不同注入介质对泥岩层滑移的影响研究

INFLUENCE OF DIFFERENT INJECTION MEDIA ON MUDSTONE SLIP

在注CO_(2)与注水两种开发方式下,均会出现泥岩层段的套管剪切损坏加剧的现象。为了明确不同注入介质对泥岩层滑移的影响,将室内实验所得储层岩石物理力学参数与现场实际区块的井网资料相结合,建立了泥岩层剪切滑移流固耦合数值模型,通过有限元方法进行求解,分析了不同注入介质在一定注入速度条件下生产3年过程中的孔隙压力、油层变形量和泥岩层滑移量的分布与变化情况。根据计算结果可知,由于水和CO_(2)黏度与密度的差异,导致开发初期注CO_(2)井周围孔隙压力高于注水井。随着开发时间的延长,注CO_(2)井孔隙压力降低速率大于注水井,在生产3年后,注CO_(2)油层整体孔隙压力高于注水油层,使注CO_(2)油层整体均匀上抬,但注水油层高低差更大,导致油层变形更加集中。油层变形量的不同引起了泥岩层滑移量的差异,注CO_(2)泥岩层滑移量小于注水泥岩层滑移量。基于不同注入介质对泥岩层滑移量的影响分析,给出了合理的注入方案,为防治油田套损提供了理论支撑。

In both CO_(2)injection and water injection development modes,casing shear damage in mudstone sections will be aggravated.In order to clarify the influence of different injection media on mudstone layer slip,combining the physical and mechanical parameters of reservoir rock obtained from laboratory experiments with the well pattern data of actual blocks,a fluid-structure coupling numerical model of mudstone layer shear slip was established and solved by finite element method.The distribution and variation of pore pressure,reservoir deformation and mudstone slip of different injection media at a certain injection speed during production for three years are analyzed.According to the calculation results,due to the difference in viscosity and density of water and CO_(2),the pore pressure around CO_(2)injection well is higher than that of water injection well in the early development stage.With the prolongation of development time,the decrease rate of pore pressure of CO_(2)injection well is greater than that of water injection well.After three years of production,the overall pore pressure of CO_(2)injection oil layer is higher than that of water injection oil layer,which makes the whole CO_(2)injection oil layer uniformly lift up,but the height difference of water injection oil layer is larger,resulting in more concentrated deformation of oil layer.The slip amount of mudstone layer is different due to the different deformation amount of oil reservoir,and the slip amount of mudstone layer injected with CO_(2)is less than that of cement layer.Based on the analysis of the influence of different injection media on the slip amount of mudstone layer,a reasonable injection scheme is given,which provides theoretical support for preventing casing damage in oilfield.