| 基于方位伽马的煤岩界面探测数值模拟研究 |
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| 引用本文： | 陈刚,陈龙,李泉新,刘志毅.基于方位伽马的煤岩界面探测数值模拟研究[J].煤田地质与勘探,2022,50(10):140-144. |
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| 作者姓名： | 陈刚 陈龙 李泉新 刘志毅 |
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| 作者单位： | 1.兰州大学 核科学与技术学院，甘肃 兰州 730000 |
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| 基金项目： | 国家自然科学基金项目(42102350)；中国博士后科学基金项目(2022M711442)；天地科技股份有限公司科技创新创业资金专项项目(2022-2-TD-MS005) |
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| 摘 要： | 为满足随钻方位伽马地质导向钻进需求，通过数值模拟研究围岩厚度和吸收系数不同情况下伽马射线强度响应值。模拟分析伽马探测器在含放射性地层条件下，伽马测量值API反映空间物理特征的差异性。在此基础上，建立八扇区随钻方位伽马钻进煤、泥、灰岩3层地质模型，模拟钻进煤层顶底板识别过程。模拟结果表明:当岩层吸收系数由0.08变为0.10时伽马射线强度减小一半，伽马幅度变化能够反映钻进地层岩性，而上下伽马变化顺序能够指示穿越煤层顶板或底板及分界面所在位置；当小角度穿层时，探测器到钻头的距离分别为1、3、7 m时，能够监测前方钻进8、6、2 m地层物性的变化。顺层钻进模拟可为地质导向工程提供技术指导，提高钻进效率减少无效进尺。
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| 关 键 词： | 随钻方位伽马 八扇区方位 围岩影响 钻进模拟 顶底板识别 |
| 收稿时间： | 2021-10-23 |
Numerical simulation on azimuth gamma ray detection of coal and rock interface |
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| Institution: | 1.School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China2.Xi’an Research Institute (Group) Co. Ltd., China Coal Technology and Engineering Group Corp., Xi’an 710077, China |
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| Abstract: | In order to meet the requirements of geosteering drilling with LWD azimuth gamma, the response value of gamma ray intensity under different surrounding rock thicknesses and absorption coefficients was studied by numerical simulation. Meanwhile, the variation of special and physical characteristics reflected by API value measured by gamma detector under the radioactive formation conditions was simulated and analyzed. On this basis, the geological model of the three layers of coal, mudstone and limestone of 8-sectors azimuth gamma ray drilling was established to simulate the identification process of roof and floor of coal bed drilled. The simulation results show that the gamma ray intensity is reduced by half when the absorption coefficient of rock layer is changed from 0.08 to 0.10. Generally, the gamma amplitude could reflect the lithology of the drilled formation, and the upper and lower gamma change order can indicate the location of roof, floor and interface of the coal bed penetrated. In the case of penetration at small angle, the change of physical properties of the 8 m, 6 m and 2 m formation ahead of drilling could be monitored if the distance from detector to bit is 1 m, 3 m and 7 m respectively. The simulation of bedding drilling could provide technical guidance for the geosteering project, so as to improve the drilling efficiency and reduce the invalid footage. |
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