Geophysical characterization and petrographic analysis of cap and reservoir rocks within the Lund Sandstone in Kyrkheddinge

Abstract: Geophysical investigations in the Kyrkheddinge area including seismic surveys and wire-line logging were carried out by Swedegas AB between 1978-1985. This study has used the data to make a geophysical and petrographic characterization of cap-rock and reservoir sections within the Lund Sandstone in Kyrkheddinge to evaluate the conditions for storing gas in the bedrock. The Lund Sandstone comprises deposits of Campanian and Santonian age. Four lithologies have been identified; quartzose sandstone, calcareous sandstone, arenaceous limestone, and argillaceous limestone. Log correlation between four wells shows a dome-shaped trap structure beneath the surface at approximately 600 m depth and a lateral continuity of several cap-rock and reservoir units. Petrophysical properties show heterogeneous reservoir sandstone units with excellent porosity and permeability values as well as impermeable heterogeneous cap-rock units with varying clay content. The Lund Sandstone displays in general suitable properties for storing gas. However, seismic data revealed the existence of a possible fault that may have affected the closed structure of the B reservoir, which led to abandoning the project beside strategic decision on optimal placing and storage type. Further studies on how the fault affects the storage possibilities is recommended. Moreover, investigations have identified potential sand intervals with overlying cap-rocks at greater depths than the sand B reservoir which could be studied in more detail. There is a great potential to use the vast amount of data and knowledge from the site investigations at Kyrkheddinge for cap-rock and reservoir modeling, and research regarding storage of natural gas and CO2.