Composite Permeability Model of Shale Matrix with the Effect of Adsorption

DOI

10.2991/tmcm-15.2015.29How to use a DOI?

Keywords

shale gas; organic permeability; inorganic permeability; composite permeability; slippage; free molecule flow

Abstract

The shale matrix is composed of organic matter and inorganic matter. Methane often adsorbs in organic pores and water adsorbs in inorganic matter. Adsorption layer blocked the spaces of pores, and leads to the decrease of porosity and permeability. However, the influence of adsorption layer on shale permeability is neglected on present research. As a result, the value of calculated Composite Permeability is larger than its true value. Considering the adsorption, slippage and free molecule flow effects, this paper proposes the organic permeability model, inorganic permeability model and composite permeability model based on capillary calculation model and existing apparent permeability calculation model. In comparison with the experimental results, it is found that the proposed model help to get the reliable results and it is more practical in predicting the shale gas reservoir permeability. Also, the proposed model is used to predict shale permeability of Shan-xi Formation, Paleozoic, Ordos basin, China. The results show that: (1) At the beginning time of development (the pressure is 30MPa), the decreasing of the permeability in organic matter is sensitive when pore diameter is less than 10nm. At the late stage of development (the pressure is 5MPa), the smaller the organic pore diameters are, the greater the permeability in organic matter will increase (2) With the decreasing of pressure and increasing of Langmuir pressure, the increasing rate of permeability increases.(3) with the increasing of water saturation, the damage of inorganic permeability becomes serious.

Copyright

© 2015, the Authors. Published by Atlantis Press.

Open Access

This is an open access article distributed under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

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TY  - CONF
AU  - Cheng Cao
AU  - Tiantai Li
AU  - Bojiang Fan
PY  - 2015/11
DA  - 2015/11
TI  - Composite Permeability Model of Shale Matrix with the Effect of Adsorption
BT  - Proceedings of the 2015 International Conference on Test, Measurement and Computational Methods
PB  - Atlantis Press
SP  - 114
EP  - 118
SN  - 2352-538X
UR  - https://doi.org/10.2991/tmcm-15.2015.29
DO  - 10.2991/tmcm-15.2015.29
ID  - Cao2015/11
ER  -