High-Temperature Centralizers in PC-Pumped Down-Hole Wells

A new, high-temperature rod guide has been developed as a centralizer for a sucker rod string in progressive cavity (PC) pumped down-hole production wells.

A PC pump is a positive displacement pump that was developed in 1930 by René Moineau. The pump is comprised of two main parts, a rotor and a stator. As the rotor rotates inside the stator, a series of cavities move fluids through the pump in the desired direction, which is determined by the direction of rotation. Today, the PC pump is commonly used for oil and gas production.

In this application, the pump is connected to a string of production tubing that is lowered into a wellbore and set at a desired location. The pump’s rotor is attached to a string of sucker rods that rotates from the surface by a drive head. Every revolution of the rotor moves a cavity of fluid into the production tubing until the fluid is produced at the surface.

Steam Assisted Gravity Drain

In a steam assisted gravity drain (SAGD) well, two horizontal well bores are drilled closely together, one directly above the other, into the same formation. Super heated steam is pumped through the upper wellbore, injecting the steam into the formation. The steam is used to heat the heavy crude oil, which lowers its viscosity. The oil flows to the bottom of the formation. The crude can then be extracted through the lower wellbore with a down-hole PC pump. Due to the high temperature of the steam and down-hole fluids, a progressing cavity metal-to-metal pump is commonly used for this application.

Rod Guides/Centralizers

Early in 2008, a major operator needed a sucker rod guide/centralizer that would be capable of withstanding temperatures exceeding 450 degrees Fahrenheit. These centralizers were needed in conjunction with the metal-to-metal pump used in a SAGD well to centralize the sucker rod string within the production tubing, reduce system vibrations and minimize production tubing wear throughout the system.

To develop rod guides, one company has an Oklahoma-based laboratory capable of mimicking down-hole conditions. This lab allows the company to test and compare different polymers and polymer additives against the harsh conditions found in down-hole environments.

The lab is also capable of testing the different sucker rod guide designs by comparing characteristics, such as flow properties and hydraulic drag. This testing process helps ensure that only the most durable materials and best designs are used in its down-hole products.