关键词: 压裂, 支撑剂, 石英砂, 长期导流能力, 铺砂浓度, 粒径组合, 铺置模式

Abstract: The use of quartz sand instead of ceramsite proppant can effectively reduce the construction costs and is widely used in fracturing reforming in tight oil and gas reservoirs. To explore the influence of quartz sand proppant on the long-term conductivity of fractures, choosing 20-40 mesh, 40-70 mesh and 70-140 mesh quartz sand to carry out long-term conductivity test experiments to explore the effects of effective stress, sand concentration, particle size combination, laying mode and other factors on the long-term conductivity of quartz sand and fit the parameterized empirical model. The results show that, the long-term conductivity increases first and then decreases with the increase of sand paving concentration, reflecting the evolution from "support" to "blocking". Under the condition of low sand paving concentration, large-diameter quartz sand is easy to break and block flow channel, therefore, fine sand can be preferred in high closure pressure reservoirs, and medium sand or coarse sand can be preferred in low closure pressure reservoirs. When considering mixed paving, low-viscosity fracturing fluid should be used to pump the large-particle quartz sand first, and then use high-viscosity fracturing fluid to pump small-sized quartz sand. The prediction model of mixed paving conductivity given in the paper is suitable for the optimal design of particle size and proportion of mixed paving proppant.

Key words: fracturing, proppant, quartz sand, long-term conductivity, paving sand concentration, particle size combination, paving mode