EXPERIMENTAL STUDY ON WATER INJECTION HUFF AND PUFF OF LOW PERMEABILITY FRACTURED SANDSTONE RESERVOIRS

摘要

In order to improve the o il recovery of fractured low perm eability reservoirs, the feldspathic sandstones of a low perm eability fractured reservoir in western China were studied. The cores w ith different w ettability values were simulated under form ation conditions (22MPa, 83 °C) to study the dynamic behavior of the in itia l stage and the elastic m ining stage. The research on the mechanism of Water injection h u ff and p u ff and o il recovery based on factors such as capillary force, perm eability and throughput cycle were carried out. According to the comprehensive analysis, (1) the recovery rate increased by 4.3 〜 15.23 under the action of water injection; (2) water injection can have effects on various wet state reservoirs, the stronger the hydrophilicity, the higher the recovery degree; (3) C apillary force exerts displacement and sorption on cracks and m atrix system. The pressure deflection effect formed between the high and low perm eability layers affects the oil-w ater interaction process between the heterogeneous o il layers, improves the sweep coefficient and the o il displacement efficiency, and reduces the remaining oil.