水饱和度作用下低渗透气藏滑脱效应实验研究

Experiment of slippage effect under water saturation in hypotonic coal bed

地面钻井压裂技术开发煤层气过程中,钻井开采带来的钻井液、完井液及酸化、压裂液等外来流体侵入储层后,导致储层的水饱和度增加,储层渗透率的降低,储层气体滑脱效应对渗透率的影响显著,气体运移规律复杂,抽采困难等问题。为了解决上述工程问题,本文利用实验手段对含水饱和度下滑脱效应影响的煤层气运移规律进行研究。得到了不同围压范围内,气体滑脱效应变化规律,在低围压条件下,滑脱因子随着水饱和度的增加而增大,水饱和度越大,煤样有效渗透率越低,滑脱效应对气体有效渗透率的影响越显著;在高围压条件下,滑脱因子随着水饱和度的增大而降低,气体运移不再符合克氏理论。通过所得规律的机理分析对含水情况下滑脱效应影响的煤层气的运移规律研究提供理论指导。

In the process of development CBM with ground drilling fracturing technology,the external fluid invasion such as drilling fluid,well completion fluid and acidification fluid resulted in the problems of increasing the water saturation of reservoir and decreasing in coal bed slippage effects.The paper for the permeability complication for gas moving difficulty for pumping and collecting.In order to solve these engineering problems.The paper used the experimental method to study the coalgas seepage rule considering the slippage effects under water saturation and obtained the change rule of gas slippage effects with different confining pressure.Under lower confining pressure,the slippage factor will be increased with the water saturation increasing;the more higher water saturation,the effective permeability willbe lower,the more significant slippage effects for the gas permeability;Under higher confining pressure,slippage factor willbe decreased with the water saturation increasing,the gas seepage was no longer accords with the Klinkenberg theory.Through mechanism analysis,the paper provided necessary theoretical guidance for considering slippage effects seepage rule of CBM under saturation water.