5 research outputs found
Seismic Delineation Of A Geothermal Reservoir
Surface seismic reflection surveys and VSP's have been extensively carried out in the
Monteverdi area, within the Larderello region. Calibration of these seismic observations
with data from numerous deep wells allowed the interpretation of the 2-D traverses so
that a good geologic-structural reconstruction for the whole area was achieved. Many
important reflectors were detected inside the Metamorphic basement by VSP's acquired
in several wells in the area. These reflections were attributed to changes in petrophysical characteristics of the medium, particularly changes in fracture density, rather than to contrasts in lithology.
Since at this time the main goal of the exploration in the Larderello region is the
location of producing layers inside the basement, a major effort was applied to acquiring
and modeling numerous VSP's in existing wells. In particular, a multioffset VSP was
carried out in the COLLA 2 well with the specific goal of detecting fractured horizons
within the reservoir of the Monte:verdi area. Because of the three-dimensionality of the
seismic wave propagation in such a complicated geological structure, the standard onedimensional VSP modeling is not reliable. Therefore, 2-D and 3-D methods of modeling
were applied.
The modeling of the VSP data predicts important reflections at the depths corresponding
to the main fractured zones intersected by drilling. These fractured zones
should show subhorizontal distribution and thickness of tens of meters