Research Status and Development Trends in Sand Washing and Well Cleaning Technologies

In the process of sand washing and well cleaning, when the sand washing fluid carries the formation sand upward, the formation sand can easily be re-deposited under the influence of gravity, resulting in sand sticking and sand plugging. For deep wells and ultra-deep wells, sand washing and well cleaning face complicated wellbore trajectories, larger friction for sand-carrying fluid, and increased construction pressures, where the construction pressure can even exceed the carrying capacity of sand washing and well cleaning equipment. Thus it is difficult to smoothly implement conventional sand washing and well cleaning technologies, and the operation risk is high. Due to the low formation pressure and leak-proneness in low-pressure absorption wells, the sand washing fluid leaks seriously during sand washing and well cleaning operations, and the sand carrying capacity decreases, resulting in reduced sand washing and well cleaning efficiency and even failure to flush out the sand. The continuous improvement of sand washing and well cleaning technologies in China and abroad has effectively solved the above-mentioned difficulties in sand washing and well cleaning operations. In order to promote the sand washing and well cleaning technologies in China, the status of sand washing and well cleaning technologies in China and abroad was reviewed in terms of the structure, working principle, technical characteristics, and development trends of sand washing and well cleaning tools. Suggestions for the development trends of sand washing and well cleaning technologies in China were proposed by considering the characteristics of sand washing and well cleaning in China, so as to promote the development of sand washing and well cleaning technologies in China.