Subsidence rings and fracture pattern around dolines in carbonate platforms â€“ Implications for evolution and petrophysical properties of collapse structures
- Permanent Link:
- Subsidence rings and fracture pattern around dolines in carbonate platforms â€“ Implications for evolution and petrophysical properties of collapse structures
- Series Title:
- Marine and Petroleum Geology
- Menezes, Daniel F.
Bezerra, Francisco H.
Maia, Rubson P.
Cazarin, Caroline L.
- Publication Date:
- Subjects / Keywords:
- Dolines ( local )
Karst ( local )
Aquifer ( local )
Oil Reservoirs ( local )
Permeability ( local )
Collapse Risk ( local )
- serial ( sobekcm )
- This work focuses on the study of collapse dolines, which are the most expressive collapse structures in carbonate rocks, and their relations with preexisting and syn-collapse fractures. The study area has two fracture sets that were formed before folding, early N-S/E-W- and late NE-SW/NW-SE-striking sets, which concentrate most of the dissolution in the region and allow the formation of the dolines. We define subsidence rings as the circular and ellipsoidal concentric zones around collapse structures, which are subjected to subsidence due to major collapses and represent locations where new fractures are formed. In these subsidence rings, the downfaulted topography plunges towards the doline center and reaches more than 10â€¯m in relation to unaffected areas away from dolines. The topographic data indicate that the mean radius of the combined rings is ~twice the radius of the collapse, which corresponds to the closed depression due to failure and downfall of blocks. The subsidence process enlarges, links preexisting fractures, and forms a new set of semicircular concentric opening mode fractures, here named collapse fractures. Increases in the apertures and densities of these fractures occur towards the dolines, which increases fracture porosity around collapse structures. Fractures are reactivated as normal faults close to the main collapse at the doline edge. This increase in fracture intensity could represent an indicator of permo-porous quality improvement in these areas. Further, this fracturing increases structural instability, raising the risk of accidents in areas built on soluble carbonate rocks, since the affected area may be much larger than previously predicted. Subsidence rings around collapse dolines could merge with other rings from neighboring collapse structures and potentially increase porosity and permeability, as well as linking areas in carbonate reservoirs.
- Original Version:
- Marine and Petroleum Geology, Vol. 113 (2020-03-01).
- Source Institution:
- University of South Florida Library
- Holding Location:
- University of South Florida
- Rights Management:
- This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.
No images or PDF downloads are available for this resource.
Cras ut cursus ante, a fringilla nunc. Mauris lorem nunc, cursus sit amet enim ac, vehicula vestibulum mi. Mauris viverra nisl vel enim faucibus porta. Praesent sit amet ornare diam, non finibus nulla.
Cras efficitur magna et sapien varius, luctus ullamcorper dolor convallis. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Fusce sit amet justo ut erat laoreet congue sed a ante.
Phasellus ornare in augue eu imperdiet. Donec malesuada sapien ante, at vehicula orci tempor molestie. Proin vitae urna elit. Pellentesque vitae nisi et diam euismod malesuada aliquet non erat.
Nunc fringilla dolor ut dictum placerat. Proin ac neque rutrum, consectetur ligula id, laoreet ligula. Nulla lorem massa, consectetur vitae consequat in, lobortis at dolor. Nunc sed leo odio.