Huang Xing, Li Qiyue, Wei Xin'ao, Yang Xiaoxiao, Luo Dayou, Zeng Haideng, Wang Hongwei
School of Resources and Safety Engineering, Central South University, Changsha 410083, China.
Department of Civil and Environmental Engineering, Francis College of Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA.
Sensors (Basel). 2020 Apr 23;20(8):2395. doi: 10.3390/s20082395.
Liquid carbon dioxide phase change fracturing technology (LCPCFT) has been widely used in engineering blasting due to the advantage of no flames, and no toxic and harmful gas. However, few studies have been conducted on the acquisition of shock wave pressure and its loading characteristics, which are key parameters in fracturing. Referring to the CO in-situ fracturing technology, an indoor test system for shock wave pressure generated during LCPCFT has been built, with a protected polyvinylidene fluoride (PVDF) piezoelectric sensor. Then three verification experiments with different radial distances between the fracturing tube and test points were carried out on the test system, and in each experiment, four PVDF sensors as four test points were arranged with different axial distance from the detonating point to test the pressure distribution. The experimental results show that when the radial distance between the fracturing tube and test points is not too large (≤345 mm), the pressure generated during LCPCFT is approximately uniformly distributed within the axial length of the fracturing tube, but when it is relatively large (≈895 mm), the results between different test points are in a certain degree of dispersion. And finally, this paper uses the intraclass correlation coefficient (ICC) and coefficient of variation (C) of peak pressure and impulse to process the test results to evaluate the reliability and stability of the test system. Evaluation results show that the test results are in good consistency. The test system in this paper has good stability and high reliability. The test system provides a useful tool for accurately obtaining the shock wave pressure, which is helpful for further research on LCPCFT.
液态二氧化碳相变压裂技术（LCPCFT）因其无火焰、无有毒有害气体的优点而在工程爆破中得到广泛应用。然而，关于压裂关键参数冲击波压力的获取及其加载特性的研究却很少。参照二氧化碳原位压裂技术，搭建了一套用于液态二氧化碳相变压裂技术冲击波压力测试的室内试验系统，采用了具有防护的聚偏氟乙烯（PVDF）压电传感器。然后在该试验系统上进行了3次压裂管与测点径向距离不同的验证试验，每次试验中，布置4个PVDF传感器作为4个测点，与起爆点轴向距离不同，以测试压力分布。试验结果表明，当压裂管与测点的径向距离不太大（≤345mm）时，液态二氧化碳相变压裂技术产生的压力在压裂管轴向长度范围内近似均匀分布，但当径向距离较大（≈895mm）时，不同测点的结果存在一定程度的离散。最后，本文采用峰值压力和冲量的组内相关系数（ICC）和变异系数（C）对试验结果进行处理，以评估试验系统的可靠性和稳定性。评估结果表明试验结果具有良好的一致性。本文的试验系统具有良好的稳定性和较高的可靠性。该试验系统为准确获取冲击波压力提供了有用工具，有助于对液态二氧化碳相变压裂技术的进一步研究。
