Gas Chimney Record in Seismic and Surface Geochemical Data - Case Study From the Carpathian Foredeep (SE Poland)

Marzec, Paweł; Sechman, Henryk; Pietsch, Kaja; Porębski, Szczepan J.; Guzy, Piotr; Izydor, G.

doi:10.3997/2214-4609.20140907

Cited by 1 publication

(1 citation statement)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During geophysical exploration, columnar anomalies of deteriorated seismic signal have often been recorded on the seismic images of the Miocene succession but are generally regarded as artefacts. However, one anomaly has been recently interpreted as a gas chimney (Marzec et al ., ). The chimney may reflect the focused degassing of a Miocene reservoir through a leaking cap seal.…”

Section: Introductionmentioning

confidence: 97%

Interpretation of a gas chimney in the Polish Carpathian Foredeep based on integrated seismic and geochemical data

et al. 2016

View full text Add to dashboard Cite

Gas chimneys are common in offshore petroliferous basins, but little known on land where seismic columnar anomalies are often attributed as poor data quality or processing artefacts. This study utilizes high-quality 3D seismic data to document a seismic columnar anomaly penetrating through the Miocene heterolithic submarine fan-deltaic infill of the Carpathian Foredeep. The interpreted gas chimney exhibits vertically clustered velocity push-down features throughout the attenuated amplitude column accompanied by gas shows in well tests, has its root in gas-bearing Palaeozoic interval and culminates in an anomalous geochemical gas record at soil level. The chimney system, ca 2 km in height and 500-m wide, begins above the flank of a rotational bedrock fault-block and extends vertically along a fault-controlled conduit. At shallower levels, it passes upwards into amplitude wipeout zones that spread laterally around and partly across thin, gas-charged reservoirs showing bright spots associated with an AVO response. At shallow levels, gas pathways through muddy slope and deltaic clinoforms are not imaged in low-fold regions of the seismic volume. The surface geochemical anomalies, in contrast to the microbial methane signature of the Miocene succession, show significant enrichment in higher alkanes and alkenes with C 2 H 6 /C 3 H 8 ratios indicative of a deep-sourced, thermogenic gas or gas condensate. These anomalies form a semi-enclosed halo around the chimney. Despite the juxtaposition of biogenic and thermogenic methane, the chimney structure imaged on seismic data supports a causal link of gases derived from Palaeozoic source rocks ascending to the surface.

show abstract

Section: Introductionmentioning

confidence: 97%