C. Dacre, D. Palandro, A. Oldak, A. Ireland, Sean M. Mercer
To achieve reclamation certification, oil-and-gas operations in Alberta, Canada are required to monitor the revegetation of idle well pads that no longer support operations. Currently, monitoring is completed by oblique, helicopter-collected photography and on-the-ground field surveys. Both monitoring strategies present safety and logistical challenges. To mitigate these challenges, a remote-sensing project was completed to develop and deploy a reproducible workflow using high-spatial-resolution satellite imagery to monitor revegetation progress on idle well pads. Seven well pads in the Aspen region of Alberta, Canada were selected for workflow development, using imagery from 2007, 2009, and 2011. Land-cover classes were derived from the satellite imagery using a training dataset, a series of vegetation indices derived from the satellite imagery, and regression tree classification programs, and were used to evaluate changes in vegetation cover over time. A refined version of this general workflow was then deployed across 39 well pads in the Firebag region of Alberta, Canada, using imagery from 2010 to 2016. In 2016, fieldwork was conducted across a subset of 16 well pads in the Firebag region, which facilitated a formal accuracy assessment of the land-cover classifications. This project demonstrated that high-spatial-resolution satellite imagery could be used to develop accurate land-cover classifications on these relatively small landscape features and that temporal land-cover classifications could be used to track revegetation through time. Overall, these results show the feasibility of remote-sensing–based workflows in monitoring revegetation on idle well pads.
{"title":"High-resolution satellite imagery applied to monitoring revegetation of oil-sands-exploration well pads","authors":"C. Dacre, D. Palandro, A. Oldak, A. Ireland, Sean M. Mercer","doi":"10.1306/EG.07071717001","DOIUrl":"https://doi.org/10.1306/EG.07071717001","url":null,"abstract":"To achieve reclamation certification, oil-and-gas operations in Alberta, Canada are required to monitor the revegetation of idle well pads that no longer support operations. Currently, monitoring is completed by oblique, helicopter-collected photography and on-the-ground field surveys. Both monitoring strategies present safety and logistical challenges. To mitigate these challenges, a remote-sensing project was completed to develop and deploy a reproducible workflow using high-spatial-resolution satellite imagery to monitor revegetation progress on idle well pads. Seven well pads in the Aspen region of Alberta, Canada were selected for workflow development, using imagery from 2007, 2009, and 2011. Land-cover classes were derived from the satellite imagery using a training dataset, a series of vegetation indices derived from the satellite imagery, and regression tree classification programs, and were used to evaluate changes in vegetation cover over time. A refined version of this general workflow was then deployed across 39 well pads in the Firebag region of Alberta, Canada, using imagery from 2010 to 2016. In 2016, fieldwork was conducted across a subset of 16 well pads in the Firebag region, which facilitated a formal accuracy assessment of the land-cover classifications. This project demonstrated that high-spatial-resolution satellite imagery could be used to develop accurate land-cover classifications on these relatively small landscape features and that temporal land-cover classifications could be used to track revegetation through time. Overall, these results show the feasibility of remote-sensing–based workflows in monitoring revegetation on idle well pads.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.07071717001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48725333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-09-01DOI: 10.1306/EG.0206171600917003
G. Ferguson, L. Ufondu
Development of geothermal energy in sedimentary basins is an attractive option given the availability of data from the oil and gas industry. Previous geothermal studies in sedimentary basins have focused on temperatures and petrophysical properties. In this study, the focus is placed on historical reservoir performance. In the Western Canada Sedimentary Basin, estimated temperatures and measured fluid production and injection rates at existing wells are combined to provide a per-well estimate of thermal power production. Nearly 700 of these hypothetical geothermal wells would produce 1 MW of power, and a total of 6 GW could be produced if all wells were converted to geothermal wells. Many of these wells may not be suitable for immediate use because of temperature anomalies resulting from injection of cooler water into target strata. Further research is needed to characterize the magnitude and extent of these anomalies. Geothermal potential should also be considered in the development of oil and gas resources in sedimentary basins.
{"title":"Geothermal energy potential of the Western Canada Sedimentary Basin; clues from coproduced and injected water","authors":"G. Ferguson, L. Ufondu","doi":"10.1306/EG.0206171600917003","DOIUrl":"https://doi.org/10.1306/EG.0206171600917003","url":null,"abstract":"Development of geothermal energy in sedimentary basins is an attractive option given the availability of data from the oil and gas industry. Previous geothermal studies in sedimentary basins have focused on temperatures and petrophysical properties. In this study, the focus is placed on historical reservoir performance. In the Western Canada Sedimentary Basin, estimated temperatures and measured fluid production and injection rates at existing wells are combined to provide a per-well estimate of thermal power production. Nearly 700 of these hypothetical geothermal wells would produce 1 MW of power, and a total of 6 GW could be produced if all wells were converted to geothermal wells. Many of these wells may not be suitable for immediate use because of temperature anomalies resulting from injection of cooler water into target strata. Further research is needed to characterize the magnitude and extent of these anomalies. Geothermal potential should also be considered in the development of oil and gas resources in sedimentary basins.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.0206171600917003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42545753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-09-01DOI: 10.1306/EG.0206171600817004
R. Lahann, J. Rupp, C. Medina, G. Carlson, K. Johnson
The stress regime in the Illinois Basin was investigated to assess how the rock column might respond to the injection of fluids, including coproduced formation brines and supercritical CO2.This response is a concern because injection practices could increase pore fluid pressure and potentially induce seismicity. Data were collected to determine the magnitude and orientation of a three-component stress field: vertical stress (Sv) and minimum (Sh) and maximum (SH) horizontal stresses. The Sv was evaluated with a six-layer lithostratigraphic column. A two-layer pressure–depth Sv model was generated for the central part of the basin, and a single pressure gradient model was constructed for the surrounding region. In the central part of the basin, the Sv gradient is 24.9 MPa/km (1.11 psi/ft) to a depth of 2134 m (7000 ft), followed by a gradient of 27.1 MPa/km (1.20 psi/ft) below 2134 m (7000 ft). For the area surrounding the deep basin, the Sv gradient was 25.5 MPa/km (1.13 psi/ft). The Sh was evaluated from multiple data sources, primarily hydraulic fracture records or extended leak-off tests. The Sh gradient calculations ranged from 24.1 to 27.3 MPa/km (1.07 to 1.21 psi/ft). The Sh values for the basal Paleozoic clastic units are lower than those for units in the overlying horizons. The SH was based on a critically stressed model yielding values between 40.0 and 82.6 MPa/km (1.77 to 3.65 psi/ft). Stress orientation data for the Illinois Basin were collected from multiple sources. The orientation of SH across the study area is relatively uniform in strike at approximately N60°E. Marked deviations in SH result from localized structural discontinuities.
{"title":"State of stress in the Illinois Basin and constraints on inducing failure","authors":"R. Lahann, J. Rupp, C. Medina, G. Carlson, K. Johnson","doi":"10.1306/EG.0206171600817004","DOIUrl":"https://doi.org/10.1306/EG.0206171600817004","url":null,"abstract":"The stress regime in the Illinois Basin was investigated to assess how the rock column might respond to the injection of fluids, including coproduced formation brines and supercritical CO2.This response is a concern because injection practices could increase pore fluid pressure and potentially induce seismicity. Data were collected to determine the magnitude and orientation of a three-component stress field: vertical stress (Sv) and minimum (Sh) and maximum (SH) horizontal stresses. The Sv was evaluated with a six-layer lithostratigraphic column. A two-layer pressure–depth Sv model was generated for the central part of the basin, and a single pressure gradient model was constructed for the surrounding region. In the central part of the basin, the Sv gradient is 24.9 MPa/km (1.11 psi/ft) to a depth of 2134 m (7000 ft), followed by a gradient of 27.1 MPa/km (1.20 psi/ft) below 2134 m (7000 ft). For the area surrounding the deep basin, the Sv gradient was 25.5 MPa/km (1.13 psi/ft). The Sh was evaluated from multiple data sources, primarily hydraulic fracture records or extended leak-off tests. The Sh gradient calculations ranged from 24.1 to 27.3 MPa/km (1.07 to 1.21 psi/ft). The Sh values for the basal Paleozoic clastic units are lower than those for units in the overlying horizons. The SH was based on a critically stressed model yielding values between 40.0 and 82.6 MPa/km (1.77 to 3.65 psi/ft). Stress orientation data for the Illinois Basin were collected from multiple sources. The orientation of SH across the study area is relatively uniform in strike at approximately N60°E. Marked deviations in SH result from localized structural discontinuities.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.0206171600817004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42541155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.1306/EG.1221161600417009
J. Sams, G. Veloski, J. Diehl, Richard Hammack
This study demonstrates the application of aeromagnetic surveys for locating late 1800s-era oil and gas wells in Hillman State Park. The study area in southwestern Pennsylvania offered several unique challenges to locating legacy wells. Location records for many of Pennsylvania’s legacy wells do not exist. Those that do exist are often incomplete and inaccurate, and old wells were commonly abandoned without effective plugging. Now, unplugged legacy wells may serve as vertical migration pathways for fluids and gas associated with modern oil and gas operations. Wells in Hillman State Park were abandoned in the early 1900s, leaving little evidence of a well site. However, the steel well casing commonly remained at the site. Between 1940 and 1960, 50% of the land area at Hillman State Park was surface mined for coal. The removal of coal overburden also removed the upper well casings in surface-mined areas to the depth of the coal. The wells were then buried under mine spoil during regrading operations. Today, much of Hillman State Park is covered in trees and dense vegetation, and locating wells with ground-level searches is difficult, time consuming, and often futile. The airborne magnetic survey used in this study identified well locations, including buried wells in mined areas, based on the unique magnetic signature of vertical, steel well casing. The results of the aeromagnetic survey were combined with aerial photography, historic maps, and high-resolution topographic data in a geographic information system to refine well locations prior to verification with a ground search.
{"title":"Methods and challenges to locating legacy wells in western Pennsylvania: Case study at Hillman State Park","authors":"J. Sams, G. Veloski, J. Diehl, Richard Hammack","doi":"10.1306/EG.1221161600417009","DOIUrl":"https://doi.org/10.1306/EG.1221161600417009","url":null,"abstract":"This study demonstrates the application of aeromagnetic surveys for locating late 1800s-era oil and gas wells in Hillman State Park. The study area in southwestern Pennsylvania offered several unique challenges to locating legacy wells. Location records for many of Pennsylvania’s legacy wells do not exist. Those that do exist are often incomplete and inaccurate, and old wells were commonly abandoned without effective plugging. Now, unplugged legacy wells may serve as vertical migration pathways for fluids and gas associated with modern oil and gas operations. Wells in Hillman State Park were abandoned in the early 1900s, leaving little evidence of a well site. However, the steel well casing commonly remained at the site. Between 1940 and 1960, 50% of the land area at Hillman State Park was surface mined for coal. The removal of coal overburden also removed the upper well casings in surface-mined areas to the depth of the coal. The wells were then buried under mine spoil during regrading operations. Today, much of Hillman State Park is covered in trees and dense vegetation, and locating wells with ground-level searches is difficult, time consuming, and often futile. The airborne magnetic survey used in this study identified well locations, including buried wells in mined areas, based on the unique magnetic signature of vertical, steel well casing. The results of the aeromagnetic survey were combined with aerial photography, historic maps, and high-resolution topographic data in a geographic information system to refine well locations prior to verification with a ground search.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.1221161600417009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41456544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.1306/EG.1221161600317002
J. Meng, J. Pashin, P. Clark
ABSTRACT Surface and airborne gas monitoring programs are becoming an important part of environmental protection in areas favorable for subsurface storage of carbon dioxide. Understanding structural architecture and its effects on the flux of fluids, specifically CO 2 and CH 4 , in the shallow subsurface and atmosphere is helping with designing and implementing next-generation monitoring technologies, including unmanned aerial vehicles (UAVs). An important aspect of this research is using subsurface fracture data to inform the design of flight pathways for UAVs in the Farnsworth oil unit of the Anadarko Basin. The target zone for CO 2 storage and enhanced oil recovery in the Farnsworth oil unit is in the upper Morrow sandstone at subsurface depths greater than 2000 m (6562 ft). Field study reveals that sandstone and chert in the High Plains Aquifer contain numerous joints that provide crucial insight into aquifer architecture and subsurface flow pathways. Properties of more than 1700 joints were measured in the field and in high-resolution satellite images. Two distinctive joint systems interpreted as a conjugate pair were identified in the study area. Joint spacing follows a lognormal statistical scaling rule. These fractures appear to be the product of an east–northeast regional compressive stress and may have a significant effect on flow in the High Plains Aquifer system. Based on the results of this research, design of UAV flight paths should be oblique to fractures in a way that maximizes the likelihood of CO 2 and CH 4 flux of systematic joints and cross joints.
{"title":"Structural architecture of the Farnsworth oil unit: Implications for geologic storage of carbon dioxide","authors":"J. Meng, J. Pashin, P. Clark","doi":"10.1306/EG.1221161600317002","DOIUrl":"https://doi.org/10.1306/EG.1221161600317002","url":null,"abstract":"ABSTRACT Surface and airborne gas monitoring programs are becoming an important part of environmental protection in areas favorable for subsurface storage of carbon dioxide. Understanding structural architecture and its effects on the flux of fluids, specifically CO 2 and CH 4 , in the shallow subsurface and atmosphere is helping with designing and implementing next-generation monitoring technologies, including unmanned aerial vehicles (UAVs). An important aspect of this research is using subsurface fracture data to inform the design of flight pathways for UAVs in the Farnsworth oil unit of the Anadarko Basin. The target zone for CO 2 storage and enhanced oil recovery in the Farnsworth oil unit is in the upper Morrow sandstone at subsurface depths greater than 2000 m (6562 ft). Field study reveals that sandstone and chert in the High Plains Aquifer contain numerous joints that provide crucial insight into aquifer architecture and subsurface flow pathways. Properties of more than 1700 joints were measured in the field and in high-resolution satellite images. Two distinctive joint systems interpreted as a conjugate pair were identified in the study area. Joint spacing follows a lognormal statistical scaling rule. These fractures appear to be the product of an east–northeast regional compressive stress and may have a significant effect on flow in the High Plains Aquifer system. Based on the results of this research, design of UAV flight paths should be oblique to fractures in a way that maximizes the likelihood of CO 2 and CH 4 flux of systematic joints and cross joints.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.1221161600317002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48091927","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}
Jared Hawkins, Srikanta Mishra, R. Stowe, K. Makwana, J. Main
ABSTRACT Two different approaches have been used to evaluate the potential for CO 2 geologic sequestration and CO 2 -assisted enhanced oil recovery in the major oil fields in Ohio: a volumetrics-based method, which uses field volumetric data to calculate CO 2 storage capacity, and a production-based method, which uses historical oil and gas production data to calculate CO 2 storage capacity. The fields were selected based on their historical importance as oil and gas producers as well as the availability of data in published sources. The storage capacity found using the production data–based methodology—878 million t—is believed to be more representative than that found using the volumetrics-based method because it uses actual production data to calculate void space for CO 2 storage rather than estimated efficiency factors. This estimated capacity is higher than previously reported values based on efficiency factors and is enough to support the storage of 25% of annual emissions from 45 of Ohio’s largest power plants for a period of 36 yr.
{"title":"A revised assessment of the CO2 storage capacity and enhanced oil recovery potential in the major oil fields of Ohio","authors":"Jared Hawkins, Srikanta Mishra, R. Stowe, K. Makwana, J. Main","doi":"10.1306/EG.05161615019","DOIUrl":"https://doi.org/10.1306/EG.05161615019","url":null,"abstract":"ABSTRACT Two different approaches have been used to evaluate the potential for CO 2 geologic sequestration and CO 2 -assisted enhanced oil recovery in the major oil fields in Ohio: a volumetrics-based method, which uses field volumetric data to calculate CO 2 storage capacity, and a production-based method, which uses historical oil and gas production data to calculate CO 2 storage capacity. The fields were selected based on their historical importance as oil and gas producers as well as the availability of data in published sources. The storage capacity found using the production data–based methodology—878 million t—is believed to be more representative than that found using the volumetrics-based method because it uses actual production data to calculate void space for CO 2 storage rather than estimated efficiency factors. This estimated capacity is higher than previously reported values based on efficiency factors and is enough to support the storage of 25% of annual emissions from 45 of Ohio’s largest power plants for a period of 36 yr.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.05161615019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48071843","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}
ABSTRACT The successful implementation of geologic carbon sequestration depends on the careful evaluation of the petrophysical characteristics of the storage reservoir. Two petrophysical properties, porosity and permeability, constrain the reservoir in terms of its storage potential and injectivity. These two key parameters may vary significantly in scale within a reservoir. Likewise, the analytical tools that are useful for measuring these properties also vary and only assess pores of a given scale. In this investigation, 52 rock samples that consist of carbonates having a high degree of dolomitization were obtained from the Cambrian–Ordovician Knox Supergroup from different depth intervals; these samples span a significant area of the Midwestern United States. The samples were analyzed for total porosity and pore-size distribution using a variety of techniques, including petrographic image analysis, helium porosimetry, gas adsorption, mercury porosimetry, and ultrasmall-angle/small-angle neutron scattering. Capillary entrapment, or “residual saturation,” is that part of the injected CO 2 that remains trapped in micropores after the pressure elevated by the injection process returns to ambient reservoir pressure. Results from low-pressure nitrogen and carbon dioxide adsorption and from mercury injection capillary pressure are important in that they provide insights about small pore size that otherwise cannot be resolved by standard helium porosimetry or by image analysis software. Results from these analyses suggest that micro- and mesoporosity control capillary entrapment, whereas macroporosity controls permeability.
{"title":"Characterization of porosity and pore-size distribution using multiple analytical tools: Implications for carbonate reservoir characterization in geologic storage of CO2","authors":"C. Medina, M. Mastalerz, J. Rupp","doi":"10.1306/EG.02071716010","DOIUrl":"https://doi.org/10.1306/EG.02071716010","url":null,"abstract":"ABSTRACT The successful implementation of geologic carbon sequestration depends on the careful evaluation of the petrophysical characteristics of the storage reservoir. Two petrophysical properties, porosity and permeability, constrain the reservoir in terms of its storage potential and injectivity. These two key parameters may vary significantly in scale within a reservoir. Likewise, the analytical tools that are useful for measuring these properties also vary and only assess pores of a given scale. In this investigation, 52 rock samples that consist of carbonates having a high degree of dolomitization were obtained from the Cambrian–Ordovician Knox Supergroup from different depth intervals; these samples span a significant area of the Midwestern United States. The samples were analyzed for total porosity and pore-size distribution using a variety of techniques, including petrographic image analysis, helium porosimetry, gas adsorption, mercury porosimetry, and ultrasmall-angle/small-angle neutron scattering. Capillary entrapment, or “residual saturation,” is that part of the injected CO 2 that remains trapped in micropores after the pressure elevated by the injection process returns to ambient reservoir pressure. Results from low-pressure nitrogen and carbon dioxide adsorption and from mercury injection capillary pressure are important in that they provide insights about small pore size that otherwise cannot be resolved by standard helium porosimetry or by image analysis software. Results from these analyses suggest that micro- and mesoporosity control capillary entrapment, whereas macroporosity controls permeability.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.02071716010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44035134","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}
ABSTRACT Cambrian–Ordovician strata of the midwestern United States are considered a promising reservoir for geologic storage of carbon dioxide. To assess the potential of the Ordovician St. Peter Sandstone, storage-resource estimates were generated using a hierarchical approach to estimating prospective storage resources. The method employs a series of increasingly sophisticated analyses to better facilitate an understanding of the uncertainty in the estimates. Results demonstrate how uncertainty of storage-resource estimates varies as a function of data availability and quality as well as the underlying assumptions used in the application of specific storage efficiency factors. In the simplest analysis, storage-resource estimates were calculated from updated regional-scale mapping of the gross thickness of the formation and by applying a single best estimate of the mean porosity for the entire formation. This analysis follows the technique prescribed by the US Department of Energy and yields storage-resource estimates ranging from 3.3 to 35.1 billion t CO 2 in the Michigan Basin and 1.0 to 11.0 billion t CO 2 in the Illinois Basin at the 10% and 90% probability levels. The second analysis incorporated generalized models of the diagenetic history of the formation throughout the two basins by implementing depth-dependent functions of porosity that lead to more realistic portrayals of spatially variable results. Similar resource estimates were calculated for the Michigan Basin, but reduced estimates (43%) were found for the Illinois Basin. The third analysis explicitly accounted for the local-scale spatial variability in reservoir quality using net-porosity calculations, resulting in a significant increase in the low-range resource estimate for the Michigan Basin and dramatic increases for Illinois Basin resource estimates (factor of 3 to 11 increases). A fourth analysis was conducted for the Michigan Basin that used advanced reservoir characterization to define reservoir properties for multiple reservoir facies and yielded resource estimates significantly larger than the third analysis and a larger range of uncertainty. This study highlights how different factors impact the expected uncertainty in storage-resource estimates, and analysis suggests that estimates from the first two approaches provide excessively conservative results, whereas the second two approaches tend to overestimate the resource.
{"title":"Geologic-carbon-sequestration potential of the Ordovician St. Peter Sandstone, Michigan and Illinois Basins, United States","authors":"D. Barnes, K. Ellett, J. Rupp","doi":"10.1306/EG.02071716007","DOIUrl":"https://doi.org/10.1306/EG.02071716007","url":null,"abstract":"ABSTRACT Cambrian–Ordovician strata of the midwestern United States are considered a promising reservoir for geologic storage of carbon dioxide. To assess the potential of the Ordovician St. Peter Sandstone, storage-resource estimates were generated using a hierarchical approach to estimating prospective storage resources. The method employs a series of increasingly sophisticated analyses to better facilitate an understanding of the uncertainty in the estimates. Results demonstrate how uncertainty of storage-resource estimates varies as a function of data availability and quality as well as the underlying assumptions used in the application of specific storage efficiency factors. In the simplest analysis, storage-resource estimates were calculated from updated regional-scale mapping of the gross thickness of the formation and by applying a single best estimate of the mean porosity for the entire formation. This analysis follows the technique prescribed by the US Department of Energy and yields storage-resource estimates ranging from 3.3 to 35.1 billion t CO 2 in the Michigan Basin and 1.0 to 11.0 billion t CO 2 in the Illinois Basin at the 10% and 90% probability levels. The second analysis incorporated generalized models of the diagenetic history of the formation throughout the two basins by implementing depth-dependent functions of porosity that lead to more realistic portrayals of spatially variable results. Similar resource estimates were calculated for the Michigan Basin, but reduced estimates (43%) were found for the Illinois Basin. The third analysis explicitly accounted for the local-scale spatial variability in reservoir quality using net-porosity calculations, resulting in a significant increase in the low-range resource estimate for the Michigan Basin and dramatic increases for Illinois Basin resource estimates (factor of 3 to 11 increases). A fourth analysis was conducted for the Michigan Basin that used advanced reservoir characterization to define reservoir properties for multiple reservoir facies and yielded resource estimates significantly larger than the third analysis and a larger range of uncertainty. This study highlights how different factors impact the expected uncertainty in storage-resource estimates, and analysis suggests that estimates from the first two approaches provide excessively conservative results, whereas the second two approaches tend to overestimate the resource.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.02071716007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49142055","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}
Eric B. Avalos, D. Malone, E. Peterson, W. Anderson, R. Gehrels
ABSTRACT Two-dimensional seismic refraction tomography was used to map the bedrock topography beneath Hallsands beach in southwest Devon, United Kingdom. Seismic refraction data were acquired from 11 spreads, 4 parallel to the beach and 7 normal to the beach, with either 12 or 24 geophones at 5-m (16-ft) spacing. Eight sediment cores were used to calibrate the velocity model. The bedrock consists of metasedimentary rocks that have a seismic velocity of 2100–2500 m/s (6900–8200 ft/s) and is overlain by variable amounts of gravel, peat, and muddy peat. Wood peat and peaty mud are differentiated within the peat as 700-m/s (2300-ft/s) velocity for wood peat and 1200-m/s (4000-ft/s) velocity for peaty mud. These refraction data were collected and processed in two dimensions, then imported into Petrel, a three-dimensional (3-D) geological modeling software package. The 3-D geologic model was built using the velocity attribute of the seismic refraction data. These selected data points were used to create 3-D horizons, surfaces, and contacts constraining the target bedrock surface from the overlying unconsolidated deposits. The bedrock surface beneath Hallsands beach is marked by two paleochannels. One paleochannel occurs in the north end of the beach beneath the axis of the modern valley. A second paleochannel occurs in the southern section of Hallsands beach centered along the axis of a tributary valley. Bedrock occurs at a depth of approximately −10 m (−33 ft) in the southern and northern sections of the main valley. Bedrock occurs at a depth of approximately −2 m (−6 ft) along the valley wall at the southern end of the beach east of the parking lot. Shore-perpendicular refraction lines differentiate layers within the peat, whereas shore-parallel lines delineate wood-peat, peaty-mud, and bedrock topography.
{"title":"Two-dimensional seismic refraction tomography of a buried bedrock valley at Hallsands beach, Devon, United Kingdom","authors":"Eric B. Avalos, D. Malone, E. Peterson, W. Anderson, R. Gehrels","doi":"10.1306/EG.07131615014","DOIUrl":"https://doi.org/10.1306/EG.07131615014","url":null,"abstract":"ABSTRACT Two-dimensional seismic refraction tomography was used to map the bedrock topography beneath Hallsands beach in southwest Devon, United Kingdom. Seismic refraction data were acquired from 11 spreads, 4 parallel to the beach and 7 normal to the beach, with either 12 or 24 geophones at 5-m (16-ft) spacing. Eight sediment cores were used to calibrate the velocity model. The bedrock consists of metasedimentary rocks that have a seismic velocity of 2100–2500 m/s (6900–8200 ft/s) and is overlain by variable amounts of gravel, peat, and muddy peat. Wood peat and peaty mud are differentiated within the peat as 700-m/s (2300-ft/s) velocity for wood peat and 1200-m/s (4000-ft/s) velocity for peaty mud. These refraction data were collected and processed in two dimensions, then imported into Petrel, a three-dimensional (3-D) geological modeling software package. The 3-D geologic model was built using the velocity attribute of the seismic refraction data. These selected data points were used to create 3-D horizons, surfaces, and contacts constraining the target bedrock surface from the overlying unconsolidated deposits. The bedrock surface beneath Hallsands beach is marked by two paleochannels. One paleochannel occurs in the north end of the beach beneath the axis of the modern valley. A second paleochannel occurs in the southern section of Hallsands beach centered along the axis of a tributary valley. Bedrock occurs at a depth of approximately −10 m (−33 ft) in the southern and northern sections of the main valley. Bedrock occurs at a depth of approximately −2 m (−6 ft) along the valley wall at the southern end of the beach east of the parking lot. Shore-perpendicular refraction lines differentiate layers within the peat, whereas shore-parallel lines delineate wood-peat, peaty-mud, and bedrock topography.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.07131615014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66166407","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}
P. Sammarco, M. Nuttall, D. Beltz, Lance Horn, G. Taylor, E. Hickerson, G. Schmahl
Drilling for oil/gas and trawling on a continental shelf can cause damage to hard-bottom communities. Moving these activities offshore poses a threat to offshore communities. Habitat complexity is correlated with species diversity. The relationship of bottom relief to benthic species richness is not well understood in deeper communities. Relief may act as a proxy for species richness and disturbance risk. Geographic patterns in relief and richness are also not well understood. We gathered information on bottom relief and species richness of the sessile epibenthic community using a remotely operated vehicle. We surveyed hard bottom on the flanks of 13 banks in the north–central Gulf of Mexico, greater than 27-m (89-ft) depth, on the shelf and at the shelf edge. We found a positive asymptotic relationship between mean relief and species richness at the transect level. Secondary analyses at the drop site level revealed a similar relationship; variance was higher. The relationship was positively linear at the bank level. Analyses using standard deviation of relief yielded even stronger positive results. There was no significant relationship between species richness and latitude or longitude over the study area (215 km [133 mi]). When species richness was plotted in three dimensions, however, peaks in richness emerged in the southeastern study area and the western region, with a trough between them, coinciding with bottom relief. Species richness is positively correlated with bottom relief on banks in the northern Gulf of Mexico. Relief and species richness may be predicted at many spatial scales, up to hundreds of kilometers.
在大陆架上钻探石油/天然气和拖网作业可能会对硬底社区造成损害。将这些活动转移到海上对近海社区构成了威胁。生境复杂性与物种多样性相关。在较深的群落中，底栖生物物种丰富度与底部起伏的关系尚不清楚。缓解可以作为物种丰富度和干扰风险的代理。地形起伏和丰富程度的地理格局也没有得到很好的了解。我们利用遥控车辆收集了无根底栖生物群落的底部起伏和物种丰富度信息。我们调查了墨西哥湾中北部13个海岸侧翼的硬底，深度超过27米(89英尺)，在大陆架和大陆架边缘。在样带水平上，平均地形起伏与物种丰富度呈渐近正相关。在落点水平的二次分析显示了类似的关系;方差更高。在银行层面，这种关系是正线性的。使用标准偏差的分析得到了更积极的结果。在研究区域(215 km [133 mi])，物种丰富度与经纬度关系不显著。然而，在三维空间绘制物种丰富度时，研究区东南部和西部出现了丰富度峰值，两者之间有一个低谷，与底部起伏一致。物种丰富度与墨西哥湾北部岸底起伏呈显著正相关。地形起伏和物种丰富度可以在数百公里的空间尺度上进行预测。
{"title":"The positive relationship between relief and species richness in mesophotic communities on offshore banks, including geographic patterns","authors":"P. Sammarco, M. Nuttall, D. Beltz, Lance Horn, G. Taylor, E. Hickerson, G. Schmahl","doi":"10.1306/EG.12071615020","DOIUrl":"https://doi.org/10.1306/EG.12071615020","url":null,"abstract":"Drilling for oil/gas and trawling on a continental shelf can cause damage to hard-bottom communities. Moving these activities offshore poses a threat to offshore communities. Habitat complexity is correlated with species diversity. The relationship of bottom relief to benthic species richness is not well understood in deeper communities. Relief may act as a proxy for species richness and disturbance risk. Geographic patterns in relief and richness are also not well understood. We gathered information on bottom relief and species richness of the sessile epibenthic community using a remotely operated vehicle. We surveyed hard bottom on the flanks of 13 banks in the north–central Gulf of Mexico, greater than 27-m (89-ft) depth, on the shelf and at the shelf edge. We found a positive asymptotic relationship between mean relief and species richness at the transect level. Secondary analyses at the drop site level revealed a similar relationship; variance was higher. The relationship was positively linear at the bank level. Analyses using standard deviation of relief yielded even stronger positive results. There was no significant relationship between species richness and latitude or longitude over the study area (215 km [133 mi]). When species richness was plotted in three dimensions, however, peaks in richness emerged in the southeastern study area and the western region, with a trough between them, coinciding with bottom relief. Species richness is positively correlated with bottom relief on banks in the northern Gulf of Mexico. Relief and species richness may be predicted at many spatial scales, up to hundreds of kilometers.","PeriodicalId":11706,"journal":{"name":"Environmental Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1306/EG.12071615020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66169141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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