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Does rock expansion play a role in increased recovery of oil when heat is supplied to the reservoir at the hands of steam or hot water ?

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Any rock expansion would hinder oil recovery due to a reduction in void space either between grains or in fissures. For oil to flow more readily it needs connected void spaces in which to collect and then flow through. The more tightly packed a rock is the less the ability of oil to flow.

Oil flows well in porous media like sand and sandstone due to the void/pore spaces. Shale doesn't have void spaces like sandstone and getting oil out of shale is very difficult. Previously shale had to be mined, crushed and heated on the surface to extract the oil.

With the advent of shale fracking, shale is fractured in-situ, underground. The introduced voids allow oil to collect and flow.

Heating the oil makes it less viscous which increases its ability to flow more easily. This is why oil is heat via steam underground.

To test this, put some butter in a pan and try to make it flow. It won't because it's solid. Heat the butter and see how it flows as more easily as it gets hotter.

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Directionally, yes. Treat it exactly like a compressibility term in the material balance equation (pressure drop and temperature rise both cause the grain material to expand). Second-order effects mentioned by the last contributor (e.g. permeability reduction from pore throat contraction) would need to be taken into account, but that's a productivity term, not a volumetric term.

This reference gives the bulk modulus of Fused Silica (kinda-sorta like sand grains?) as 6e6psi so the compressibility is 0.16e-6 psi. The coefficient of thermal expansion is 0.55e-6 per degree Celsius, so tripling that (for bulk coefficient) we get about 1.5e-6 per Celsius. So each degree Celsius produces (approximately) the same volumetric effect as a 10psi pressure change.

In practice, however, there is so much physics and physical chemistry going on in a thermal flood (passive or active) that I would be very surprised to see an interpretable response at the reservoir scale.

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The thermal expansion of a rock grain is severely limited by the overburden stress applied due to the overlaying strata. Since this force is usually quite massive, the amount of expansion per degree of temperature change is not significant. In addition, it takes a huge amount of energy to effectively heat a reservoir rock mass since it is dissipated into the fluid in the pore space, effecting a viscosity change. Thermal expansion of the fluid is a factor however. When the fluid expands it increases in volume and thereby enhances the production pressure gradient.

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