Excessive submergence tends to balance out, as it just adds more suction head for a net zero effect.
Setting at a depth deeper than expected would increase pressure, but that would be evident from first start, as would undersized discharge. As such, the discharge pressure would always have been constant (high) from initial startup, you would not have noticed any rising pressure from either of those causes and you wouldn't be asking why it is increasing now.
Excessive drawdown might increase discharge pressure, if fluid above the pump elevation was decreasing, but that probably would not be a steady state condition and keep on getting worse until it reached a new equilibrium point, or ran dry.
More oil flow into the well bore (a lower GOR) might cause an increase in pressure, if gas and lighter condensate flows showed a corresponding reduction. The discharge column would thus be more dense, requiring more pressure for the same net flow, similar to an ingress of water does (lower GWR), but in that case more oil is a nicer problem to have.
Of course effective viscosity might also be increasing with either more oil, or water in the stream, or wax and dirt caught in the tubing, all adding to the flow friction and increase of discharge pressures.
And last, but not least, somebody might have been messing with surface choak valve settings, or other valves and equipment in the surface piping.
But as I said above, given nobody was tinkering around with the equipment, and the general tendency for oil to deplete before water does, the typical cause is simply more water in the well production stream as the well ages. You can check that by comparing the pressure history against gas, oil and water ratio production records.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
Right. That's normally true for typical pumped systems, as the typical flow stream isn't changing properties on a monthly basis. Nothing stays the same for long on (gas/oil/water) well pumps.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
