酸气-咸水作用下岩石特异性破坏机理研究

The acid gas reinjection refers to injection of captured of acid gases (usually CO2 and H2S) from large sources of emissions through the pipe and the borehole into the underground non-productive or non-economic formations. With the severe fluctuation of sulfur market and the worldwide enhancement on the regulation of acid gas emissions, acid gas re-injection is an alternative to large-scale producers to deal with excess sulfur. At the same time, the acid gas re-injection can reduce the atmospheric emissions of carbon dioxide and sulfur dioxide, so acid gas re-injection is an option of carbon capture and storage, and it is also a promising technology to mitigate acid rain worldwide..Up to now, Canada has been carried out over 40 acid gas reinjection projects, while China is no precedent. But recently some large state-owned enterprises including CNPC are in the pipeline to carry out relevant acid gas reinjection projects. The proposed application aims to build a strong constitutive relationship for the mechanical behavior of rock under coupled acid-gas and saline water conditions. The updated core flooding apparatus with reactive flow and tri-axial deformation is used to investigate the evolution of the specific mechanical behavior of rock under the acid gases and saline water. By integrated the proposed constitutive relationship and numerical models into the developed mechanical - chemical - multiphase flow software, the specific mechanical behavior of the rock specimen under acid gas reinjection is simulated and verified.

酸气回注是指将天然气等中分离出来的酸性气体（通常是CO2和H2S）通 过井孔注入地下长期封存以减少排放的过程。随着硫磺价格下降和各国对酸气排放规制的增 强，酸气回注逐步走向工程化，具有显著的应用前景。加拿大已经开展过40多个酸气回注项目，而我国尚无先例。.酸气回注必须回答地质封存的力学稳定性问题。针对酸气-咸水作用下的岩石特异性破坏机理及耦合过程研究，目前普遍缺乏实验的系统验证的前提下，本项目通过使用开发的酸气和咸水作用下岩石流通-反应三轴试验仪，开展在不同酸气组分和不同压力下的室内岩石三轴破坏实验研究；有别于损伤模型，提出考虑饱和度和压力的岩石特异性破坏行为的本构关系，同时通过力学-化学-多相渗流耦合软件的二次开发，模拟试样尺度下酸气回注过程中这一特异性力学行为的演化规律。

酸气回注是指将天然气中分离出来的酸性气体（通常是CO2和H2S）通过井孔注入地下储层长期封存以减少排放的过程。由于酸性气体与地层流体和岩石之间存在复杂的耦合作用机理，酸气回注工程必须首先回答其地质力学稳定性问题。本项目团队搭建了集声源定位—波速成像—光纤测量于一体的岩石物理实验系统，研究了四川盆地储层砂岩的力学特性和渗流反应特征，通过一系列致密砂岩在不同饱和度条件下的流体注入破坏过程实验可以发现：在饱和岩石中，轴向加载引起的孔隙压力增加对断层成核具有控制作用；通过提出一种基于多通道FBG传感器阵列的光纤感测技术的创新性方法，在一系列砂岩岩芯驱替实验后，首次得到关于水-二氧化碳两相流体流动中岩石力学场的FBG原始数据，这为酸气回注工程中的风险评估提供了极其重要的参数集。本项目团队开发了热-流体-力学-化学（THMC）耦合模拟数值计算程序AEEA，在解释室内试验现象的基础上预测酸气回注过程对储/盖层岩石的影响机理，同时对阿姆河盆地酸气回注现场进行了案例研究，充分验证了我们实验过程中获得一些物性参数和开发模型的适用性。这一课题研究填补了酸气回注领域国内研究的空白。