SUCKER ROD PUMP con't

WAYS TO DECREASE PRODUCTION COSTS

FOR SUCKER-ROD PUMPING 

-roughly two-thirds of the producing oil wells are on this type of lift.

-To maximize profits from these wells in the ever-changing economic situation with rising costs of electric power, installation designs must ensure optimum conditions.

IMPROVING ENERGY EFFICIENCY 

energy losses both downhole and on the surface

      must be minimized.

1- Downhole Energy Losses

2- Surface Losses 

-The sources of down-hole energy losses in the

 

sucker-rod pumping system are :

 

-the pump, the rod string, and the fluid column.

 

The energy required for operating the polished

 

rod at the surface  is thus 

 

-the sum of the useful hydraulic work

 

performed by the pump and the downhole 

 

energy losses.

 

-This power is called the polished rod power or 

 

PRHP.

 

-The energy efficiency of the downhole 

 

components of the sucker-rod pumping system can

 

be known by the relative amount of energy

 

losses in the well.

 

This is called Lifting Efficiency.

 

 

 

Surface Losses 

 

 

mechanical energy losses Starting from the polished rod:

frictional losses arise in the stuffing box, in the pumping unit’s

structural bearings, in the speed reducer

 

(gearbox), and in the

 belt drive.

the electrical power taken by the motor is always greater than

 the mechanical power developed at the motor’s shaft.

The power losses in an electric motor are classified as mechanical

         and electrical.

Mechanical losses occur in the motor’s bearings

 

due to friction.

other losses include windage loss consumed by air surrounding the

 rotating parts.

an overall efficiency ηmot is used to represent

all losses in the

 motor, which, for average electric motors,

 

lies in the range of 85% to 93%.  

 

Optimum Energy Efficiency 

 

 

the energy efficiency is found from: 

 

 

Where : 

 

A more detailed formula

 

 

 


—the possible values of both the surface mechanical efficiency, ηmech, 

 

and the motor efficiency, ηmot, vary in

quite narrow ranges.

—At the same time, their values are not easy to improve upon; that is 

 

why. their effects on the system’s total efficiency are not very significant.

—On the other hand, lifting efficiency can be considered as the 

 

governing factor since it varies in a broad range depending on the pumping 

 

mode selected.

—Thus considerable improvements on the pumping system’s overall 

 

energy efficiency can only be realized by achieving a maximum of lifting 

 

efficiency.

—lifting efficiency mainly depends on the pumping mode selected (i.e.

 

the combination of plunger size, stroke length, pumping speed, and rod 

string design).