Abstract: The analysis is made about the drainage performance of gas wells under different combination of coal seams (5#、8#、9#) in Linfin block. It illustrates that the productivity under multi-layer production of 5#+8# or 5#+9# is better than that under single-layer production of 5# and multi-layer production of 5#+8#+9# or 5#+sandstone+9#. Based on the test data and theoretical calculation, the effects of interlayer geological condition differences on CBM well productivity are studied intensively. The result shows: the chief reasons affecting the productivity can be explained as the interlayer differences of hydrogeological conditions, pressure and permeability, gas content and cementation, and total resource.

Key words: Linfin block, combination of producing layers, productivity, single-layer production, multi-layer production, interlayer differences