ION Geophysical Corp. began an exchange of eligible holders’ outstanding 8.125% senior secured second priority notes due 2018, the company said March 29.

This exchange is part of ION Geophysical’s entry into a support agreement with noteholders collectively holding more than two-thirds of the aggregate outstanding principal amount, which on March 28, was $175 million.

ION Geophysical will pay the $1,000 principal amount of its new 9.125% second priority notes due 2021 for each $1,000 principal amount of notes validly tendered for exchange.

Also, ION Geophysical will use $15 million in cash to purchase notes for exchange from participants wishing to tender them at a discount; the company is also offering consents from eligible holders regarding amendments to the indenture governing the notes.

The exchange offer, including the cash tender option, will expire on April 25.

D.F. King & Co. Inc. is the information agent and Oppenheimer & Co. Inc. is the dealer manager.

ION Geophysical Corp. is based in Houston.