Wang Peng, Shangqi Zhai, Wu Hao, Qiongyuan Wu, Jianli Yan
To clarify the movement of water flooding front in fluvial reservoirs, this research takes BZ oilfield as an example. By comprehensively considering the [w1] equivalent flowing resistance theory of oil-water two phases, the horizontal micro-element equivalent method, and the strong heterogeneity of fluvial facies reservoir, the calculation model of non-piston water flooding front in horizontal well pattern is established. Firstly, five horizontal injection-production well groups in BZ oilfield are taken as examples to calculate the water breakthrough time of oil wells respectively. The calculation results are in good agreement with the actual production performance. In detail, the front advancing speed of the high permeability strip is 0.8 ∼ 1.6m/d, and the speed in low permeability strip is 0.12 ∼ 0.35m/d. When the oil well sees water, the advance speed of the low permeability strip becomes slower, resulting in uneven displacement and easily forming non-dominant potential areas. Moreover, the water flooding front advancing distance is simulated to be 300 ∼ 450m by establishing the reservoir numerical simulation model, which is close to the result of the proposed model, indicating that the calculation method is reliable. The research is of great significance for predicting the water breakthrough time of horizontal production wells, judging the weak affected area on the mainstream line, and timely optimizing water injection and tapping reservoir potential.
{"title":"Research on Water Flooding Front Based on Dynamic and Static Data Inversion—A case study","authors":"Wang Peng, Shangqi Zhai, Wu Hao, Qiongyuan Wu, Jianli Yan","doi":"10.1144/petgeo2023-061","DOIUrl":"https://doi.org/10.1144/petgeo2023-061","url":null,"abstract":"To clarify the movement of water flooding front in fluvial reservoirs, this research takes BZ oilfield as an example. By comprehensively considering the [w1] equivalent flowing resistance theory of oil-water two phases, the horizontal micro-element equivalent method, and the strong heterogeneity of fluvial facies reservoir, the calculation model of non-piston water flooding front in horizontal well pattern is established. Firstly, five horizontal injection-production well groups in BZ oilfield are taken as examples to calculate the water breakthrough time of oil wells respectively. The calculation results are in good agreement with the actual production performance. In detail, the front advancing speed of the high permeability strip is 0.8 ∼ 1.6m/d, and the speed in low permeability strip is 0.12 ∼ 0.35m/d. When the oil well sees water, the advance speed of the low permeability strip becomes slower, resulting in uneven displacement and easily forming non-dominant potential areas. Moreover, the water flooding front advancing distance is simulated to be 300 ∼ 450m by establishing the reservoir numerical simulation model, which is close to the result of the proposed model, indicating that the calculation method is reliable. The research is of great significance for predicting the water breakthrough time of horizontal production wells, judging the weak affected area on the mainstream line, and timely optimizing water injection and tapping reservoir potential.","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141666749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dinesh Kumar, Ravi Sharma, A. S. Maurya, Rajesh Pandey
In hydrocarbon exploration, total organic carbon content (TOC) and Rock-eval pyrolysis are commonly employed geochemical techniques that offer concise insights into kerogen type, effective source rock identification, and thermal maturity. In the current study, the data obtained from Rock-eval pyrolysis has been used for defining the source rock quality, generative potential, kerogen type, maturity of the source sediments, and kerogen kinetics of the Baisakhi-Bhadesar Formation of Kimmeridgian -Tithonian (154.7−145.6 Ma) age. Basinal level HI, TOC, source rock maturity, transformation ratio, and heat flow maps have been generated by integrating the data from pyrolysis and the previously available data from wells drilled in the basin. The Total Organic Carbon (TOC) content of the Kimmeridgian-Tithonian sequence ranges from 0.03 to 12.71% in the studied samples, with an average TOC content of 1.28 %, indicating good source rock quality. The Hydrogen index (HI), in collaboration with T max and VRo data, demonstrates that the Baisakhi - Bhadesar Formation is characterised by type II, mixture of type II/ III and type III kerogen facies and exhibits good source quality and poor to good generative potential in the basin. The studied samples are marginally mature to mature in nature (Tmax 430-450 0 C, VRo % ranges from 0.52% to 0.72%). Maturity analysis of the basin suggests that, during the Late Jurassic, most areas were under the oil window zone, except the Bhakhari Tibba and Miajlar areas. The Transformation ratio overlay for the Kimmeridgian-Tithonian source sequences shows better transformations of the source rock in the area of the Shagarh sub-basin. Kerogen kinetics of the studied Baisakhi-Bhadesar Formation demonstrate that the activation energy ranges between 46-74 Kcal/mol with the significant distribution of activation energy 54 Kcal/mol (42.07 %), representing a strong heterogeneous type of organic matter in the sediments. Based on lithological, paleontological, and electrolog studies, a shallow marine to near-shore environment of deposition with sediment input direction from the southeast has been inferred for Kimmeridgian-Tithonian Sequences. The results of this study quantitatively establish the role of the Kimmeridgian-Tithonian sequence as source rock, ultimately contributing to the generation of hydrocarbons in the basin along with spatial changes in the quality of source sediments in different parts of the basin.
{"title":"Petroleum source rocks characterisation and depositional environment of Kimmeridgian-Tithonian Sequences, Jaisalmer Basin, Western Rajasthan, India","authors":"Dinesh Kumar, Ravi Sharma, A. S. Maurya, Rajesh Pandey","doi":"10.1144/petgeo2023-097","DOIUrl":"https://doi.org/10.1144/petgeo2023-097","url":null,"abstract":"\u0000 In hydrocarbon exploration, total organic carbon content (TOC) and Rock-eval pyrolysis are commonly employed geochemical techniques that offer concise insights into kerogen type, effective source rock identification, and thermal maturity. In the current study, the data obtained from Rock-eval pyrolysis has been used for defining the source rock quality, generative potential, kerogen type, maturity of the source sediments, and kerogen kinetics of the Baisakhi-Bhadesar Formation of Kimmeridgian -Tithonian (154.7−145.6 Ma) age. Basinal level HI, TOC, source rock maturity, transformation ratio, and heat flow maps have been generated by integrating the data from pyrolysis and the previously available data from wells drilled in the basin. The Total Organic Carbon (TOC) content of the Kimmeridgian-Tithonian sequence ranges from 0.03 to 12.71% in the studied samples, with an average TOC content of 1.28 %, indicating good source rock quality. The Hydrogen index (HI), in collaboration with T\u0000 max\u0000 and VRo data, demonstrates that the Baisakhi - Bhadesar Formation is characterised by type II, mixture of type II/ III and type III kerogen facies and exhibits good source quality and poor to good generative potential in the basin. The studied samples are marginally mature to mature in nature (Tmax 430-450\u0000 0\u0000 C, VRo % ranges from 0.52% to 0.72%). Maturity analysis of the basin suggests that, during the Late Jurassic, most areas were under the oil window zone, except the Bhakhari Tibba and Miajlar areas. The Transformation ratio overlay for the Kimmeridgian-Tithonian source sequences shows better transformations of the source rock in the area of the Shagarh sub-basin. Kerogen kinetics of the studied Baisakhi-Bhadesar Formation demonstrate that the activation energy ranges between 46-74 Kcal/mol with the significant distribution of activation energy 54 Kcal/mol (42.07 %), representing a strong heterogeneous type of organic matter in the sediments. Based on lithological, paleontological, and electrolog studies, a shallow marine to near-shore environment of deposition with sediment input direction from the southeast has been inferred for Kimmeridgian-Tithonian Sequences. The results of this study quantitatively establish the role of the Kimmeridgian-Tithonian sequence as source rock, ultimately contributing to the generation of hydrocarbons in the basin along with spatial changes in the quality of source sediments in different parts of the basin.\u0000","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141684080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper covers a novel micro-level application of image processing in understanding the topological and petrophysical properties of Indian Gondwana Shale using an X-ray computed micro tomography images. The complexity and randomness in the pore system are explained through the concept of fractal dimension (FD). In this article, a quantitative analysis of 2D and 3D fractal dimension of pores, grains, and interface has been done for the Indian Gondwana Shale, using the Box counting method. A pore network is formed by the connection of many sub-pore clusters, each with a different volume. Hence, an image segmentation algorithm has been applied to label different sub-clusters, and subsequently, analysis of FD is done on such sub-clusters of pores and grains. We implemented a novel application of Betti numbers (B0, B1 and B2) and Euler characteristics on our sample and calculated the possible flow channels of the sample. The FD of grains was found to be greater than the FD of pore-grains interface, while the FD of pores was found to be the least. Consequently, we also observed how the FD of both pores and grains is majorly controlled by the largest sub-cluster, and during fluid intrusion, we see a significant decrease in FD of pores. Lastly, the pore network, with a larger B0 and larger difference of B1 can be proved best for the storage of hydrocarbon content and its fluid movement understanding due to more flow channels.
{"title":"A quantitative study of microstructure of Indian Gondwana shale: a fractal and algebraic topology approach","authors":"P. Sarkar, S. Sahoo, Umang Nagpal, T. N. Singh","doi":"10.1144/petgeo2023-105","DOIUrl":"https://doi.org/10.1144/petgeo2023-105","url":null,"abstract":"This paper covers a novel micro-level application of image processing in understanding the topological and petrophysical properties of Indian Gondwana Shale using an X-ray computed micro tomography images. The complexity and randomness in the pore system are explained through the concept of fractal dimension (FD). In this article, a quantitative analysis of 2D and 3D fractal dimension of pores, grains, and interface has been done for the Indian Gondwana Shale, using the Box counting method. A pore network is formed by the connection of many sub-pore clusters, each with a different volume. Hence, an image segmentation algorithm has been applied to label different sub-clusters, and subsequently, analysis of FD is done on such sub-clusters of pores and grains. We implemented a novel application of Betti numbers (B0, B1 and B2) and Euler characteristics on our sample and calculated the possible flow channels of the sample. The FD of grains was found to be greater than the FD of pore-grains interface, while the FD of pores was found to be the least. Consequently, we also observed how the FD of both pores and grains is majorly controlled by the largest sub-cluster, and during fluid intrusion, we see a significant decrease in FD of pores. Lastly, the pore network, with a larger B0 and larger difference of B1 can be proved best for the storage of hydrocarbon content and its fluid movement understanding due to more flow channels.","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141121156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The formation of Punta del Este Basin is associated with the fragmentation of West Gondwana and consequently the opening of the South Atlantic Ocean during the Early Cretaceous. The basin comprises the Cretaceous depocenter of the Uruguayan continental margin (UCM). This study provides a seismic stratigraphic analysis of the sedimentary interval of the Cretaceous post-rift in the basin by defining its seismic facies, depositional sequences, shelf-edge trajectories, and palaeophysiographic settings. All depositional sequences of the Cretaceous post-rift represent intense basinward progradation marked by two depositional trends. The Lower Cretaceous sedimentary interval exhibits a dominant flat-to-descending shelf-edge trajectory, with migration up to 37 km. Deposition occurred over an irregular physiography with proximal NW–SE and distal WSW–ENE trends controlled by the characteristics of the volcanic margin. Basin geometry has strong implications for understanding the deposition of a deep-water turbidite system in the UCM, with a strong analogy to the recent discovery of Venus well in the Orange Basin, offshore Namibia. Towards the Late Cretaceous, the NW–SE depositional trend was controlled by a NE-SW slope break, indicating deposition over the South and North highs. A low-angle ascending shelf-edge trajectory was observed, with migration up to 16 km.
{"title":"Seismic stratigraphy of the Cretaceous post-rift in Punta del Este Basin (offshore Uruguay) and its implications for deep-water reservoirs","authors":"Sequeira Marcos, Morales Ethel, Conti Bruno","doi":"10.1144/petgeo2023-063","DOIUrl":"https://doi.org/10.1144/petgeo2023-063","url":null,"abstract":"The formation of Punta del Este Basin is associated with the fragmentation of West Gondwana and consequently the opening of the South Atlantic Ocean during the Early Cretaceous. The basin comprises the Cretaceous depocenter of the Uruguayan continental margin (UCM). This study provides a seismic stratigraphic analysis of the sedimentary interval of the Cretaceous post-rift in the basin by defining its seismic facies, depositional sequences, shelf-edge trajectories, and palaeophysiographic settings. All depositional sequences of the Cretaceous post-rift represent intense basinward progradation marked by two depositional trends. The Lower Cretaceous sedimentary interval exhibits a dominant flat-to-descending shelf-edge trajectory, with migration up to 37 km. Deposition occurred over an irregular physiography with proximal NW–SE and distal WSW–ENE trends controlled by the characteristics of the volcanic margin. Basin geometry has strong implications for understanding the deposition of a deep-water turbidite system in the UCM, with a strong analogy to the recent discovery of Venus well in the Orange Basin, offshore Namibia. Towards the Late Cretaceous, the NW–SE depositional trend was controlled by a NE-SW slope break, indicating deposition over the South and North highs. A low-angle ascending shelf-edge trajectory was observed, with migration up to 16 km.","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141121425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In fold-and-thrust belts where there is a high degree of structural complexity, artificial geometrical distortions are often present on seismic reflection profiles. They need to be minimized during modelling. We document a workflow in which depth-mapping, velocity model building, well calibration and cross-section balancing are integrated into the seismic interpretation process to generate trustworthy structural models in complex zones. The proposed methodology is exemplified by a case study from the foothills zone of the Colombian Eastern Cordillera. In addition, sequential kinematic restoration of the modelled structure allowed evaluation of hydrocarbon migration routes during the period between the Oligocene and the middle Miocene. Following the previously mentioned workflow, we document a failed exploratory case study where all elements of the petroleum system are present except the trap. In this context, the documented case is a typical velocity pull-up. From this and published case studies we conclude that in Andean settings and probably most on land contractional-foothill settings, seismic image only, does not provide enough evidence of the presence of the trap but additional surface geological signatures must be documented. The proposed workflow therefore appears to be a useful tool for evaluating the exploration risk in structurally-complex fold-and-thrust belt settings.
{"title":"Integrated geological and geophysical workflow for structural modelling; case study from the contraction foothills zone of the Colombian Eastern Cordillera","authors":"Carlos Andrés Becerra-Bayona, Andrés Mora","doi":"10.1144/petgeo2023-113","DOIUrl":"https://doi.org/10.1144/petgeo2023-113","url":null,"abstract":"In fold-and-thrust belts where there is a high degree of structural complexity, artificial geometrical distortions are often present on seismic reflection profiles. They need to be minimized during modelling. We document a workflow in which depth-mapping, velocity model building, well calibration and cross-section balancing are integrated into the seismic interpretation process to generate trustworthy structural models in complex zones. The proposed methodology is exemplified by a case study from the foothills zone of the Colombian Eastern Cordillera. In addition, sequential kinematic restoration of the modelled structure allowed evaluation of hydrocarbon migration routes during the period between the Oligocene and the middle Miocene. Following the previously mentioned workflow, we document a failed exploratory case study where all elements of the petroleum system are present except the trap. In this context, the documented case is a typical velocity pull-up. From this and published case studies we conclude that in Andean settings and probably most on land contractional-foothill settings, seismic image only, does not provide enough evidence of the presence of the trap but additional surface geological signatures must be documented. The proposed workflow therefore appears to be a useful tool for evaluating the exploration risk in structurally-complex fold-and-thrust belt settings.","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141003257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alistair Maguire, Leanne Smart, Lucinda K. Layfield, Mike Bower, N. Schofield
Developments in ultradeep azimuthal resistivity (UDAR) technology has recently progressed from their application in high-angle and horizontal wells to low-angle and vertical wells. This has presented the opportunity to assess their suitability as derisking tools because of their ability to look ahead of the bit, up to c . 100 ft ( c. 30.5 m). Dominated by a complex interplay of structure, sedimentation, and volcanic activity, the NE Atlantic Margin presents a challenging environment to plan and drill wells safely and within planned budget, with many wells drilled within the Faroe-Shetland Basin (FSB) currently the most expensive to-date within the United Kingdom continental shelf (UKCS). The limited number of wells drilled in the FSB and their geographical sparsity relative to those of other areas of the UKCS, make offset analysis and derisking a challenge. The often-unpredictable distribution of igneous rocks throughout the basin presents significant challenges in the planning and drilling of oil and gas wells. Up to 88% of igneous intrusions within the FSB are estimated to be below seismic resolution, which alongside variation in composition, presents significant issues related to drilling safely, efficiently and successfully. Within this paper, we investigate the use of UDAR technology and how they could be deployed in areas of complex volcanic geology such as the West of Shetland (WoS). This paper reviews the nature of the drilling experiences within the FSB to date, the impact it has on exploration, and how improvements in drilling technology could help decrease nonproductive time (NPT). Thematic collection: This article is part of the UKCS Atlantic Margin collection available at: https://www.lyellcollection.org/topic/collections/new-learning-from-exploration-and-development-in-the-ukcs-atlantic-margin
{"title":"Look-ahead-while-drilling resistivity tools and their role in drilling sedimentary basins containing complex volcanic geology","authors":"Alistair Maguire, Leanne Smart, Lucinda K. Layfield, Mike Bower, N. Schofield","doi":"10.1144/petgeo2024-012","DOIUrl":"https://doi.org/10.1144/petgeo2024-012","url":null,"abstract":"\u0000 Developments in ultradeep azimuthal resistivity (UDAR) technology has recently progressed from their application in high-angle and horizontal wells to low-angle and vertical wells. This has presented the opportunity to assess their suitability as derisking tools because of their ability to look ahead of the bit, up to\u0000 c\u0000 . 100 ft (\u0000 c.\u0000 30.5 m).\u0000 \u0000 Dominated by a complex interplay of structure, sedimentation, and volcanic activity, the NE Atlantic Margin presents a challenging environment to plan and drill wells safely and within planned budget, with many wells drilled within the Faroe-Shetland Basin (FSB) currently the most expensive to-date within the United Kingdom continental shelf (UKCS). The limited number of wells drilled in the FSB and their geographical sparsity relative to those of other areas of the UKCS, make offset analysis and derisking a challenge. The often-unpredictable distribution of igneous rocks throughout the basin presents significant challenges in the planning and drilling of oil and gas wells. Up to 88% of igneous intrusions within the FSB are estimated to be below seismic resolution, which alongside variation in composition, presents significant issues related to drilling safely, efficiently and successfully.\u0000 Within this paper, we investigate the use of UDAR technology and how they could be deployed in areas of complex volcanic geology such as the West of Shetland (WoS). This paper reviews the nature of the drilling experiences within the FSB to date, the impact it has on exploration, and how improvements in drilling technology could help decrease nonproductive time (NPT).\u0000 \u0000 Thematic collection:\u0000 This article is part of the UKCS Atlantic Margin collection available at:\u0000 https://www.lyellcollection.org/topic/collections/new-learning-from-exploration-and-development-in-the-ukcs-atlantic-margin\u0000","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140655426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-resolution image data is instrumental in quantifying the variation of rock fabric in formation evaluation that conventional well logs fail to capture. However, the acquisition of image data for all wells in a reservoir is restricted due to technology limitations and operational constraints and the high cost involved. The main objective of this paper is to propose a workflow to extrapolate rock fabric information from imaged wells to nearby un-imaged wells for enhanced formation evaluation in un-imaged wells. To propagate rock fabric information, we trained a supervised learning algorithm in a well with core photos, CT-scan images, and conventional well logs. Subsequently, the trained model is used to identify fabric-influenced well-log-based rock classes using only conventional well logs in un-imaged depth intervals/well (referred to as fabric-based rock classes). We applied the proposed workflow to two wells in a siliciclastic formation with spatial variation in rock fabric. Comparison of the detected fabric-based rock classes in the nearby depth intervals/well using the trained model with image-based rock classes resulted in an average accuracy of 94%. The outcomes of this paper contribute to accelerated identification of rock types honoring rock fabric while minimizing extensive imaging and coring efforts. Thematic collection: This article is part of the Digitally enabled geoscience workflows: unlocking the power of our data collection available at: https://www.lyellcollection.org/topic/collections/digitally-enabled-geoscience-workflows
高分辨率图像数据有助于在地层评估中量化传统测井记录无法捕捉的岩石结构变化。然而，由于技术限制、操作约束和高昂的成本，油藏中所有油井的图像数据采集都受到限制。本文的主要目的是提出一种工作流程，将已成像油井中的岩石结构信息推断到附近的未成像油井中，以增强对未成像油井的地层评估。为了传播岩石结构信息，我们在一口井中用岩心照片、CT 扫描图像和常规测井记录训练了一种监督学习算法。随后，利用训练好的模型，仅使用未成像深度区间/井中的常规测井记录，识别受构造影响的基于测井记录的岩石类别（称为基于构造的岩石类别）。我们将提议的工作流程应用于硅质岩层中的两口井，这两口井的岩石结构存在空间变化。使用训练有素的模型对附近深度区间/井中检测到的基于构造的岩石类别与基于图像的岩石类别进行比较，平均准确率达到 94%。本文的成果有助于加快识别岩石类型，同时最大限度地减少大量的成像和取芯工作。 专题收藏：本文是《数字化地球科学工作流程：释放我们数据收集的力量》（Digitally enabled geoscience workflows: unlocking the power of our data collection）的一部分，详情可登录 https://www.lyellcollection.org/topic/collections/digitally-enabled-geoscience-workflows。
{"title":"Propagating Image-Based Rock Classes from Cored to Non-Cored Depth Intervals Using Supervised Machine Learning","authors":"P. Sahu, Andres Gonzalez, Z. Heidari, O. Lopez","doi":"10.1144/petgeo2023-147","DOIUrl":"https://doi.org/10.1144/petgeo2023-147","url":null,"abstract":"High-resolution image data is instrumental in quantifying the variation of rock fabric in formation evaluation that conventional well logs fail to capture. However, the acquisition of image data for all wells in a reservoir is restricted due to technology limitations and operational constraints and the high cost involved. The main objective of this paper is to propose a workflow to extrapolate rock fabric information from imaged wells to nearby un-imaged wells for enhanced formation evaluation in un-imaged wells. To propagate rock fabric information, we trained a supervised learning algorithm in a well with core photos, CT-scan images, and conventional well logs. Subsequently, the trained model is used to identify fabric-influenced well-log-based rock classes using only conventional well logs in un-imaged depth intervals/well (referred to as fabric-based rock classes). We applied the proposed workflow to two wells in a siliciclastic formation with spatial variation in rock fabric. Comparison of the detected fabric-based rock classes in the nearby depth intervals/well using the trained model with image-based rock classes resulted in an average accuracy of 94%. The outcomes of this paper contribute to accelerated identification of rock types honoring rock fabric while minimizing extensive imaging and coring efforts.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Digitally enabled geoscience workflows: unlocking the power of our data collection available at:\u0000 https://www.lyellcollection.org/topic/collections/digitally-enabled-geoscience-workflows\u0000","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140657480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Di Lauro, A. Hartley, J. Duncan, E. Rosseland Knutsen, J. Howell, D. Jolley
Distribution of the Triassic succession in the North Sea is poorly understood because of structural complexities associated with halokinesis and limited stratigraphic control. This study uses a seismic and well based dataset to improve understanding of development of the Triassic succession in the Ula Field Area, of the Norwegian North Sea. Core interpretation revealed a fluvial-dominated depositional environment in the Ula Field Area. Palynological studies allowed dating of cored intervals, revealing Ladinian and Carnian sections, time-equivalent to the Julius and Joanne members of the Skagerrak Formation. Well-log interpretation provided insight into the intra-Triassic stratigraphy of the Ula Field Area. A section considered to be equivalent to and extending from the Smith Bank Formation to the Jonathan Member of the Skagerrak Formation was interpreted and correlated across the area. In the proposed correlation, the Julius Member thins towards the Ula Field Area and is replaced by a time equivalent sandstone unit. The Jonathan Member displays a sandier composition compared to the equivalent section in the UK sector. Seismic facies-based interpretation of Triassic stratigraphy within salt minibasins allowed recognition and mapping of intra-Triassic units and showed that mudstone members thin towards the northeast. Interpreted internal geometries within minibasins allowed determination of the timing of halokinesis. Integration of different datasets allowed palaeogeographic reconstructions for the Anisian, early Ladinian, Carnian and Norian to be constructed. To conclude, the distribution of stacked fluvial channel deposits indicates that they occur both within minibasins and across salt highs such that ongoing halokinesis had no topographic expression and that channels were free to migrate across the area.
{"title":"The Influence of Salt Tectonics on the Distribution of the Triassic Skagerrak Formation in the Ula Field, Norwegian North Sea","authors":"L. Di Lauro, A. Hartley, J. Duncan, E. Rosseland Knutsen, J. Howell, D. Jolley","doi":"10.1144/petgeo2022-025","DOIUrl":"https://doi.org/10.1144/petgeo2022-025","url":null,"abstract":"Distribution of the Triassic succession in the North Sea is poorly understood because of structural complexities associated with halokinesis and limited stratigraphic control. This study uses a seismic and well based dataset to improve understanding of development of the Triassic succession in the Ula Field Area, of the Norwegian North Sea.\u0000 Core interpretation revealed a fluvial-dominated depositional environment in the Ula Field Area. Palynological studies allowed dating of cored intervals, revealing Ladinian and Carnian sections, time-equivalent to the Julius and Joanne members of the Skagerrak Formation. Well-log interpretation provided insight into the intra-Triassic stratigraphy of the Ula Field Area. A section considered to be equivalent to and extending from the Smith Bank Formation to the Jonathan Member of the Skagerrak Formation was interpreted and correlated across the area. In the proposed correlation, the Julius Member thins towards the Ula Field Area and is replaced by a time equivalent sandstone unit. The Jonathan Member displays a sandier composition compared to the equivalent section in the UK sector. Seismic facies-based interpretation of Triassic stratigraphy within salt minibasins allowed recognition and mapping of intra-Triassic units and showed that mudstone members thin towards the northeast. Interpreted internal geometries within minibasins allowed determination of the timing of halokinesis. Integration of different datasets allowed palaeogeographic reconstructions for the Anisian, early Ladinian, Carnian and Norian to be constructed. To conclude, the distribution of stacked fluvial channel deposits indicates that they occur both within minibasins and across salt highs such that ongoing halokinesis had no topographic expression and that channels were free to migrate across the area.","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140689147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Researchers have used lacunarity, a parameter that quantifies scale-dependent clustering in patterns to distinguish fracture networks that belong to the same fractal system. Also, in a previous study, the authors showed that lacunarity is efficient in representing the connectivity and fluid flow in synthetic fractal-fracture models having a single fractal dimension. The objective of this research is to investigate if the concepts thus developed is applicable to outcrop analogues which are representative of sub-surface fractured reservoirs. A set of nested fracture networks belonging to a single fractal system but mapped at different scales and resolutions is considered in this study. Lacunarity and connectivity values of these maps are evaluated using geospatial data analysis techniques. Fracture continuum (FC) models are built from these fracture maps and a streamline simulator, TRACE3D is used to flow simulate these maps. Results show that, although, the fractal dimension of these maps is same, but there exist stubble differences in the values of lacunarity, percolation connectivity, and also the fluid recovery values. It is further noted that the clustering, connectivity, and fluid recovery values can be pairwise correlated very well for these natural fracture maps. Thus, the overall results indicate that connectivity in fracture maps and hence in turn their flow properties are controlled by lacunarity or scale-dependent clustering attributes. Therefore, there could be novel applicability of lacunarity parameter in calibrating discrete fracture network (DFN) models with respect to connectivity of natural fracture maps and prediction of flow behavior in fractured reservoirs. Thematic collection: This article is part of the Digitally enabled geoscience workflows: unlocking the power of our data collection available at: https://www.lyellcollection.org/topic/collections/digitally-enabled-geoscience-workflows
{"title":"Predicting fluid flow in fractured reservoirs by application of lacunarity analysis of natural fracture analogues","authors":"Ajay K. Sahu, Ankur Roy","doi":"10.1144/petgeo2023-091","DOIUrl":"https://doi.org/10.1144/petgeo2023-091","url":null,"abstract":"Researchers have used lacunarity, a parameter that quantifies scale-dependent clustering in patterns to distinguish fracture networks that belong to the same fractal system. Also, in a previous study, the authors showed that lacunarity is efficient in representing the connectivity and fluid flow in synthetic fractal-fracture models having a single fractal dimension. The objective of this research is to investigate if the concepts thus developed is applicable to outcrop analogues which are representative of sub-surface fractured reservoirs. A set of nested fracture networks belonging to a single fractal system but mapped at different scales and resolutions is considered in this study. Lacunarity and connectivity values of these maps are evaluated using geospatial data analysis techniques. Fracture continuum (FC) models are built from these fracture maps and a streamline simulator, TRACE3D is used to flow simulate these maps. Results show that, although, the fractal dimension of these maps is same, but there exist stubble differences in the values of lacunarity, percolation connectivity, and also the fluid recovery values. It is further noted that the clustering, connectivity, and fluid recovery values can be pairwise correlated very well for these natural fracture maps. Thus, the overall results indicate that connectivity in fracture maps and hence in turn their flow properties are controlled by lacunarity or scale-dependent clustering attributes. Therefore, there could be novel applicability of lacunarity parameter in calibrating discrete fracture network (DFN) models with respect to connectivity of natural fracture maps and prediction of flow behavior in fractured reservoirs.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Digitally enabled geoscience workflows: unlocking the power of our data collection available at:\u0000 https://www.lyellcollection.org/topic/collections/digitally-enabled-geoscience-workflows\u0000","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140254572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
André Gondim Brandão, O. P. Wennberg, Leonardo Borghi, João Paulo Oliveira, Vinicius Carneiro
In the BM-C-33 area, divided into the Raia Manta and Raia Pintada development areas, reservoirs are arranged into three structural highs: Gávea, Seat, and Pão de Açúcar. These reservoirs consist of Pre-salt limestones deposited on volcanic sequences and underwent complex diagenetic evolution. Successive post-depositional processes, including silicification, affected original mineral assemblage, modified pore textures, and caused intense fracturing. Based on borehole image logs (BHI), wireline data from four wells, and 2D and 3D seismic data, this study details natural fracture acoustic and resistivity properties. It also discusses the relationship of faults, fractures, and vugs with diagenetic and tectonic processes. The authors used the data to divide the Pre-salt section (Cabiúnas and Macabu formations) into three informal stratigraphic units. The analysis of interpreted fractures within these units suggests that major fracturing occurred due to regional tectonic stress, with local aspects like structural positioning interfering. The results of the fracture analysis imply a direct relationship between fracturing and silicification. Additionally, fracture density, vug volume distribution, and the presence of dissolution features like enlarged fractures limited to specific units imply stratigraphic control on fluid percolation. Finally, the study examines structural particularities in BM-C-33 area that potentially impacted intensity and extension of diagenetic alterations.
{"title":"Fracture analysis in borehole images from BM-C-33 area, outer Campos Basin, Brazil","authors":"André Gondim Brandão, O. P. Wennberg, Leonardo Borghi, João Paulo Oliveira, Vinicius Carneiro","doi":"10.1144/petgeo2023-134","DOIUrl":"https://doi.org/10.1144/petgeo2023-134","url":null,"abstract":"In the BM-C-33 area, divided into the Raia Manta and Raia Pintada development areas, reservoirs are arranged into three structural highs: Gávea, Seat, and Pão de Açúcar. These reservoirs consist of Pre-salt limestones deposited on volcanic sequences and underwent complex diagenetic evolution. Successive post-depositional processes, including silicification, affected original mineral assemblage, modified pore textures, and caused intense fracturing. Based on borehole image logs (BHI), wireline data from four wells, and 2D and 3D seismic data, this study details natural fracture acoustic and resistivity properties. It also discusses the relationship of faults, fractures, and vugs with diagenetic and tectonic processes. The authors used the data to divide the Pre-salt section (Cabiúnas and Macabu formations) into three informal stratigraphic units. The analysis of interpreted fractures within these units suggests that major fracturing occurred due to regional tectonic stress, with local aspects like structural positioning interfering. The results of the fracture analysis imply a direct relationship between fracturing and silicification. Additionally, fracture density, vug volume distribution, and the presence of dissolution features like enlarged fractures limited to specific units imply stratigraphic control on fluid percolation. Finally, the study examines structural particularities in BM-C-33 area that potentially impacted intensity and extension of diagenetic alterations.","PeriodicalId":49704,"journal":{"name":"Petroleum Geoscience","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140424571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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