The 21st century is a century of natural gas, with the unconventional gas development becoming a global hot spot, which is gradually changing the pattern of world energy. The amount of unconventional gas resources in China is over 70 tcm. The total resources of tight gas are more than 12 tcm, with the favorable exploration area of about 118,000 km2, and a large scale of production in the Ordos and Sichuan basins. China's CBM resources are over 36.8 tcm, and development activities have become progressive in the south of Qinshui basin and east of Ordos basin. Shale gas resource in China is estimated at about 30.7 tcm, and four target marine areas have been selected and field trials are carried out in Sichuan basin at the same time.
Through comparison research of characteristics and technologies of unconventional gas reservoir between china and other countries, key technologies of unconventional gas exploration and development have been summarized. Tight gas can be seen as distributed widely in the plane; vertically stacked layers; with relatively low abundance, relatively small well-controlled reserve. The four key technologies of development are respectively geological area selection, drilling and completion, stimulation and well pattern infilling. The CBM mainly consists of adsorbed gas; the performance of pore structure is showing as the pore-fracture systems which require long-term water pumping to lower formation pressure in order to produce gas from the coal bed. The key technologies of development would be geological area selection, laboratory testing, drilling and completion, stimulation and water pumping-gas production, and so on. Shale gas can be seen as coexistence of free gas and adsorbed gas, with the characteristics of widely distribution, great thickness, low gas content and extremely low permeability. The key technologies of development include geological area selection, tight core test, horizontal well drilling and completion, stimulation and economic assessment techniques.
China's growing demand for clean energy will give an opportunity to develop unconventional gas, it may also bring some challenges such as law well production, high development cost and some of the key technology needs further research.
