I took a look at the drilling model and it looks like 2/3 of the upper zone will be lost as you can see that is where there are only a few drills. You can see that some of the drilling that was done to define the lower zone goes through the upper zone, and this can probably be salvaged. I marked the part that will probably get thrown out as "In Question"

http://www.screencast.com/users/joe128pack/folders/Jing/media/bfdf324c-9803-4710-9ea5-93ce48b60329