CRZO Carrizo Oil and Gas Inc

Carrizo Oil & Gas, Inc. (NASDAQ: CRZO) today announced that the company closed its previously announced joint venture transaction in the Marcellus Shale with a subsidiary of Reliance Industries Limited ("Reliance").

In connection with the joint venture, Reliance acquired a 20% interest in approximately 52,200 net Carrizo acres in Pennsylvania considered highly prospective for Marcellus Shale natural gas at a purchase price of $65 million. Reliance paid $11.4 million in cash to Carrizo at closing with $1.7 million more expected later this year. In addition, Reliance will pay an expected $52 million of Carrizo's share of future drilling, completion, and seismic costs ("development carry"). The joint venture agreement is effective immediately.

Simultaneous with the closing of this transaction, an affiliate of Carrizo's already existing joint venture partner, Avista Capital Partners ("Avista"), closed on the sale its entire interest in the same properties to Reliance for approximately $327 million. Under the terms of Carrizo's current joint venture agreement with Avista, Carrizo expects to receive approximately $44 million in cash from Avista based on the sale of Avista's approximately 52,200 net acres. The amounts to be received by Avista and Carrizo are subject to adjustment, pending completion of land title work.

The new Carrizo/Reliance joint venture agreement covers approximately 104,400 gross acres in northern and central Pennsylvania. Under the terms of the agreement, Carrizo retains a 40% working interest in the acreage and Reliance owns 60%. In addition to funding its own share of future development obligations, Reliance will fund 75% of Carrizo's portion of these costs over the next two years or until the earlier full utilization of the $52 million development carry, subject to certain conditions and extensions. Carrizo will continue as operator with Reliance having the right to assume operations in certain parts of Central Pennsylvania after one year.

Carrizo's joint venture with Avista Capital will continue, and now covers approximately 140,000 gross Marcellus acres primarily in the states of West Virginia and New York.

Carrizo Oil & Gas, Inc. is a Houston-based energy company actively engaged in the exploration, development, exploitation and production of oil and natural gas primarily in the Barnett Shale in North Texas, the Marcellus Shale in Appalachia, the Niobrara Formation in Colorado, the Eagleford Shale in South Texas, and in proven onshore trends along the Texas and Louisiana Gulf Coast regions. Carrizo controls significant prospective acreage blocks and utilizes advanced 3-D seismic techniques to identify potential oil and gas reserves and drilling opportunities. Carrizo also controls large acreage positions in other productive shale resource plays.

Reliance Industries (RIL) is the largest private sector company in India with a current market capitalization of over $71 billion. It is a global energy leader and one of the largest refining and petrochemical producers in the world. For the year ended March 31, 2010, RIL reported revenues in excess of US$ 44.6 billion, cash profit of US$ 6.2 billion, net earnings of US$ 3.6 billion and net worth of US$ 30.6 billion. RIL is the first private sector company from India to feature in the Fortune Global 500 list of 'World's Largest Corporations' and ranks 100th amongst the world's Top 200 companies in terms of profits. RIL ranks 75th in the Financial Times FT Global 500 list of the world's largest companies. For more information, please visit RIL's website at www.ril.com.

Avista Capital Partners is a leading private equity firm with offices in New York, Houston, and London. Founded in 2005, Avista's strategy is to make controlling or influential minority investments primarily in growth-oriented healthcare, energy, and media companies. Through its team of seasoned investment professionals and industry experts, Avista seeks to partner with exceptional management teams to invest in and add value to well-positioned businesses. For more information, visit www.avistacap.com.

Statements about the new and existing joint ventures and the sales transaction (including the benefits, results, effects, post-closing matters and timing of the foregoing), purchase price, development carry, amount received from Avista, and all other statements in this release other than historical facts are forward-looking statements. These statements rely on a number of assumptions concerning future events and are subject to a number of uncertainties and factors. Among the factors that could cause results to differ materially from those indicated by such forward-looking statements are; purchase price and drilling carry adjustments, the existence of title defects, lease consents and similar matters, amounts ultimately received by and from Avista, actions by joint venture partners, delays, costs and difficulties relating to the purchase and joint venture transactions, results of exploration activities, commodity price changes, capital needs and uses and other factors described in risk factors and elsewhere in the Company's Annual Report on Form 10-K for the twelve months ended December 31, 2009, and in its other filings with the SEC.

Contact: Carrizo Oil & Gas, Inc. Richard Hunter Vice President of Investor Relations Paul F. Boling Chief Financial Officer (713) 328-1000