Sucker-Rod (Beam) Pump Downhole

Overview

A sucker-rod pump is the downhole half of the most common artificial-lift system in oil production: the nodding beam pump, or pumpjack. The surface unit converts a motor's rotation into the up-and-down motion of a polished rod, which drives a long string of sucker rods down the well to this pump. The pump itself is deceptively simple, a precision barrel and two ball check valves, but that simple mechanism lifts crude thousands of feet on every stroke, day after day, for the life of the well. The whole assembly is run as an insert pump that seats inside the tubing.

Lift comes entirely from the two check valves trading roles as the plunger reciprocates, so reliability hinges on the fit of the plunger in the barrel and the seal of the balls on their seats.

How it works

The plunger reciprocates inside the Working Barrel, a honed steel cylinder whose liner is the precision seal surface. On the upstroke the Plunger & Traveling Valve lifts the fluid column above it: its traveling valve closes, carrying that column up the tubing, while the Standing Valve at the barrel base opens and draws a fresh charge of well fluid in below the plunger.

On the downstroke the action reverses. The standing valve closes to trap the fluid that just entered, and the traveling valve opens so the plunger slips down through the column, ready to lift it on the next upstroke. Both valves are hardened ball-and-seat checks, because they cycle millions of times against sandy crude.

The pump is locked into the tubing by the Hold-Down Assembly, whose seating cups anchor and seal it in the seating nipple, and it connects up to the rod string through the Rod Connection. Free gas is the enemy of a rod pump, it can compress instead of lift and cause gas lock, so the Gas Anchor below the intake separates gas out before fluid reaches the standing valve.