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盐腔注采周期的变化导致腔内温度周期性变化,进一步导致围岩热应力的周期性变化。由于盐岩抗拉强度低,当这种周期性热应力为拉应力且数值较大时,盐岩将破碎从而导致腔体垮塌。结合声呐带压测腔实测的盐穴腔体形状和体积数据,采用有限元数值模拟方法,将温度场与已建力学模型进行耦合建立热应力模型,并对常规模型和热应力模型进行对比,以分析热应力对腔体稳定性的影响。结果表明:在常规模型中表现稳定的部分区域,在热应力模型中却发生垮塌现象,热应力模型计算结果与声呐实测带压测腔结果吻合,由此推断温度变化所产生的热应力是影响腔体稳定性的重要因素,严重时可能导致腔体垮塌。因此,腔体热应力影响因素的提出,进一步完善了腔体稳定性评价体系,使评价结果更加接近于地层的真实情况。
The change of injection and production period of salt chamber leads to the periodic change of chamber temperature, which further leads to the periodic change of thermal stress of surrounding rock. Due to the low tensile strength of salt rock, when this periodic thermal stress is tensile stress and the value is large, the salt rock will crush and cause the cavity to collapse. Combined with the measured salt cavern cavity shape and volume data measured by sonar pressure measuring chamber, the thermal stress model was established by coupling the temperature field with the established mechanics model by using the finite element numerical simulation method. The conventional model and thermal stress model were compared, To analyze the thermal stress on the stability of the cavity. The results show that some areas which are stable in the conventional model collapse in the thermal stress model, and the calculated results of the thermal stress model are in good agreement with the measured cavity pressure in the sonar. Therefore, it is concluded that the thermal stress caused by the temperature variation is affected Cavity stability is an important factor in serious cases may lead to collapse of the cavity. Therefore, the factors of cavity thermal stress are put forward to further improve the cavity stability assessment system, so that the evaluation results closer to the real situation of the formation.