# Research on an Equivalent Algorithm for Predicting Gas Content in Deep Coal Seams
## 5 Example of Coal Seam Gas Content Prediction
### Predictive Testing  
The accuracy of the prediction results is judged by comparing the gas content values predicted by the gas geological method [32] and equivalent algorithm with the gas content  
Figure 1: Coal seam gas content contour displayed by prediction software.  
Figure 2: Contour line of coalbed methane content (m\({}^{3}\)/t).  
values measured in the mining face. The gas geological method is actually a comprehensive analysis of the geological structure, gas, and structural coal conditions of coal seams, mining areas, working faces, or tunnels. It identifies their differences and connections in time and space and determines the gas emission rate at each location based on a certain combination of quantitative indicators.  
The inspection site is selected from the 6121 fully mechanized mining face of the 12 th coal seam in a certain mine, as indicated by the two dashed boxes in Figures 3 and 4. The equivalent layer in this area is thick mudstone with an average depth of 850 m. The residual gas volume of the coal seam is calculated to be 2.7 m\({}^{3}\)/t.  
The actual gas emission monitoring values and the gas emission amounts obtained from two locations using the prediction method and gas geological method proposed in this article are shown in Table 5.  
By comparing the prediction results of the method proposed in this article, the calculation results of the gas geological method, and the monitoring data of gas emission, it was found that:  
(1) Although the gas content estimations generated by the gas geological method remained relatively consistent in April, they failed to accurately reflect the actual fluctuations in gas content that occurred in May.  
Figure 4: Isoline values of coal seam gas content predicted by gas geological method.  
Figure 3: Equivalent algorithm for predicting the contour values of coal seam gas content.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Forecast Date**} & **Gas Monitoring Report (m\({}^{3}\)/t)** & **Gas Geological Method Prediction (m\({}^{3}\)/t)** & **Equivalent Algorithm Prediction (m\({}^{3}\)/t)** \\ \hline April 2023 & 4.4 & 4.3 & 5.0 \\ May 2023 & 5.0 & 4.3 & 5.4 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Statistics of average gas content at 6121 fully mechanized mining faces.  
(2) The gas content estimated through the equivalent algorithm exhibits commendable accuracy in mirroring the actual fluctuations in gas content; however, the numerical outcomes are consistently elevated, ranging between 0.4 to 0.6 m\({}^{3}\)/t. The principal explanation for this discrepancy lies in the proximity of the working face to adjacent goal areas, resulting in a degree of pre-discharge of coal seam gas. Nevertheless, it is imperative to note that the equivalent algorithm's predictions do not account for the multifaceted influence of mining parameters and thus yield values that approximate the virgin state of the coal prior to extraction.  
Test results indicate that, after excluding the potential interference from mining factors, the predicted coal seam gas content, as calculated by the equivalent algorithm, aligns closely with the actual coal seam gas content. While a degree of error is present, it falls within the tolerable limits as determined by field standards.