Permeability determination of the medium according to the analysis of laboratory hydraulic fracturing curves.

Recently, attention to the development of low-permeable reservoirs has been increasing. More and more attention is being paid to the search for various methods of data analysis of mini-hydraulic fracturing and computer modeling of the hydraulic fracturing process, which will simplify the entire procedure of hydraulic fracturing in a real field and reduce financial costs. The increase in interest is due to the fact that the results of the hydraulic fracturing are used to determine some important characteristics of the formation.

One of such important characteristics of a reservoir is permeability. In the course of this study, the data obtained from a series of laboratory experiments on mini-hydraulic fracturing were processed. The main goal was to determine the value of permeability of the medium in which the hydraulic fracture was formed and propagated, with the help of various standard methods. The second objective of the study was to compare the calculated values with real ones known from preliminary conducted laboratory experiments.

In the frame of the work, the laboratory experiments on mini-hydraulic fracturing were carried out using a special experimental setup [1]. The uniqueness of this experimental setup lies in the fact that it allows to perform a triaxial loading of the sample under consideration. The sample material was selected according to the similarity criteria between the fracturing process in the experiment and the fracturing process in the real field. These features make it possible to approximate the conditions of a laboratory experiment on hydraulic fracturing to real field conditions.

As a result, pressure-time dependencies were obtained for series of laboratory experiments. Further analysis of the curves was carried out in the time period after fracture closure.

In the course of data analysis, the flow regimes in the medium during the time period after fracture closure were estimated. After that, the values of permeability were calculated using approach introduced by Nolte [2, 3]. The permeability values were also estimated using the method proposed by Horner [4] and later modified by Nolte [5]. All theoretically obtained values were compared with real values of permeabilities.

Acknowledgements

The reported study was funded by RFBR, project number 20-35-80018, and state task 0146-2019-0007.

References

1. Trimonova M., Baryshnikov N., Zenchenko E., Zenchenko P., Turuntaev S.: “The Study of the Unstable Fracture Propagation in the Injection Well: Numerical and Laboratory Modelling,” (2017).

2. Nolte, K. G.: “Determination of Fracture Parameters from Fracturing Pressure Decline,” Las Vegas (1979).

3. Nolte, K. G.: “A General Analysis of Fracturing Pressure Decline With Application to Three Models,” (1986).

4. Horner, D. R.: “Pressure Build-Up in Wells,” Netherlands (1951).

5. Nolte, K. G., Maniere, J. L., Owens, K. A.: “After-Closure Analysis of Fracture Calibration Tests,” Texas (1997).