Analysis on production features and influence factors of coalbed methane in deep section of north Shizhuang Block

In order to solve a problem of a low coalbed methane production from a depth below 1 000 m in the south part of Qinshui Basin, based on the southeast edge of Qinshui Basin and with north Shizhuang Block as the study key point, a comprehensive analysis method of the production data was applied to the study on the gas production features of deep seam, the gas drainage variation law and the production dynamics of the typical mines with different production. The key influence factors of deep seam production capacity were provided. The study results showed that the daily gas production volume of deep seam was less than 500 m3. The time of the gas appearance was 16 ～ 178 days. The moving liquid level of the single raw wells in No. 3 seam was low and moving liquid level of combined raw wells in No. 3 and No. 15 seam was high. The flow pressure at the well bottom was 1.70～2.59 MPa. The factors affected to the production capacity would be including the geological condition, engineering technical condition and other drainage aspects. The geological factor mainly was the low permeability of the coal reservoir. The joint mining of No. 3 seam and No. 15 seam and some wells with a short distance to the fault could cause a high water production. The factors of engineering technical condition mainly would be that fracturing of the some wells could not form effective channels and the methane gas could not be discharged. The drainage factor mainly meant that in the drainage process, the frequent shutdown and others could cause the discontinued drainage affected to the gas production volume.