Optimization method of oriented perforation parameters improving uneven fractures initiation for horizontal well fracturing

Abstract

Horizontal well oriented perforation fracturing is a common technique for unconventional oil and gas production. With the wide application of this technology, issues such as uneven fracture initiation and high initiation pressure appeared, which limited the fracturing effect for unconventional oil and gas. To improve the current situation for oriented perforation fracturing, we establish a numerical model of oriented perforation fracturing for horizontal wells using three-dimensional lattice method. The effects of perforation depth and diameter on fracture initiation pressure, fracture morphology and stimulating area are obtained through numerical simulation. Meanwhile, we propose a depth-controlled and a diameter-controlled oriented perforation design method for uniform fracture initiation. The research results show that, the growth of perforation depth and diameter would lower fracture initiation pressure. Increasing the perforation depth can improve the issue of uneven fracture initiation for oriented perforation fracturing in horizontal wells. Compared with conventional oriented perforation, the depth-controlled and diameter-controlled oriented perforation can significantly improve the uneven fracture initiation issue. The depth-controlled oriented perforation can effectively increase the stimulating area, and induce narrow and long fractures in high elastic modulus formations. The diameter-controlled oriented perforation is suitable for high in-site stress and can reduce fracture initiation pressure. The depth-controlled oriented perforation optimal design is applied to an objective well, Well H-21 of the Chang 73 target layer in Changqing Oilfield, China. Numerical results show that the proposed method can reduce the fracture initiation pressure by 12.6% and increase the fracture area by 11.80%, which can effectively solve the issue of uneven fracture initiation.