Coalbed Methane Exploration Results of the Liulin Permit in China

Abstract

Since 1994, North China Petroleum Bureau has cooperated with Lowell Petroleum N.L to exploit coalbed methane in the Liulin Permit which is 218 square kilometers in area. The Permit is structurally situated in the southern limb of the Lishi structural nose which is in the middle of the eastern margin of Ordos Basin. Main coal seams are Numbers 4 and 5 of the Shanxi Formation, Lower Permian and Number 8 of the Taiyuan Formation, Upper Carboniferous.

Three wells have been completed and operations of coring, gas content determination, geophysical logging and well testing have been performed. The exploration results have proved that Seam 4, 5 and 8 are the main potential seams of the Permit. In the eastern part of the Permit, three target seams have similar thickness of 3 m to 5 m, and the formation pressure is relatively low. In the west part of the Permit, Seam 8 is dominant among all seams with thickness of 8–10 m, and the formation pressure is 1.2 Mpa higher than normal pressure. The gas content of the Permit is high and varies from 10 to 15 m³/ton. Well testing and reservoir simulation of Seam 8 yield a rather high permeability, which is comparable to one of the main production seams in the San Juan Basin. On the whole, the reservoir characters of the Permit show that Liulin Permit possesses high producibility.

Based on exploration results, coalbed methane resources of Liulin Permit was calculated and the value is 24.26 billion m³.