180
M. Cao et al.
When the volumetric stress increased from 13 MPa to 39 MPa, the permeability of
the specimen after pyrolysis at 600 °C decreased from 377.61 × 10 −8 µm 2 to 253.59 ×
10 −8 µm 2 , and the degree of reduction in permeability at this stage increased to 32.84%
to 41.79%.
4 Conclusions
Oil shale is a source rock with low permeability but extremely sensitive to temperature,
and heat injection is an effective method to modify the permeability of oil shale under
in-situ conditions. In this paper, the permeability change of oil shale under different
temperatures and In-situ stress conditions was investigated with the combination of the
mercury injection experiment, weight loss experiment.
(1) The temperature effect on the porosity and weight loss rate of oil shale can be
divided into three stages. From 20 °C to 300 °C, the interlayer water and adsorbed
water in the oil shale begins to evaporate, and the weight loss rate and porosity of
the specimen show a slight increase; when the temperature increased from 300 °C
to 400 °C, the kerogen in the rock body pyrolyzed and the weight loss rate and
porosity increased rapidly; From 400 °C to 600 °C, the kerogen in the specimens
was further pyrolyzed, and the weightlessness and porosity were further increased,
but the growth rate slowed down.
(2) The temperature effect on the permeability of oil shale can be divided into three
stages. From 20 °C to 300 °C, the permeability of oil shale had a very weak increase,
and it only increased by 1.54 to 3.13 times of that at 20 °C; while the temperature
increased from 300 °C to 400 °C, the permeability of oil shale increased rapidly,
and it increased by 24.3 to 92.4 times of that at 30 °C; For the temperature ranging
from 400 °C to 600 °C, the growth rate of the permeability slowed down, and it
only increased to 1.69 to 2.49 times of that at 400 °C.
(3) Under different temperatures, the effect of the volumetric stress on permeability
can be divided into three stages. For the temperature ranging from 20 °C to 300 °C,
the effect of volumetric stress on the permeability of oil shale is small; When the
temperature increased from 300 °C to 400 °C, the effect of volume stress on the
permeability increased significantly, and the permeability decreased by 22.23%
with the increase of volume stress; From 400 °C to 600 °C, the effect of volumetric
stress on permeability is further enhanced, the degree of reduction of permeability
increased to 32.84% to 41.79%.
References
1. Fletcher, T.H., Gillis, R., Adams, J., Hall, T., Mayne, C.L., Solum, M.S., Pugmire, R.J.:
Characterization of macromolecular structure elements from a green river oil shale, II. characterization of pyrolysis products by13C NMR, GC/MS, and FTIR. Energy Fuels 28(5),
2959–2970 (2014)
M. Cao et al.
When the volumetric stress increased from 13 MPa to 39 MPa, the permeability of
the specimen after pyrolysis at 600 °C decreased from 377.61 × 10 −8 µm 2 to 253.59 ×
10 −8 µm 2 , and the degree of reduction in permeability at this stage increased to 32.84%
to 41.79%.
4 Conclusions
Oil shale is a source rock with low permeability but extremely sensitive to temperature,
and heat injection is an effective method to modify the permeability of oil shale under
in-situ conditions. In this paper, the permeability change of oil shale under different
temperatures and In-situ stress conditions was investigated with the combination of the
mercury injection experiment, weight loss experiment.
(1) The temperature effect on the porosity and weight loss rate of oil shale can be
divided into three stages. From 20 °C to 300 °C, the interlayer water and adsorbed
water in the oil shale begins to evaporate, and the weight loss rate and porosity of
the specimen show a slight increase; when the temperature increased from 300 °C
to 400 °C, the kerogen in the rock body pyrolyzed and the weight loss rate and
porosity increased rapidly; From 400 °C to 600 °C, the kerogen in the specimens
was further pyrolyzed, and the weightlessness and porosity were further increased,
but the growth rate slowed down.
(2) The temperature effect on the permeability of oil shale can be divided into three
stages. From 20 °C to 300 °C, the permeability of oil shale had a very weak increase,
and it only increased by 1.54 to 3.13 times of that at 20 °C; while the temperature
increased from 300 °C to 400 °C, the permeability of oil shale increased rapidly,
and it increased by 24.3 to 92.4 times of that at 30 °C; For the temperature ranging
from 400 °C to 600 °C, the growth rate of the permeability slowed down, and it
only increased to 1.69 to 2.49 times of that at 400 °C.
(3) Under different temperatures, the effect of the volumetric stress on permeability
can be divided into three stages. For the temperature ranging from 20 °C to 300 °C,
the effect of volumetric stress on the permeability of oil shale is small; When the
temperature increased from 300 °C to 400 °C, the effect of volume stress on the
permeability increased significantly, and the permeability decreased by 22.23%
with the increase of volume stress; From 400 °C to 600 °C, the effect of volumetric
stress on permeability is further enhanced, the degree of reduction of permeability
increased to 32.84% to 41.79%.
References
1. Fletcher, T.H., Gillis, R., Adams, J., Hall, T., Mayne, C.L., Solum, M.S., Pugmire, R.J.:
Characterization of macromolecular structure elements from a green river oil shale, II. characterization of pyrolysis products by13C NMR, GC/MS, and FTIR. Energy Fuels 28(5),
2959–2970 (2014)