Spontaneous fluid emissions in the Northern Apennines: geochemistry, structures and implications for the petroleum system

Abstract

Natural seeps in the Northern Apennines document a variability of fluids and reservoirs in terms of origin, age and evolution. Their spatial distribution appears controlled by the presence or absence of the tectonic overburden provided by the Ligurian nappe. The general trend of deepening of the Mesozoic basement toward the internal part of the thrust belt is reflected by the nature of the seeps, characterized by thermogenic methane and oil at the foothills, whereas the innermost seeps show occurrence of dry thermogenic gas suggesting overcooking of the residual oil. At the front of the Ligurian nappe, or in places never covered by it, the seepages are associated with biogenic methane related to bacterial degradation of the organic-rich intervals occurring in the Pliocene and Pleistocene marine succession. The coupling of geochemical and structural analysis allows reconstructing the tectono-thermal evolution of the belt, improving our knowledge on the processes acting within the reservoir and controlling important parameters of the petroleum system, such as the reservoir porosity and its modifications, and the migration patterns.

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

“…1a) (Martinelli et al, 1989) as well as in other springs flowing out of TU flysch formations (i.e., Well SalsMag1 in Boschetti et al, 2010) or from LU-TU formations in the middle-frontal part of the Apennine chain (i.e., Regnano site point 3c in Fig. 1a; Capozzi and Picotti, 2010).…”

“…1a, b: Minissale et al, 2000;Capozzi and Picotti, 2002;Heinicke et al, 2010). In several cases Sr 2+ and B tot contents are strongly related; B tot , which can be mobilised from the organic matter buried during sedimentary processes, is normally associated with oilfield water if its value is in the order of 100 mg l −1 (White, 1965) while Sr 2+ ranges from 100 to 500 mg l −1 (Conti et al, 2000;Capozzi and Picotti, 2010).…”

“…1a; Buttinelli et al, 2011) flowing out from the same unit show similar chemical characteristics (salinity up to 11 g l −1 ). Their water isotopes are positive (δ 18 O around +5 ‰/+6 ‰) while pCO 2 stays around 1 kPa (Conti et al, 2000;Capozzi and Picotti, 2010). EL flysch acts as an aquifer and stores Ca-HCO 3 water (point no.…”

“…Moreover, there are no local mineralogical phases that could provide Cl − . (Conti et al, 2000), 3b and 3c (Capozzi and Picotti, 2010) -mud volcanoes; 5 -common shallow groundwater; 6 (Cervi, 2003), 7 (Venturelli et al, 2003) -springs; 8 -hydrocarbon seep. Black line: evaporation line from seawater.…”

Fold–thrust belts: overlooked provinces or justifiably avoided?

“…Roure et al (2010) observe that apatite fission track data and analyses of hydrocarbon-bearing fluid inclusions can reduce the range of uncertainty and allow better prediction of the timing of hydrocarbon generation and the pressure/temperature conditions in the reservoir during cementation and hydrocarbon trapping. Capozzi & Picotti (2010) show how the analysis G. P. GOFFEY ET AL.…”