Need some clarification about skin factor

[petspec19]

Hello,

I need some clarification about skin factor.

As it is know, positive skin factor creates damage zone around the well-bore, and bottom-hole pressure drop is different from predicted one by Darcy's law i.e. is low. It seems that we have larger drawdown, and more production. Does this make sense? Isn't it the aim of the production engineers to get lower drawdown, to have more underbalance for fluid flow?

However, the productivity index, PI, will be low for lower bottom-hole pressure. Thus , lower quantity of oil will be produced per 1 psi drawdown.

Can anyone please help to establish connection between low PI due to positive skin factor and increased drawdown because of positive skin-factor? I got confused.

Thanks.

 

[sd55]

petspec19,

A positive skin indicates damage, this causes a greater drawdown per unit of production therefore a lower PI. Your statements show proper understanding of rate vs drawdown. After stimulation to reduce skin factor to zero or even negative, the drawdown per unit volume is reduced, therefore a higher PI.

Hope this doesn't appear to be circle logic.

sd55