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煤岩层孔隙度空间属性模型构建技术及应用

Construction technology and application of spatial attribute model of Coal-Rock strata porosity

  • 摘要: 随着煤炭开采强度的增加,矿井水害风险日益严峻,孔隙度作为地层水文地质条件的关键参数之一,其空间分布的精确刻画对矿井防治水工作至关重要。以青龙寺煤矿为例,基于140个钻孔数据、煤层底板等高线图、煤层厚度图以及地质剖面图等,其中66个钻孔包含测井数据,采用离散光滑插值(DSI)构建了井田地层几何模型。研究中,针对主采煤层及其顶底板、主要隔水层等关键地层,网格剖分垂向精度达到0.2 m,总计使用约3 500万个六面体体元离散化地质空间。在此基础上,通过设定密度阈值(2.3 g/cm3),分段选择体积物理模型与回归分析相结合的方式计算孔隙度曲线,将其映射到网格模型中,并以岩性模型为约束,利用序贯高斯模拟算法构建了孔隙度属性模型。结果表明,通过设定密度阈值并动态优化计算参数,并引入岩性模型作为地质统计学约束,确保了孔隙度属性在各岩性空间内符合原始数据分布规律,以此提升了孔隙度解释的准确性,从而构建了符合岩性分布特征的孔隙度属性模型。同时,通过工作面顶板孔隙度模型,可辅助预测其富水性变化,为矿井防治水工作提供数据支撑。例如,通过5-20303工作面顶板25、40 m层位孔隙度模型与瞬变电磁探测结果交叉验证,间接证明模型可靠,且高孔隙区与低阻异常区存在显著关联,可为顶板富水性评价提供地质参数和指示信息。该研究为三维地质属性建模的发展提供了参考,也为矿井水文地质特征分析提供了新的技术手段。

     

    Abstract: With the increasing intensity of coal mining, the risk of mine water hazards has become more severe. As one of the key parameters of hydrogeological conditions in strata, porosity plays a vital role in mine water prevention and control. Accurately characterizing its spatial distribution is essential. Taking the Qinglongsi coal mine as a case study, a stratigraphic geometric model was constructed using discrete smooth interpolation (DSI) based on data from 140 boreholes, contour maps of the coal seam floor, coal seam thickness maps, and geological cross-sections. Among the boreholes, 66 contained logging data. For key stratigraphic layers, such as the main mining coal seam and its roof and floor, as well as major aquicludes, the model achieved a grid vertical resolution of 0.2 meters, with approximately 35 million hexahedral elements used to discretize the geological space. Based on this model, porosity curves were calculated by segmentally combining volumetric physical models with regression analysis using a density threshold of 2.3 g/cm3. These curves were then mapped onto the grid model. Constrained by a lithological model, the porosity attribute model was further generated using a sequential Gaussian simulation algorithm. The results show that by setting a density threshold, dynamically optimizing calculation parameters, and incorporating the lithological model as a geostatistical constraint, the porosity attributes within each lithological unit closely follow the distribution patterns of the original data. This significantly improves the accuracy of porosity interpretation and leads to the construction of a porosity model that aligns with lithological distribution characteristics. Furthermore, the porosity model of the working face roof can help predict variations in water-bearing capacity, providing data support for mine water hazard prevention. For instance, cross-validation between the porosity models at the 25 m and 40 m horizons of the 5-20303 working face roof and the transient electromagnetic detection results indirectly demonstrates the reliability of the model. Moreover, a significant correlation exists between high-porosity zones and low-resistivity anomalies, which can provide geological parameters and indicative information for evaluating aquifer enrichment in the roof. This study provides a valuable reference for the development of 3D geological property modeling and offers a new technical approach for analyzing hydrogeological characteristics in mines.

     

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