Strain Evolution in the Strata Overlying the Kraka Salt Pillow, Inferred from Stratigraphic Reconstruction

Kenni Dinesen Petersen, Michael John Welch, Ole Rønø Clausen

Research output: Chapter in Book/Report/Conference proceedingBook chapterResearchpeer-review


In this paper, we employ a novel but simple approach to recover the strain evolution of the chalk overlying the Kraka structure. This approach allows for three-dimensional reconstruction of the flexural strain evolution related to growth of the salt pillow without making strong assumptions about mechanical properties. The strain is estimated from differential subsidence that is in calculated by backstripping, and we distinguish compactional strain (mostly vertical) from flexural strain (mostly horizontal). This reveals an overall radial pattern of extensional strain around the Kraka salt pillow. The method also resolves narrow high-strain zones within the chalk, which are either linear or form concentric patterns around the Kraka salt pillow, typically c.100 m wide and c.300 m apart. While some of the fainter concentric structures may be artefacts, the linear structures and more prominent concentric structures are thought to reflect fracture corridors or small faults, and correspond to features observed on colour-processed and ant-tracked seismic data. When this horizontal strain data is used model the distribution and orientation of natural fractures, the results are remarkably consistent with the fractures observed on borehole images. The 3D strain evolution that can be inferred from differential subsidence analysis may therefore provide a simple proxy that can be used to identify zones of high fracture density.
Original languageEnglish
Title of host publicationGeomechanical Controls on Fracture Development in Chalk and Marl in the Danish North Sea : Understanding and Predicting Fracture Systems
Publication date2023
ISBN (Electronic)978-3-031-35327-7
Publication statusPublished - 2023
SeriesPetroleum Engineering


  • Chalk
  • Salt
  • Backstripping
  • Structural restoration
  • Strain


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