Deep-seated hydrocarbons in the seep “Brecciated Limestones” of the Maiella area (Adriatic foreland basin): Evaporitic sealing and oil re-mobilization effects linked to the drawdown of the Messinian Salinity Crisis

Subsurface seepage dynamics and flow types in a Messinian paleoseep system (Maiella Mts., Central Italy)

“…2a). This confirms that fluids were able to flow across and out of the MES (Iadanza et al, 2015;Bertoni and Cartwright, 2015), as already suggested in previous works based only on seismic interpretations (CIESM, 2008;Lazar et al, 2012;Bertoni et al, 2013). The feeder channels crop out as discrete funnel-shaped fluid flow features filled with flow-mobilized pelites, crusts and nodules, similar to the fluid conduits that typify areas of focused fluid flow (Moss and Cartwright, 2010;Andresen, 2012).…”

“…Brittle fractures acting as fluid conduits are interpreted to testify to a continuous flux of supersaturated fluids because, once created, the pathways for fluid escape generated through hydraulic fracturing tend to continue acting as conduits (Cosgrove, 2001;Mazzini et al, 2003;Clari et al, 2009). This is in good agreement with the evidence that the Limestone Buildups were also impregnated by crude oil during the later stage of hydrocarbon migration, which was dominated by slow oil seepage (Iadanza et al, , 2015.…”

“…Hydrocarbon escape was conceivably favored by a sudden and vigorous release of overpressured fluids from below, which was in turn triggered by the high depressurization of subsurface sediments and fluids during the huge Messinian drawdown . In the later phase, slow oil seepage took place, as recorded by tar impregnation of the carbonates (Iadanza et al, 2015).…”

“…According to Andresen (2012), the structure generated in a seepage setting depends on four factors: the structural setting, the fluid source, In case of the "Brecciated Limestones" of the Messinian paleoseep area, the distinctive structures revealed by the three lithofacies (Limestone Buildups, Patchy Limestones, Flow-mobilized Sediments) shared the same tectonic setting, the same source of hydrocarboncharged fluids, originally derived from a Triassic/Liassic oil trap (Iadanza et al, 2015), and flowed through the same host rock lithologies Fig. 8.…”

The Messinian salinity crisis: open problems and possible implications for Mediterranean petroleum systems

“…These changes and their isostatic effects would cause overpressure and catastrophic fluid expulsions, even through the thick Messinian evaporitic unit that is usually considered an ideal seal (Bertoni & Cartwright 2015). Another aspect would be the degradation and/or remigration of pre-existing hydrocarbons (AlBelushi et al 2013;Iadanza et al 2015), with important implications for assessing the overall quality of the Mediterranean petroleum systems. In our model, the magnitude of these processes would be considerably lower, translating to a significantly lower exploration risk for pre-Messinian targets (cf.…”