Disequilibrium compaction overpressure in shales of the Bavarian Foreland Molasse Basin: Results and geographical distribution from velocity-based analyses

Journal article
(Original article)


Publication Details

Author(s): Drews M, Bauer W, Caracciolo L, Stollhofen H
Journal: Marine and Petroleum Geology
Publication year: 2018
Volume: 92
Pages range: 37-50
ISSN: 0264-8172
Language: English


Abstract


Shale velocity data from sonic logs and vertical seismic profiles, drilling data and in situpressure measurements from a total of 116 wells have been analyzed to gain an improved understanding of the lateral and vertical distribution and formation of overpressure in the Bavarian Foreland Molasse Basin. Pore pressure from sonic and vertical seismic profile velocities has been analyzed by establishing a normal compaction trend for Cenozoic and Mesozoic shales combined with a classical Eaton approach. The study demonstrates that a single shale normal compaction trend for the Bavarian Foreland Molasse Basin is sufficient to estimate pore pressure and thus overpressure from sonic and vertical seismic profile velocity. Maximum overpressure develops at depths between 1500 and 2500 m and increases with depth at a constant effective stress of 20 MPa. The strong dependency of overpressure on burial depth, constant effective stress and restriction to shale units that are overlain by sequences with very high sedimentation rates indicates that disequilibrium compaction is the main cause for overpressure. Also, variable presence of Cretaceous shales is a key control of overpressure occurrence in Oligocene shales in the Bavarian Foreland Molasse Basin, since Cretaceous shales likely act as a “pressure buffer” to underpressured Mesozoic carbonates. Successful detection and prediction of overpressure from vertical seismic profile data is encouraging for future pre-drill prediction of overpressure from velocity data of seismic surveys in the Bavarian Foreland Molasse Basin, resulting in improved well planning, reliable calculation of project costs, and improved safety during drilling activities in the Bavarian Foreland Molasse Basin. The presented overpressure distributions will be a key input for future geomechanical, basin and reservoir modelling studies in the Bavarian Foreland Molasse Basin.



FAU Authors / FAU Editors

Bauer, Wolfgang Dr.
Lehrstuhl für Geologie (Exogene Dynamik)
Caracciolo, Luca Dr.
Lehrstuhl für Geologie (Exogene Dynamik)
Drews, Michael Dr.
Lehrstuhl für Geologie (Exogene Dynamik)
Stollhofen, Harald Prof. Dr.
Lehrstuhl für Geologie (Exogene Dynamik)


How to cite

APA:
Drews, M., Bauer, W., Caracciolo, L., & Stollhofen, H. (2018). Disequilibrium compaction overpressure in shales of the Bavarian Foreland Molasse Basin: Results and geographical distribution from velocity-based analyses. Marine and Petroleum Geology, 92, 37-50. https://dx.doi.org/10.1016/j.marpetgeo.2018.02.017

MLA:
Drews, Michael, et al. "Disequilibrium compaction overpressure in shales of the Bavarian Foreland Molasse Basin: Results and geographical distribution from velocity-based analyses." Marine and Petroleum Geology 92 (2018): 37-50.

BibTeX: 

Last updated on 2018-10-08 at 22:54