And the importance of PREN
Waterflood injection wells are critical in maintaining reservoir pressure and optimizing oil recovery. This is especially important in deepwater environments, where the design of wells and facilities must minimize the risk of corrosion-related failures. A failure in an injection well can significantly impact production rates and increase Lease Operating Expenses (LOE).
One essential consideration in tubular design for waterflood injection is the Pitting Resistance Equivalent Number (PREN). PREN is a measurement used to compare the resistance of various alloys to localized corrosion, based on their chemical composition. The formula specified by NACE MR0175 for calculating PREN is as follows:
PREN = CR% + 3.3 x (Mo% + 0.5 + W%) + 16 x N%
For saltwater injection applications, it is recommended that materials have a PREN greater than 40. This ensures greater corrosion resistance, especially when facing challenges like oxygen contamination in the injected water.
One of the most commonly used materials for these applications is Super 25 Chrome (Super 25 Cr). Thanks to its PREN value of 40+, Super 25 Cr offers a high level of resistance to pitting and crevice corrosion, making it an ideal choice for seawater injection wells. Duplex and super-duplex stainless steels are also frequently utilized due to their superior mechanical properties and excellent corrosion resistance.
However, global supply chain challenges have led to extended lead times for materials like Super 25 Cr. Recognizing this, PipeSearch maintains access to commonly needed long-lead delivery items, allowing operators to source essential materials on short notice.
With the rising demand for highly resistant alloys like Super 25 Cr, duplex, and super-duplex stainless steels, understanding and prioritizing PREN is crucial for ensuring the reliability and longevity of waterflood injection systems in offshore environments.