of unknown earlier relationships between gas boreholes and the geological environment. The Miocene deposits filling the Carpathian Foredeep, due to their lithological and facies diversity, provide excellent conditions for testing and implementing Machine Learning techniques. The presented texture attributes are the desired input components for self-learning systems for seismic facies classification.
Portable XRF spectrometer with helium flow as a tool for lithological interpretation
(Wydawnictwa AGH, 2020) Skupio, Rafał
Portable EDXRF (Energy Dispersive X-Ray Fluorescence) spectrometer with the ability to perform rock tests in a helium atmosphere was applied to prepare unique calibration coefficients and mineralogical models. These data could be used for the chemical profiling, chemostratigraphy, gamma-ray, TOC and lithological interpretation of borehole geological profile. The measurements were conducted on 19 samples of sandstones and compared to the XRF data without helium flow. The acquired dataset was calibrated to the chemical laboratory tests (ICP-MS), gamma-ray spectrometry measurements (RT-50) and combined with the mineralogical data (XRD). The new methodology enables the measurement of sodium and enhances the possibility of detecting magnesium, thorium and uranium, compared to standard handheld XRF spectrometers. The applied method is dedicated to whole cores (without sample preparation) or cuttings which must be cleaned, dried, milled and pressed.