Experimental Study on Fracture Propagation Morphology of Deviated Well in Tight Reservoir

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ABSTRACT: The highly efficient production method of tight reservoir in complex fault block reservoir is large slope cluster well volume fracturing. The characteristics of fracture initiation and propagation in deviated Wells of tight reservoirs under different stress states and well trajectory parameters have not been clarified yet. Based on the laboratory physical simulation test of true triaxial hydraulic fracturing, this paper studies the law of fracture propagation caused by various factors such as horizontal stress difference, well inclination Angle and azimuth Angle. The experimental results show that under low horizontal stress difference coefficient, spiral perforation is beneficial to the initiation of multi-hole fracture, but the fracture near the wellbore is seriously distorted. Directional perforation under high horizontal stress difference coefficient is favorable for hole initiation, forming complex fractures dominated by single smooth fractures and supplemented by secondary fractures. 20° or 80° well oblique fracture is smooth fracture, fracture surface distortion degree is small, perforation orifice initiation point is less; When the inclination Angle is 40° and 60°, the perforating hole has more fracture initiation points, high fracture extension pressure and high fracture plane distortion. When the azimuth Angle is less than 80°, it is beneficial to add sand on site. 1. INTRODUCTION China’s unconventional oil and gas reserves are rank among the top in the world, unconventional oil and gas are mainly tight oil and gas (Zhen et al., 2019; Sun et al., 2019). Due to its low porosity and low permeability characteristics, tight reservoirs are mainly stimulated by horizontal well volume fracturing (Zhu et al., 2019; Hou et al., 2021). However, the tight sand-mudstone reservoirs in complex fault-block reservoirs have many vertical layers, and the scale of the plane sand bodies varies greatly. The most effective mining method for vertical multi-layer tight sand-mudstone reservoirs is volume fracturing with high-angle cluster wells. The mechanism of hydraulic fracture initiation and propagation of perforated fracturing in highly deviated wells is unknown, and it is difficult to add sand during on-site construction, resulting in high construction pressure and small reservoir stimulation volume. Therefore, it is of great significance to study the fracture propagation pattern and construction influencing factors of perforated hydraulic fracturing in highly deviated wells for reservoir stimulation.