Drilling and completing oil and gas wells at extreme depths, under extreme high pressure and at high temperature (HPHT) conditions, often has the additional challenge of sour gas (H2S or CO2).
Casing and Tubing is required to endure this corrosive environment under extreme pressure while maintaining the strength required to complete wells at depths of 30,000’ and greater.
EA-125SS tieback casing string (7” X .950” wall) on location in the inland waters of Louisiana.
The high cost of the materials that can endure these harsh conditions limits exploration at ultra-deep levels.
Typical ultra deep HPHT wells are comprised of carbon-steel support casing (the outer layers) and nickel alloy production tubing (the inner layer in contact with the oil and gas). Between those layers is typically a production tieback string, which is the “insurance policy” that contains any problems caused by a possible production tubing leak or failure.
The production tieback is often made of expensive stainless steel. Energy Alloys, which provides oilfield metals, services and solutions to oil and gas manufacturers, challenged our engineers to come up with a carbon-steel based, lower-cost alternative for the production tieback casing that would:
- Handle the highly corrosive properties of a hydrogen sulfide environment.
- Withstand the requirements of both high pressure and high temperature.
- Provide the strength required to ensure the integrity of the tieback casing to depths of 30,000’.
- Ensure consistent delivery of these properties for the life of the well.
- TimkenSteel sales engineers worked closely with Energy Alloys and their customer to understand the challenge of gaining cost efficiency while not sacrificing performance to enable deeper completions.
- Our team of metallurgists worked closely with Energy Alloys to jointly develop a sour service product with 125K minimum yield to meet the requirements of the end user.
- They set to work on engineering a new alloy steel for the production tieback, with a customized chemistry and heat treat process, combined with our ability to make heavy wall (0.750” or greater) casing in range 3 lengths that could withstand the pressure.
- While the composition of the steel was critical, the ability to consistently hold to the specification was equally important, since failure is not an option at those depths.
- TimkenSteel has melted more than 30 heats on this new customized alloy with great success, and the steel is in use in critical projects in the Gulf of Mexico.
- The cost is significantly less than high chrome or stainless materials.
- This breakthrough allowed the customer to move forward and complete these critical wells with a cost competitive product.
Shawn Seanor, executive vice president at TimkenSteel, leads the company’s sales and business development. He joined the company in 1984 as part of the project management team that launched the Faircrest Steel Plant. Shawn holds a bachelor's degree in management engineering from Grove City College and a master's degree in business administration from Kent State University.