OK, let's try this again. I said:

Deviated drilling speeds up the extraction rate and thus pushes the envelope on current production at the expense of longet term yields. The depletion rate may be very sharp after the extraction starts declining. In HO's original example, once the water encroachment reaches the drilling contact points, that's pretty much all she wrote.

Decline refers to production drops. Thus the decline rate is the year-on-year percentage drop in a producing field (basin, country).

Depletion refers to the exhaustion over time of URR which is itself some percentage of OOIP.

In my text, the extraction rate is the daily flow (barrels per day) as a percentage of URR.

So, here's what I should have said.

Deviated drilling increases the extraction rate and thus pushes the envelope on current production at the expense of longer term yields. The decline rate may be very sharp once production has peaked after such drilling was inaugurated. In HO's original example, once the water encroachment reaches the drilling contact points, that's pretty much all she wrote.

That's better. Now all our terms are defined and there is even the possibility that we can all understand what we are talking about.