GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 3.1 543 PetroMod 1D software by Schlumberger. In order to obtain quantitative information about risks related to hydrocarbons maturity and quantity in the projected borehole sites, we opted for a 1D modeling via PetroMod 1D on both study cases. This software does not need geological framework as input (of course being it a 1D modeling) but just to define stratigraphic chart, PSE and boundary conditions to set up the initial model (Fig. 2). To build the initial model we set up the stratigraphic charts’ parameters. Both cases are similar because they belong to the same basin with the same uncertainties due to few direct information, having just one borehole for calibration. In order to check the consistency of our initial model, we compared some calculated (not pre-assigned) data with information by Samperi et al. (2019): the good fitting for some of them (e.g. porosity, thermal conductivity, Poisson ratio) validated our approach. Therefore, we decided to rely on PetroMod data calculation/simulation. We used hydrogen indexes obtained by a first simulation to improve the initial model. Successively, we ran a second simulation. Results. The flow rates resulting from the two modelling exercises are largely dependent on lithology definition: rough lithology and petrophysical parameters suggest that there are always and only hydrocarbons accumulation beneath shale layers. These results display 3D hypothetical movement of the fluids in depth, well-fitting the geological frameworks. It could be useful only as a qualitative information while, many assumptions should be necessary used for quantitative information. In both study areas the results highlight little quantities of hydrocarbons (Fig. 3a). The resulting little quantities of hydrocarbons suggests that they the drilling risk is expected to be low because: - Both study areas could have deep reservoir well confined (Fig.3a). Just in the IAP there is a small amount of gas in the Plio-Quaternary cover, but not significant to cause drilling- problems. Furthermore, absence of gas during perforation of the DSDP Site 374 represents favorable conditions. - Vitrinite reflectance is very low in both areas so, the hydrocarbons maturity has not reached in the upper most part of the sections (Fig. 3c). - Both cases highlight overpressure below the Messinian salt layer. An abrupt change in pressure has seen in the IAP, reaching 14.67 MPa just below the MU. Instead, at the base of the Malta Escarpment, the modeling denotes a gradual overpressure that starts at the lower part of the MU, reaching about 11 MPa at its base (Fig.3b). Anyway, both the drilling will not reach the lower MU. - Salt porosity is close to 0 so, it is an excellent seal for fluid (Fig. 3). Conclusions. If the deepest target of these boreholes is in the upper MU, the drilling operation seems to be safe. Until the depth of 150 m below the UU, no overpressures are computed, and hydrocarbons spill risk is not present. The only risk related to the conditions of the Plio-Quaternary succession, in the IAP, should be seepages but, they are generally well recognized and appear to be very small on the available seismic section. In conclusion, we think that an accurate siting of borehole can be selected without risk. References Camerlenghi A., Del Ben A., Hübscher C., Forlin E., Geletti R., Brancatelli G., Micallef A., Saule M. and Facchin L.; 2019: Seismic markers of the Messinian salinity crisis in the deep Ionian Basin. Basin Research. Dannowski A., Kopp H., Klingelhoefer F., Klaeschen D., Gutscher M. A. Krabbenhoeft A., Dellong D., Rovere M., Graindorge D., Papenberg C. and Klaucke, I.; 2019: Ionian Abyssal Plain: a window into the Tethys oceanic lithosphere. Solid Earth, 10(2), 447-462. Erickson, A. J. and Von Herzen R. P.; 1978: Down-hole temperature measurements, Deep Sea Drilling Project, Leg 42A. Initial Reports of the Deep Sea Drilling Project, 42, Part I, 857-871. Esestime P., Hewitt A., and Hodgson N.; 2016 : Zohr–A newborn carbonate play in the Levantine Basin, East- Mediterranean. First Break, 34(2), 87-93. Finetti I. R., and Del Ben A.; 2005: Crustal tectono-stratigraphy of the Ionian Sea from new integrated CROP seismic data. Deep Seismic Exploration of the Central Mediterranean and Italy, CROP PROJECT , 19, 447-470.