The China National Offshore Oil Corporation (CNOOC) announced on October 23 the discovery of a deep methane coalbed gas field with reserves exceeding 110 billion cubic meters.
This deep methane coalbed gas field is named Shenfu, located in Yulin City, Shaanxi Province, on the eastern edge of the Ordos region. This new discovery is significant for China’s energy security, aiding the growth of the country’s unconventional oil and gas reserves and production.
Shenfu deep CBM field in Yulin City, Shaanxi Province. (Photo: CMG).
Methane is a natural gas found in coal seams. Unlike conventional gas fields, it is stored through an adsorption process. Methane primarily accumulates on the surfaces of coal particles as adsorbed gas, while also existing in fractures and pores as free or dissolved gas.
Methane in coal is found at depths exceeding 1,500 meters. China boasts abundant reserves of over 30 trillion cubic meters located deeper than 2,000 meters. Deep methane fields account for approximately one-third of the total methane reserves in China.
In comparison to average and shallow types, the accumulation mechanism and geological conditions of deep coalbed methane are more complex. As depth increases, the formation temperature, pressure, and stress also rise significantly, making exploration more challenging and costly.
The coal seam of the Shenfu field is about 2,000 meters deep, with a single layer thickness ranging from 6 to 23 meters, yielding an average gas content of 15 cubic meters per ton of coal. Currently, over 100 exploratory wells have been drilled in the area, with a maximum daily gas production of 26,000 cubic meters per well.
Shenfu is the second important deep methane field discovered by CNOOC, following the Linxing field, which has similar gas reserves. According to Xu Changgui, deputy exploration engineer at CNOOC, this new discovery indicates vast exploration and development potential on the eastern edge of the Ordos region. “This discovery lays a solid foundation for the company to establish a large gas production base onshore, potentially tapping into up to one trillion cubic meters of verified gas in place,” said Zhou Xinhuai, CEO of CNOOC.
