Abstract:

The sand?carrying migration law of slick water in fractures is of great guiding significance to the practice of slick water fracturing.Sand transport profiles with different injection parameter combinations were tested by a visual parallel plate fracture simulator.The results show that the sand?carrying capacity of the slick water is favorable under the combination of slick water for fracturing +70~140 mesh proppant +8% sand ratio.In this case,no sand banks are observed at the fracture inlets,and the proppant does not fill the fractures adequately,under the combinations of low?viscosity slick water +40~70 mesh proppant +10% sand ratio and high?viscosity slick water +20~40 mesh proppant +20% sand ratio, the amount of sand filling fractures is large, and the sand banks in deep fractures are high,while the filling at fracture inlets is poor.With the increase in construction displacement, the various combination modes all exhibit growing positions of the front edges of the sand banks, decreasing heights of front edges, and insignificant changes in balance heights. Injection combination is an important aspect affecting the sand bank pattern. The sand bank patterns and characterization parameters corresponding to different injection parameter combination modes vary greatly. Therefore, the combination mode needs to be optimized on site to improve the conductivity of fractures at the inlet.

Key words: Slick water, Migration law, Front edge position, Balance height, Sand bank pattern

摘要：

滑溜水在裂缝中的携砂运移规律，对指导滑溜水压裂实践有重要意义。采用可视化平行板裂缝模拟装置，测试了不同注入参数组合的输砂剖面。结果表明，造缝滑溜水+70~140目支撑剂+8%砂比时，滑溜水携砂能力好，裂缝入口端未出现砂堤，支撑剂对裂缝的充填不充分；在低黏滑溜水+40~70目支撑剂+15%砂比和高黏滑溜水+20~40目支撑剂+20%砂比条件下，裂缝填砂量较大，深部裂缝砂堤较高，但裂缝入口处充填差；随着施工排量的增加，几种组合模式均表现出砂堤前缘距入口距离增大，前缘高度减小，平衡高度变化不大的情况。注入组合是影响砂堤形态的重要因素，不同注入参数组合模式对应的砂堤形态和表征参数相差较大，现场需对组合模式进行优化，提高入口处裂缝的导流能力。

关键词: 滑溜水, 运移规律, 前缘位置, 平衡高度, 砂堤形态