Analysis of Pore Pressure Distribution in Shale Formations under Hydraulic, Chemical, Thermal and Electrical Interactions
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- 作者：Hamid Roshan (1) hamidrooshan@yahoo.com
M. A. Aghighi (2) - 关键词：Thermodynamics of irreversible processes – ; Shale formation – ; Pore pressure
- 刊名：Transport in Porous Media
- 出版时间：March 2012
- 出版年：2012
- 期刊代码：69_01693913
- 类别：ch
- 卷：92
- 期：1
- 页码：61-81
- 数据来源：sp
摘要
Change in pore pressure in chemically active rocks such as shale is caused by several mechanisms and numerous studies have been carried out to investigate these mechanisms. However, some important coupling terms or driving forces have been neglected in these studies due to simplifying assumptions. In this study, a hydro-chemo-thermo-electrical model based on finite element method is presented to investigate the change in pore pressure in shale formations resulted from thermal, hydraulic, chemical and electric potential gradients. The change in pore pressure is induced by hydraulic conduction, chemical, electrical and thermal osmotic flow. In order to solve the problem of ion transfer under the influence of an electrical field, the Nernst–Planck equation is used. In addition, ion advection is considered to investigate its possible effect on ion transfer for the range of shale permeability. All equations are derived based on the thermodynamics of irreversible processes in a discontinuous system. The numerical results are compared against existing and derived uncoupled analytical solutions and good agreement is observed. The numerical results showed that the ion transfer and pore pressure are considerably affected by the electric field in the vicinity of the wellbore. It was also found that advection can play a remarkable role in ion transfer in shale formations. It was further shown that the change in pore pressure in shale formation is characterized by the combined effect of hydraulic, chemical, thermal and electro osmotic flow.