致密气藏多尺度支撑机理研究与应用

致密砂岩气作为重要的非常规天然气资源，需经过压裂改造才能实现有效开发。选取四川盆地致密砂岩露头岩芯，雕刻制作粗糙裂缝面岩板开展多尺度裂缝导流能力和支撑剂回流实验，分析导流能力及支撑剂回流的影响规律。研究表明，为了获得较高且稳定的导流能力，近井主裂缝需要有足够的支撑剂以提供更大的剩余缝宽，远井剪切裂缝只加入少量小粒径支撑剂也能有效改善高闭合应力条件下的导流能力；对于支撑剂充填的主裂缝，裂缝导流能力随着闭合应力和支撑剂浓度的变化存在临界闭合应力及临界支撑剂浓度。在支撑剂充填层中加入纤维，临界出砂流速呈数量级增长，可以有效预防压后裂缝的支撑剂回流。致密气藏多尺度支撑理念在四川盆地川西拗陷致密气储层开展的压裂工程实践取得了显著的增产效果，为中国致密气藏经济高效开发提供了有效支撑和借鉴。

Research and Application of Multi-scale Support Mechanism in Tight Gas Reservoir

Tight sandstone gas is an important unconventional natural gas resource, which requires fracturing to achieve effective development. In this paper, the tight sandstone outcrop cores in the Sichuan Basin are selected, and the rough fracture rock samples are carved to carry out multi-scale fracture conductivity and proppant backflow experiments, and analyze the influence of conductivity and proppant backflow. The results show that in order to obtain stable conductivity, the main fracture near the well needs to have enough proppant to provide a larger remaining fracture width, and only a small amount of small particle size proppant in the shear fracture of the far well can be effectively improved. For main fractures filled with proppant, the fracture conductivity has the critical closure stress and critical proppant concentration. Adding fibers to the proppant packing layer increases the sanding critical flow velocity by an order of magnitude, which can effectively prevent proppant backflow in fractures after fracturing. The multi-scale support concept of tight gas reservoirs has achieved significant stimulation effects in the fracturing engineering practice of tight gas reservoirs in the west Sichuan Depression of the Sichuan Basin, providing effective support and reference for the economical and efficient development of tight gas reservoirs.