Surface sediment gases as indicators of subsurface hydrocarbons – examining the record in laboratory and field studies

摘要: Abstract Near-surface sediment gases are commonly examined in surface geochemistry surveys to evaluate subsurface hydrocarbon generation and entrapment. Sediment reside interstitial spaces, bound mineral or organic surfaces, and/or entrapped carbonate inclusions. Characterizing migrated with minimal compositional isotopic fractionation is challenging, different methods currently use extract analyze gases. These have not been compared controlled laboratory experiments. The key calibration experiments know the charge gas composition thus a basis extraction procedure. For this study, marine sediments were homogenized cleansed of in-situ light hydrocarbons bacteria. Replicate samples prepared charged two compositions concentration levels, along requisite blank control samples. characterized by four laboratories using variety procedures; three headspace (interstitial), adsorbed (acid extraction), one ball mill (occluded). results each method evaluated. demonstrated that selected do provide compound specific isotopes similar However, some indicate systematic sampling procedures associated altered original compositions. Thus it our recommendation conjunction tight sealing storage container water preparation procedure best