A Numerical Study of Expanding Multiple Clusters of Fractures in Temporary Plugging Fracturing of Horizontal Wells

Temporary plugging fracturing technology is an effective method to improve the extent of the fracture stimulation of horizontal wells, which could effectively improve the degree of inter-fracture mobility in low permeability reservoirs. At present, research on temporary plug frac for horizontal wells mainly focuses on the development of fractures, lacking optimization analysis for different parameters. Based on the reservoir parameters of the Chenghai block, this paper established a numerical model for temporary plugging fracturing of horizontal wells, which considered the non-uniformity of natural fractures and reservoir permeabilities. The model simulated the developing behavior of temporary plugging for inter-fractures and intra-fractures. A “fracture coverage area” concept was introduced to investigate the influence of parameters such as two-way stress difference, discharge, and cluster spacing. A generally used simulation method for temporary plugging fracturing of horizontal wells in heterogeneous reservoirs was formed. The conditions for implementing temporary plug frac were clarified and the key parameters were optimized. The study results showed that when the two-way stress difference is less than 4 MPa, temporary plugging of the opened natural fractures can be implemented to promote the expansion of the main fractures; and when the two-way stress difference is greater than or equal to 4 MPa, the main fractures can be temporarily plugged after the main fractures have expanded, promoting the initiation of natural fractures and guiding the main fractures to change direction. Therefore, 4 MPa is recommended as the critical two-way stress difference for implementing temporary plugging fracturing. As the discharge rate increases, the length and width of the fractures gradually increase, and the fracture coverage area reaches its maximum value when the discharge rate is 5–8 m3/min. When the inter-cluster spacing is less than or equal to 12 m, temporary plugging can significantly extend the fractures that have not been effectively expanded. The fracture coverage area is the largest when the inter-fracture spacing is 5–8 m. This numerical simulation method for temporary plugging fracturing of horizontal wells can provide guidance for optimizing construction parameters on site and effectively improve the effect of temporary plugging fracturing.