Assessing Regional Validity of NMR Core Calibration using SCAN Amstelland-01 & De Bilt-01 Geothermal Exploration Wells

Geothermal energy is a growing sustainable heating solution in the Netherlands, but expansion is hindered by limited subsurface data in roughly half the country. The SCAN program, led by EBN and TNO, addresses this by acquiring seismic data and drilling geothermal exploration wells in regions with limited data.

A key focus is evaluating reservoir permeability, essential for achieving the high flow rates needed for viable geothermal projects. The data acquisition program includes Nuclear Magnetic Resonance (NMR) logs, which provide porosity and permeability estimates. However, quantitative interpretation requires calibration to core data. This study investigates whether NMR core calibration of the Rotliegend Group from one well (Amstelland-01) can be applied to another well roughly 30km away (De Bilt-01).

In Amstelland-01, core calibration significantly improves permeability estimates, doubling the arithmetic average from 38 mD to 82 mD. By applying this calibration to De Bilt-01 and validating against its core data we test the regional applicability and validity of Amstelland-01’s NMR calibration to other wells in the area. Results provide crucial insights into the behavior and confidence of NMR logs in the regional Rotliegend Group and have implications on data acquisition strategies for new wells.