二氧化碳注入下岩层变形和流体运移分析:(Ⅱ)实例分析

第I部分[1]提出了一个两相流-岩层流固耦合模型,为了应用该模型对超临界二氧化碳注入过程中岩层力学响应和流体运移进行评估,采用Comsol商业程序,提出了相应的数值分析方法。给出了模型参数的确定方法,并采用室内试验数据对模型进行了验证;通过现场的温度和压力条件以及岩层的Van Genuchten参数,确定了二氧化碳的密度和黏度。基于三轴压缩试验、有效应力系数试验和渗透性试验,对力学模型及耦合关系中的参数进行了验证。最后给出一个应用实例,该岩层位于地下680⁷00 m深度,宽度为100 m,分析了不同二氧化碳注入速率下注入压力的演化规律,得到了岩层中孔隙压力、竖向应变和损伤变量的分布,并对二氧化碳的运移规律也进行了分析。研究结果为超临界二氧化碳注入过程中岩层力学响应和流体运移的评估提供了理论基础。

Analysis of reservoir deformation and fluid transportation induced by injection of CO2 into saline aquifer:(II)Case study

The first part proposed a two-phase flow-reservoir coupling model, in order to apply this model to evaluate the stability of reservoir and fluid transportation, the commercial algorithm, Comsol Multiphysics, is used and the corresponding numerical modeling method is proposed. The determination procedure of model parameters is firstly presented and the simulation results are validated by the laboratory tests. The density and viscosity of CO2 are determined according to the in situ condition of temperature and pressure, the Van Genuchten parameters of rock layer are from the literature. Based on the triaxial compression tests, effective stress coefficient tests and permeability tests, the model parameters involved in mechanical model and coupling relations are identified. We then perform a case study. The rock layer is situated at depth between 680 to 700 m, and the width is 100 m. The evolution of injection pressure under different injection rates is studied, the distributions of pore pressure, vertical strain and damage variable are presented; the CO2 transportation is also analyzed. The present work offers theoretical basis for evaluating the stability of reservoir and fluid transportation.