低煤阶煤层气井排采初期压降幅度研究

Study on Pressure Drop Extent during Initial Drainage Stage in Low Rank Coal CBM Wells

排采制度是影响煤层气井产能的关键因素,尤其对于含气量较低的低煤阶煤层气井。为了确定低煤阶煤层气井排采初期的压降幅度,通过分析影响黄陇煤田煤储层渗透率变化的基质自调节作用和速敏效应,认为速敏效应是造成该区低煤阶煤储层在排采过程中渗透率变小的主要原因,提出以实验室煤岩心速敏实验数据和实验井生产统计数据为依据确定低煤阶煤层气井排采初期的压降幅度,得出了研究区煤层气井排采初期的临界压降幅度。

The drainage system is a key factor impacting on CBM well capacity, especially on low rank coal CBM wells with lower methane content. To determine pressure drop extent during initial stage in low rank coal CBM wells, analyzed matrix self regulating process and velocity sensitivity effect impacting coal reservoir permeability variation in Huanglong coalfield, considered that the velocity sensitivity effect is the main cause to diminish permeability during low rank coal reservoir drainage process in the area. Thus put forward CBM well pressure drop extent during initial stage on the basis of laboratory coal core velocity sensitivity data and test well production statistic data, and educed CBM well critical pressure drop extent during initial drainage stage in the study area.