气体钻井中致密砂岩流固耦合实验研究

Experimental study on liquid-solid coupling of tight sandstone during gas drilling

应力改变与岩石的各种物性参数及变形破坏密切相关。通过对四川盆地须家河组致密砂岩进行压敏和声波时差实验,研究气体钻井中致密砂岩储层渗透率及波速与围压的关系。实验结果表明:一方面,气体钻井过程中储层随地层压力降低而导致的渗透率损失程度比气藏衰竭开发过程中的更大;另一方面,在三轴应力条件下,随着围压的增加,致密砂岩声学特性将遵从多项式函数的变化规律,该压实规律进一步阐明了渗透率的变化趋势。

The effecl of stress on various physical parameters and deformatinn failure of rocks should follow some laws or prineiplcs. Through the experiments of stress sensitivity and acoustic travel time of the tight sandstone of Xnjiahe Formation in Sichuan Basin, tile relation between effective stress and permeability and wave veloeity were studied during gas drilling. Experimental results show thai, on the one hand, the degree of permeability loss, caused by the decrease of formational pressure, is greater than that during depletion development of gas reservoir in lhe process of gas drilling; on the other hand, under the conditions of triaxial stress, the acoustic characteristics of tight sandstone should obey the change rule on mathematics polynomial tunction with the increasing of confinement pressure. The rule fmther shows the change trend of permeability.