Please use this identifier to cite or link to this item:
http://hdl.handle.net/2122/2029
Authors: | Mariucci, M. T.* Amato, A.* Gambini, R.* Giorgioni, M.* Montone, P.* |
Title: | Along-depth stress rotations and active faults: an example in a 5-km deep well of Southern Italy | Journal: | Tectonics | Series/Report no.: | 4/21 | Publisher: | American Geophysical Union | Issue Date: | 11-Jul-2002 | DOI: | 10.1029/2001TC001338 | URL: | http://www.agu.org/pubs/crossref/2002/2001TC001338.shtml | Keywords: | borehole breakout structural analysis in deep wells active faults Southern Apennines |
Subject Classification: | 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress | Abstract: | We have analyzed a 1500 m section at 3.9 to 5.4 km depth in a well of the southern Apennines, in order to better characterize the local active stress field and its correlation with tectonic structures. In this paper we present and discuss the results obtained from the comparison between breakouts and structural analysis from dipmeter data. We have found that the mean breakout direction is in agreement with the regional stress field that in this area is characterized by normal faulting (σ1 = σv) with NE-SW trending extension (horizontal σ3). Since the regional stress field is relatively well known in this region, we could detect and study some anomalous horizontal stress directions along the well, which we interpret as due to faults crosscutting the borehole. A detailed comparison between the breakout-inferred stress variations along depth and the faults identified by the dipmeter analysis reveals that some of these faults are associated with stress rotations, whereas others do not show any variation. The former can be interpreted either as “open” fractures or as faults that slipped recently with a near-complete stress drop, and the latter can be interpreted as “sealed” faults. In particular, we found that the main thrust faults of the area, mainly active in Pliocene times, appear to be sealed, whereas ∼E-W trending high-angle (normal?) faults determine strong stress rotations, suggesting that they are the main active structures of the region. This suggests that the study area is located in a transfer zone between the two main “Apenninic” (NW-SE trending) fault systems which ruptured in the last 150 years. This study has shown that a detailed analysis of the structural and geometrical characteristics of deep wells can be used for the reconnaissance of active structures. This approach can contribute to seismic hazard studies and, if carried out in an oil-bearing section, can help to maximize the hydrocarbon production. |
Appears in Collections: | Article published / in press |
Files in This Item:
File | Description | Size | Format | Existing users please Login |
---|---|---|---|---|
Mar-etal02.pdf | 1.45 MB | Adobe PDF |
WEB OF SCIENCETM
Citations
50
14
checked on Feb 10, 2021
Page view(s)
171
checked on Apr 17, 2024
Download(s)
23
checked on Apr 17, 2024