地应力对油页岩地层劈裂注浆裂隙扩展的影响

Influence of Ground Stress on Fracture Propagation of Split Grouting in Oil Shale Formation

地应力的差异性对劈裂注浆的裂缝扩展有着重要的影响。针对油页岩原位裂解区止水,本文提出定向射孔与劈裂注浆相结合的新方法,引导裂缝扩展。根据油页岩参数,利用RFPA软件,分析有无射孔对裂缝扩展的影响,并进一步分析地应力差异对有射孔时裂缝扩展的影响。结果表明,与无射孔注浆相比,有射孔注浆可定向劈裂并减小注浆压力;当x方向应力大于y方向应力时,射孔之间产生的大量裂缝将射孔连通形成帷幕;当x方向应力小于y方向应力时,随着应力差异的逐渐变大,裂缝扩展逐渐从x方向向y方向偏转,直到应力差异成为影响裂缝扩展的主要因素,射孔之间才未形成裂缝且不能连通。此研究成果可为油页岩原位裂解区止水工程提供借鉴。

The difference in ground stress has an important influence on the fracture propagation of split grouting. Aiming at the water stoppage in the oil shale in-situ retorting zone, this paper proposes a new method combining directional perforation and split grouting to guide fracture propagation. According to the oil shale parameters, RFPA was used to analyze the influence of perforation on fracture propagation, and further analyze the influence of ground stress difference on fracture propagation with perforation. The results show that compared with non-perforated grouting, perforated grouting can direct splitting and reduce grouting pressure; When the stress in the x direction is greater than the stress in the y direction, a large number of fractures generated between the perforations connect the perforations to form a curtain；When the stress in the x direction is less than the stress in the y direction, as the stress difference gradually increases, the fracture propagation gradually deflects from the x direction to the y direction，until the stress difference becomes the main factor affecting fracture propagation, no fractures are formed between the perforations and the perforations cannot be connected. This study can provide a reference for the water stop project in the oil shale in-situ retorting zone.