New ChampionX Cage Design Lowers Pressure Drop to Reduce Rod Lift Wear

A new single-piece cage valve design from pumping equipment company ChampionX has improved the efficiency, reliability and performance of rod lift systems.

The new design optimizes fluid flow dynamics and minimizes energy loss when the reciprocating rod pump’s cages open and close. The HFX cage from ChampionX’s business unit Harbison-Fischer reduces the pressure drop and keeps gas and solids in the fluid as it moves through the pump.

Ramamurthy Narasimhan, NPD engineering manager at ChampionX, told Hart Energy that requests from Permian Basin and Rockies customers for a new cage that performed better than conventional cage designs prompted the company to develop the single-piece HFX valve cage design in 2019.

Conventional rod lift cage design often has unpredictable pressure drop and energy loss, he said, which happens due to restriction and instability inside the cage.

To address that issue, ChampionX turned to a design that would minimize the energy loss during the opening and closing of the standing and traveling valve, he said. 

Four features in the HFX cage combine to provide 25% less pressure drop than conventional cages, he said. Features include a reduced ball restriction length, a concave surface to catch the ball at a fully open position, a divergence and convergence of flowback and fluid dynamics, and an insert cage cone design that fills in the wake region to prevent rebound fluids.

“Lowering pressure drop reduces wear and stress on rod lift systems, which allows pumps to run more efficiently,” Kenny Hudson, technical services manager at ChampionX, told Hart Energy. 

All travel and check valves have a restricted area, he said, and that area is longer in conventional cage valves.

“We were trying to optimize the length of the ball restriction,” he said. 

The development team reduced the travel length of the restriction by 10% up to 100% and found that 40% was the optimum reduction to bring energy loss down, said Narasimhan, who led the HFX development process. 

Using double ball lifting force helps open the standing valve and the traveling valve faster, he continued.

“That means you can fill the pump faster so you can pump” more efficiently and increase production rates, he said. “It helps the customer to minimize rod and pump stress.”

In conventional cages, fluids can create a wake region similar to a vacuum area. 

Typically, when fluid enters near the ball, the fluid accelerates, and once on the far side of the ball, it decelerates, Narasimhan said. The change in velocities allows dissolved gas to escape and sand to drop out of the fluid. 

Instead, the HFX cage’s concave design holds the ball fully open and stable, which allows a minimum disturbance for the fluids passing through the area and keeps dissolved gas and sand in the fluid stream. 

With field trials beginning in 2021, Hudson said ChampionX field trialed the 1.25-inch traveling valves first and the 1.5-inch traveling valves second. The 1.25-inch and 1.5-inch standing valves had field trials earlier this year.

“They are now in use in the Permian Basin, South Texas and the Bakken,” Hudson said.

ChampionX is now offering 2.5-inch and 3.5-inch sizes for both standing and traveling valves, Narasimhan said.