Shale oil reservoirs generally exhibit strong heterogeneity, and the in-situ stress field, rock mechanical properties, and lithological non-uniformity around the target zone are significant. These factors lead to large variations in initiation pressure at different perforation clusters along a horizontal well, resulting in unbalanced fracture initiation and propagation among clusters within a fracturing stage. This significantly restricts both the stimulated reservoir volume (SRV) and the overall stimulation efficiency. To address these issues, this study first optimized the depth positions of perforation clusters within each fractured well stage by minimizing the differences in initiation pressure among the perforation clusters. Subsequently, the stress interference effects between multiple clusters of fractures were considered to calculate the non-uniform stress field during the reservoir fracturing process. A multi-cluster hydraulic fracture propagation model for shale oil was then developed, culminating in a method for regulating the uniform propagation of multi-cluster fractures. Using horizontal shale oil well NC1 as a case, we first performed an optimization of the non-uniform perforation cluster layout with the objective of minimizing the differences in initiation pressure among the perforation clusters. A comparative analysis of fracture propagation before and after the optimization of the perforation clusters was conducted, and the effectiveness of fracture control post-optimization was evaluated. The results indicated that after optimizing the perforation clusters, the average initiation pressure difference across the entire well stage decreased from 7.04 MPa to 1.03 MPa. The average fracture length variation coefficient across all stages reduced from 0.22 to 0.09, with a decrease in the fracture length variation coefficient in each stage, and all cluster fractures in each stage initiated. The standard deviation of the inflow rates for each cluster of fractures in well NC1, derived from high-frequency pressure wave deconvolution, was found to be less than 10, indicating a relatively uniform distribution of inflow rates among the clusters. The regulation of hydraulic fracture initiation and propagation was significantly effective. This research provides a theoretical framework for enhancing the effectiveness of perforation cluster fracturing in horizontal shale oil wells and for regulating the uniform propagation of fractures among clusters, offering valuable guidance for the design of multi-cluster perforations in field applications.
REN LAN
,
LI JIA
,
YU ZHIHAO
,
LIN RAN
,
WU JIANFA
,
SONG YI
,
SHEN CHENG
,
GAN WENJIE
,
LI ZHIQIANG
. Simulation of Uniform Fracture Propagation via Perforation Cluster Placement Optimization in Shale Oil Horizontal Wells[J]. Petroleum Reservoir Evaluation and Development, 0
: 2025379
-2025379
.
DOI: 10.13809/j.cnki.cn32-1825/te.2025379
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