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Paul L Broughton - One of the best experts on this subject based on the ideXlab platform.
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ghost rock karstification of devonian limestone flooring the athabasca oil sands in western canada
Geomorphology, 2018Co-Authors: Paul L BroughtonAbstract:Abstract This study interprets a new style of ghost-rock karstification at a site in northeast Alberta, western Canada. The karstic area of the Upper Devonian paleotopography was localized at the western end of the Bitumount Trough, a 50 km-long collapse structure that resulted from removal of a 120 m thick interval of Salt Beds of the Middle Devonian Prairie Evaporite only 200 m below. Ghost-rock karstification developed in massive light grey limestone Beds that alternate with chlorite-rich argillaceous intervals, of the Moberly Member, Devonian Waterways Formation. These weathered rock profiles expanded latterly and were deepened by slowly moving hydraulic gradient-driven phreatic groundwater descending along clusters of closely spaced 2–10 cm-wide joints that cross-cut the fracture-shattered limestone Beds. The uppermost Beds of greyish green chlorite-rich argillaceous limestone were decalcified as the flows along the joint clusters carried insoluble residues consisting of quartz silt mixed with illite-chlorite clays into the substrate. These chlorite-rich insoluble residues accumulated as replacement fabrics within decalcified porous zones of the altered limestone in the substrate. As the joint opening plugged with insoluble residues within the deepened decalcification weathered rock intervals, the alterite zones expanded laterally to form vertical pod-shaped structures. These 5–20 m in diameter and 10–20 m-deep pseudo-sinkhole zones consisting of alterite retained ghost-rock traces of the original limestone strata. This area was subsequently covered by the Lower Cretaceous Athabasca Oil Sands.
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Subglacial blowouts in western Canada: insights into extreme meltwater pressures and hydrofracturing
Boreas, 2017Co-Authors: Paul L BroughtonAbstract:This study interprets deformations of indurated 10s of metres thick bedrock strata by subglacial meltwater pressures at maximum levels, resulting in types of hydrodynamic structures not previously recognized. The structures provide insights into the range of extreme pressures possible with the backup of meltwaters sufficient to deform multi-metre thick indurated Beds, unlike elsewhere. Subglacial meltwater flows into the subsurface below the 50–100 m thick bitumen platform aquiclude of the Cretaceous Athabasca Oil Sands deposit were driven by the hydraulic head of the 1.5-km-thick Laurentide Ice Sheet. These meltwaters over-pressured the regional Devonian aquifer waters, but the low permeability of the aquifer below the site of the Muskeg River Mine was insufficient to accommodate the voluminous influxes of subglacial meltwater. The resulting meltwater flows backed-up, resulting in elevating aquifer pressures to maximum levels along the margins of the underlying Devonian Keg River reef mound and within water-saturated Cretaceous sand Beds offset to the east. The meltwater pressure build to extreme levels hydrofractured strata at sites along the margins of the Keg River mound preconditioned by dissolution-induced subsidence in underlying Salt Beds. Release of the confining pressure upon withdrawal of the Laurentide Ice Sheet resulted in 45-m-high open blowout structures that punctured the bitumen platform at sites above the northern margin of the Keg River mound. Other blowout chimney sites above the southern margin of the mound were plugged because of insufficient pressure build to clear vents of all ejecta. Concurrently, pressured meltwater flows along the eastern margin resulted in dykes that cross-cut and buckled Devonian limestone Beds. Some dykes extended into overlying water-saturated unconsolidated Cretaceous sand Beds, channelling pressured water and hydroplastic mudflows that dissipated the extreme meltwater flow pressures and prevented puncturing of the overlying bitumen platform. These unusual deformation structures in western Canada resulted from catastrophic failure of hydrofractured rock zones responding to extreme meltwater pressures, in contrast to unconsolidated sediment deformations resulting from only moderately elevated meltwater pressures commonly observed elsewhere.
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devonian Salt dissolution collapse breccias flooring the cretaceous athabasca oil sands deposit and development of lower mcmurray formation sinkholes northern alberta basin western canada
Sedimentary Geology, 2013Co-Authors: Paul L BroughtonAbstract:Abstract The sub-Cretaceous paleotopography underlying giant Lower Cretaceous Athabasca oil sands, northern Alberta, has an orthogonal lattice pattern of troughs up to 50 km long and 100 m deep between pairs of cross-cutting lineaments. These structures are interpreted to have been inherited from a similar pattern of dissolution collapse-subsidence troughs in the underlying Middle Devonian Salt Beds. Removal of more than 100 m of halite Salt fragmented the overlying Upper Devonian strata into fault blocks and collapse breccias that subsided into the underlying dissolution troughs. The unusually low 1:2 to 1:3 thickness ratios of halite Salts to the overlying strata resulted in the Upper Devonian strata collapse-subsidence into underlying Salt dissolution troughs being more cataclysmic during the first phase of Salt removal. The second phase of slower but complete Salt removal between the earlier troughs resulted in a more gradual subsidence of the overlying strata. This obliterated the earlier pattern of giant cross-cutting dissolution troughs bounded by major lineaments. The collapse breccia fabrics underlying the earlier troughs differ from those from areas between the troughs. Collapse breccias underlying the large troughs often have crushed fabrics distributed in zones that rapidly pinched out between fault blocks. Breccias between troughs developed as giant mosaics of detached carbonate blocks that formed breccia pipe complexes. Multiple sinkholes up to 100 m deep aligned along multi-km linear valley trends that dissected the sub-Cretaceous paleotopography. These sinkhole trends formed orthogonal patterns inherited from underlying lattice of NW–SE and NE–SW Salt structured lineaments. These cross-cutting sinkhole trends have a smaller 5 km scale reticulate pattern similar to the giant 50 km scale pattern of collapse-subsidence troughs. Other sinkholes developed as lower McMurray strata sagged when underlying Devonian fault blocks and breccia pipes differentially subsided.
Jaak J.k. Daemen - One of the best experts on this subject based on the ideXlab platform.
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feasibility analysis of using abandoned Salt caverns for large scale underground energy storage in china
Applied Energy, 2015Co-Authors: Tongtao Wang, Danan Qu, Baocai Xu, Yinping Li, Haijun Yang, Jianjun Li, Yun Yang, Jaak J.k. DaemenAbstract:Rock Salt in China is primarily bedded Salt, usually composed of many thin Salt layers and interlayers (e.g. anhydrite, mudstone, and glauberite). Thus, the feasibility analysis of abandoned Salt caverns located in Salt Beds to be used as Underground Gas Storage (UGS) facilities is full of challenges. In this paper, we introduce the feasibility analysis of China’s first Salt cavern gas storage facility using an abandoned Salt cavern. The cavern is located in Jintan city, Jiangsu province, China. The mechanical properties and permeability of the bedded Salts are obtained by experiments. Based on the results of the analyses, it appears to be quite feasible to convert the abandoned Salt caverns of Jintan city to UGS facilities. The stability of the cavern is evaluated by the 3D geomechanical numerical simulations, and the operating parameters are proposed accordingly. Results indicate that the maximum volume shrinkage of the cavern is less than 25% and the maximum deformations are less than 2% of the caverns’ maximum diameters after operating for 20years. It is recommended that the weighted average internal gas pressure be maintained as 11MPa to control the extent of the plastic zones to a safe level. Safety factors decrease with operating time, especially those of the interface between rock Salt and mudstone layers decrease significantly. Effective strain is generally greater than 2%, and locally is greater than 3% after operating 20years. The maximum pressure drop rate should be kept to less than 0.55MPa/day. Based on above proposed parameters, China’s first Salt cavern gas storage facilities were completed, and gas was first injected, in 2007. To check the status of the caverns after operating for 6years, the volumes of the caverns were measured in 2013 by Sonar under working conditions. Measurement results show that the cavern shapes did not change much, and that volume shrinkages were less than 2%. Comprehensive results show that the feasibility analysis method proposed in this paper is reliable.
Tongtao Wang - One of the best experts on this subject based on the ideXlab platform.
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feasibility analysis of using abandoned Salt caverns for large scale underground energy storage in china
Applied Energy, 2015Co-Authors: Tongtao Wang, Danan Qu, Baocai Xu, Yinping Li, Haijun Yang, Jianjun Li, Yun Yang, Jaak J.k. DaemenAbstract:Rock Salt in China is primarily bedded Salt, usually composed of many thin Salt layers and interlayers (e.g. anhydrite, mudstone, and glauberite). Thus, the feasibility analysis of abandoned Salt caverns located in Salt Beds to be used as Underground Gas Storage (UGS) facilities is full of challenges. In this paper, we introduce the feasibility analysis of China’s first Salt cavern gas storage facility using an abandoned Salt cavern. The cavern is located in Jintan city, Jiangsu province, China. The mechanical properties and permeability of the bedded Salts are obtained by experiments. Based on the results of the analyses, it appears to be quite feasible to convert the abandoned Salt caverns of Jintan city to UGS facilities. The stability of the cavern is evaluated by the 3D geomechanical numerical simulations, and the operating parameters are proposed accordingly. Results indicate that the maximum volume shrinkage of the cavern is less than 25% and the maximum deformations are less than 2% of the caverns’ maximum diameters after operating for 20years. It is recommended that the weighted average internal gas pressure be maintained as 11MPa to control the extent of the plastic zones to a safe level. Safety factors decrease with operating time, especially those of the interface between rock Salt and mudstone layers decrease significantly. Effective strain is generally greater than 2%, and locally is greater than 3% after operating 20years. The maximum pressure drop rate should be kept to less than 0.55MPa/day. Based on above proposed parameters, China’s first Salt cavern gas storage facilities were completed, and gas was first injected, in 2007. To check the status of the caverns after operating for 6years, the volumes of the caverns were measured in 2013 by Sonar under working conditions. Measurement results show that the cavern shapes did not change much, and that volume shrinkages were less than 2%. Comprehensive results show that the feasibility analysis method proposed in this paper is reliable.
Jeanmarie Rouchy - One of the best experts on this subject based on the ideXlab platform.
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carbonate deposition and diagenesis in evaporitic environments the evaporative and sulphur bearing limestones during the settlement of the messinian salinity crisis in sicily and calabria
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: Antonio Caruso, Catherine Pierre, Mariemadeleine Blancvalleron, Jeanmarie RouchyAbstract:Abstract The depositional and diagenetic processes involved in the formation of carbonates in the evaporitic environment of the Messinian Salinity Crisis are investigated in Southern Italy (Sicily and Calabria). Strong differences are observed between the studied sections that reflect specific depositional and diagenetic evolution in the interconnected sub-basins resulting from the syn-sedimentary tectonic fragmentation of the Central Sicilian and Calabrian domains. These carbonates formed diachronously in restricted perched sub-basins between the Tripoli Formation and the hypersaline settings of the MSC. The Calcare di Base (CdB) that can be interbedded with gypsum layers occurs rhythmically at the transition between the upper part of the Tripoli Formation and the massive gypsum, and at places synchronously with the deposition of the Lower Gypsum unit. It deposited initially as primary peloidal and microbial limestones, but their original structure and mineral composition were modified by the superimposition of early to late diagenetic processes. The first diagenetic step was the development of interstitially grown gypsum and halite crystals from trapped saturated brines that locally led to the formation of Salt Beds. The Sulphur Limestone (SL) resulted from the activity of sulphate reducing bacteria that occurred locally in the deeper parts of the various basins where anoxic bottom waters favoured microbial processes fuelled by biogenic methane and crude oil, and caused the carbonate replacement of gypsum and the formation of native sulphur. The migration of hydrocarbon and H 2 S-rich fluids caused the epigenetic dissemination of sulphur and a late diagenetic carbonate replacement of the gypsum. Later influxes of continental fresh waters were responsible for the dissolution of the halite crystals and their replacement by sparry calcite. The vugs, formed during both the gypsum/calcite conversion and the halite dissolution, either remained empty or were filled with calcite, celestine, fibrous silica, anhydrite, secondary gypsum, and native sulphur. The initial accumulation of fine-grained carbonate and gypsum sediments was strongly destabilised by volumetric changes resulting from mineral replacements and fluidisation processes. Their superimposition explains the vuggy and boxwork-like textures, in situ brecciation and lateral displacement, which are responsible for the chaotic organisation without necessarily involving basin-scale re-sedimentation in the form of debris flows.
Jianjun Li - One of the best experts on this subject based on the ideXlab platform.
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feasibility analysis of using abandoned Salt caverns for large scale underground energy storage in china
Applied Energy, 2015Co-Authors: Tongtao Wang, Danan Qu, Baocai Xu, Yinping Li, Haijun Yang, Jianjun Li, Yun Yang, Jaak J.k. DaemenAbstract:Rock Salt in China is primarily bedded Salt, usually composed of many thin Salt layers and interlayers (e.g. anhydrite, mudstone, and glauberite). Thus, the feasibility analysis of abandoned Salt caverns located in Salt Beds to be used as Underground Gas Storage (UGS) facilities is full of challenges. In this paper, we introduce the feasibility analysis of China’s first Salt cavern gas storage facility using an abandoned Salt cavern. The cavern is located in Jintan city, Jiangsu province, China. The mechanical properties and permeability of the bedded Salts are obtained by experiments. Based on the results of the analyses, it appears to be quite feasible to convert the abandoned Salt caverns of Jintan city to UGS facilities. The stability of the cavern is evaluated by the 3D geomechanical numerical simulations, and the operating parameters are proposed accordingly. Results indicate that the maximum volume shrinkage of the cavern is less than 25% and the maximum deformations are less than 2% of the caverns’ maximum diameters after operating for 20years. It is recommended that the weighted average internal gas pressure be maintained as 11MPa to control the extent of the plastic zones to a safe level. Safety factors decrease with operating time, especially those of the interface between rock Salt and mudstone layers decrease significantly. Effective strain is generally greater than 2%, and locally is greater than 3% after operating 20years. The maximum pressure drop rate should be kept to less than 0.55MPa/day. Based on above proposed parameters, China’s first Salt cavern gas storage facilities were completed, and gas was first injected, in 2007. To check the status of the caverns after operating for 6years, the volumes of the caverns were measured in 2013 by Sonar under working conditions. Measurement results show that the cavern shapes did not change much, and that volume shrinkages were less than 2%. Comprehensive results show that the feasibility analysis method proposed in this paper is reliable.