渗透率应力敏感性对煤层气井产能的影响

Stress Sensitivity of Permeability Affected to Production Capacity of Coal Bed Methane Well

为了得到煤层气井产能方程,并对其敏感参数进行分析,基于煤层流体渗流规律,推导了在达西渗流和非达西渗流下考虑渗透率应力敏感性的产能方程,研究了韩城WL1井某煤层的煤层气井流入动态。结果表明:不管是达西渗流还是非达西渗流,考虑应力敏感性后煤层气井的产能明显减少,无阻流量最多可以减少12.4%;当改变渗透率应力敏感系数后,发现敏感系数越大,煤层气井的产能下降越多;如果生产压差较小,虽然应力敏感性影响不明显,但是产气量较低,生产压差过大又会浪费地层能量。因此,开发时制定合理生产压差是非常重要的。

In order to get a production equation of a coal bed methane well and to analyze the sensitive parameters, based on the vadose law of the seam fluid, the production capacity equation with the permeability and stress sensitivity under the Darcy flow and non-Darcy flow were deduced and the inflow performances of the coal bed methane well in a seam of WL1 well was studied. The results showed that whether a Darcy flow or non-Darcy flow, after the stress sensitive, the production capacity of the coal bed methane well was obviously re- duced. The no resistance flow would be reduced by 12. 4% in maximum. When stress sensitive coefficient of the the permeability rate changed, the higher sensitive coefficient, the more the production capacity of the coal bed methane would be reduced. Once the produc- tion pressure difference was small, although the stress sensitivity influence was not obvious, the production value would be low. Once the production pressure difference was too high, the strata energy would be waste. Therefore, a rational production pressure difference set at the development period would be very important.