Exhibit 99.1

CARRIZO OIL & GAS, INC. ANNOUNCES $95 MILLION JOINT VENTURE

AGREEMENT WITH GAIL (INDIA) LIMITED

HOUSTON, September 29, 2011 - Carrizo Oil & Gas, Inc. (NASDAQ: CRZO) today announced the closing of an unincorporated joint venture with a wholly owned subsidiary of GAIL (INDIA) LIMITED (“GAIL”). Under the joint venture agreement, Carrizo sold 20% of Carrizo’s interest in approximately 20,200 net mineral acres leased by the Company in the highly prospective condensate zone of the Eagle Ford Shale for total consideration of $95 million, comprised of $63.65 million in cash and the assumption of an additional $31.35 million of Carrizo’s future drilling and d