中文摘要：

对特定的砂岩储层,不同深度射孔的围压不同,油藏流动与不同围压的共同作用将对砂岩产生不同的力学效应,进而影响油井出砂.研究建立射孔试验的三维颗粒流数值模型,模拟油藏流速一定时,分析围压改变时的砂岩力学特性.砂岩的宏观应力曲线表明围压越小的砂岩标准化切向应力越大,对应的偏应力越小,说明流体运动对岩体的应力变化起主要作用,而大围压自身对砂岩破坏起着重要的控制作用.另外,平行黏结的应力分布表明油井附近的张拉应力和剪应力较大,流体运动对小围压砂岩的应力影响较大;颗粒的位移和旋转也同样说明围压小的砂岩颗粒运动更激烈,离散的颗粒被携带进入油井的几率越大.上述结果与实际开采中的砂岩力学响应吻合,说明了油藏流速相同时,大围压相较于流体运动对砂岩颗粒的作用力要大,砂岩的破坏由围压决定,而流体运动主要携带砂岩颗粒.该成果为不同赋存环境的砂岩储层出砂预测提供了重要的理论依据.

英文摘要：

As for the given sand reservoir,the perforation holes in different depth with different confining pressure,the oil flowing combined with different confining pressure will change the mechanical effect of the reservoir sand and affecting the sand production.A numerical model for perforation test with the same oil flow rate based on 3-Dimensional Particle Flow Code（PFC3D） was forward to simulate the mechanical characteristics when changing the confining pressure.The micro-stress curve indicated that under smaller confining pressure,the oil flow increased the normalized tangential stress and decreased the deviatoric stress of the sandstone more easily,so the oil flowing more greatly determined the stress variation of the sandstone,but the larger confining pressure itself controlled the sandstone failure.In addition,stress distribution on the parallel bonds indicated greater tensile stress and shear stress near the inner oil wellbore and larger flow rate increased the stress on the parallel bonds much more.The particle displacement and rotation also explained that the particles movement was much more under smaller confining pressure and the sand particles dislodged more easily into the oil wellbore.The above results agreeing with the practical mechanical response for reservoir extraction indicated that larger confining pressure comparing with the oil flow affected more greatly on the particles,so the confining pressure determined the sandstone failure and the oil flow mainly carried the dislodged particles.The results may provide an important theoretical base for sand production prediction.