Semi-conventional play: Definition, exploration strategy and the example of the Chalk Group in Denmark

Alessandro Sandrin

Research output: Contribution to journalArticleResearchpeer-review


Play analysis has been widely used in hydrocarbon exploration for decades with great success. In recent years, progress has also been made to describe reservoir properties of very low permeability reservoirs. However, compar-atively little research has been conducted into play analysis for such reser-voirs, which may lead to misleading estimates of their hydrocarbon potential. Here, the concept of a semi-conventional play is defined and characterised as having a reservoir of such low permeability that a hydrocarbon column can form down-dip of an effective dry trap. A new exploration approach is proposed for such plays using the Chalk Group Play in the Danish North Sea as an example. It is suggested that together with the usual risk elements, a more detailed analysis of ‘charge’ is necessary, paying particular attention to identifying possible hydrocarbon entry-points, palaeostructures and the maximum distance from these entry-points that the hydrocarbons may have reached since they first entered the reservoir. The application of this novel approach for semi-conventional plays in mature basins could help unlock further resources in proximity of existing fields, and reduce the risk of failure in frontier exploration.

Original languageEnglish
Article number4836
Number of pages6
JournalGeological Survey of Denmark and Greenland Bulletin
Publication statusPublished - 2020


  • Chalk
  • Denmark
  • Low-permeability reservoir
  • Play analysis

Programme Area

  • Programme Area 4: Mineral Resources


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