Towards characterization of natural fractures in a caprock shale: an integrated borehole-outcrop study of the Agardhfjellet For-mation, Svalbard, Arctic Norway. Schaaf, N. W., Senger, K., Mulrooney, M. J., Ogata, K., Braathen, A., & Olaussen, S. In Oslo, 2017. doi abstract bibtex The Longyearbyen CO2 Lab aims to capture carbon dioxide emitted by the local coal-fuelled power plant and store it in an unconventional, siliciclastic, Late Triassic - Middle Jurassic reservoir located at ca. 700 to 1000 m depth. The caprock consists of Late Jurassic - Early Cretaceous shales of the Agardhfjellet Formation, characterized by organic rich, highly fissile mudstones with silty intervals, reflecting offshore anoxic conditions. Pressure data observations, including severe underpressure in the reservoir and an overpressured aquifer above the top seal, suggest efficient sealing properties of the caprock, confirmed by numerous leak-off tests. In addition, a natural gas accumulation is envisaged to be capped by internal horizontal barriers in the cap rock. Despite the proven sealing capacity of the Agardhfjellet Formation its lower section is intensely fractured, as demonstrated by observations in outcrops and drill cores. These fractures could be reactivated and exploited as preferential fluid flow pathways during and after CO2 injection. In this study we characterize the natural fracture network in the two lowermost members (i.e. Oppdalen and Lardyfjellet Mbs.) of the Agardhfjellet Formation in order to quantify its architecture and predict the fluid flow pathways. We conducted manual fracture mapping on 90 m of continuous drill core to quantify the vertical distribution of predominantly sub-horizontal and low angle fractures. Field data (i.e. scanlines) were used to quantify horizontal distribu-tion and orientation of the sub-vertical fractures and determine if they are genetically linked to sub-seismic faults present in the section. Wireline logs including an acoustic televiewer and caliper meas-urements supplemented those data. In addition, ground and drone-based photogrammetry was applied to generate 3D models of laterally and vertically extensive outcrops for both stratigraphic and structural correlations. About 1500 fractures from cores and 1000 fractures from the field were obtained and pro-cessed. Our results indicate a predominance of low angle fracturing, sometimes with striations, throughout the majority of the analyzed core interval. In addition, outcrop data mainly consist of high angle joints. The fracture trends observed in the field exhibit dominant E-W and N-S directions. The estimated vertical fracture frequency is up to 20 fractures per meter, with a horizontal fracture spacing between 2.5 and 40 cm, possibly providing a pervasive network of fluid migration pathways. From a structural complexity viewpoint, it therefore appears uncertain whether the investigated lower section of the Agardhfjellet Formation represents the inferred horizontal pressure barrier.
@inproceedings{schaaf_towards_2017,
address = {Oslo},
title = {Towards characterization of natural fractures in a caprock shale: an integrated borehole-outcrop study of the {Agardhfjellet} {For}-mation, {Svalbard}, {Arctic} {Norway}},
doi = {10.13140/RG.2.2.23744.74249/1},
abstract = {The Longyearbyen CO2 Lab aims to capture carbon dioxide emitted by the local coal-fuelled power plant and store it in an unconventional, siliciclastic, Late Triassic - Middle Jurassic reservoir located at ca. 700 to 1000 m depth. The caprock consists of Late Jurassic - Early Cretaceous shales of the Agardhfjellet Formation, characterized by organic rich, highly fissile mudstones with silty intervals, reflecting offshore anoxic conditions. Pressure data observations, including severe underpressure in the reservoir and an overpressured aquifer above the top seal, suggest efficient sealing properties of the caprock, confirmed by numerous leak-off tests. In addition, a natural gas accumulation is envisaged to be capped by internal horizontal barriers in the cap rock. Despite the proven sealing capacity of the Agardhfjellet Formation its lower section is intensely fractured, as demonstrated by observations in outcrops and drill cores. These fractures could be reactivated and exploited as preferential fluid flow pathways during and after CO2 injection. In this study we characterize the natural fracture network in the two lowermost members (i.e. Oppdalen and Lardyfjellet Mbs.) of the Agardhfjellet Formation in order to quantify its architecture and predict the fluid flow pathways. We conducted manual fracture mapping on 90 m of continuous drill core to quantify the vertical distribution of predominantly sub-horizontal and low angle fractures. Field data (i.e. scanlines) were used to quantify horizontal distribu-tion and orientation of the sub-vertical fractures and determine if they are genetically linked to sub-seismic faults present in the section. Wireline logs including an acoustic televiewer and caliper meas-urements supplemented those data. In addition, ground and drone-based photogrammetry was applied to generate 3D models of laterally and vertically extensive outcrops for both stratigraphic and structural correlations. About 1500 fractures from cores and 1000 fractures from the field were obtained and pro-cessed. Our results indicate a predominance of low angle fracturing, sometimes with striations, throughout the majority of the analyzed core interval. In addition, outcrop data mainly consist of high angle joints. The fracture trends observed in the field exhibit dominant E-W and N-S directions. The estimated vertical fracture frequency is up to 20 fractures per meter, with a horizontal fracture spacing between 2.5 and 40 cm, possibly providing a pervasive network of fluid migration pathways. From a structural complexity viewpoint, it therefore appears uncertain whether the investigated lower section of the Agardhfjellet Formation represents the inferred horizontal pressure barrier.},
author = {Schaaf, Niklas W. and Senger, Kim and Mulrooney, Mark Joseph and Ogata, Kei and Braathen, Alvar and Olaussen, Snorre},
year = {2017},
}
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{"_id":"gwAqMcyAnDGPiHpu5","bibbaseid":"schaaf-senger-mulrooney-ogata-braathen-olaussen-towardscharacterizationofnaturalfracturesinacaprockshaleanintegratedboreholeoutcropstudyoftheagardhfjelletformationsvalbardarcticnorway-2017","author_short":["Schaaf, N. W.","Senger, K.","Mulrooney, M. J.","Ogata, K.","Braathen, A.","Olaussen, S."],"bibdata":{"bibtype":"inproceedings","type":"inproceedings","address":"Oslo","title":"Towards characterization of natural fractures in a caprock shale: an integrated borehole-outcrop study of the Agardhfjellet For-mation, Svalbard, Arctic Norway","doi":"10.13140/RG.2.2.23744.74249/1","abstract":"The Longyearbyen CO2 Lab aims to capture carbon dioxide emitted by the local coal-fuelled power plant and store it in an unconventional, siliciclastic, Late Triassic - Middle Jurassic reservoir located at ca. 700 to 1000 m depth. The caprock consists of Late Jurassic - Early Cretaceous shales of the Agardhfjellet Formation, characterized by organic rich, highly fissile mudstones with silty intervals, reflecting offshore anoxic conditions. Pressure data observations, including severe underpressure in the reservoir and an overpressured aquifer above the top seal, suggest efficient sealing properties of the caprock, confirmed by numerous leak-off tests. In addition, a natural gas accumulation is envisaged to be capped by internal horizontal barriers in the cap rock. Despite the proven sealing capacity of the Agardhfjellet Formation its lower section is intensely fractured, as demonstrated by observations in outcrops and drill cores. These fractures could be reactivated and exploited as preferential fluid flow pathways during and after CO2 injection. In this study we characterize the natural fracture network in the two lowermost members (i.e. Oppdalen and Lardyfjellet Mbs.) of the Agardhfjellet Formation in order to quantify its architecture and predict the fluid flow pathways. We conducted manual fracture mapping on 90 m of continuous drill core to quantify the vertical distribution of predominantly sub-horizontal and low angle fractures. Field data (i.e. scanlines) were used to quantify horizontal distribu-tion and orientation of the sub-vertical fractures and determine if they are genetically linked to sub-seismic faults present in the section. Wireline logs including an acoustic televiewer and caliper meas-urements supplemented those data. In addition, ground and drone-based photogrammetry was applied to generate 3D models of laterally and vertically extensive outcrops for both stratigraphic and structural correlations. About 1500 fractures from cores and 1000 fractures from the field were obtained and pro-cessed. Our results indicate a predominance of low angle fracturing, sometimes with striations, throughout the majority of the analyzed core interval. In addition, outcrop data mainly consist of high angle joints. The fracture trends observed in the field exhibit dominant E-W and N-S directions. The estimated vertical fracture frequency is up to 20 fractures per meter, with a horizontal fracture spacing between 2.5 and 40 cm, possibly providing a pervasive network of fluid migration pathways. From a structural complexity viewpoint, it therefore appears uncertain whether the investigated lower section of the Agardhfjellet Formation represents the inferred horizontal pressure barrier.","author":[{"propositions":[],"lastnames":["Schaaf"],"firstnames":["Niklas","W."],"suffixes":[]},{"propositions":[],"lastnames":["Senger"],"firstnames":["Kim"],"suffixes":[]},{"propositions":[],"lastnames":["Mulrooney"],"firstnames":["Mark","Joseph"],"suffixes":[]},{"propositions":[],"lastnames":["Ogata"],"firstnames":["Kei"],"suffixes":[]},{"propositions":[],"lastnames":["Braathen"],"firstnames":["Alvar"],"suffixes":[]},{"propositions":[],"lastnames":["Olaussen"],"firstnames":["Snorre"],"suffixes":[]}],"year":"2017","bibtex":"@inproceedings{schaaf_towards_2017,\n\taddress = {Oslo},\n\ttitle = {Towards characterization of natural fractures in a caprock shale: an integrated borehole-outcrop study of the {Agardhfjellet} {For}-mation, {Svalbard}, {Arctic} {Norway}},\n\tdoi = {10.13140/RG.2.2.23744.74249/1},\n\tabstract = {The Longyearbyen CO2 Lab aims to capture carbon dioxide emitted by the local coal-fuelled power plant and store it in an unconventional, siliciclastic, Late Triassic - Middle Jurassic reservoir located at ca. 700 to 1000 m depth. The caprock consists of Late Jurassic - Early Cretaceous shales of the Agardhfjellet Formation, characterized by organic rich, highly fissile mudstones with silty intervals, reflecting offshore anoxic conditions. Pressure data observations, including severe underpressure in the reservoir and an overpressured aquifer above the top seal, suggest efficient sealing properties of the caprock, confirmed by numerous leak-off tests. In addition, a natural gas accumulation is envisaged to be capped by internal horizontal barriers in the cap rock. Despite the proven sealing capacity of the Agardhfjellet Formation its lower section is intensely fractured, as demonstrated by observations in outcrops and drill cores. These fractures could be reactivated and exploited as preferential fluid flow pathways during and after CO2 injection. In this study we characterize the natural fracture network in the two lowermost members (i.e. Oppdalen and Lardyfjellet Mbs.) of the Agardhfjellet Formation in order to quantify its architecture and predict the fluid flow pathways. We conducted manual fracture mapping on 90 m of continuous drill core to quantify the vertical distribution of predominantly sub-horizontal and low angle fractures. Field data (i.e. scanlines) were used to quantify horizontal distribu-tion and orientation of the sub-vertical fractures and determine if they are genetically linked to sub-seismic faults present in the section. Wireline logs including an acoustic televiewer and caliper meas-urements supplemented those data. In addition, ground and drone-based photogrammetry was applied to generate 3D models of laterally and vertically extensive outcrops for both stratigraphic and structural correlations. About 1500 fractures from cores and 1000 fractures from the field were obtained and pro-cessed. Our results indicate a predominance of low angle fracturing, sometimes with striations, throughout the majority of the analyzed core interval. In addition, outcrop data mainly consist of high angle joints. The fracture trends observed in the field exhibit dominant E-W and N-S directions. The estimated vertical fracture frequency is up to 20 fractures per meter, with a horizontal fracture spacing between 2.5 and 40 cm, possibly providing a pervasive network of fluid migration pathways. From a structural complexity viewpoint, it therefore appears uncertain whether the investigated lower section of the Agardhfjellet Formation represents the inferred horizontal pressure barrier.},\n\tauthor = {Schaaf, Niklas W. and Senger, Kim and Mulrooney, Mark Joseph and Ogata, Kei and Braathen, Alvar and Olaussen, Snorre},\n\tyear = {2017},\n}\n\n","author_short":["Schaaf, N. W.","Senger, K.","Mulrooney, M. 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