| Title | A Generic Workflow to Assess (Stimulated) Clastic Aquifer Potential |
|---|---|
| Authors | Maarten PLUYMAEKERS, Hans VELDKAMP, Jan-Diederik VAN WEES |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | resource assessment, clastic aquifers, stimulation, web-based information systems |
| Abstract | Geothermal development in aquifer settings, targeted beforehand by oil and gas exploration, can benefit largely from putting subsurface information and models in a geothermal context. To this end we developed a generic resource and performance assessment methodology to designate prospective high permeable clastic aquifers and to assess the amount of potential geothermal energy. It is capable to build from a wealth of deep subsurface data from oil and gas exploration and production which is publicly and digitally available. The performance assessment results in potential maps giving an overview of the expected doublet power which can be retrieved on an economic basis and a potential indicator, which provides insight in subsurface suitability for specific applications. The workflow has been applied for the Netherlands and results are publically accessible through the web-based portal ThermoGIS (www.thermogis.nl). ThermoGIS complements existing subsurface information systems available in the Netherlands and supports the geothermal community in assessing the feasibility of a geothermal system at any location and provides a non-expert insight in the geothermal energy potential on a national and regional scale. Public access to relevant subsurface data has facilitated spectacular growth of low enthalpy geothermal projects for greenhouse heating and the number of issued licenses promises an even faster growth in the future. In the Netherlands hot water is extracted from permeable clastic aquifers of around 2000 m depth which have been explored for oil and gas production in the past. Recently, we extended the workflow to assess the implications of hydraulic stimulation for low permeability clastic aquifers at deep depth-levels ( more than 2000m) where permeability detoriates as a consequence of mechanical compaction and cementation. For the stimulation and well layout we adopt long horizontal well trajectories up to 2 km length with vertical fracs along the well bore. The implications on subsurface potential are significant as it unlocks considerable clastic aquifer potential. Our calculations indicate that hydraulic stimulation is capable of producing higher flow rates and power than without stimulation with moderate excess in Levelized Costs of Energy (LCOE). In addition it extends the depth and spatial extent the potential. The LCOE for the reservoir stimulation scenario can stay well below 12-13 EUR/GJ, depending on reservoir transmissivities which can be as low as 0.5 Darcymeter. |