Poroelastic modeling of cutting rock in pressurized condition
Poroelastic modeling of cutting rock in pressurized condition
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DOI：
10.1016/j.petrol.2018.06.009
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发表时间：
2018-10
影响因子：
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通讯作者：
Pengju Chen;S. Miska;Rui Ren;Mengjiao Yu;E. Ozbayoglu;N. Takach
中科院分区：
文献类型：
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作者：
Pengju Chen;S. Miska;Rui Ren;Mengjiao Yu;E. Ozbayoglu;N. Takach
在加压条件下切割岩石与在环境条件下切割岩石有本质的不同。在加压状态下，切削齿不仅破碎岩石基质，而且带动孔隙流体向前流动。由于应力与孔隙压力的耦合作用，切削齿引起的孔隙压力变化会影响岩石中的有效应力，最终影响机械比能（MSE）。刀具运动引起的应力和孔隙压力变化是切削过程中的孔隙弹性效应。为了研究加压切削过程，建立了基于线性孔隙弹性理论的切削模型。该模型能较好地预测岩石中的耦合应力和孔隙压力，更好地理解切削过程中的孔隙弹性效应。为了得到期望的解，使用傅里叶变换。在得到傅里叶空间的解析解后，利用离散傅里叶变换将解数值反演回实空间。还引入了莫尔-库仑破坏准则来确定切削齿前方岩石的破坏情况。最终，该模型可以预测加压切削过程中的切削力和MSE。将模型与已发表的实验数据进行了比较，发现模型与实验结果具有较好的一致性。研究了静水压力和岩屑的存在对MSE的影响，并讨论了切削过程中的孔隙弹性效应。本文的研究结果可应用于钻井中的钻头-岩石相互作用。
Cutting rock in pressurized conditions is essentially different as compared to the ambient conditions. Under pressurized condition, cutter is not only fragmenting the rock matrix, but also driving pore fluid to flow forward. Due to the coupling of stresses and pore pressure, the pore pressure change caused by cutter will affect effective stresses in the rock and eventually affect mechanical specific energy (MSE). The change in stresses and pore pressure caused by cutter movement are the poroelastic effects in cutting process.To study pressurized cutting process, we developed a cutting model based on the theory of linear poroelasticity. The model can predict coupled stresses and pore pressure in the rock and give a better understanding of the poroelastic effect in the cutting process. To obtain the desired solution, a Fourier Transform is employed. After the analytic solution in Fourier space is obtained, a Discrete Fourier Transform is employed to numerically invert the solution back to the real space. The Mohr-Coulomb failure criterion is also introduced to determine failure of the rock ahead of the cutter. Eventually, the model can predict cutting forces and MSE in pressurized cutting process. The model is also compared to the published experimental data and a good consistency between model and experiment results was found.The influence of hydrostatic pressure and the existence of cuttings on MSE are studied and poroelastic effect during cutting process is also discussed. The results in this paper can be applied to bit-rock interaction in well drilling.