4.5 Article

Two-dimensional numerical modelling of strategies to avoid thermal stress induced flow channeling in fractured geothermal reservoirs

Journal

GEOTHERMICS
Volume 90, Issue -, Pages -

Publisher

PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.geothermics.2020.101978

Keywords

Geothermal; Enhanced geothermal systems; Flow channelling; THM model; MDEM; Thermal breakthrough

Funding

  1. KPN project Controlled Fracturing for Increased Recovery
  2. Research Council of Norway [244506/E30]
  3. Lundin

Ask authors/readers for more resources

The study shows that flow channeling induced by thermal drawdown in fractured geothermal reservoirs is not inevitable, but depends on factors such as fracture aperture and injection rate. Interventions such as variable injection rates and sequential injection can improve the chances for even flow and better production efficiency. Advanced numerical models capable of THM modeling are needed for accurate geothermal production analysis in low permeability fracture networks due to significant effects of stress and pressure changes on flow patterns and production values.
Thermal drawdown induced flow channeling in fractured geothermal reservoirs has been found to be inevitable in previous work. This hypothesis is questioned and found not to be true for all scenarios. We investigate flow in a simple two-fracture network to investigate the basic behavior of thermal drawdown induced flow pattern changes, using a Thermo-Hydro-Mechanical (THM) numerical model. In addition, we propose two operational interventions to mitigate the negative effects of uneven flow on geothermal production. We found that uneven flow is not inevitable, but dependent on several factors, including initial fracture aperture, the actual value of the aperture, and the total injection rate. A small difference in aperture, a higher aperture value and a larger total injection rate are all factors improving the chances for even flow. The operation interventions include variable injection rates, and sequential injection in the fractures before normal production. Both are shown to improve the chances for even flow and better production. Overall, changes in stress and pressure as a result of cooling, are found to have significant effects on flow pattern and production values, underlining the need for advanced numerical models capable of THM modeling for accurate geothermal production analysis in low permeability fracture networks.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.5
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available