Deep hydraulic fracturing stress measurements in the KTB (Germany) and Cajon Pass (USA) Scientific Drilling Projects: A summary

The determination of in situ stresses along deep vertical profiles was declared a key issue for two scientific deep drilling projects:

• the German Continental Deep Drilling Project (KTB) situated in northeast Bavaria in an area of complex variscian thrust tectonics and

• the CAJON PASS Project, located only about 4 km from the San Andreas Fault Zone In southern California.

In the KTB project 7 successful hydrofrac stress measurements could be completed in a 4 km deep pilot hole between 0.8 to 3.0 km. At the Cajon Pass site a series of 23 hydrofrac stress measurements was performed in 2 wells between 0.9 to 3.5 km.