基于流固耦合作用的砂岩地浸采铀效果数值模拟分析

Numerical Simulation Analysis of Uranium In-situ Leaching inSandstone Based on Fluid-Structure Interaction

为探究低渗砂岩铀矿在不同因素下的产量变化情况,根据储层有效应力与渗流特性的关系,建立有效应力-渗流数值模型。通过日产水量分析流固耦合作用下储层的产量变化规律,并结合变异系数法分析注入压力、初始渗透率和井间距对产量的影响。研究表明:考虑流固耦合作用下的储层产量会更快进入稳定状态,产量更高;应力敏感性系数越大,有效应力减小对地层渗透率影响越明显。注入压力越大,地层有效应力减小区域下降幅度增大,地层渗透率增大区域升高幅度增大,产量逐渐增多;流固耦合作用下,产量随着初始渗透率增大而增多且增长速度较快;流固耦合作用下,随着井间距的增大,注采井间有效应力减小的影响减弱,注采井间渗透率增大趋势也在下降,产量逐渐降低。结合各因素变异系数变化可得,注入压力对产量效果影响更明显。本研究有助于建立完整的砂岩铀矿地浸采铀生产方案。

In order to explore the production changes of uranium ore in low-permeability sandstone under different factors,a numerical model of effective stress-seepage was established according to the relationship between the effective stress and seepage characteristics of the reservoir.The daily water production was used to analyze the production variation of the reservoir under fluid-structure interaction,and the effects of injection pressure,initial permeability and well spacing on production were analyzed by combining the coefficient of variation method.The results show that the reservoir production will enter the stable state faster and the production will be higher under the consideration of fluid-structure interaction,and the greater the stress sensitivity coefficient,the more obvious the effect of the reduction of effective stress on the formation permeability.The greater the injection pressure,the greater the decrease in the area of the formation effective stress,and the increase in the area of formation permeability increases,resulting in a gradual increase in production.Under the consideration of fluid-structure interaction,the yield increases with the increase of initial permeability and the growth rate is faster.Under the consideration of fluid-structure interaction,with the increase of well spacing,the effect of decreasing effective stress between injection-production wells is weakened,and the increasing trend of permeability between injection-production wells is also decreased,resulting in a gradual decrease in production.Combined with the changes of the coefficient of variation of various factors,it can be obtained that the injection pressure has a more obvious effect on the yield effect.This study will help to establish a complete uranium production scheme for uranium in-situ leaching in low-permeability sandstone uranium mines.