崔鹏飞，高明忠，尚德磊，等. 基于保压取心的深部煤层原位压力计算原理及方法初探[J]. 煤田地质与勘探，2023，51(8)：59−67. DOI: 10.12363/issn.1001-1986.22.12.0934
引用本文: 崔鹏飞，高明忠，尚德磊，等. 基于保压取心的深部煤层原位压力计算原理及方法初探[J]. 煤田地质与勘探，2023，51(8)：59−67. DOI: 10.12363/issn.1001-1986.22.12.0934
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CUI Pengfei，GAO Mingzhong，SHANG Delei，et al. A preliminary study of pressure-preserved coring calculation principle and method for in-situ pressure in deep coal seams[J]. Coal Geology & Exploration，2023，51(8)：59−67. DOI: 10.12363/issn.1001-1986.22.12.0934
Citation: CUI Pengfei，GAO Mingzhong，SHANG Delei，et al. A preliminary study of pressure-preserved coring calculation principle and method for in-situ pressure in deep coal seams[J]. Coal Geology & Exploration，2023，51(8)：59−67. DOI: 10.12363/issn.1001-1986.22.12.0934
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基于保压取心的深部煤层原位压力计算原理及方法初探

A preliminary study of pressure-preserved coring calculation principle and method for in-situ pressure in deep coal seams

    摘要
  • 摘要: 准确获取煤层原位瓦斯压力是防治瓦斯灾害的关键环节，现阶段仍需探寻测量准确、经济投入小、测定周期短的瓦斯压力测定手段。基于深部煤层原位保压取心原理技术，提出了深部煤层原位瓦斯压力计算方法并形成其测定流程，构建了保压空间内瓦斯压力演化数值模型，对比理论与数值模拟结果验证方法的可靠性，进一步探究煤层不同原位瓦斯压力下保压空间内瓦斯压力演化规律。结果表明：保压空间中瓦斯压力示数并非煤层原位瓦斯压力，当保压空间中压力示数为0.3 MPa时，煤层原位瓦斯压力约0.38 MPa；保压空间中瓦斯压力平衡值越大，原位状态游离瓦斯占比越大，平衡后游离瓦斯质量占比也越大；随着保压空间中瓦斯由原位状态向新平衡态转换，游离瓦斯质量占比逐渐增加，吸附态瓦斯质量占比则相应减小；保压空间内瓦斯压力演化规律分为3个阶段，自取心完成后分别经历瓦斯压力快速增加、缓慢增加以及最终平衡阶段；基质内吸附态瓦斯压力缓慢衰减，游离态瓦斯压力快速衰减，保压空间内瓦斯压力先快速增加后趋于稳定最终达到压力平衡；煤心渗透率越大，保压空间中瓦斯压力达到平衡所需时间越短，但其保压空间中瓦斯压力最终平衡压力与煤心渗透率无关。

     

    Abstract: The accurate acquisition of in-situ gas pressure in coal seams is a key link in the chain of the prevention and control of gas disasters. Presently, it is still necessary to explore accurate, low-cost, and time-saving methods for determining gas pressure. Based on the in-situ pressure-preserved coring for deep coal seams, this study proposed a calculation method for in-situ gas pressure in deep coal seams and developed the calculation process. Using the constructed numerical model of the gas pressure evolution in the pressure-preserved space, this study verified the reliability of the proposed method by comparison with the theoretical and numerical simulation results. Accordingly, this study further explored the evolutionary pattern of the gas pressure in the pressure-preserved space under different in-situ gas pressures in coal seams. The results indicate that (1) the indicated value of gas pressure in the pressure-preserved space is not the in-situ gas pressure in coal seams. When the indicated value was 0.3 MPa, the in-situ gas pressure of coal seams was about 0.38 MPa; (2) a higher gas pressure after equilibrium in the pressure-preserved space corresponds to a higher proportion of in-situ free gas and a higher proportion of the mass of free gas after equilibrium; (3) with the conversion of gas in the pressure-preserved space from the in-situ state to a new equilibrium state, the proportion of the mass of free gas increases gradually, while that of the mass of adsorbed gas decreases correspondingly; (4) after coring, the gas pressure in the pressure-preserved space evolves from rapid increase to slow increase and then to equilibrium since the pressure of the adsorbed gas in the matrix decreases slowly while the pressure of free gas decreases rapidly; (5) a higher permeability of coal cores corresponds to a shorter time required for the gas pressure in the pressure-preserved space to reach equilibrium. However, the final gas pressure in the pressure-preserved space after equilibrium is independent of the permeability of coal cores.

     

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