煤层气井压裂引起的渗透率损伤研究

由于煤层的应力敏感性,在煤层气井的压裂过程中,随着高压流体的持续注入,压裂裂缝的产生势必会对附近的煤层渗透率产生影响。针对煤层气井压裂引起的渗透率损伤问题,通过理论计算的方法,建立了压裂引起的诱导应力与渗透率之间的关系式,通过计算实例,分析了压裂引起的渗透率的损伤特征。研究认为:压裂产生的诱导应力和引起的渗透率损伤均在裂缝两侧呈对称性分布;压裂对裂缝附近煤层渗透率会产生直接的影响,渗透率损伤现象明显;压裂引起的渗透率损伤可能是某些已压裂的煤层气井增产效果不明显的原因之一。

Research on the permeability damage caused by the hydraulic fracturing for coalbed methane wells

The generation of hydraulic fracture will inevitably have an impact on the permeability of the coal nearby in the fracturing process. For the problem of coal bed permeability damage caused by fracturing, the equation between the induced stress and permeability was established.By calculation example, the characteristics of permeability damage caused by hydraulic fracturing were analyzed. Studies suggest that: the distribution of induced stress and permeability damage caused by hydraulic fracturing are symmetrical on the both sides of fracture. Hydraulic fracturing has a direct impact on the permeability of coalbed near the fracture, and the permeability damage phenomenon is very obvious. Permeability damage caused by hydraulic fracturing may be one of the reasons that the stimulation effect of some coalbed methane wells is not satisfactory.