沁水盆地东南部潘庄区块煤层气开发条件得天独厚，已经实现了产业化，部分气井经过近15 a排采产量衰竭，有必要利用气井全生命周期数据评价产气规律和抽采效果。通过对产气量数据统计和实测剩余含气量与原始含气量的对比，分析了潘庄气井全生命周期产气特征，评价了煤层气地面抽采效果。对146口气井产气量统计分析发现，中、高及特高产井占比92%，平均1 a左右实现稳产，稳产期平均持续11 a，年平均采气速度17%，平均最终采收率达214%，与之相比国内大部分煤层气井产量低，而潘庄区块大部分气井稳产期到来早，持续时间长，采气速度快，最终采收率高。高产原因如下：首先，该区煤层气赋存及开采条件优越，煤的热成熟度高，生气量大，赋存了大量游离气资源，地质构造简单和处于地下水滞留区形成了优越的气体保存条件，煤体结构以原生和碎裂结构为主，裂隙发育，为气体产出和运移提供了通道；其次，研究区气井钻完井、压裂、排采措施基本类似，大部分气井单采3号煤层，产量大于3,9,15号煤合层排采，开采方案合理。研究区15年地面煤层气抽采效果明显，抽采5,7,13 a含气量降低率分别为42%、55%和82%，根据原位资源量和累计抽采量估算的剩余含气量为-43~8 m3/t，中、高及特高产井的最终剩余含气量达到零或负值，说明可采资源量远远大于地质探明储量，对煤层气以吸附气为主理论、容积法估算煤层气资源储量提出了挑战。

Panzhuang block in the southeast Qinshui Basin is the most potential coalbed methane (CBM) field,and industrial development has been realized.Some CBM wells have been exhausted after nearly 15-year production,so it is necessary to evaluate the gas production distribution and drainage effect in the full life-cycle production data.In the paper,by gas production data statistics and the analogy of residual gas content and primary gas content,the gas production distribution is analyzed and drainage effect in the full life-cycle production is evaluated.According to the analysis of 146 gas wells,The medium and high yield wells account for 92%,their early stable period begins at the first year or so,stable period lasts 11 years,gas recovery speed gets to 17% and ultimate recovery rate is 214% averagely,and contrasted with other generally lowly productive wells in China,the highly productive wells in Panzhuang exhibit early stable period,long stable period,fast gas recovery speed and highly ultimate recovery rate.CBM production is generally high for the following reasons: first,excellent CBM occurrence and drainage conditions is the foundation for generally high production,high coal rank is due to large amount of gas-generating in the geological history,simple geological structure and being in the retention area of groundwater is good gas preservation conditions guarantee the occurrence of abundant free gas resources; coal body is mainly primary and cataclastic structure,and fracture provides the gas migration pathway.Second,gas well drilling,completion,fracturing and drainage follows similar steps,most gas well production of separate drainage for No.3 coal is greater than that of cooperative drainage for No.3,9,15 coal seam,and the development plan is reasonable.The drainage effect of the surface CBM wells during 15 years is obvious.The residual gas content test shows that the gas content reduction rate is 42%,55% and 82% at the 5th,7th and 13th year,respectively.According to the in-situ resource and cumulative drainage estimation the residual gas content ranges in -43-8 m3/t,and that of medium and high yield wells decreases to zero or negative.The recoverable resource is far more than geological reserves,which puts forward the challenge for CBM adsorption theory and the volume method for evaluating CBM resources.

1 地质背景

2 煤层气井产气规律

   2.1 稳产期与产气量

   2.2 采气速度和最终采出率

3 抽采效果分析

   3.1 检验井剩余含气量分析

   3.2 剩余含气量估算

4 开发条件差异性分析

   4.1 水动力条件

   4.2 构造条件

   4.3 煤体结构

   4.4 工程因素

5 结论