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New Insights on Active Stress Field in Italy and its Implications with Tectonics
Type
Poster session
Language
English
Status
Unpublished
Conference Name
EGU General Assembly
Issued date
April 2, 2006
Conference Location
Vienna, Austria
Abstract
Active stress field in Italy is quite well-known but in detail it lacks a univocal interpretation in some areas of both orientations and magnitudes. We analyzed new deep boreholes and compared the results of stress analysis with the active faults crossed
by or near the wells to estimate the influence of different structures on well data. In
some cases, gently or abrupt changes in the stress directions have been observed along
the well in the vicinity of a tectonic structure. In areas where tectonic structures are unknown, these stress changes observed in other boreholes can support other kind of
evidence in identifying and characterizing active faults.
We also present results on stress magnitudes inferred from leak-off tests in oil wells
(more than two hundreds new data, kindly provided by ENI S.p.A). We calculated
the values of the principal stress axis at depths ranging from about 200m to 5000m
and analysed them considering the leak-off data uncertainties. Then we compared the
results to the horizontal stress orientations from borehole breakout analysis and from
other geophysical and geological stress indicators and interpreted them within the
different tectonic framework.
Finally, we analyzed the pictures of stress regime at different depths speculating about
the reasons of regime changes that are observed in some areas. The active stress field depicted by the new analysis shows, at regional scale, a general agreement with strain data (geodesy and seismic anisotropy) although some interesting characteristics arise at local scale.
by or near the wells to estimate the influence of different structures on well data. In
some cases, gently or abrupt changes in the stress directions have been observed along
the well in the vicinity of a tectonic structure. In areas where tectonic structures are unknown, these stress changes observed in other boreholes can support other kind of
evidence in identifying and characterizing active faults.
We also present results on stress magnitudes inferred from leak-off tests in oil wells
(more than two hundreds new data, kindly provided by ENI S.p.A). We calculated
the values of the principal stress axis at depths ranging from about 200m to 5000m
and analysed them considering the leak-off data uncertainties. Then we compared the
results to the horizontal stress orientations from borehole breakout analysis and from
other geophysical and geological stress indicators and interpreted them within the
different tectonic framework.
Finally, we analyzed the pictures of stress regime at different depths speculating about
the reasons of regime changes that are observed in some areas. The active stress field depicted by the new analysis shows, at regional scale, a general agreement with strain data (geodesy and seismic anisotropy) although some interesting characteristics arise at local scale.
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