桂和荣,李俊,陈永青,等. 基于主量元素地球化学的岩屑层位源解析[J]. 煤炭学报,2024,49(2):929−940. DOI: 10.13225/j.cnki.jccs.YH23.1176
引用本文: 桂和荣,李俊,陈永青,等. 基于主量元素地球化学的岩屑层位源解析[J]. 煤炭学报,2024,49(2):929−940. DOI: 10.13225/j.cnki.jccs.YH23.1176
GUI Herong,LI Jun,CHEN Yongqing,et al. Geochemical source analysis of rock cuttings based on major elemental geochemistry[J]. Journal of China Coal Society,2024,49(2):929−940. DOI: 10.13225/j.cnki.jccs.YH23.1176
Citation: GUI Herong,LI Jun,CHEN Yongqing,et al. Geochemical source analysis of rock cuttings based on major elemental geochemistry[J]. Journal of China Coal Society,2024,49(2):929−940. DOI: 10.13225/j.cnki.jccs.YH23.1176

基于主量元素地球化学的岩屑层位源解析

Geochemical source analysis of rock cuttings based on major elemental geochemistry

  • 摘要: 近年来,岩屑录井在“华北型”煤田底板灰岩层注浆加固工程中发挥了重要作用。然而,现有的岩屑录井仅停留在颜色、颗粒大小及形貌特征等物理指标的识别上,难以精准判层,钻孔设计“顺层率”难以保障,制约着底板灰岩水害区域治理效果。基于石炭纪太原组薄层灰岩及其碎屑岩夹层的元素地球化学差异特点,选取淮北煤田桃园煤矿为研究区,对太原组上段薄层灰岩L1灰~L4灰地层(注浆治理目的层为L3灰)垂直钻孔岩心进行取样,利用X射线荧光光谱仪(XRF)定量测定了薄层灰岩及其夹层的主量元素背景值,通过聚类分析、因子分析等数理统计手段建立薄层灰岩主量元素地球化学识别模式;同时对地面定向钻水平分支孔岩屑同样开展主量元素测试,并基于已建立的地球化学识别模式进行岩屑层位源解析以及识别模式验证。结果显示:高CaO丰度、烧失量(LOI)可以作为注浆加固改造目的层L3灰的特征指标,MgO(0.5%±)、MnO(0.03%±)、P2O5(0.08%±)丰度可作为注浆目的层上覆标志层J3的识别指标;聚类分析识别模式可有效区分太原组一灰~三灰(L1灰~L3灰);以元素因子得分建立的识别模式可以将太原组碎屑岩夹层与薄层灰岩进行有效区分;以岩样地球化学背景值运行判别模型得到的Fisher判别方程对注浆目的层L3灰岩屑来源解析的准确率为100%。基于上述认识,论证了以确保设计“顺层率”为目标的水平分支孔岩屑地球化学源解析方法应用之可行性,进而提出了一种地面定向钻“顺层率”控制技术方案。本研究基于元素地球化学理论,对地面定向钻岩屑携带的特征地球化学信息进行了目的层层位辨识,在现场快速定量测试技术手段的支持下,可为解决华北型煤田底板灰岩水害区域注浆改造顺层难题提供了新的思路。

     

    Abstract: In recent years, shale logging has played a crucial role in the grouting reinforcement engineering of the floor limestone strata in “North China-type”coalfields. However, existing shale logging techniques are limited to the recognition of physical indicators such as color, particle size, and morphology. This limitation makes an accurate stratification challenging, and the “along-stratum rate” in borehole design is difficult to be ensured. These constraints hinder the effectiveness of water damage control in the floor limestone strata areas. This study, based on the elemental geochemical differences in the Carboniferous Taiyuan Formation thin-layered limestone and its clastic interlayers, selected the Taoyuan Coal Mine in the Huaibei Coalfield as the research area. Some vertical core samples were obtained from drill holes in the upper part of the Taiyuan Formation, including L1 limestone to L4 limestone (with L3 limestone as the grouting control target layer). Using the X-ray fluorescence spectrometry (XRF), the major elemental background values of thin-layered limestone and its interlayers were quantitatively determined. Also, a major elemental geochemical identification model was established for thin-layered limestone using mathematical statistical methods such as cluster analysis and factor analysis. Simultaneously, major elemental testing was conducted on shale samples from directional drilling horizontal branch holes. The identification pattern validation was completed through shale stratigraphic source analysis based on the established geochemical identification model. The results showed that high CaO content and Loss on Ignition (LOI) value could serve as characteristic indicators for the target layer L3 limestone in grouting and reinforcement. Abundances of MgO (0.5%±), MnO (0.03%±), and P2O5 (0.08%±) could be used as recognition indicators for the overlying marker layer J3. The cluster analysis identification model effectively distinguished the Taiyuan Formation L1 to L3 limestone. The model established using element factor scores effectively differentiated clastic interlayers from thin-layered limestone in the Taiyuan Formation. The Fisher discriminant equation obtained by running the model with rock geochemical background values achieved an accuracy rate of 100% in the source analysis of cuttings from grouting target layer L3 limestone. Based on the above findings, the feasibility of applying the elemental geochemical source analysis method, aimed at ensuring the “in-layer rate” in horizontal branch hole cuttings, was demonstrated. This, in turn, led to the proposal of a ground directional drilling “in-layer rate” control technology scheme. This study, grounded in elemental geochemical theory, identified the target layer stratification through characteristic geochemical information carried by cuttings from directional drilling. With the support of on-site rapid quantitative testing techniques, the technology offers new insights into addressing the challenge of grouting and modification at bottom limestone water hazard areas in the North China-type coalfields.

     

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