Hua Chunlei, Wang Zhaofeng, Su Erlei, Dong Jiaxin, Yue Jiwei, Cui Yongjie, Zhang Kangjia
State Collaboration Innovation Center of Coal Work Safety and Clean-efficiency Utilization, Jiaozuo454000, China.
College of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo454000, China.
ACS Omega. 2022 Nov 1;7(45):41341-41352. doi: 10.1021/acsomega.2c05120. eCollection 2022 Nov 15.
Coal seam gas pressure is one of the basic parameters for coalbed methane resource exploitation and coal mine gas disaster prevention. However, the present coal seam gas pressure measurement technology requires harsh field measurement conditions and a long testing period. In this study, a novel non-seal gas pressure measurement technology is proposed, and this technology is mainly aimed at three different changes before and after the collection of coal samples and realizes the real gas pressure measurement through the compensation of gas leakage, in situ volume recovery of the coal core, and reservoir temperature simulation. The technique not only can measure the original gas pressure of coal seam quickly and accurately but also does not need to seal the measuring hole. This paper focuses on the study of a key factor that affects the accuracy of non-seal gas pressure measurement: the restoration of in situ volume. Based on this, the influence of four different volume recovery methods on the measurement accuracy is compared with the self-developed non-sealing gas pressure measuring system. Experimental results show that the volume of the coal core cannot be completely restored by stress loading. Although the contact injection method can restore the original volume of the coal core, the pressure recovery error is large due to the replacement and displacement of the gas effect of water and the inclusion of the coal body effect of oil. Interestingly, the combination of stress loading and contact oil injection can not only restore the original volume of the coal core but also minimize the pressure recovery error, which is only less than 10%. Finally, based on the abovementioned experimental results, the volume recovery method of non-seal gas pressure measurement technology is improved. Therefore, the research results of this paper provide a scientific basis for the field application of non-seal gas pressure measurement technology.
煤层瓦斯压力是煤层气资源开采和煤矿瓦斯灾害防治的基本参数之一。然而，目前的煤层瓦斯压力测量技术对现场测量条件要求苛刻，测试周期长。本研究提出了一种新型的非密封瓦斯压力测量技术，该技术主要针对煤样采集前后三种不同的变化情况，通过瓦斯泄漏补偿、煤芯原位体积恢复和储层温度模拟实现真实瓦斯压力测量。该技术不仅能快速、准确地测量煤层原始瓦斯压力，而且无需密封测量孔。本文重点研究了影响非密封瓦斯压力测量精度的一个关键因素：原位体积恢复。基于此，利用自主研发的非密封瓦斯压力测量系统，比较了四种不同体积恢复方法对测量精度的影响。实验结果表明，通过应力加载不能完全恢复煤芯体积。虽然接触注入法能恢复煤芯原始体积，但由于水的气体置换和驱替作用以及油的煤体包裹作用，压力恢复误差较大。有趣的是，应力加载和接触注油相结合不仅能恢复煤芯原始体积，而且能将压力恢复误差降至最小，仅小于10%。最后，基于上述实验结果，对非密封瓦斯压力测量技术的体积恢复方法进行了改进。因此，本文的研究成果为非密封瓦斯压力测量技术的现场应用提供了科学依据。
