致密砂岩储层基块孔喉细小,同时气藏开发全过程易产生水相圈闭损害,制约致密气开发进程。矿场试验与室内实验研究均已证明储层热处理技术可以解除储层水相圈闭损害并增加渗透率,但受限于其适应的储层物性条件不清而一直未推广应用。选取库车凹陷、惠民凹陷、冀东凹陷地区典型致密砂岩岩心,为模拟热处理压裂液滞留的裂缝面或生产过程水相聚集的近井带,利用3 % KCL溶液完全饱和实验岩心,开展了升温速率为2 ℃/min的热激实验,测试了不同RQI（储层品质系数）的致密砂岩热激前后渗透率,分析了储层品质系数RQI与增渗幅度之间关系。研究表明,致密砂岩岩样从室温加热至100 ℃,渗透率变化不明显,加热至200 ℃,渗透率略微降低,加热至300~400 ℃,部分岩样渗透率增幅达200 %~500 %,但也有部分岩样渗透率无明显变化,这与岩样的储层品质系数RQI有关;适合热激增渗的含水致密砂岩储层品质系数临界值为0.25,当RQI值小于0.25时,岩样热激增渗幅度与RQI值呈单调递减的函数关系;在RQI值一定且热激温度大于200 ℃的情况下,温度越高热激增渗效果越好。

The pore throat of tight sandstone reservoir block is narrow, and during the whole process of gas reservoir development, the water phase trapping damage is easy to prone, which restrict the development process of tight gas. The field test and laboratory experimental study have proved that the heat treatment technology for reservoirs can remove this damage and increase the permeability, but it has not been popularized and applied because of the unclear reservoir physical properties. Therefore, typical tight sandstone cores in Kuqa Depression, Huimin Depression and Jidong Depression are selected in order to simulate the fracture surface where heat treatment fracturing fluid stays or the near-wellbore zone where water phase gathers in the production process. A thermal shock experiment is carried out with 3 % KCL solution completely saturated experimental cores, the permeability of tight sandstone with different reservoir quality coefficient RQI before and after thermal shock is tested, and the relationship between the reservoir quality coefficient RQI and the increasing permeability is analyzed. The researches show that the permeability of tight sandstone samples does not change obviously when heated from room temperature to 100 ℃, but decreases slightly when heated to 200 ℃, and increases by 200 %~500 % when heated to 300~400 ℃, but the permeability of some samples does not change obviously, which is related to the reservoir quality coefficient RQI of the samples. The critical value of quality coefficient of water-bearing tight sandstone reservoir suitable for thermal surge permeability is 0.25. When RQI value is less than 0.25, the thermal surge permeability amplitude of rock samples is monotonically decreasing with RQI value. When RQI value is constant and heat shock temperature is greater than 200 ℃, the higher the temperature, the better the effect of thermal surge infiltration.