Ann: Hera Drilling Results Update, page-43

Haven't read all in detail but hope this helps (not sure if you r already doing the right thing), but the term npv multiple doesnt sound right at all.

npv simply discounts all future cash flow to todays value using a rate. How many years of cash flow will depend on you. Some estimate 10 years of cash flow based on todays earnings plus growth factor with a terminal value in yr11 which could be based on an earnings multiple. So there is no need to apply a multiple to a npv anywhere. 

earnings multiple is just an easy/lazy way to work out how much something is worth without worrying about changing future cash flow. E.g. it assumes quite a consistent cash flow (whether its in growth or decline or flat).