# Experimental Study on High-Energy Gas Fracturing Artificial Coal
## 3 High-Energy Gas Fracturing Test  
### Fracturing Agent Formulation and Parameters  
Based on the results of the above analysis, the fracturing agent should meet the following requirements. The fracturing agent does not produce toxic and harmful gases; the energy utilization rate is high when fracturing the coal body; the fracturing agent can produce a large amount of gas that can steadily drive the fracture expansion; the production, transportation, and use process of the fracturing agent should be able to ensure safety. As a result of the analysis, the above requirements were achieved through the following methods. (1) Carefully selecting raw materials and performing oxygen balance calculations to reduce toxic and harmful gases. (2) The gas-production speed of the fracturing agent is controlled by adjusting the ratio so that the intensity of the stress wave generated near the borehole by the high-energy gas impact is between the dynamic tensile strength and dynamic compressive strength of coal. (3) Select ammonium perchlorate as the main gas-producing agent, which can produce a large amount of gas after thermal decomposition. (4) There are no explosive substances such as ammonium nitrate, ammonium hyper phosphate, and nitroamine in the fracturing agent, which will not spontaneously combust under general stimulation such as friction, impact, and static electricity, ensuring the safety of production, storage, transportation, and use. Through screening and oxygen balance calculation, a fracturing agent suitable for coal mines was developed. The fracturing agent formula is shown in Table 1. According to the oxygen balance calculation, the oxygen balance value of the fracturing agent is 1.6 %, which means that few toxic and harmful gases, such as CO and CH4, will be produced in the process of fracturing coal with the fracturing agent. To find the basic performance parameters of the fracturing agent. The rate of ignition, explosion heat, gas production, and the density of the fracturing agent were tested by the target line method, constant temperature method, pressure method, and weighing method, respectively [25]. The results are shown in Table 2. From the table, it can be seen that the developed fracturing agent produces at least 1400 L/kg of gas, and it can generate a lot of heat. The impact sensitivity and friction sensitivity of the fracturing agent were tested using the explosion probability method [25], and the test conditions and results are shown in Table 3. From Table 3, it can be seen that the friction sensitivity and impact sensitivity of the fracturing agent are 8% and 10%, respectively, while the sensitivity of general fire explosives under the same conditions is above 20%, which means the sensitivity of the fracturing agent in this paper is low. Table 3 also shows the test results of the pressure and temperature resistance of the fracturing agent. The results show that the fracturing agent will not affect normal use when the pressure is less than 120 MPa and the temperature is lower than 163 \({}^{\circ}\)C. \begin{table}
\begin{tabular}{c c c c} \hline
**Raw Material** & **Specification** & **Ratio/\%** & **Effect** \\ \hline HTPB [1] & Type I & Binder \\ TDI [2] & Industrial Grade & 13.39 & Curing agent \\ KZ 3 & Industrial Grade & 3.5 & Plasticizer \\ AP [4] & Type III & 73.0 & Cas generating Agent \\ AP [4] & Type IV & 5.0 & \\ Al [5] & Industrial Grade & 5.0 & Heating agent \\ Others & & 0.11 & \\ \hline \end{tabular} Notes: [1] HTPB (HO- [CH\({}_{2}\)CH-CHCH\({}_{2}\)]n-OH) is Hydroxyl-terminated polybutadiene; [2] TDI(C\({}_{3}\)H\({}_{6}\)N\({}_{2}\)O\({}_{2}\)) is Toluene disocyanate; [3] KZ(C\({}_{26}\)H\({}_{50}\)O\({}_{4}\)) is dicotyl sebacte; [4] AP(NH\({}_{4}\)ClO\({}_{4}\)) is Ammonium perchlorate; [5] Al is Aluminum.  
\end{table} 
Table 1: Composition of high-energy gas fracturing agent.