**5. Translation of lab-scale results into field-scale ones**

With the properties of multi-scale pore structures and various reservoir modes, the shale gas reservoir is complex in reservoir space and occurrence modes, which in turn leads to different flow mechanisms in multi-scale spaces. Therefore, adopting single-scale equations and flow simulation methods will not accurately reveal the flow mechanism in complex shale gas reservoirs [60]. Jiao et al. [61] established an effective conversion relation between physical simulation parameters and field parameters based on similarity criterion to better simulate gas reservoir development. The ideas in literature [61] are narrated as follows.

First, considering the flow mechanism of shale gas in the reservoir, the selected characteristic physical parameters are permeability *K*, porosity *ϕ*, pore radius *r*, length *L*, original pressure *pi*, flow rate of gas production *q*, gas compression factor *Z*, reservoir temperature *T*, standard temperature *Tsc*, and standard atmospheric pressure *psc*. According to the π theory, there are four basic dimensions named length dimension [L], mass dimension [M], time dimension [T], and temperature dimension [K]. Therefore, each of π is obtained, and field parameters are analyzed to deduce physical simulation parameters in the experiment according to the similarity criterion, as shown in **Table 4**.

Second, based on the similarity criterion, the conversion relation between physical simulation parameters and field parameters can be established, which is expressed as:

$$q\_g = \frac{\pi r^2 K\_{rg} K T\_{sc} p\_i^2}{\mathrm{L uZ T} p\_{sc}} \left(\frac{\mathrm{L uZ T} p\_{sc}}{\pi r^2 K\_{rg} K T\_{sc} p\_i^2} q\right)\_m \tag{10}$$

where *m* indicates that the parameters inside the brackets are for the physical simulation.

Finally, choose the core sample "Ning 211-1" for an example to conduct dynamic physical experiment under different conditions, which is used to verify the


**Table 4.**

*Similarity criterion numerals of the gas reservoir physical simulation.*


*Mechanism, Model, and Upscaling of the Gas Flow in Shale Matrix: Revisit DOI: http://dx.doi.org/10.5772/intechopen.91821*

**Table 5.** *Parameters for application.*

### **Figure 5.**

*Comparison of actual values of reservoir and predicted field results based on similarity conversion.*

rationality of the similarity criterion. The related parameters, values of physical simulation (*qm*), converted values of field (*qg*), and actual values of reservoir (*q*) are presented in **Table 5**.

**Figure 5** displays the curves of actual values of reservoir and predicted field results based on similarity conversion, the latter of which are calculated from the physical experiment. The results calculated by similarity criterion are basically consistent with the on-site tested data. It is expected that applying the similarity translation from physical simulation of gas reservoirs is capable of predicting the development performance effectively, showing the rationality of the translation method.
