Experimental study on the effect of fracture surface morphology on plugging zone strength based on 3D printing
School of Engineering / Centre for Sustainable Energy and Resources
National Natural Science Foundation of China Sichuan Province Youth Science and Technology Innovation Team Project Sichuan Province Science and Technology Project State Key Laboratory of Oil and Gas Reservoir Geology and exploitation
In this paper, laser scanning combined with stereo-lithography appearance (SLA) is used to study the influence of fracture surface morphology on the plugging effect of laboratory fracture plugs, in order to incorporate the fracture surface fluctuation into the design of plugging formula for fractured formations. To our knowledge, this is the first study on the maximum plugging pressure considering the real fracture surface fluctuation using 3D printing technology. The experimental results show a significant positive correlation between the maximum plugging pressure of the average bulge height, the average inclination angle of fracture surface, and the JRC coefficient. With the increase of these characteristic parameters of fracture surfaces, the maximum plugging pressure also increases. Observation of the fracture plugging zone after the experiment indicates that the front edge of the fracture plugging zone is the same as the violent local fluctuations in the height of the fracture surface. The present research suggests that the fluctuation of fracture surface provides many inclined supporting surfaces and strengthens the supporting effect of fracture surface on loss control materials (LCM). The dislocation of the “step-like” flow channel caused by the sudden change of the fracture can induce local single-particle straining and local multi-particle bridging in the flow channel, which significantly improves the maximum plugging pressure of the fracture plugging zone. According to the fracture surface fluctuation difference, the plugging effect of the same formula for fractures with the same opening is different, so it is necessary to improve the plugging formula design in combination with a geological engineering background. This understanding is of great significance for the analysis of fracture plugging mechanisms and optimized design of plugging formulas for fractured reservoirs. It will contribute to the high-efficiency and environment-friendly exploitation of energy and resources.