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Pure and Applied Geophysics

, Volume 166, Issue 5–7, pp 1089–1106 | Cite as

Pressure-dependent Production Efficiency of an Enhanced Geothermal System (EGS): Stimulation Results and Implications for Hydraulic Fracture Treatments

  • Günter ZimmermannEmail author
  • Torsten Tischner
  • Björn Legarth
  • Ernst Huenges
Article

Summary

A series of stimulation experiments were carried out at the geothermal research well in Groß Schönebeck (EGrSk 3/90) located in the northeastern part of Germany. The intended purpose of these experiments was to develop concepts for a productivity increase of the geothermal well to create an Enhanced Geothermal System (EGS). Two different kinds of stimulation types were performed. Hydraulic gel-proppant stimulations were conducted in sandstone sections with high initial permeability. Then a different fracturing concept was applied injecting high amounts of water. This waterfrac stimulation was realized in the entire open section including sandstones and volcanic rocks. Evidence of the creation and properties of a very long vertical fracture was retrieved from pressure response analyses demonstrating a bilinear flow regime. The production efficiency of the produced artificial fractures shows a strong dependence on reservoir pressure. At increased reservoir pressure the artificial fractures of all stimulated intervals are highly conductive and subsequently become less conductive during pressure decline. Hence the range of a suitable reservoir pressure is constrained by this fracture efficiency and limits the usage of this well as an injection well for geothermal power production.

Keywords

Geothermal gel-proppant-fracs water-fracs reservoir stimulation 

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Copyright information

© Birkhäuser Verlag, Basel 2009

Authors and Affiliations

  • Günter Zimmermann
    • 1
    Email author
  • Torsten Tischner
    • 2
  • Björn Legarth
    • 1
    • 3
  • Ernst Huenges
    • 1
  1. 1.Helmholtz Centre PotsdamGFZ German Research Centre for GeosciencesPotsdamGermany
  2. 2.Bundesanstalt für Geowissenschaften und RohstoffeHannoverGermany
  3. 3.Shell Exploration and ProductionHH AssenThe Netherlands

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