Northeast Petroleum University, College of Petroleum Engineering, Daqing, China.
Daqing Oilfield Co Ltd, Daqing, China.
PLoS One. 2024 Aug 2;19(8):e0303251. doi: 10.1371/journal.pone.0303251. eCollection 2024.
Hydraulic fracturing technology is an effective way to develop tight sandstone reservoirs with low porosity and permeability. The tight sandstone reservoir is heterogeneous and the heterogeneity characteristics has an important influence on fracture propagation. To investigate hydraulic fracture performance in heterogeneous tight reservoir, the X-ray diffraction experiments are carried out, the Weibull distribution method and finite element method are applied to establish the uniaxial compression model and the hydraulic fracture propagation model of heterogeneous tight sandstone. Meanwhile, the sensitivity of different heterogeneity characterization factors and the multi-fracture propagation mechanism during hydraulic fracture propagation is analyzed. The results indicate that the pressure transfer in the heterogeneous reservoir is non-uniform, showing a multi-point initiation fracture mode. For different heterogeneity characterization factors, the heterogeneity characteristics based on elastic modulus are the most sensitive. The multi-fracture propagation of heterogeneous tight sandstone reservoir is different from that of homogeneous reservoir, the fracture propagation morphology is more complex. With the increase of stress difference, the fracture propagation length increases. With the increase of injection rate, the fracture propagation length increases. With the increase of cluster spacing, the propagation length of multiple fractures tends to propagate evenly. This study clarifies the influence of heterogeneity on fracture propagation and provides some guidance for fracturing optimization of tight sandstone reservoirs.
水力压裂技术是开发低孔低渗致密砂岩储层的有效方法。致密砂岩储层是非均质性的，其非均质性特征对裂缝扩展有重要影响。为了研究非均质致密储层中的水力裂缝性能，进行了 X 射线衍射实验，应用威布尔分布方法和有限元方法建立了非均质致密砂岩的单轴压缩模型和水力裂缝扩展模型。同时，分析了不同非均质特征参数和水力裂缝扩展过程中多裂缝扩展机制的敏感性。结果表明，非均质储层中的压力传递不均匀，呈现多点起裂的裂缝模式。对于不同的非均质特征参数，基于弹性模量的非均质特征最敏感。非均质致密砂岩储层的多裂缝扩展与均质储层不同，裂缝扩展形态更加复杂。随着应力差的增加，裂缝扩展长度增加。随着注入速率的增加，裂缝扩展长度增加。随着簇间距的增加，多条裂缝的扩展长度趋于均匀扩展。本研究阐明了非均质性对裂缝扩展的影响，为致密砂岩储层压裂优化提供了一定的指导。
