State Key Lab of Coal and Coalbed Methane Co-mining Y'an Lanyan Coal and coalbed Methane Co-mining
Technology Company Limited

为研究煤层气井长期排采特征及抽采效果,以寺河区块开发较早的煤层气井实际生产数据为基础,采用理论分析与试验测试等方法,分析了煤层气井排采过程中套压、产水量、产气量随抽采时间的长期变化规律,并对抽采效果进行了验证。研究结果表明:在煤层气资源赋存条件差异不大的情况下,区内煤层气井排采曲线与小构造关系密切,大部分气井套压在短时间内达到峰值,而后逐渐降低,产水量主要集中在排采阶段的前3年,产气峰值一般出现在排采后的4~6年,少数井产气峰值出现在排采后的1~2年。煤层气地面抽采效果显著,降低了煤矿投入,提高了掘进速度,减少了瓦斯超限事故。由于煤层气井具有排采周期长,不同构造部位产气效果及排采特征差异性大的特点,应根据煤层气赋存条件及井下采掘进度,在瓦斯含量高的区域提前10~15年进行地面预抽。

In order to study the long-term drainage features and drainage effect of a coalbed methane well, based on an actual production data of the early develop ed coalbed methane wells in Sihe Block, the theoretical analysis and experimental test as well as other methods were applied to analyze the long-term variation laws of the casing pressure, water production and gas production with the drainage time passed in the drainage process of the coalbed method wells and the verification was C onducted on the gas drainage effect. The study results showed that under the coalbed methane deposition condition with a less big difference, the drainage curve of the coalbed methane well within the block would have a close relation with the small structure. The casing pressure of the most methane wells would reach the peak value within a short time and then would be steadily decreased. The water production mainly concentrated at the first three years of the gas drainage stage. The gas producti on peak value would be appeared after 4 ~ 6 years of the gas drainage operation and the gas peak value of some methane wells would be appeared after 1 ~ 2 years of the gas drainage operations. The surface gas drainage effect of the coalbed methane wells was obvious, the input of the coal mine would be reduced, the mine heading speed would be increased and the gas overlimite accident occurred was reduced. Due to the coalbed methane well with a long drainage period, the gas production effe ct and drainage features at the different tectonic part would have a big difference features. According to the coalbed methane deposition conditions and the mining and heading speed in the underground mine, a surface well gas pre-drainage should be conducted in advance 10 ~ 15 years in the high gas content area.