CDB project is China's largest onshore natural gas cooperation project. The contractor is Chevron Corporation. On December 18, 2007, Pe-troleum Contract for Petroleum Development and Production of the CDB Block,Sichuan Basin, the people's republic of china has been signed and came into effect on February 1, 2008. It is mainly located in Xuanhan county, Dazhou city, Sichuan province, Wanyuan city and Kaixian cou-nty, Chongqing. According to the principles of overall planning and construction and operation by phases, natural gas development is divided into three phases. The first phase of Luojiazhai (including Gunziping) gas field is in progres and it is expected to achieve first gas by December 2012.