Carrizo Oil & Gas Inc. (NASDAQ: CRZO) opened a public offering of $600 million, in aggregate principal amount, of senior notes, the company said April 14.

The notes are due 2023.

Also, a cash tender offer is being made for a buyback of all 8.625% notes due 2018, and there is a conditional call for redemption of those notes that are not bought back prior to the redemption date. The tender offer and the redemption are subject to conditions, Carrizo added.

Net proceeds from the note offering, and some net proceeds from an offering of about 5.2 million common shares closed on March 20, will finance the redemption. Any excess proceeds will pay outstanding revolving credit facility debts and support general corporate purposes.

RBC Capital Markets LLC, Wells Fargo Securities LLC, Citigroup Global Markets Inc., Credit Suisse Securities (USA) LLC, BBVA Securities Inc., Capital One Securities Inc. and Credit Agricole Securities (USA) Inc. are joint book-running managers.

SG Americas Securities LLC, Mitsubishi UFJ Securities (USA) Inc., Regions Securities LLC, IBERIA Capital Partners LLC, and KeyBanc Capital Markets Inc. are joint lead managers.

Houston-based Carrizo Oil & Gas Inc. explores and develops domestic natural gas and oil.