Near-Surface Geochemical Anomalies Integrated with Seismic and Well Data over the Contact of the Outer Carpathians and the Carpathian Foredeep (SE Poland)

Table 1

Molecular composition and hydrocarbon ratios of natural gases from autochthonous Miocene strata and Mesozoic basement.

Well	Depth (m)	Age of reservoir	Molecular composition (vol.%)							Hydrocarbon ratios
			CH4	C2H6	C3H8	C4H10+	N2	CO2	He	C1/Σ(C2-C5)	C2/C3
Le-11^1	575–594	Miocene	98.6	0.60	0.09	0.069	0.48	0.14	0.007	129.9	6.7
Sz-18^1	815–841	Miocene	98.2	0.66	0.11	0.099	0.86	0.08	0.010	113.0	6.0
Bc-11^1	839–900	Miocene	99.5	0.12	0.03	0.043	0.10	0.04	0.21	515.5	4.0
Ta-45^1	2243–2257	Miocene	77.0	1.34	0.47	0.580	20.2	0.47	0.049	32.2	2.9
Bc-3^2	1346–1352	Cenomanian	98.6	0.32	0.06	0.110	0.89	0.04	0.01	201.2	5.3
Wi-5^2	1450–1486	Upper Jurassic	63.6	1.88	0.60	0.500	28.6	4.95	0.06	21.3	3.1

¹²After [18]; after [38].