Fabrication of a three-dimensional simulated reservoir core model based on area projection micro-stereolithography

Petroleum exploitation plays a very important role in national energy security. With continuous exploitation of oil fields in my country, the efficiency of conventional water injection oil production is decreasing year by year. Enhanced oil recovery (EOR) technologies, such as polymer flooding, microbial flooding, micro–nano flooding, and other flooding technologies have been proposed and developed for application. However, the microscopic displacement mechanism and displacement effect of these technologies are still unclear. Current oil displacement research needs to be verified by core displacement experiments. However, the current displacement experiments all use artificial cores, glass etching channels, photoetched microchannels, etc., as the oil displacement environment. These displacement environments are insufficient in terms of oil displacement dimensions and observation phenomena. Due to this, there is an urgent need for a core manufacturing method that is more suitable for laboratory oil displacement research. In this study, we proposed a method for manufacturing a simulated three-dimensional core structure based on micro-stereolithography technology. This method not only has the advantages of fast manufacturing speed and high forming accuracy, but is also able to realize the visualization, parameterization, and customized design of a micron structure. The core model self-searched by stereo lithography has a three-dimensional pore structure in the order of hundreds of microns and can be used to simulate the experimental study of reservoir displacement flow mechanism. In this research, a high-precision surface projection micro-stereolithography equipment was built, and the optimal printing process parameters were obtained through a combination of theoretical analysis and experiments. Then, a microsphere stacked core model was proposed that can be used to simulate formation cores. By analyzing the forming mechanism of the core model, a stacking method was selected with a higher forming accuracy to design the core model. Finally, the core of a 100-micron-sized microsphere accumulation was realized by micro-stereolithography to achieve three-dimensional molding. The simulated core manufacturing method in this study has high adaptability to special core structure manufacturing and provides a new idea for studying the microscopic displacement mechanism of various EOR technologies under a laboratory microscope.