Research On Gunpowder System And Deflagration Characteristics Of High-energy Gas Fracturing

High-energy Gas Fracturing is also called deflagration fracturing, but so far, for research of this fracturing technology still stays in qualitative level. The site design and construction, such as the charge of gunpowder,the gunpowder fire efficacy and the size of gunpowder burning rate, with more experience. However, it can not accord to the specific circumstances of reservoir to choose the best way to knock gunpowder. In view of the above problems, this thesis extensively investigates common gunpowder of the fracturing site, and has research for deflagration characteristics of these gunpowder.Based on investigating field common gunpowder, we established the complete equipment for researching gunpowder deflagration characteristics, including the closed bomb vessel,the pressure calibration machine,the high frequency pressure sensor,the function signal generator,the data acquisition and processing device,the laptop and the software of P~t testing. Using the above laboratory equipment, we test the P~t curve of nitration cotton gunpowder,shoot to nail gunpowder,double fang-3 gunpowder in the closed bomb vessel. Combined the calculation formula of gunpowder combustion rate, we draw out the burning rata chart of these three gunpowder. According to the burning rate chart, we can quantitatively describe the size of burning rate under certain pressure, and then we have a combination for different burning rate gunpowder, through the reasonable charging structure, and make it regularly deflagration in the wellbore, then produce multiple pulse wave for continuous load fracturing in the strata, forming more and more fractured system, lastly it enhances and improves the penetration and diverting capacity of strata. Therefore, the technology of multistage burning rates bums induction greatly improve the charge of gunpowder and the utilization of fracturing energy, extend the duration of the strata, then strengthen the fracturing effect of strata.In the basis of gunpowder burning rate formula, we deduce and establish speed geometric model of gunpowder deflagration,mass conservation model of gunpowder deflagration,energy conservation model of gunpowder deflagration and the wellbore temperature calculation model after gunpowder deflagration. Using these models, we calculate the curve of nitration cotton gunpowder,shoot to nail gunpowder and double fang-3 gunpowder, and comparison with the measured P~t curve.The present paper is in the basis of the existing research results, then we establish the gunpowder deflagration dynamic models in the bottom-hole environment, to achieve the purpose of researching the changes of environment pressure and environment temperature in the process of gunpowder deflagration.