Ann: Operations Update, page-41

The other positive from this update is that the proppant remains in the reservoir. Only Fracc Juice and some groundwater has flowed back. So that is very good news in the fact that the complex fracture zones created by the stimulation have retained the proppant.

The other thing to take away is the fact the HRZ contains non swelling clays, which helps with keeping the complex fracture pathways open and minimises proppant embedment. This would seem to be backed up by some groundwater being recovered, as swelling clays would tend to retain any associated groundwater.