LIGHT HYDROCARBONS IN SOIL GAS ABOVE PROSPECTIVE OIL- AND GAS-BEARING STRUCTURES: POMERANIAN SYNCLINORIUM, NW POLAND

摘要: The occurrence of methane and heavier homologues unsaturated hydrocarbons was recorded in 226 soil gas samples recovered from a study area the Pomeranian Synclinorium, NW Poland. Samples were collected at stations located along three survey lines (I–I', II–II’ III–III') 200 m spacing. Concentrations methane, total alkanes (C2-C4) alkenes reached 13.7 vol. %, 18.4 ppm 0.56 ppm, respectively. Soil than interpreted to be derived subsurface hydrocarbon accumulations. These migrated up into near-surface zone structural discontinuities fractures which observed on seismic profiles. The migration rate accumulations towards surface determined by ethane/ethylene (C2/C2=) ratio. statistical distribution ethane:propane (C2/C3) ratio plots C2/C3+C4 C1/C2+C3 ratios indicated that condensate, or oil with cap probably occur area. Variations normalized values alkane C2-C4 concentrations allowed geochemical anomaly zones identified. evidence for accumulations. Hydrocarbon are most likely beneath central part profile II–II' may also SW NE parts III–III' where both Carboniferous Zechstein Main Dolomite prospective. In these areas, fault-bounded anticlinal highs. Surface anomalies confirm presence non-commercial accumulation discovered D-1 well, possibility another an adjacent tectonic block. analyses combined data provide prospectivity