Crude oil from shale producing regions, also known as tight oils, are opportunity crudes for refineries. These differ from the traditional sources of crude oil from large reservoirs in their widely varying properties. These properties include specific gravity, sulfur content, total acid number (TAN), and more.
In an AIChE’s CEP magazine article, Implement an Effective Corrosion Mitigation Program, Emerson’s Tim Olsen describes how these opportunity crudes increase the opportunity for piping and equipment corrosion and how refiners can address this challenge.
However, refinery configurations are typically fixed — they are optimally designed for a specific crude oil composition and desired product qualities and quantities, allowing some flexibility based on the catalyst within the reactors.
Blending crudes help achieve close to the desired properties without incompatibilities:
…with processing conditions or materials of construction (e.g., whether it may cause accelerated fouling due to precipitating asphaltenes) or has a higher risk of corrosion.
Factors which may affect corrosion rates may include:
…the acid types within the crude, distribution of the acid quantity within crude oil boiling point ranges, piping metallurgy, and added inhibitors.
Tim highlights the tight oil properties from some of the major shale producing regions in the United States. Not only do properties such as total acid number affect corrosion rates, but also the process configuration, such as:
…a low point or dead-leg in a pipe may collect water and provide a favorable environment for accelerated corrosion.
He describes organizations involved in tracking these crude oil properties and defining specifications to help refiners avoid incompatibilities.
Strategies for reducing corrosion include:
- careful crude oil (blend) feedstock selection
- appropriate use of chemical inhibitors
- online corrosion monitoring of the process fluid and wall thickness in several locations
- inspections during turnarounds
- considerations for piping metallurgy upgrades to process higher-TAN crudes—more expensive metallurgies can be more resistant to corrosion (depending on the acid)
- timely repair or replacement of assets damaged by corrosion.
Read the article to see how technologies such as non-intrusive, wireless ultrasonic transmitters, wireless corrosion monitoring transmitters, and field signature method (FSM) metal loss detection can be used as part of your corrosion mitigation program. Tim also highlights the standards and recommended practices to help develop and sustain this corrosion mitigation program.
You can connect and interact with other refining industry and wireless sensor experts in the Refining and Wireless groups in the Emerson Exchange 365 community and connect in person at the October 1-5, 2018 Emerson Exchange conference in San Antonio, Texas.