Deliverability model to simulate landfill gas collection systems

Hello

I want to model the suction in landfill gas collection systems using Deliverability model. In landfills, we set a suction pressure and it collects the gas. I assume that this is what Deliverability models does. If so, how should I specify the parameters specially productivity index? Please look at the attached file.

The bottomhole pressure should be assigned somehow to meet the suction in the wells? Like what I wrote in the attached file?

Did I understand the PI parameters correctly? 

How to determine the skin factor?

Thanks