应用数字岩心和有效介质模型研究岩石弹性性质

基于三维数字岩心用有限元的方法计算了干岩样、完全饱和岩样和部分饱和岩样的弹性模量,并把数值模拟结果与理论和试验分别做了比较。结果表明,通过数值模拟得到岩石弹性模量-孔隙度关系与试验相符合,并且由数值模拟得到的流体替换对岩石弹性性质的影响与Gassmann理论相符合,数值模拟得到的部分饱和流体岩石的弹性模量与Gassmann-Wood(GW)理论也是符合的。同时把数值模拟结果与自洽理论和差分有效介质理论计算结果进行比较,发现没有一个理论计算结果能和试验结果符合,相反,数值模拟结果与试验数据基本符合。这表明了基于三维数字岩心预测岩石弹性性质的可靠性与精确性。

Rock Elastic Properties Determined by Using Digital Rock and Effective Medium Model

The elastic modulus of dry,fluid saturated and partially saturated rock samples and the P-wave and S-wave velocities of water saturated rocks were calculated by using the finite element method based on 3D digital cores.The result was contrasted respectively with those of theoretical and experimental analyses.The results show that relations between the elastic moduli and porosity and the relations between velocity and porosity obtained by numerical simulation are in agreement with the experiment data.The effect of the fluid substitution on the elastic properties is in agreement with the Gassmann theory.The elastic modulus of the partially saturated rocks obtained by numerical simulation is also agreement with the Gassmann-Wood(GW) theory.The numerical simulation result is contrasted with that of calculation with effective difference theory.It is found out that none of the theoretical calculation results are consistent with that of experiment.In contrast,the numerical results are basically in agreement with the experimental data.The feasibility and accuracy rock elastic properties obtained by using digital are demonstrated.