This study contributes to geothermal exploration in 1660-1520 Ma old reworked bedrock in Sweden. Our primary objectives are to constrain the orientation of horizontal stresses, and to discuss implications for geothermal exploration. High-resolution acoustic televiewer image data reveal the downhole distribution of stress indicators (borehole breakouts, drilling induced fractures and petal centerline fractures), pre-existing structures (natural fractures, foliation). About 135 m of stress indicators are measured from 0.2-1.0 km. The results suggest a uniform NNW-SSE mean maximum horizontal stress orientation. A total of 1525 pre-existing structures (natural fractures, foliation) are mapped in borehole GE-1. The prevailing stress regime controls if natural fractures and foliation are well-oriented for stimulation. For strike-slip and normal faulting stress regimes, well-oriented fractures are steeply dipping towards WSW. For a reverse faulting stress regime, shallow dipping fractures are well-oriented for simulation. The downhole distribution of stress indicators and other stress measurements in the region and other parts of Fennoscandia tentatively suggest a strike-slip stress regime, but additional studies are needed to constrain the complete stress field at study depth and towards EGS reservoir target depth. Our secondary objective is to highlight that interpretation of high-resolution acoustic data particularly in metamorphic crystalline rocks are subjective, and that more guidelines for data interpretation are needed. The interactive interpretation of the images is based on visual analyses of complex pre-existing structures and stress indicators with highly variable shapes. The application of three methods for data analyses in the GE-1 borehole propose that drilling induced fractures are little influenced by the method applied. Interpretations on individual borehole breakout azimuths may, however result in over 10 differences in orientation. Supplementary material at https://doi.org/10.6084/m9.figshare.c.7082902
{"title":"Image analysis of acoustic data and interpretation of rock stress orientations for geothermal exploration in Gothenburg borehole GE-1, Southwest Sweden","authors":"Maria Ask, Simona Pierdominici, J. Rosberg","doi":"10.1144/sp546-2023-36","DOIUrl":"https://doi.org/10.1144/sp546-2023-36","url":null,"abstract":"\u0000 This study contributes to geothermal exploration in 1660-1520 Ma old reworked bedrock in Sweden. Our primary objectives are to constrain the orientation of horizontal stresses, and to discuss implications for geothermal exploration. High-resolution acoustic televiewer image data reveal the downhole distribution of stress indicators (borehole breakouts, drilling induced fractures and petal centerline fractures), pre-existing structures (natural fractures, foliation). About 135 m of stress indicators are measured from 0.2-1.0 km. The results suggest a uniform NNW-SSE mean maximum horizontal stress orientation. A total of 1525 pre-existing structures (natural fractures, foliation) are mapped in borehole GE-1. The prevailing stress regime controls if natural fractures and foliation are well-oriented for stimulation. For strike-slip and normal faulting stress regimes, well-oriented fractures are steeply dipping towards WSW. For a reverse faulting stress regime, shallow dipping fractures are well-oriented for simulation. The downhole distribution of stress indicators and other stress measurements in the region and other parts of Fennoscandia tentatively suggest a strike-slip stress regime, but additional studies are needed to constrain the complete stress field at study depth and towards EGS reservoir target depth.\u0000 Our secondary objective is to highlight that interpretation of high-resolution acoustic data particularly in metamorphic crystalline rocks are subjective, and that more guidelines for data interpretation are needed. The interactive interpretation of the images is based on visual analyses of complex pre-existing structures and stress indicators with highly variable shapes. The application of three methods for data analyses in the GE-1 borehole propose that drilling induced fractures are little influenced by the method applied. Interpretations on individual borehole breakout azimuths may, however result in over 10 differences in orientation.\u0000 \u0000 Supplementary material at\u0000 https://doi.org/10.6084/m9.figshare.c.7082902\u0000","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"50 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140437082","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}
During the Cretaceous, the Berriasian-Aptian interval witnessed a transition from a relatively cool climate with intermittent polar ice to a greenhouse state that persisted throughout the Late Cretaceous. These palaeoclimatic changes were associated with the construction of Large Igneous Provinces (LIPs), which significantly perturbed the ocean-atmosphere system by introducing large amounts of CO 2 , trace metals, and micronutrients, thereby impacting the biosphere. Our study focused on the Tethyan Ocean during the Early Cretaceous, examining the resilience of planktonic and shallow-water benthic calcifying algae to environmental changes. We observed their adaptation, recovery dynamics, and the influence of palaeo CO 2 levels on their resilience. Calcification patterns of calcareous nannoplankton served as a proxy for ecological and engineering resilience. While calcareous nannoplankton as a whole showed high resistance, individual taxa exhibited varying levels of resilience. Nannoconids, particularly narrow-canal ones, were highly sensitive and had low resistance. In contrast, Watznaueria barnesiae showed the least sensitivity and highest resistance, likely due to its adaptive strategies and long lifespan. Nannoplankton calcification recovery (engineering resilience) from the Weissert Event took approximately 3 million years. After OAE1a, instead, nannoplankton did not return to pre-perturbation conditions. In shallow-water platforms, Dasycladales, aragonitic benthic calcifiers, exhibited lower resilience compared to nannofossils. They experienced a decline in species diversity across both the Weissert Event and the OAE 1a, which could indicate higher sensitivity to reduced carbonate saturation under high p CO 2 conditions. After the Valanginian Weissert Event, Dasycladales were able to recover, albeit they show a much lower engineering resilience compared to nannoconids, as it took nearly 10 million years to revert to pre-disturbance diversity. The OAE 1a represented a more intense perturbation: their decrease of species diversity was much more drastic and permanent, and Dasycladales were unable to recover, losing their dominant role as carbonate platform biocalcifiers for the remainder of the Cretaceous. Our study provides an assessment of the resilience of Tethyan phytoplanktonic and shallow-water benthic calcifying algae to disturbances during the Early Cretaceous, with implications for tipping points associated with palaeo-CO 2 levels. The differential responses in terms of timing and magnitude and the recovery dynamics contribute to the understanding of the potential impacts of current and future global changes on the resilience of marine ecosystems and the thresholds that may lead to ecological crises.
在白垩纪，柏里阿斯-安普斯时期见证了从间歇性极地冰川的相对凉爽气候向持续整个晚白垩世的温室气候的转变。这些古气候变化与大火成岩带（LIPs）的形成有关，大火成岩带通过引入大量的二氧化碳、痕量金属和微量营养元素，对海洋-大气系统造成了极大的扰动，从而对生物圈产生了影响。我们的研究重点是早白垩世的哲罗纪海洋，考察浮游和浅水底栖钙化藻类对环境变化的适应能力。我们观察了它们的适应性、恢复动态以及古二氧化碳水平对其恢复力的影响。钙质浮游动物的钙化模式是生态和工程复原力的代表。虽然钙质浮游动物整体表现出较高的抗逆性，但个别类群表现出不同程度的抗逆性。褐藻类，尤其是窄腔褐藻类，高度敏感，抵抗力较低。相比之下，Watznaueria barnesiae 的敏感性最低，抵抗力最高，这可能是由于它的适应策略和较长的寿命。从魏塞特事件中恢复浮游动物钙化（工程复原力）大约需要 300 万年。而在 OAE1a 之后，浮游动物并没有恢复到扰动前的状态。在浅水平台上，Dasycladales（文石底栖钙化生物）的复原能力低于海纳化石。在魏氏事件和 OAE 1a 期间，它们的物种多样性都有所下降，这可能表明在高 p CO 2 条件下，它们对碳酸盐饱和度降低的敏感性更高。在瓦朗基年魏塞特事件之后，Dasycladales得以恢复，尽管它们显示出的工程复原能力远低于楠木类，因为它们花了近1000万年的时间才恢复到扰动前的多样性。OAE 1a 代表了更强烈的扰动：其物种多样性的减少更为剧烈和持久，Dasycladales 无法恢复，在白垩纪的剩余时间里失去了其作为碳酸盐平台生物钙化器的主导作用。我们的研究评估了早白垩世哲人浮游植物和浅水底栖钙化藻类对干扰的恢复能力，并对与古CO2水平相关的临界点产生了影响。在时间和程度上的不同反应以及恢复动态有助于了解当前和未来全球变化对海洋生态系统恢复能力的潜在影响，以及可能导致生态危机的临界点。
{"title":"The resilience of Tethyan planktonic and benthic calcifying algae to Early Cretaceous perturbations: comparison between the Valanginian Weissert Event and the early Aptian Oceanic Anoxic Event 1a","authors":"E. Erba, Mariano Parente","doi":"10.1144/sp545-2023-125","DOIUrl":"https://doi.org/10.1144/sp545-2023-125","url":null,"abstract":"\u0000 \u0000 During the Cretaceous, the Berriasian-Aptian interval witnessed a transition from a relatively cool climate with intermittent polar ice to a greenhouse state that persisted throughout the Late Cretaceous. These palaeoclimatic changes were associated with the construction of Large Igneous Provinces (LIPs), which significantly perturbed the ocean-atmosphere system by introducing large amounts of CO\u0000 2\u0000 , trace metals, and micronutrients, thereby impacting the biosphere. Our study focused on the Tethyan Ocean during the Early Cretaceous, examining the resilience of planktonic and shallow-water benthic calcifying algae to environmental changes. We observed their adaptation, recovery dynamics, and the influence of palaeo CO\u0000 2\u0000 levels on their resilience. Calcification patterns of calcareous nannoplankton served as a proxy for ecological and engineering resilience. While calcareous nannoplankton as a whole showed high resistance, individual taxa exhibited varying levels of resilience. Nannoconids, particularly narrow-canal ones, were highly sensitive and had low resistance. In contrast,\u0000 Watznaueria barnesiae\u0000 showed the least sensitivity and highest resistance, likely due to its adaptive strategies and long lifespan. Nannoplankton calcification recovery (engineering resilience) from the Weissert Event took approximately 3 million years. After OAE1a, instead, nannoplankton did not return to pre-perturbation conditions. In shallow-water platforms, Dasycladales, aragonitic benthic calcifiers, exhibited lower resilience compared to nannofossils. They experienced a decline in species diversity across both the Weissert Event and the OAE 1a, which could indicate higher sensitivity to reduced carbonate saturation under high\u0000 p\u0000 CO\u0000 2\u0000 conditions. After the Valanginian Weissert Event, Dasycladales were able to recover, albeit they show a much lower engineering resilience compared to nannoconids, as it took nearly 10 million years to revert to pre-disturbance diversity. The OAE 1a represented a more intense perturbation: their decrease of species diversity was much more drastic and permanent, and Dasycladales were unable to recover, losing their dominant role as carbonate platform biocalcifiers for the remainder of the Cretaceous. Our study provides an assessment of the resilience of Tethyan phytoplanktonic and shallow-water benthic calcifying algae to disturbances during the Early Cretaceous, with implications for tipping points associated with palaeo-CO\u0000 2\u0000 levels. The differential responses in terms of timing and magnitude and the recovery dynamics contribute to the understanding of the potential impacts of current and future global changes on the resilience of marine ecosystems and the thresholds that may lead to ecological crises.\u0000","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"29 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140436547","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 Bogdo-Baskunchak Nature Reserve is a geoheritage site in the Caspian Depression, near the Lower Volga River. The Salt Lake Baskunchak and the Mount Big Bogdo with the gypsum field are the main objects of interest. Local legends about this place, history of salt mining and trading, as well as geological exploration make this geoheritage site special. This intact natural landscape, as seen by the first scientific expeditions of the 18th century organised by the Imperial Academy of Sciences and Arts in St. Petersburg. Reports and papers about this area are associated with Pallas, Humboldt, Murchison, Eichwald, Auerbach, Pravoslavlev, Efremov and other scientists and expeditions. Extensive research and important discoveries were made in this area mostly in mineralogy, stratigraphy, palaeontology, sedimentology, salt tectonics, and mining. This area reflects the long history of its exploration and could be a good example of organising protection of geological landmarks and monuments in arid regions.
{"title":"Bogdo-Baskunchak Nature Reserve as a Geoheritage site","authors":"Ivan Vtorov","doi":"10.1144/sp543-2022-229","DOIUrl":"https://doi.org/10.1144/sp543-2022-229","url":null,"abstract":"\u0000 The Bogdo-Baskunchak Nature Reserve is a geoheritage site in the Caspian Depression, near the Lower Volga River. The Salt Lake Baskunchak and the Mount Big Bogdo with the gypsum field are the main objects of interest. Local legends about this place, history of salt mining and trading, as well as geological exploration make this geoheritage site special. This intact natural landscape, as seen by the first scientific expeditions of the 18th century organised by the Imperial Academy of Sciences and Arts in St. Petersburg. Reports and papers about this area are associated with Pallas, Humboldt, Murchison, Eichwald, Auerbach, Pravoslavlev, Efremov and other scientists and expeditions. Extensive research and important discoveries were made in this area mostly in mineralogy, stratigraphy, palaeontology, sedimentology, salt tectonics, and mining. This area reflects the long history of its exploration and could be a good example of organising protection of geological landmarks and monuments in arid regions.","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"5 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140435714","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}
T. Velayatham, S. Holford, M. Bunch, Rosalind King, N. Schofield
Igneous intrusions in sedimentary petroleum basins are often perceived as having a negative impact on the elements of the petroleum system, though the impact of intrusion-related deformation features on petroleum systems and broader geoenergy applications is not well understood. In this study, we use 3D seismic reflection data to document a variety of deformation styles that are spatially and temporally associated late Cenozoic magmatic activity in the Bass Basin, offshore southeastern Australia; three types of normal fault systems (conjugate faults, concentric faults, radial faults) and fluid escape pipes. These deformation features occur in the overburden up to ∼600 m above underlying igneous intrusions, within the Eocene to Miocene Demons Bluff and Torquay formations. The conjugate faults bound grabens and are interpreted to have formed in response to underlying dyke intrusions. The radial faults are interpreted to have formed in response to overburden uplift, though the link between these and associated igneous activity is less clear. We identify 101 fluid escape features that show variation in both the morphology of their surficial depressions and of the seismic reflection characteristics of their infilling deposits. These features are interpreted to be hydrothermal or volcanic vents with underlying pipe-like feeders, depending on their spatial association with adjacent or underlying igneous intrusions. The concentric fault systems are associated with surficial depressions, and quantitative analysis of reflection sags within these depressions suggest that they are a result of subsurface subsidence in response to formation of maar-craters. The intrusion-related deformation features documented in this study may have multiple effects on working petroleum systems, such as providing secondary fluid flow pathways that can either reduce seal integrity, or enabling migration of fluids into shallower reservoirs.
{"title":"3D Seismic analysis of complex faulting patterns and fluid escape features and their relation to late Cenozoic magmatism in the Bass Basin, offshore southeast Australia","authors":"T. Velayatham, S. Holford, M. Bunch, Rosalind King, N. Schofield","doi":"10.1144/sp547-2023-158","DOIUrl":"https://doi.org/10.1144/sp547-2023-158","url":null,"abstract":"\u0000 Igneous intrusions in sedimentary petroleum basins are often perceived as having a negative impact on the elements of the petroleum system, though the impact of intrusion-related deformation features on petroleum systems and broader geoenergy applications is not well understood. In this study, we use 3D seismic reflection data to document a variety of deformation styles that are spatially and temporally associated late Cenozoic magmatic activity in the Bass Basin, offshore southeastern Australia; three types of normal fault systems (conjugate faults, concentric faults, radial faults) and fluid escape pipes. These deformation features occur in the overburden up to ∼600 m above underlying igneous intrusions, within the Eocene to Miocene Demons Bluff and Torquay formations. The conjugate faults bound grabens and are interpreted to have formed in response to underlying dyke intrusions. The radial faults are interpreted to have formed in response to overburden uplift, though the link between these and associated igneous activity is less clear. We identify 101 fluid escape features that show variation in both the morphology of their surficial depressions and of the seismic reflection characteristics of their infilling deposits. These features are interpreted to be hydrothermal or volcanic vents with underlying pipe-like feeders, depending on their spatial association with adjacent or underlying igneous intrusions. The concentric fault systems are associated with surficial depressions, and quantitative analysis of reflection sags within these depressions suggest that they are a result of subsurface subsidence in response to formation of maar-craters. The intrusion-related deformation features documented in this study may have multiple effects on working petroleum systems, such as providing secondary fluid flow pathways that can either reduce seal integrity, or enabling migration of fluids into shallower reservoirs.","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"14 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140439361","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}
C. M. Sena, M. Musial, S. Quental, K. L. Canner, E. Funk, A. Nozari
The combination of traditional subsurface interpretation techniques with advanced data analytics is a key steppingstone for better predicting reservoir quality, especially in heterogeneous and complex geological systems. The Peshkabir oil and gas field, located in the north of the Kurdistan Region of Iraq and within the Tawke Production Sharing Contract, is one such heterogeneous system. Well oil rates vary significantly across the field and cannot be simply correlated to fracture densities measured at the wells. Understanding which fractures matter and what influences reservoir deliverability is a question of major importance for maximizing oil production. The carbonate reservoirs include karstified vuggy zones and hydrothermal dolostones, in addition to an extensively developed fractured network. This paper presents a geological conceptual model for the Peshkabir field, and an application of Python based data science techniques to identify key predictors of reservoir deliverability from drilling, logging and production data. We demonstrate that the major advantage of the application of advanced data analytics is that it can enable the recognition of patterns and associations in a complex, high-dimensional parameter environment whereas traditional interpretation methods typically only allow for the comparison of two or three parameters at a time. This method allows the integration of dynamic and static data effectively and empowers the interpreter to incorporate all the available insights which, coupled with domain knowledge, allows for data-driven decision-making.
{"title":"Multiscale and multidisciplinary data-driven reservoir characterization of a fractured carbonate field in Kurdistan","authors":"C. M. Sena, M. Musial, S. Quental, K. L. Canner, E. Funk, A. Nozari","doi":"10.1144/sp548-2023-114","DOIUrl":"https://doi.org/10.1144/sp548-2023-114","url":null,"abstract":"\u0000 The combination of traditional subsurface interpretation techniques with advanced data analytics is a key steppingstone for better predicting reservoir quality, especially in heterogeneous and complex geological systems. The Peshkabir oil and gas field, located in the north of the Kurdistan Region of Iraq and within the Tawke Production Sharing Contract, is one such heterogeneous system. Well oil rates vary significantly across the field and cannot be simply correlated to fracture densities measured at the wells. Understanding which fractures matter and what influences reservoir deliverability is a question of major importance for maximizing oil production. The carbonate reservoirs include karstified vuggy zones and hydrothermal dolostones, in addition to an extensively developed fractured network. This paper presents a geological conceptual model for the Peshkabir field, and an application of Python based data science techniques to identify key predictors of reservoir deliverability from drilling, logging and production data. We demonstrate that the major advantage of the application of advanced data analytics is that it can enable the recognition of patterns and associations in a complex, high-dimensional parameter environment whereas traditional interpretation methods typically only allow for the comparison of two or three parameters at a time. This method allows the integration of dynamic and static data effectively and empowers the interpreter to incorporate all the available insights which, coupled with domain knowledge, allows for data-driven decision-making.","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"14 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140440852","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 large oil discoveries that have occurred in recent decades in the pre-salt section of the South Atlantic sedimentary basins have promoted a significant volume of scientific research regarding the origin of these deposits. Most of the current studies of this stratigraphic interval focus on regional aspects or sedimentological and diagenetic processes. However, few studies encompass the geological characteristics of the pre-salt deposits from a reservoir-scale perspective. This work addresses the construction of a detailed reservoir-oriented stratigraphic framework for the giant Tupi Field. Discovered in 2006 following a successful exploratory campaign in the southeastern Brazilian deep-water, the Tupi Field's main reservoirs are sag-phase carbonates from the Aptian-aged Barra Velha Formation. These rocks accumulated in alkaline to highly alkaline lacustrine settings, which allowed the development of unusual syngenetic elements, such as magnesian clays, calcitic spherulites, and calcitic shrubs. The reservoirs' depositional organization was essentially conditioned by climatic oscillations and tectonic activity, which controlled sedimentation rates and accommodation styles through space and time. The high-resolution stratigraphic framework established in this article supports a detailed understanding, at different scales, of the Tupi Field's sedimentological evolution and its main vertical and lateral facies distribution. These aspects have, in turn, provided essential inputs for reservoir characterization and constrained critical heterogeneities of the 3D geocellular model, even in reservoirs affected by diagenetic processes.
近几十年来，在南大西洋沉积盆地的盐前地段发现了大量石油，促进了有关这些矿藏起源的大量科学研究。目前对这一地层区间的研究大多侧重于区域方面或沉积学和成岩过程。然而，很少有研究从储层尺度的角度研究前盐沉积的地质特征。这项工作旨在为巨大的图皮油田构建一个以储层为导向的详细地层框架。Tupi 油田是 2006 年在巴西东南部深水区成功勘探后发现的，其主要储层是始新世时期 Barra Velha 地层的矢状相碳酸盐岩。这些岩石在碱性至高度碱性的湖相环境中堆积，从而形成了不同寻常的共生元素，如镁质粘土、方解石球粒岩和方解石灌木。这些储层的沉积组织主要受气候振荡和构造活动的影响，它们在空间和时间上控制着沉积速率和容纳方式。本文所建立的高分辨率地层框架有助于在不同尺度上详细了解图皮油田的沉积演化及其主要的垂直和横向面分布。这些方面反过来又为油藏特征描述提供了重要信息，并制约了三维地球细胞模型的关键异质性，甚至在受成岩过程影响的油藏中也是如此。
{"title":"High-resolution stratigraphy and characterization of reservoir-critical heterogeneities in the giant Tupi Field, pre-salt Santos Basin, Brazil","authors":"S. Pedrinha, Victor de Mello Artagão","doi":"10.1144/sp548-2023-91","DOIUrl":"https://doi.org/10.1144/sp548-2023-91","url":null,"abstract":"\u0000 The large oil discoveries that have occurred in recent decades in the pre-salt section of the South Atlantic sedimentary basins have promoted a significant volume of scientific research regarding the origin of these deposits. Most of the current studies of this stratigraphic interval focus on regional aspects or sedimentological and diagenetic processes. However, few studies encompass the geological characteristics of the pre-salt deposits from a reservoir-scale perspective.\u0000 This work addresses the construction of a detailed reservoir-oriented stratigraphic framework for the giant Tupi Field. Discovered in 2006 following a successful exploratory campaign in the southeastern Brazilian deep-water, the Tupi Field's main reservoirs are sag-phase carbonates from the Aptian-aged Barra Velha Formation. These rocks accumulated in alkaline to highly alkaline lacustrine settings, which allowed the development of unusual syngenetic elements, such as magnesian clays, calcitic spherulites, and calcitic shrubs. The reservoirs' depositional organization was essentially conditioned by climatic oscillations and tectonic activity, which controlled sedimentation rates and accommodation styles through space and time.\u0000 The high-resolution stratigraphic framework established in this article supports a detailed understanding, at different scales, of the Tupi Field's sedimentological evolution and its main vertical and lateral facies distribution. These aspects have, in turn, provided essential inputs for reservoir characterization and constrained critical heterogeneities of the 3D geocellular model, even in reservoirs affected by diagenetic processes.","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"21 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140440975","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 record of igneous activity (magmatism and volcanism) can significantly affect natural resource exploration and exploitation, including the search for hydrocarbons, critical minerals, natural hydrogen, and geothermal energy sources, as well as using mafic igneous rocks as storage sites for CO 2 . These effects will vary depending on the nature and timing of the activity, the structural framework, and the crustal architecture of the affected country-rock. To understand these effects and the interplay with other factors, we must first know the igneous record's distribution, timing, and petrology. In this paper, we describe a new geospatial database of the igneous rock record designed to provide a baseline digital resource that is application-agnostic and can be applied across the broadest range of research and resource exploration activities. We discuss the challenges we have faced and solved at each of the three main stages of geospatial mapping: database design, database population, and database visualisation. This includes the importance of a comprehensive audit trail so that users can differentiate between well and poorly-constrained interpretations, helping identify areas requiring additional work and data acquisition. The result is a geospatial database that will facilitate a better understanding of the Earth system and natural resource exploration.
{"title":"Mapping the Earth's Igneous Record. A Geospatial Database Approach","authors":"P. Markwick, Douglas A. Paton","doi":"10.1144/sp547-2023-64","DOIUrl":"https://doi.org/10.1144/sp547-2023-64","url":null,"abstract":"\u0000 \u0000 The record of igneous activity (magmatism and volcanism) can significantly affect natural resource exploration and exploitation, including the search for hydrocarbons, critical minerals, natural hydrogen, and geothermal energy sources, as well as using mafic igneous rocks as storage sites for CO\u0000 2\u0000 . These effects will vary depending on the nature and timing of the activity, the structural framework, and the crustal architecture of the affected country-rock. To understand these effects and the interplay with other factors, we must first know the igneous record's distribution, timing, and petrology. In this paper, we describe a new geospatial database of the igneous rock record designed to provide a baseline digital resource that is application-agnostic and can be applied across the broadest range of research and resource exploration activities. We discuss the challenges we have faced and solved at each of the three main stages of geospatial mapping: database design, database population, and database visualisation. This includes the importance of a comprehensive audit trail so that users can differentiate between well and poorly-constrained interpretations, helping identify areas requiring additional work and data acquisition. The result is a geospatial database that will facilitate a better understanding of the Earth system and natural resource exploration.\u0000","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"37 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140438419","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}
Benoit Vincent, C. Rigollet, Jean Cochard, Sara Khalil, Andrés Felipe Mejia-Durán, D. Grégoire, Nicolas E. Beaudoin, B. Brigaud, Thomas Blaise, Thierry Reuschle, P. Pellenard, P. Landrein
The “Calcaires du Barrois” Formation is a succession of dominantly micritic limestone of Kimmeridgian to Tithonian age, outcropping in the eastern part of the Paris Basin. This is an active karstic aquifer of main interest for the Andra (French National Agency for Radioactive Waste Management) who study the feasibility of a deep geological repository of radioactive waste in an Underground Research Laboratory (URL) located approximately 450m below the surface. Surface installations of the CIGEO (Industrial Centre for Geological Disposal) project are planned to be located in the upstream recharge zone of the aquifer. It is of primary interest to characterise the “Calcaires du Barrois” Formation to provide guidelines for the planning and the sizing of these facilities, with the objective of minimising the impact on the aquifer system. An integrated study was designed for this purpose linking petrography (thin section, and SEM, Scanning Electron Microscope), C & O stable isotope geochemistry, XRD (X-Ray Diffraction), petrophysics and geomechanics, and based on the analysis of three key cored wells penetrating the formation at different relative depths. The “Calcaires du Barrois” underwent several stages of diagenesis that defined the current properties. Unconformities associated with the Jurassic-Cretaceous transition led to prolonged early subaerial exposures during which freshwater flowed efficiently through the upper half of the formation. Through mineralogical stabilisation, among other processes, microporosity was preserved in micrites in this interval consisting of clean limestone with thin marl layers. The lower half of the formation, more argillaceous, was not or only slightly affected by this early meteoric diagenesis and recrystallization and cementation of micrites occurred during burial diagenesis, involving chemical compaction. Later, during the return to the surface associated to the Cenozoic orogens, another phase of meteoric diagenesis affected the uppermost few metres below the outcropping portions of the formation, but without modifying significantly the previously acquired petrophysical properties. Consequently, an intra-formational boundary was progressively developed at around 75m (from the top reference). This boundary separates (1) a lower half of the “Calcaires du Barrois” with dense and tight micrites, showing high Young's Modulus values, and a moderate intensity of fractures, from (2) a upper half with microporous micrites showing low Young's Modulus values, and almost devoid of fractures. A transitional zone of about 30m-thick, with intermediate properties, sitting above this boundary and below the only thin metre-scale macroporous grainstone level of the formation, accommodated most of the deformation linked to the Cenozoic west-European orogens and is intensively fractured. The current hydrogeological model considers a purely sedimentological boundary to delimit two sub-aquifers within the “Calcaires du Barrois” Form
Calcaires du Barrois "地层是以微砂岩为主的石灰岩层，属金美里纪至提托尼纪，出露于巴黎盆地东部。这是一个活跃的岩溶含水层，是法国国家放射性废物管理局（Andra）研究放射性废物深层地质储存库可行性的主要关注点，该储存库位于地下约 450 米处的地下研究实验室（URL）。CIGEO（地质处置工业中心）项目的地表设施计划位于含水层的上游补给区。对 "Calcaires du Barrois "地层的特征进行研究，为规划和确定这些设施的规模提供指导，目的是最大限度地减少对含水层系统的影响。为此，我们设计了一项综合研究，将岩相学（薄片和扫描电子显微镜）、C 和 O 稳定同位素地球化学、X 射线衍射（X-Ray Diffraction）、岩石物理学和地质力学联系起来，并以对穿透该地层不同相对深度的三口关键取芯井的分析为基础。Calcaires du Barrois "经历了几个阶段的成岩作用，确定了目前的性质。与侏罗纪-白垩纪过渡时期相关的不整合地貌导致了长期的早期次生暴露，在此期间，淡水有效地流经地层的上半部分。通过矿物质稳定等过程，微孔被保留在了这一区间的微晶石中，微晶石由带有薄泥灰岩层的洁净石灰岩组成。地层的下半部分，更多的是霰石，没有受到或仅受到这种早期流星成因的轻微影响，在埋藏成因过程中，微晶发生了再结晶和胶结，包括化学压实。后来，在与新生代造山运动相关的回归地表过程中，另一阶段的流星成岩作用影响了地层露头部分以下的最上层几米，但没有明显改变之前获得的岩石物理特性。因此，在大约 75 米处（从顶部参考点算起）逐渐形成了一个岩层内部边界。该边界将(1) 下半部分的 "Calcaires du Barrois "与(2) 上半部分的 "Calcaires du Barrois "分隔开来，下半部分的微晶致密而紧密，杨氏模量值高，裂缝强度适中，上半部分的微晶多孔，杨氏模量值低，几乎没有裂缝。厚度约为 30 米的过渡带具有中间性质，位于该边界之上，地层中唯一的米级大孔薄粒岩层之下，容纳了与新生代西欧造山运动有关的大部分变形，断裂密集。目前的水文地质模型认为，"Calcaires du Barrois "地层中的两个亚水层是以纯粹的沉积学边界划分的，但这一模型必须重新评估，因为它证明了真正的边界位于地层中明显更高的位置，并且是从多阶段成岩历史中继承下来的。这些发现将补充并影响 CIGEO 项目的工程规划。
{"title":"Multi-stage micrite diagenesis in the late Jurassic of the Eastern Paris Basin: petrophysical and mechanical properties for engineering purposes","authors":"Benoit Vincent, C. Rigollet, Jean Cochard, Sara Khalil, Andrés Felipe Mejia-Durán, D. Grégoire, Nicolas E. Beaudoin, B. Brigaud, Thomas Blaise, Thierry Reuschle, P. Pellenard, P. Landrein","doi":"10.1144/sp548-2023-139","DOIUrl":"https://doi.org/10.1144/sp548-2023-139","url":null,"abstract":"\u0000 The “Calcaires du Barrois” Formation is a succession of dominantly micritic limestone of Kimmeridgian to Tithonian age, outcropping in the eastern part of the Paris Basin. This is an active karstic aquifer of main interest for the Andra (French National Agency for Radioactive Waste Management) who study the feasibility of a deep geological repository of radioactive waste in an Underground Research Laboratory (URL) located approximately 450m below the surface. Surface installations of the CIGEO (Industrial Centre for Geological Disposal) project are planned to be located in the upstream recharge zone of the aquifer. It is of primary interest to characterise the “Calcaires du Barrois” Formation to provide guidelines for the planning and the sizing of these facilities, with the objective of minimising the impact on the aquifer system.\u0000 An integrated study was designed for this purpose linking petrography (thin section, and SEM, Scanning Electron Microscope), C & O stable isotope geochemistry, XRD (X-Ray Diffraction), petrophysics and geomechanics, and based on the analysis of three key cored wells penetrating the formation at different relative depths.\u0000 The “Calcaires du Barrois” underwent several stages of diagenesis that defined the current properties. Unconformities associated with the Jurassic-Cretaceous transition led to prolonged early subaerial exposures during which freshwater flowed efficiently through the upper half of the formation. Through mineralogical stabilisation, among other processes, microporosity was preserved in micrites in this interval consisting of clean limestone with thin marl layers. The lower half of the formation, more argillaceous, was not or only slightly affected by this early meteoric diagenesis and recrystallization and cementation of micrites occurred during burial diagenesis, involving chemical compaction. Later, during the return to the surface associated to the Cenozoic orogens, another phase of meteoric diagenesis affected the uppermost few metres below the outcropping portions of the formation, but without modifying significantly the previously acquired petrophysical properties. Consequently, an intra-formational boundary was progressively developed at around 75m (from the top reference). This boundary separates (1) a lower half of the “Calcaires du Barrois” with dense and tight micrites, showing high Young's Modulus values, and a moderate intensity of fractures, from (2) a upper half with microporous micrites showing low Young's Modulus values, and almost devoid of fractures. A transitional zone of about 30m-thick, with intermediate properties, sitting above this boundary and below the only thin metre-scale macroporous grainstone level of the formation, accommodated most of the deformation linked to the Cenozoic west-European orogens and is intensively fractured.\u0000 The current hydrogeological model considers a purely sedimentological boundary to delimit two sub-aquifers within the “Calcaires du Barrois” Form","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140439471","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}
Shale reservoirs host ubiquitous multi-scale natural fractures created by factors such as pore pressure build-up after petroleum generation and palaeo crustal stress changes during tectonic episodes. Natural fractures are among postulated drivers of stimulated shale well productivity and related variability. Quantifying the aforementioned role and optimizing recovery calls for litho-structural assessments. In this interdisciplinary study, natural fracture density (fractures per unit length) for North and South American shales (Marcellus, Eagle Ford, Haynesville, Barnett, Fayetteville and Vaca Muerta) was estimated from published observations of outcrops, cores and borehole images. Associated production for latest horizontal wells, drilled in the most productive locations (sweet spots), was normalized by lateral length and reservoir thickness. It was found to correlate positively with density of small-scale natural fractures. Durations of transient linear flow, diagnosed from production data, were play-specific, negatively correlated with small-scale natural fracture density and led to realization of picodarcy matrix permeability. Conversely, large-scale (tectonic) fractures limit stimulation efficiency and pose environmental/induced seismicity risks. Therefore, stimulation-driven reactivation of small-scale fractures facilitates drainage and enhances well productivity. Relatedly, reservoir flow regimes and production decline curves are intricately controlled by interplay of natural fracture density and matrix permeability. Variability of these parameters calls for acreage-tailored stimulations.
{"title":"Natural Fracture Density Controls Productivity in Shale Reservoirs","authors":"Clay Kurison, Mandefro B Woldeamanuel","doi":"10.1144/sp546-2023-53","DOIUrl":"https://doi.org/10.1144/sp546-2023-53","url":null,"abstract":"\u0000 Shale reservoirs host ubiquitous multi-scale natural fractures created by factors such as pore pressure build-up after petroleum generation and palaeo crustal stress changes during tectonic episodes. Natural fractures are among postulated drivers of stimulated shale well productivity and related variability. Quantifying the aforementioned role and optimizing recovery calls for litho-structural assessments. In this interdisciplinary study, natural fracture density (fractures per unit length) for North and South American shales (Marcellus, Eagle Ford, Haynesville, Barnett, Fayetteville and Vaca Muerta) was estimated from published observations of outcrops, cores and borehole images. Associated production for latest horizontal wells, drilled in the most productive locations (sweet spots), was normalized by lateral length and reservoir thickness. It was found to correlate positively with density of small-scale natural fractures. Durations of transient linear flow, diagnosed from production data, were play-specific, negatively correlated with small-scale natural fracture density and led to realization of picodarcy matrix permeability. Conversely, large-scale (tectonic) fractures limit stimulation efficiency and pose environmental/induced seismicity risks. Therefore, stimulation-driven reactivation of small-scale fractures facilitates drainage and enhances well productivity. Relatedly, reservoir flow regimes and production decline curves are intricately controlled by interplay of natural fracture density and matrix permeability. Variability of these parameters calls for acreage-tailored stimulations.","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"18 S1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140439067","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}
Hannah Wood, Andrew Barnett, Edward Follows, Priscila Ribeiro, Jaydip Guha, Josephine Wheeler, Runer Avila
The lacustrine carbonates of the Barra Velha Formation are a prolific hydrocarbon reservoir in the Santos Basin, Brazil. In many fields, they comprise decimetre- to metre-scale cycles composed of laminated calcimudstones, spherulite and shrub-dominated facies. However, locally these cycles are replaced by decametre packages of re-worked shrub grainstone/rudstone/breccia and in-situ shrub framestone with significant (>30°) depositional dips. The latter could be interpreted in several ways (e.g. fault block highs, carbonate mounds) but the integration of seismic, borehole image (BHI) log and whole core datasets converge on a model of aggrading carbonate mounds that developed in or marginal to a lake setting. The core datasets in this study demonstrate a distinctive depositional fabric within the carbonate mounds. From a production geology standpoint, the crucial difference between mound-dominated and cyclothem-dominated successions is their permeability architecture. Cyclothem-dominated intervals show prominent and laterally continuous, decimetre-scale vertical matrix permeability variations. Mound-dominated intervals lack fine-scale palaeo-horizontal layering and exhibit a greater prevalence of irregular, cm-scale conduits and higher vertical permeability. This difference can only be reliably characterised via the integration of whole core samples with other datasets and has a significant quantified impact on sweep and production performance.
Barra Velha 地层的湖相碳酸盐岩是巴西桑托斯盆地丰富的碳氢化合物储层。在许多油田，这些碳酸盐岩由层状钙钛矿、球粒岩和灌木为主的岩层组成十米至米级的循环。然而，在局部地区，这些循环被十米级的重加工灌木粒岩/泥岩/角砾岩和原位灌木框架岩群所取代，沉积倾角较大（大于 30°）。后者可以有多种解释（如断层块高、碳酸盐丘），但综合地震、钻孔图像（BHI）测井和整个岩芯数据集，可以得出一个在湖泊环境中或湖泊边缘发育的碳酸盐丘升级模型。这项研究的岩心数据集显示了碳酸盐丘内独特的沉积结构。 从生产地质学的角度来看，以碳酸盐丘为主的岩层与以环状岩为主的岩层之间的关键区别在于它们的渗透结构。Cyclothem为主的层间显示出突出的横向连续性、十米尺度的垂直基质渗透率变化。而以丘陵为主的岩层缺乏细尺度的古水平分层，更多的是不规则的厘米级导管，垂直渗透率更高。只有将整个岩心样本与其他数据集整合起来，才能可靠地描述这种差异，并且这种差异会对扫描和生产性能产生重大的量化影响。
{"title":"The Importance of Core for Carbonate Reservoir Evaluation: A Case Study from the Barra Velha Formation, Santos Basin, Brazil","authors":"Hannah Wood, Andrew Barnett, Edward Follows, Priscila Ribeiro, Jaydip Guha, Josephine Wheeler, Runer Avila","doi":"10.1144/sp548-2023-159","DOIUrl":"https://doi.org/10.1144/sp548-2023-159","url":null,"abstract":"\u0000 \u0000 The lacustrine carbonates of the Barra Velha Formation are a prolific hydrocarbon reservoir in the Santos Basin, Brazil. In many fields, they comprise decimetre- to metre-scale cycles composed of laminated calcimudstones, spherulite and shrub-dominated facies. However, locally these cycles are replaced by decametre packages of re-worked shrub grainstone/rudstone/breccia and\u0000 in-situ\u0000 shrub framestone with significant (>30°) depositional dips. The latter could be interpreted in several ways (e.g. fault block highs, carbonate mounds) but the integration of seismic, borehole image (BHI) log and whole core datasets converge on a model of aggrading carbonate mounds that developed in or marginal to a lake setting. The core datasets in this study demonstrate a distinctive depositional fabric within the carbonate mounds.\u0000 \u0000 From a production geology standpoint, the crucial difference between mound-dominated and cyclothem-dominated successions is their permeability architecture. Cyclothem-dominated intervals show prominent and laterally continuous, decimetre-scale vertical matrix permeability variations. Mound-dominated intervals lack fine-scale palaeo-horizontal layering and exhibit a greater prevalence of irregular, cm-scale conduits and higher vertical permeability. This difference can only be reliably characterised via the integration of whole core samples with other datasets and has a significant quantified impact on sweep and production performance.","PeriodicalId":281618,"journal":{"name":"Geological Society, London, Special Publications","volume":"46 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140440530","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：