This study focuses on the geochemical analysis of sedimentary rocks from the Mallawa Formation in the southern arm of Sulawesi, Indonesia. It aims to provide comprehensive and unprecedented research results on the Mallawa Formation sandstones through geochemical analysis, which has not been conducted previously. By analyzing twelve sedimentary rock samples collected from three locations—Bone, Maros, and Pangkep Regencies, the study seeks to explore provenance, source rocks, and tectonic settings by analyzing major elements, REE, and trace elements. The results indicate that SiO₂ is the most abundant component, reflecting the presence of detrital quartz, chert, feldspar fragments, and other mineral contents. The rocks are classified as sandstones with fine to coarse grains, ranging from wacke to quartz arenite. Based on various discrimination diagrams, the sandstones are associated with a passive margin transitioning into an active margin. The provenance of these sandstones originates from siliceous-clastic rocks and intermediate to felsic igneous rocks. These findings align with the paleogeography of South Sulawesi and provide new insights into the evolution of the Mallawa Formation.
{"title":"Geochemistry of the sandstone of Mallawa Formation in the Southern arm of Sulawesi, Indonesia: Implications for provenance and tectonic setting","authors":"Safruddim, A.M. Imran, Ulva Ria Irfan, Meutia Farida","doi":"10.1016/j.oreoa.2025.100096","DOIUrl":"10.1016/j.oreoa.2025.100096","url":null,"abstract":"<div><div>This study focuses on the geochemical analysis of sedimentary rocks from the Mallawa Formation in the southern arm of Sulawesi, Indonesia. It aims to provide comprehensive and unprecedented research results on the Mallawa Formation sandstones through geochemical analysis, which has not been conducted previously. By analyzing twelve sedimentary rock samples collected from three locations—Bone, Maros, and Pangkep Regencies, the study seeks to explore provenance, source rocks, and tectonic settings by analyzing major elements, REE, and trace elements. The results indicate that SiO₂ is the most abundant component, reflecting the presence of detrital quartz, chert, feldspar fragments, and other mineral contents. The rocks are classified as sandstones with fine to coarse grains, ranging from wacke to quartz arenite. Based on various discrimination diagrams, the sandstones are associated with a passive margin transitioning into an active margin. The provenance of these sandstones originates from siliceous-clastic rocks and intermediate to felsic igneous rocks. These findings align with the paleogeography of South Sulawesi and provide new insights into the evolution of the Mallawa Formation.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100096"},"PeriodicalIF":0.0,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-11DOI: 10.1016/j.oreoa.2025.100097
Ayodele O. Falade , Olubola Abiola , John O. Amigun
This study presents a novel Multi-Criteria Decision Analysis (MCDA) model, the Siliciclastic Reservoir Quality Model (SRQM), for evaluating and ranking reservoirs in oilfields. The SRQM model integrates key reservoir properties, including net pay-to-gross ratio, porosity, water saturation, and shale content, to generate a comprehensive Reservoir Quality Index. The model was applied to the 'OS' field in the Niger Delta, Nigeria, and compared to the conventional Reservoir Quality Index (RQI) approach. The results show a weak negative correlation between the two methods (-0.05764), highlighting their complementary nature. The SRQM model offers a more comprehensive evaluation by incorporating both reservoir rock architecture (porosity and Vsh) and crucial fluid content (Sw and NTG), unlike RQI which focuses solely on rock architecture. SRQM revealed reservoirs 1 and 2 in well OS-5 as the highest quality reservoirs, with an SRQM index of 0.75 and RQI values exceeding 300. Furthermore, the SRQM model revealed variations within other reservoirs. For example, Reservoir 2 in well OS-1, identified as having excellent quality using SRQM, had a relatively low RQI due to its relatively low permeability. This indicates a trade-off between potentially larger hydrocarbon volumes and reduced porosity and permeability. While Reservoirs 1 and 2 have average RQI values of 225.27 and 227.57, indicating excellent quality compared to Reservoir 3 with an average RQI of 99.99, the SRQM ratings reveal a different ranking, with Reservoir 2 (SRQM index: 1.25) and Reservoir 3 (SRQM index: 1.8) considered higher quality than Reservoir 1 (SRQM index: 2.55). This study demonstrates SRQM's ability to consider multiple factors and provide a more robust approach to evaluating reservoir quality. This approach offers a significant improvement over conventional RQI methods, aiding in optimized reservoir development strategies.
{"title":"Siliciclastic Reservoir Quality Model, a Multi-Criteria Decision Analysis approach for reservoir quality evaluation in the ‘OS’ field Niger Delta, Nigeria","authors":"Ayodele O. Falade , Olubola Abiola , John O. Amigun","doi":"10.1016/j.oreoa.2025.100097","DOIUrl":"10.1016/j.oreoa.2025.100097","url":null,"abstract":"<div><div>This study presents a novel Multi-Criteria Decision Analysis (MCDA) model, the Siliciclastic Reservoir Quality Model (SRQM), for evaluating and ranking reservoirs in oilfields. The SRQM model integrates key reservoir properties, including net pay-to-gross ratio, porosity, water saturation, and shale content, to generate a comprehensive Reservoir Quality Index. The model was applied to the 'OS' field in the Niger Delta, Nigeria, and compared to the conventional Reservoir Quality Index (RQI) approach. The results show a weak negative correlation between the two methods (-0.05764), highlighting their complementary nature. The SRQM model offers a more comprehensive evaluation by incorporating both reservoir rock architecture (porosity and Vsh) and crucial fluid content (Sw and NTG), unlike RQI which focuses solely on rock architecture. SRQM revealed reservoirs 1 and 2 in well OS-5 as the highest quality reservoirs, with an SRQM index of 0.75 and RQI values exceeding 300. Furthermore, the SRQM model revealed variations within other reservoirs. For example, Reservoir 2 in well OS-1, identified as having excellent quality using SRQM, had a relatively low RQI due to its relatively low permeability. This indicates a trade-off between potentially larger hydrocarbon volumes and reduced porosity and permeability. While Reservoirs 1 and 2 have average RQI values of 225.27 and 227.57, indicating excellent quality compared to Reservoir 3 with an average RQI of 99.99, the SRQM ratings reveal a different ranking, with Reservoir 2 (SRQM index: 1.25) and Reservoir 3 (SRQM index: 1.8) considered higher quality than Reservoir 1 (SRQM index: 2.55). This study demonstrates SRQM's ability to consider multiple factors and provide a more robust approach to evaluating reservoir quality. This approach offers a significant improvement over conventional RQI methods, aiding in optimized reservoir development strategies.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100097"},"PeriodicalIF":0.0,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-07DOI: 10.1016/j.oreoa.2025.100095
Hanane Ait Hmeid , Mustapha Akodad , Mouhssin El Halim , Fatima Ezzahra Omdi , Mourad Baghour , Ali Skalli , Chaouki Sadik , Hicham Gueddari , Mohamed Chahban , Yassine El Yousfi , Mohamed Abioui , Lahcen Daoudi
This study investigates the potential industrial applications of two types of bentonite - Calcium Bentonite (Ca-B) and Sodium Bentonite (Na-B) - from the Kert Basin in northern Morocco. The bentonite samples' structural characteristics, inclusions, and microcracks were examined using scanning electron microscopy. X-ray diffraction analysis of both the whole rock and clay fractions was conducted to determine the bentonite type and mineralogical composition. The chemical composition was assessed through X-ray fluorescence. The physico-chemical properties analyzed included cation exchange capacity, swelling index, colloidality index, water content, and pH. The plasticity index and liquid limit were determined using Atterberg limits tests. The results indicate that sodium bentonite exhibits superior absorption and plasticity compared to calcium bentonite, with a higher cation exchange capacity, particularly after activation. The analyzed bentonites contain high amounts of iron and silica, with moderate levels of calcium and aluminum. Quartz, feldspars, and clay minerals were identified in all samples, with smectite being the dominant clay mineral phase (80 %), along with traces of kaolinite, illite, and interstratified illite-smectite. These bentonites generally display high plasticity, making them well-suited for hydraulic drilling applications. Additionally, their low organic matter and calcium carbonate (CaCO3) content may indicate mechanical strength, water sensitivity, and purity.
{"title":"Comparative analysis of Na+ and Ca2+ ion effects on the physical-chemical properties of Bentonite: Implications for industrial applications","authors":"Hanane Ait Hmeid , Mustapha Akodad , Mouhssin El Halim , Fatima Ezzahra Omdi , Mourad Baghour , Ali Skalli , Chaouki Sadik , Hicham Gueddari , Mohamed Chahban , Yassine El Yousfi , Mohamed Abioui , Lahcen Daoudi","doi":"10.1016/j.oreoa.2025.100095","DOIUrl":"10.1016/j.oreoa.2025.100095","url":null,"abstract":"<div><div>This study investigates the potential industrial applications of two types of bentonite - Calcium Bentonite (Ca-B) and Sodium Bentonite (Na-B) <strong>-</strong> from the Kert Basin in northern Morocco. The bentonite samples' structural characteristics, inclusions, and microcracks were examined using scanning electron microscopy. X-ray diffraction analysis of both the whole rock and clay fractions was conducted to determine the bentonite type and mineralogical composition. The chemical composition was assessed through X-ray fluorescence<strong>.</strong> The physico-chemical properties analyzed included cation exchange capacity, swelling index, colloidality index, water content, and pH. The plasticity index and liquid limit were determined using Atterberg limits tests. The results indicate that sodium bentonite exhibits superior absorption and plasticity compared to calcium bentonite, with a higher cation exchange capacity, particularly after activation. The analyzed bentonites contain high amounts of iron and silica, with moderate levels of calcium and aluminum. Quartz, feldspars, and clay minerals were identified in all samples, with smectite being the dominant clay mineral phase (80 %), along with traces of kaolinite, illite, and interstratified illite-smectite. These bentonites generally display high plasticity, making them well-suited for hydraulic drilling applications. Additionally, their low organic matter and calcium carbonate (CaCO<sub>3</sub>) content may indicate mechanical strength, water sensitivity, and purity.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100095"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The analysis of data obtained from previous drilled wells play a crucial role in enhancing the operational safety and reducing drilling expenses. A pivotal aspect of this lies in employing a geomechanical model, offering valuable insights into predicting pore pressure, ensuring borehole stability, and optimizing casing placement. This study centers on developing an integrated geomechanical model for three wells within an oil field, especially focusing on pore pressure variations in two distinct formations. An abnormal pressure is observed at overburden zone, while the reservoir zone is characterized by a normal pressure behavior. All relevant data sources including full set logs, dipole shear sonic imager reports, image logs, drilling operation data, and leak of tests are combined as an input to the geomechanical model. The main purpose of this study is to examine the geomechanical behavior of rocks within both abnormal and normal pore pressure zones. Identification of breakout points is achieved through image logs and caliper log data, which results in providing the direction of the minimum horizontal stress. Subsequently, the entire geomechanical model undergoes adjustment and validation based on these identified points. Moreover, the calibration of minimum horizontal stress is accomplished by analyzing the leak of test data. The main finding of this study indicates that the direction of the horizontal stresses varies across different points of the reservoir. Based on the results of the image log interpretation, the minimum horizontal stress direction in well#1 is 145°, in well #2, 125°, and in well# 3, 115°. Moreover, the presence of abnormal pore pressure results in a shift in the stress regime from a normal to strike slip or reverse stress regimes. In Well#1 conforms to a strike-slip regime with wellbore stable azimuths at 30, 70, 210, and 250°. Well#2 and Well#3 exhibit a reversed regime. The well's most stable state aligning with the azimuth of maximum horizontal stress. Lastly, it is determined that the Mogi-Coulomb and the modified Lade failure criterion exhibit superior accuracy in identifying shear failure of rocks when compared to the Mohr-Coulomb criterion. By integrating diverse input data and employing comprehensive validation methods, our model emerges as a robust tool for understanding and predicting geomechanical instability in drilling operations.
{"title":"Integrated geomechanical analysis of shear failure wellbore instability in abnormal and normal pore pressure zones using diverse input data: A case study","authors":"Masoud Ziaie , Amirhossein Takmili , Saeid Sadeghnejad , Mehdi Hakimzadeh","doi":"10.1016/j.oreoa.2025.100093","DOIUrl":"10.1016/j.oreoa.2025.100093","url":null,"abstract":"<div><div>The analysis of data obtained from previous drilled wells play a crucial role in enhancing the operational safety and reducing drilling expenses. A pivotal aspect of this lies in employing a geomechanical model, offering valuable insights into predicting pore pressure, ensuring borehole stability, and optimizing casing placement. This study centers on developing an integrated geomechanical model for three wells within an oil field, especially focusing on pore pressure variations in two distinct formations. An abnormal pressure is observed at overburden zone, while the reservoir zone is characterized by a normal pressure behavior. All relevant data sources including full set logs, dipole shear sonic imager reports, image logs, drilling operation data, and leak of tests are combined as an input to the geomechanical model. The main purpose of this study is to examine the geomechanical behavior of rocks within both abnormal and normal pore pressure zones. Identification of breakout points is achieved through image logs and caliper log data, which results in providing the direction of the minimum horizontal stress. Subsequently, the entire geomechanical model undergoes adjustment and validation based on these identified points. Moreover, the calibration of minimum horizontal stress is accomplished by analyzing the leak of test data. The main finding of this study indicates that the direction of the horizontal stresses varies across different points of the reservoir. Based on the results of the image log interpretation, the minimum horizontal stress direction in well#1 is 145°, in well #2, 125°, and in well# 3, 115°. Moreover, the presence of abnormal pore pressure results in a shift in the stress regime from a normal to strike slip or reverse stress regimes. In Well#1 conforms to a strike-slip regime with wellbore stable azimuths at 30, 70, 210, and 250°. Well#2 and Well#3 exhibit a reversed regime. The well's most stable state aligning with the azimuth of maximum horizontal stress. Lastly, it is determined that the Mogi-Coulomb and the modified Lade failure criterion exhibit superior accuracy in identifying shear failure of rocks when compared to the Mohr-Coulomb criterion. By integrating diverse input data and employing comprehensive validation methods, our model emerges as a robust tool for understanding and predicting geomechanical instability in drilling operations.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100093"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1016/j.oreoa.2025.100094
Zefan Bai , Shuyi Dong , Yuhe Fan , Ben Dong , Feng Zheng , Yingchun Wang , Rongcai Song
The Qiongdongnan Basin, located on the northern continental shelf of the South China Sea, is a prominent hydrocarbon-rich region. Among its core gas fields, the Yacheng Gas Field has drawn significant attention due to its complex tectonic framework and substantial natural gas reserves. However, the mechanisms governing the phase behavior (gas or liquid) and migration of natural gas in deep strata remain poorly understood and require further investigation. This study employs advanced mass spectrometry to analyze natural gas and noble gas components sampled from the Sanya and Lingshui formations in the Yacheng Gas Field. By integrating carbon isotope ratio measurements, noble gas isotopic analyzes, and PHREEQC-based solubility modeling, the research investigates the origin, migration mechanisms, and interactions of natural gas with subsurface fluid systems in this region. The results reveal that natural gas in the Yacheng Gas Field primarily originates from a mixed crust-mantle source and is closely associated with the basin's groundwater system, particularly through significant vertical interactions with formation water. In deep strata, natural gas predominantly migrates in the gaseous phase, with solubility decreasing progressively with depth.
{"title":"The origin and migration mechanism of natural gas in the Yacheng Gas Field, Qiongdongnan Basin, South China Sea: Constraints from noble gas isotopes","authors":"Zefan Bai , Shuyi Dong , Yuhe Fan , Ben Dong , Feng Zheng , Yingchun Wang , Rongcai Song","doi":"10.1016/j.oreoa.2025.100094","DOIUrl":"10.1016/j.oreoa.2025.100094","url":null,"abstract":"<div><div>The Qiongdongnan Basin, located on the northern continental shelf of the South China Sea, is a prominent hydrocarbon-rich region. Among its core gas fields, the Yacheng Gas Field has drawn significant attention due to its complex tectonic framework and substantial natural gas reserves. However, the mechanisms governing the phase behavior (gas or liquid) and migration of natural gas in deep strata remain poorly understood and require further investigation. This study employs advanced mass spectrometry to analyze natural gas and noble gas components sampled from the Sanya and Lingshui formations in the Yacheng Gas Field. By integrating carbon isotope ratio measurements, noble gas isotopic analyzes, and PHREEQC-based solubility modeling, the research investigates the origin, migration mechanisms, and interactions of natural gas with subsurface fluid systems in this region. The results reveal that natural gas in the Yacheng Gas Field primarily originates from a mixed crust-mantle source and is closely associated with the basin's groundwater system, particularly through significant vertical interactions with formation water. In deep strata, natural gas predominantly migrates in the gaseous phase, with solubility decreasing progressively with depth.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100094"},"PeriodicalIF":0.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-24DOI: 10.1016/j.oreoa.2025.100092
Ahmed Maher
The Nubia Sandstone sediments in the Gulf of Suez, Egypt, represent significant hydrocarbon reservoirs. However, further investigation is necessary better to understand their source rock characteristics and depositional environments. These sediments lack precise chronological data and have limited palynological information, both crucial for compelling petroleum exploration. This research uses an integrated approach that combines palynology, palynofacies analysis, and petrographic methods to clarify the characteristics of the Nubia Sandstone. Two main facies are identified: the older facies in the July Field, which corresponds to the lower interval of the Nubia B Member and dates to the late Devonian, characterized by conodonts and plant fragments. In contrast, the younger facies found in the October Field and are believed to originate from the Permian-Triassic period exhibit foraminifera-rich strata and a transition from monosaccate pollen grains to Classopollis pollen grains. The results suggest that the Nubia Sandstone exhibits a range of transitional maturity to overmaturity, with the Nubia Sandstone B Member showing significant potential for hydrocarbon generation and predominantly comprising type II kerogen. The samples from the October Field show deposition in a suboxic to anoxic basin, while those from the July Field suggest a proximal oxic shelf environment. This study provides the first source rock characterization which could increase research and exploration for hydrocarbons in different areas in the Gulf of Suez containing the Nubia Sandstone.
{"title":"Petrographic, palynological, and source rock evaluation of Nubia Sandstone: A comparative study of the October and July Oil Fields, Gulf of Suez, Egypt","authors":"Ahmed Maher","doi":"10.1016/j.oreoa.2025.100092","DOIUrl":"10.1016/j.oreoa.2025.100092","url":null,"abstract":"<div><div>The Nubia Sandstone sediments in the Gulf of Suez, Egypt, represent significant hydrocarbon reservoirs. However, further investigation is necessary better to understand their source rock characteristics and depositional environments. These sediments lack precise chronological data and have limited palynological information, both crucial for compelling petroleum exploration. This research uses an integrated approach that combines palynology, palynofacies analysis, and petrographic methods to clarify the characteristics of the Nubia Sandstone. Two main facies are identified: the older facies in the July Field, which corresponds to the lower interval of the Nubia B Member and dates to the late Devonian, characterized by conodonts and plant fragments. In contrast, the younger facies found in the October Field and are believed to originate from the Permian-Triassic period exhibit foraminifera-rich strata and a transition from monosaccate pollen grains to <em>Classopollis</em> pollen grains. The results suggest that the Nubia Sandstone exhibits a range of transitional maturity to overmaturity, with the Nubia Sandstone B Member showing significant potential for hydrocarbon generation and predominantly comprising type II kerogen. The samples from the October Field show deposition in a suboxic to anoxic basin, while those from the July Field suggest a proximal oxic shelf environment. This study provides the first source rock characterization which could increase research and exploration for hydrocarbons in different areas in the Gulf of Suez containing the Nubia Sandstone.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100092"},"PeriodicalIF":0.0,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143631939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<div><div>The Ilesha schist belt, the location of the research area, comprises one of Nigeria's most notable schist belts, which has attracted attention due to its considerable mineral resources, including gold deposits. Recent studies in the region have emphasized aerogeophysical mapping of geological features and the implication this has for mineral potential. However, various types of alteration and their relationships with gold deposits in the region have not received proper consideration. This research is aimed at identifying specific type of hydrothermal alteration associated with existing gold deposits in the study area as a reference to establishing new prospective zones and producing mineral prospect map of the area. To achieve this, Landsat Enhanced Thematic Mapper plus (Landsat-7 ETM+), and Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) data were utilized to define the association of lineaments and propylitic, phyllic, and argillic alteration types with Gold deposit within the study area. The processing of Landsat-7 ETM+ data were aided by applying Band ratio procedure and Principal Component Analysis (PCA). The validation was carried out using the active mining site of the study area, X-ray diffraction (XRD) analysis of some rock samples and electrical resistivity method. The results were integrated to provide information on lineaments, alteration minerals, and different types of hydrothermal alteration within the study area. Processed Landsat-7 ETM+ data delineated the structural elements as lineaments synonymous to lithologic contacts and faults/fracture zones, trending NE–SW direction, most probably controlling the alteration zones formation, distribution and localization of mineral in the country rocks of the belt. The Band ratio procedure and Principal Component Analysis (PCA) also showed that the area is rich in alteration minerals, particularly ferrous, ferric and clay minerals. ASTER multispectral analysis gave an imprint of the key alteration types within the study area, with phyllic alterations being noticeably the major alteration type associated with Gold deposits, and poses the highest prospective zone for Gold occurrence in the study area. Validation of the observed lineament dense areas with Vertical Electrical Sounding (VES) revealed highly fracture zones, thereby validating the structural framework of the study area. Also, spatial analysis involving percentage correlation evaluation carried out to compute the spatial connection between gold locations and altered zones showed that gold mine pits strongly matched with mapped altered zones with 85 percent correlation. Lastly, mineral compositions of the altered zones were confirmed by X-ray diffraction (XRD) analysis of the analyzed samples collected within the area. The research helped in understanding the spatial distribution of gold mineralisation within the study area. It is recommended that exploitation efforts be expanded to the delineated
{"title":"Multispectral remote sensing expression of lineaments and alteration minerals in part of crystalline rock units of Southwestern Nigeria: Implication on gold prospecting","authors":"Kazeem Oladimeji Olomo , Muriana Zaid Mohammed , Oluwatoyin Khadijat Olomo , Omowumi Ademila , Marvelous Ayomide Dadamu","doi":"10.1016/j.oreoa.2025.100091","DOIUrl":"10.1016/j.oreoa.2025.100091","url":null,"abstract":"<div><div>The Ilesha schist belt, the location of the research area, comprises one of Nigeria's most notable schist belts, which has attracted attention due to its considerable mineral resources, including gold deposits. Recent studies in the region have emphasized aerogeophysical mapping of geological features and the implication this has for mineral potential. However, various types of alteration and their relationships with gold deposits in the region have not received proper consideration. This research is aimed at identifying specific type of hydrothermal alteration associated with existing gold deposits in the study area as a reference to establishing new prospective zones and producing mineral prospect map of the area. To achieve this, Landsat Enhanced Thematic Mapper plus (Landsat-7 ETM+), and Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) data were utilized to define the association of lineaments and propylitic, phyllic, and argillic alteration types with Gold deposit within the study area. The processing of Landsat-7 ETM+ data were aided by applying Band ratio procedure and Principal Component Analysis (PCA). The validation was carried out using the active mining site of the study area, X-ray diffraction (XRD) analysis of some rock samples and electrical resistivity method. The results were integrated to provide information on lineaments, alteration minerals, and different types of hydrothermal alteration within the study area. Processed Landsat-7 ETM+ data delineated the structural elements as lineaments synonymous to lithologic contacts and faults/fracture zones, trending NE–SW direction, most probably controlling the alteration zones formation, distribution and localization of mineral in the country rocks of the belt. The Band ratio procedure and Principal Component Analysis (PCA) also showed that the area is rich in alteration minerals, particularly ferrous, ferric and clay minerals. ASTER multispectral analysis gave an imprint of the key alteration types within the study area, with phyllic alterations being noticeably the major alteration type associated with Gold deposits, and poses the highest prospective zone for Gold occurrence in the study area. Validation of the observed lineament dense areas with Vertical Electrical Sounding (VES) revealed highly fracture zones, thereby validating the structural framework of the study area. Also, spatial analysis involving percentage correlation evaluation carried out to compute the spatial connection between gold locations and altered zones showed that gold mine pits strongly matched with mapped altered zones with 85 percent correlation. Lastly, mineral compositions of the altered zones were confirmed by X-ray diffraction (XRD) analysis of the analyzed samples collected within the area. The research helped in understanding the spatial distribution of gold mineralisation within the study area. It is recommended that exploitation efforts be expanded to the delineated ","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100091"},"PeriodicalIF":0.0,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research mainly focused on the Kiriburu-Meghahataburu-Bolani iron ore deposit (KMBIOD) in the Singhbhum craton, eastern India, with over 150 million tons of iron ore reserves. By applying Landsat-8/OLI multispectral remote sensing techniques, including band ratio analysis, principal component analysis (PCA), and spectral angle mapper (SAM) classification, the research effectively mapped various types of iron ores. This study employed RGB band combinations of band ratios {4(0.64–0.67 μm)/2(0.45–0.51 μm), 5(0.85–0.88 μm)/7(2.11–2.29 μm), 5(0.85–0.88 μm)/4(0.64–0.67 μm)} and PCA (PC bands 1, 5, and 6; PC bands 4, 5, and 6). These techniques were used to effectively distinguish iron ore from associated lithological units. Specific band ratios (5/7, 4/5, and 4 + 6/5) were instrumental in identifying high-grade and low-grade iron ore zones. PCA was used to provide detailed spectral information, identifying various iron ore types, including low-grade iron ore and clay minerals. The results were validated with spectral analysis and spectral angle mapper (SAM) classification methods, supported by X-ray Diffraction (XRD) analysis of iron ore samples collected during field survey. This integrated remote sensing approach proved effective for mapping iron ore in densely vegetated areas and enhancing geological understanding of mineralized zones. Landsat-8/OLI imagery demonstrated robust performance in iron ore exploration, concluding that these techniques were effective for discriminating and classifying iron ore in the Singhbhum craton and could be applied to similar regions.
{"title":"Mapping iron oxides with Landsat-8/OLI imagery from iron ore deposit in Singhbhum craton, eastern India: Its implication to mineral exploration","authors":"Arvind Chandra Pandey , Sagar Kumar Swain , Chandra Shekhar Dwivedi","doi":"10.1016/j.oreoa.2025.100089","DOIUrl":"10.1016/j.oreoa.2025.100089","url":null,"abstract":"<div><div>This research mainly focused on the Kiriburu-Meghahataburu-Bolani iron ore deposit (KMBIOD) in the Singhbhum craton, eastern India, with over 150 million tons of iron ore reserves. By applying Landsat-8/OLI multispectral remote sensing techniques, including band ratio analysis, principal component analysis (PCA), and spectral angle mapper (SAM) classification, the research effectively mapped various types of iron ores. This study employed RGB band combinations of band ratios {4(0.64–0.67 μm)/2(0.45–0.51 μm), 5(0.85–0.88 μm)/7(2.11–2.29 μm), 5(0.85–0.88 μm)/4(0.64–0.67 μm)} and PCA (PC bands 1, 5, and 6; PC bands 4, 5, and 6). These techniques were used to effectively distinguish iron ore from associated lithological units. Specific band ratios (5/7, 4/5, and 4 + 6/5) were instrumental in identifying high-grade and low-grade iron ore zones. PCA was used to provide detailed spectral information, identifying various iron ore types, including low-grade iron ore and clay minerals. The results were validated with spectral analysis and spectral angle mapper (SAM) classification methods, supported by X-ray Diffraction (XRD) analysis of iron ore samples collected during field survey. This integrated remote sensing approach proved effective for mapping iron ore in densely vegetated areas and enhancing geological understanding of mineralized zones. Landsat-8/OLI imagery demonstrated robust performance in iron ore exploration, concluding that these techniques were effective for discriminating and classifying iron ore in the Singhbhum craton and could be applied to similar regions.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100089"},"PeriodicalIF":0.0,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.oreoa.2025.100088
Riya Mondal , Tapas Acharya , Arijit Ray , Tamal Sur , Prarabdh Tiwari , Anand Singh , Arkoprovo Biswas
Mineral exploration in regions of limited bedrock exposure depends on the excellence of the predictive model yielded from geophysical and geological studies. In this aspect, the accuracy of the positions, shapes, and size of the concealed ore bodies is important for later resource evaluation. Commonly used magnetic susceptibility surveys to explore buried magnetite deposits often fail to resolve the boundary between magnetite ore, and host rocks when the host rock contains ilmenite, and/or magnetite as an accessory mineral. Electrical Resistivity Imaging (ERI), and Self-Potential (SP), are better substitutes to resolve the issue and delineate the positions and shapes of the ore bodies in gabbroic host-rock in Purulia district, West Bengal, India. The concealed magnetite ore body showed a sharp decrease in electrical resistivity value in the 2D ERI study, and a significant negative SP value was concurrent with the inferred concealed magnetite bodies, compared to the gabbroic host rock. Hence, the combined result of 2D ERI and SP indicate analogous negative anomalies to the inferred magnetite ore bodies, verified by the surface geological information and mineralogical studies. Such geophysical anomalies could be combined with field data to reconstruct magnetite ore body modeling, providing a practical approach to prospect buried magnetite ore bodies in basic host rocks.
{"title":"Integrated geophysical and geological prospecting for magnetite in the ilmenite-bearing gabbroic rock of Purulia, West Bengal, India","authors":"Riya Mondal , Tapas Acharya , Arijit Ray , Tamal Sur , Prarabdh Tiwari , Anand Singh , Arkoprovo Biswas","doi":"10.1016/j.oreoa.2025.100088","DOIUrl":"10.1016/j.oreoa.2025.100088","url":null,"abstract":"<div><div>Mineral exploration in regions of limited bedrock exposure depends on the excellence of the predictive model yielded from geophysical and geological studies. In this aspect, the accuracy of the positions, shapes, and size of the concealed ore bodies is important for later resource evaluation. Commonly used magnetic susceptibility surveys to explore buried magnetite deposits often fail to resolve the boundary between magnetite ore, and host rocks when the host rock contains ilmenite, and/or magnetite as an accessory mineral. Electrical Resistivity Imaging (ERI), and Self-Potential (SP), are better substitutes to resolve the issue and delineate the positions and shapes of the ore bodies in gabbroic host-rock in Purulia district, West Bengal, India. The concealed magnetite ore body showed a sharp decrease in electrical resistivity value in the 2D ERI study, and a significant negative SP value was concurrent with the inferred concealed magnetite bodies, compared to the gabbroic host rock. Hence, the combined result of 2D ERI and SP indicate analogous negative anomalies to the inferred magnetite ore bodies, verified by the surface geological information and mineralogical studies. Such geophysical anomalies could be combined with field data to reconstruct magnetite ore body modeling, providing a practical approach to prospect buried magnetite ore bodies in basic host rocks.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100088"},"PeriodicalIF":0.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-05DOI: 10.1016/j.oreoa.2025.100087
Ali Toorajipour , Hamed Aghaei , Behnam Shahsavani , Raoof Gholami , Nurudeen Yekeen , Ahmed Al-Yaseri
Underground Hydrogen Storage (UHS) has been proposed as a potential solution to the large-scale energy storage required to establish a net zero emissions society. The success of UHS, however, depends on several geological and petrophysical parameters of the host rock, including wettability, which dictates the plume migration pathway in the pore structure and extraction efficiency of the stored hydrogen. In this study, the changes in wettability of carbonates and anhydrite to H₂ in binary mixtures of CH₄ and CO₂ were evaluated using the gas/water/rock contact angle (CA) measurements at various pressures (3.44–17.23 MPa) and temperatures (30 °C and 75 °C). The results obtained showed that these binary mixtures have no significant impact on the H₂ wettability of the selected carbonate samples. Although the CA of CO2/water systems was slightly higher than that of CH4/water due to CO2 density, all measured CA data sets remained below 34° under all assessed conditions, indicating that the carbonate samples maintained their initial highly hydrophilic state despite the presence of gaseous impurities. It was concluded that during UHS, the in-situ CH4 and CO2 in depleted gas reservoirs and the mixing of H2 with them as potential cushion gases will not have a significant impact on the wetting behaviour of the carbonate with changing temperatures and increasing storage depth.
{"title":"Hydrogen wettability of limestone, dolomite, and anhydrite in binary mixtures of CH₄ and CO₂","authors":"Ali Toorajipour , Hamed Aghaei , Behnam Shahsavani , Raoof Gholami , Nurudeen Yekeen , Ahmed Al-Yaseri","doi":"10.1016/j.oreoa.2025.100087","DOIUrl":"10.1016/j.oreoa.2025.100087","url":null,"abstract":"<div><div>Underground Hydrogen Storage (UHS) has been proposed as a potential solution to the large-scale energy storage required to establish a net zero emissions society. The success of UHS, however, depends on several geological and petrophysical parameters of the host rock, including wettability, which dictates the plume migration pathway in the pore structure and extraction efficiency of the stored hydrogen. In this study, the changes in wettability of carbonates and anhydrite to H₂ in binary mixtures of CH₄ and CO₂ were evaluated using the gas/water/rock contact angle (CA) measurements at various pressures (3.44–17.23 MPa) and temperatures (30 °C and 75 °C). The results obtained showed that these binary mixtures have no significant impact on the H₂ wettability of the selected carbonate samples. Although the CA of CO<sub>2</sub>/water systems was slightly higher than that of CH<sub>4</sub>/water due to CO<sub>2</sub> density, all measured CA data sets remained below 34° under all assessed conditions, indicating that the carbonate samples maintained their initial highly hydrophilic state despite the presence of gaseous impurities. It was concluded that during UHS, the in-situ CH<sub>4</sub> and CO<sub>2</sub> in depleted gas reservoirs and the mixing of H<sub>2</sub> with them as potential cushion gases will not have a significant impact on the wetting behaviour of the carbonate with changing temperatures and increasing storage depth.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100087"},"PeriodicalIF":0.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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