**4. Conclusion**

Research on the fluidity of oil and gas deposits also led to the understanding of the role of thermal conductivity in studying the phenomena of hydrocarbon migration and their formation.

Also, the use of thermal conductivity in determining the secondary (injection of gases and hot water into the deposit) and tertiary (underground combustion, steam injection into the deposit) recovery mode created the need for the experimental determination of this property of the constituent rocks.

Tikhomirov scientifically established based on the determination of the thermal conductivity of the rocks constituting the oil and gas deposits that the calculation relationship of this property (thermal conductivity) is [1, 14]:

$$k\_{\text{sat},T} = 2\text{€}, \mathbf{31e}^{0,6\text{ }\rho+0,6\text{ }\text{S}\_A} T^{-0,55} \tag{21}$$

where *ksat*,*T*is the thermal conductivity of the rock saturated with the constituent fluids, *ρ* is density (g/cm<sup>3</sup> ), *T* is temperature of determination (°C).

The author estimates an error in the thermal conductivity determination of 16%.

Cermak also used a relationship to determine conductivity as a function of density (for calcareous rocks) [1, 14]:

$$k\_{\text{sat}} = 2.15 \bullet 10^{-3} \rho - 3.16 \tag{22}$$

For carbonate rocks, the above relation can be written [1, 14]:

$$k\_{\rm sat} = 4,18 \bullet 10^{-3} \rho - 7,97 \tag{23}$$

In relations (22) and (23) the density is expressed in kg/m<sup>3</sup> .

But even these equations give errors of over 15%.

But our calculation method, namely the statistical determination of thermal conductivity as a function of porosity and density, indicated a very small error (maximum 0.5%).

In this chapter, the conductivity of fluid-saturated rocks can also be determined.

As can be seen, the data in the literature are very close to the determined values. Also in this book chapter, we managed to model the thermal conductivity

depending on the density and porosity of the rocks.

The equations that best describe this behavior are polynomial, the values of the coefficients being a function of the porosity and density of the rocks.
