Abstract:

Coalbed methane(CBM) reservoirs are characterized with specialties in pore structures, gas occurrences and production mechanisms different with conventional and other unconventional gas reservoirs. The classifications of CBM reservoirs in publishing are usually proposed for direction of exploration and evaluation of candidate areas. With the progress of economically developments of various types of CBM reservoirs in overseas, especially with the rapid increases in quantity and scale of pilot tests in china, it is of important significance to discuss the classifications of CBM reservoirs for developments which comprehensively considers particularities and common properties of different kinds of CBM reservoirs, as well as major factors related to development efficiencies. The classifications of CBM reservoirs for developments are presented in the light of thickness of coalbeds, permeability, gas saturation in matrix and water saturation in natural fractures. Case studies show that fundamental problems on CBM developments related to reservoirs with high and medium permeability have been solved. As the fact that there are some key theoretical and technological questions retarded CBM developments of low permeability and tight reservoirs, solving these questions are the main directions for R&D in the future.

Key words: coal-formed gas, gas reservoirs type, gas reservoir development