云南普朗铜矿井孔测井资料综合应用
Comprehensive application of borehole log data of the Pulang copper deposit, Yunnan Province
通讯作者: 马火林(1970-),男,博士,副教授。Email:mhl70@163.com
责任编辑: 叶佩
收稿日期: 2022-03-23 修回日期: 2022-10-8
基金资助: |
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Received: 2022-03-23 Revised: 2022-10-8
作者简介 About authors
杨朝义(1987-),男,采矿工程师,主要从事矿产资源开发及生产技术管理工作。Email:
云南普朗铜矿的铜矿化体和矿体主要分布于普朗复式斑岩体内,存在复杂的多期发育。为了精细了解铜矿储层的地球物理响应特征、裂隙发育特征,为普朗铜矿的勘探和开采提供精细的矿体特征、裂隙发育及层位埋深等方面的信息,通过对普朗铜矿的钻孔测井数据采集和综合评价,结合钻孔编录、部分岩心样品资料,利用数学统计、三维交会图、卷积神经网络及裂隙参数计算等开展了普朗铜矿测井响应特征分析、岩性识别和裂隙特征分析的研究。研究区石英二长斑岩、石英闪长玢岩、角岩等三类主要岩石地层的测井响应特征表明,角岩地层的电阻率相对较高,石英闪长玢岩地层、石英二长斑岩地层的电阻率依次相对偏低,在裂隙发育层段或较为破碎的层段,电阻率降低明显。石英二长斑岩地层的充电率(极化率)相对较高,最高达10%。角岩地层的放射性强度相对较高,石英闪长玢岩地层、石英二长斑岩地层的放射性强度相对偏低。采用卷积神经网络对三类主要岩石地层进行测井岩性识别分析,准确率为97.94%。利用双侧向电阻率测井资料对地层裂隙进行判别,裂隙发育层段的电阻率会明显降低,且深侧向、浅侧向电阻率差异明显;在铜品位较高的石英二长斑岩地层,其电阻率相对偏低,高角度裂隙比较发育。相关研究结果对于普朗铜矿的矿体特征识别、矿体开采具有意义。
关键词:
The copper mineralized bodies and orebodies of the Pulang copper deposit in Yunnan Province are mainly distributed in the Pulang complex porphyry body and were formed through complex multi-stage development. This study aims to detail the geophysical response and fractures of copper reservoirs and provide detailed orebody characteristics, fractures, and horizon burial depth to be referenced in the exploration and exploitation of the Pulang copper deposit. First, the borehole-log data in the Pulang copper deposit were sampled for comprehensive evaluation. Then, in combination with the drilling reports and data on partial core samples, this study analyzed the log response characteristics and fractures and identified the lithology of the Pulang copper deposit using mathematical statistics, three-dimensional cross plots, convolutional neural networks (CNNs), and fracture parameter calculation. The log response characteristics of the three major strata of quartz monzonite porphyries, quartz diorite porphyrites, and hornstones in the study area are as follows. The hornstone strata have relatively high resistivity, followed by the quartz diorite porphyrite strata and the quartz monzonite porphyry strata in sequence. The resistivity decreases significantly at the intervals with fractures occurring or at the relatively fractured intervals. The quartz monzonite porphyry strata have a relatively high charge rate (polarization rate) of up to about 10%. The hornstone strata have relatively high radioactive intensity than the quartz diorite porphyrite strata and the quartz monzonite porphyry strata. CNNs were used to identify and analyze the lithology of the three major types of strata based on log data, with an accuracy rate of 97.94%. Finally, this study identified fractures in these strata using dual laterolog data. The resistivity significantly decreases at intervals with fractures occurring and differs greatly between deep and shallow lateral resistivity. The quartz monzonite porphyry strata with a high copper grade have relatively low resistivity and relatively well-developed high-angle fractures. The results of this study are of significance for the identification of ore body characteristics and the exploitation of ore bodies in the Pulang copper deposit.
Keywords:
本文引用格式
杨朝义, 朱乾坤, 揭绍鹏, 孔垂爱, 沙有财, 钟志勇, 沈啟武, 陈志军, 马火林.
YANG Chao-Yi, ZHU Qian-Kun, JIE Shao-Peng, KONG Chui-Ai, SHA You-Cai, ZHONG Zhi-Yong, SHEN Qi-Wu, CHEN Zhi-Jun, MA Huo-Lin.
0 引言
普朗铜矿位于云南省西北部的迪庆藏族自治州香格里拉市北东部,地处青藏高原东南缘、滇西北横断山脉东北部,临近三江并流世界遗产保护区。矿区人烟稀少、山高林密,海拔最高4 702 m,最低3 450 m。普朗铜矿为大型—超大型复式斑岩体矿床[1],矿山生产规模为1 250×104 t/a,于2000年开展普查工作,经历了主矿体勘探、整装勘查、探矿及采选、投产运行等阶段,确定了Ⅰ号斑岩体主矿体的基本形态,但Ⅰ号斑岩体与石英闪长玢岩、角岩接触带部分仍未得到完全控制。普朗铜矿床采用自然崩落法进行开采,需要进一步深化矿化富集规律研究,推进“探边摸底”深部找矿、岩性的识别和类型判别等工作。在普朗铜矿勘查阶段,已经开展了航磁、重力、高精度磁测、瞬变电磁和激电测量等地球物理勘探工作,测量得到的各类地球物理响应特征和研究区铜矿(化)体引起的矿致异常密切相关,存在低电阻率、中—高极化(激电异常)等典型电性特征。前期在矿区基本没有开展钻孔测井工作,目前,为了进行“探边摸底”深部找矿和普朗复式斑岩体内部特征调查需要,根据补充勘探的要求开展了钻孔测井综合研究。
此次基于普朗复式斑岩体内部的结构面分布规律、裂隙系统的调查和研究需要,利用矿区勘探钻孔进行测井数据采集和评价的先导性工作,为矿区铜矿储层的地球物理特征分析提供基础数据支撑。
1 普朗铜矿地质特征
图1
由于岩浆多次侵位及断裂构造长期活动,受到岩浆岩、岩浆侵位地层、热液蚀变、热液运移以及矿质沉淀的构造空间控制,矿区内分布NW向和NEE向2组断裂,它们控制了斑(玢)岩体及矿(化)体的产出。根据矿化体(矿体)产出的位置,将其划分为南矿段和北矿段[11]。
普朗铜矿为热液蚀变斑岩型铜矿床,成矿作用发生在复式斑岩体内。成矿元素以铜为主,伴有金、银、钼、硫等有用组分。已查明有14种金属矿物和16种脉石矿物,其中金属矿物有硫化物、氧化物、碳酸盐类、自然元素等;含铜矿物主要为黄铜矿,其次为孔雀石,以及微量的铜蓝、斑铜矿等[12]。主要岩性为石英二长斑岩、石英闪长玢岩、角岩等三类。
2 普朗铜矿测井响应特征
结合普朗铜矿钻孔的特点以及探测目的,本次测井工作采用MOUNT公司Matrix 便携式测井系统,包括主机、测井软件、绞车和各种井下探头等;采集的常规测井数据有10种:深侧向电阻率(RD)、浅侧向电阻率(RS)、自然伽马(GR)、钍(232Th)、钾(40K)、铀(238U)、井径(CAL)、井斜(Dev)、方位角(Azimuth)和充电率(Ma、极化率)等。
在研究区采集了多口井的测井数据,其中ZK18XX的测井综合图如图2所示。该井350~450 m井段Cu品位较高且层段发育不连续,其中395~420 m为一段较厚的高Cu品位层段,相对应的放射性自然伽马数值偏低,深侧向、浅侧向电阻率均偏低(n×102 Ω·m),且2组电阻率数值差异明显,表明该层段存在裂隙发育。
图2
图3
图3
石英闪长玢岩、石英二长斑岩、角岩等三类岩石地层的测井曲线
Fig.3
The logging curves of quartz diorite porphyrite, quartz monzonite porphyry and hornstone formation
图4
图4
三类岩性地层的3种测井参数及铜品位的三维交会图
Fig.4
Three-dimensional cross plot of three logging parameters and copper grade for three lithological formations
表1 三种岩性的测井响应和铜品位参数特征
Table 1
岩性 | 自然伽马/API | Ma/% | RD/(Ω·m) | w(Cu)/% |
---|---|---|---|---|
分布范围(平均值) | 分布范围(平均值) | 分布范围(平均值) | 分布范围(平均值) | |
石英二 长斑岩 | 31~203(135) | 1.9~10.1(4.1) | 204~2931(1223) | 0.3~1.2(0.42) |
石英闪 长玢岩 | 107~219(159) | 0.9~3.9(2.8) | 1302~3901(2015) | 0.33~0.39(0.36) |
角岩 | 116~238(173) | 2.3~4.7(3.1) | 1537~5972(3180) | 0.32~0.52(0.39) |
综合来看,角岩地层的自然伽马数值相对高一些,即放射性强度相对高一些,石英闪长玢岩地层、石英二长斑岩地层的放射性强度相对偏低一些;石英二长斑岩地层的充电率(极化率)相对高一些,角岩地层、石英闪长玢岩地层的充电率(极化率)相对偏低一些;角岩地层的深侧向电阻率相对较高,石英闪长玢岩地层、石英二长斑岩地层依次相对偏低。深侧向电阻率与充电率(极化率)的关系总体成近似的反比关系,即充电率(极化率)越高,电阻率相对偏低;电阻率高,充电率(极化率)会偏低。
3 测井资料岩性识别研究
图5
本文选取研究区5口井的测井数据及综合岩性编录资料,建立起测井资料和石英二长斑岩、石英闪长玢岩、角岩等三类不同岩性的映射关系,开展岩性识别研究。为了最大化利用测井资料,使用了井径(CAL)、自然伽马(GR)、深侧向电阻率(RD)、浅侧向电阻率(RS)、充电率(Ma)、钾含量(40K)、钍含量(232Th)和铀含量(238U)等8种测井数据;另外,将角岩、石英二长斑岩、石英闪长玢岩这三类岩性的标签(Label)分别设置为0、1、2,建立的样本数据集部分数据如表2所示。
表2 CNN训练样本集部分数据
Table 2
岩性 | CAL/cm | GR/API | RD/(Ω·m) | RS/(Ω·m) | Ma/% | w(40K)/% | w(232Th)/10-6 | w(238U)/10-6 | Label |
---|---|---|---|---|---|---|---|---|---|
角岩 | 8.4 | 195.3 | 5343.6 | 2122.7 | 4.5 | 2.9 | 12.4 | 5.6 | 0 |
8.4 | 201.2 | 5343.6 | 2182.5 | 4.7 | 3.1 | 18.8 | 9.1 | 0 | |
8.4 | 170.2 | 5000.0 | 2182.5 | 4.7 | 2.1 | 13.0 | 10.4 | 0 | |
8.3 | 175.3 | 4638.3 | 2302.5 | 4.6 | 4.5 | 0.3 | 8.9 | 0 | |
8.5 | 194.8 | 4638.3 | 2405.9 | 4.3 | 1.8 | 31.3 | 8.5 | 0 | |
8.6 | 198.3 | 4810.1 | 2405.9 | 4.3 | 1.9 | 26.8 | 1.0 | 0 | |
8.4 | 190.6 | 5972.9 | 2270.1 | 4.5 | 5.2 | 9.9 | 11.0 | 0 | |
8.5 | 201.5 | 5972.9 | 2256.6 | 4.3 | 3.0 | 1.3 | 25.9 | 0 | |
8.4 | 187.6 | 4710.3 | 2256.6 | 4.3 | 0.7 | 15.2 | 11.2 | 0 | |
8.4 | 175.9 | 4227.2 | 1883.8 | 4.1 | 8.5 | 9.9 | 1.1 | 0 | |
石英二长斑岩 | 7.7 | 100.5 | 300.1 | 116.7 | 8.2 | 1.7 | 7.5 | 3.4 | 1 |
7.7 | 98.6 | 300.1 | 116.7 | 9.0 | 1.4 | 8.3 | 2.8 | 1 | |
7.7 | 100.5 | 269.5 | 130.7 | 9.0 | 1.4 | 5.7 | 2.6 | 1 | |
7.7 | 106.2 | 269.5 | 130.7 | 9.0 | 1.4 | 5.1 | 3.3 | 1 | |
7.7 | 106.2 | 256.6 | 112.6 | 7.3 | 1.8 | 4.9 | 6.7 | 1 | |
7.7 | 104.3 | 346.4 | 229.7 | 7.0 | 2.2 | 6.1 | 5.5 | 1 | |
7.7 | 104.3 | 287.6 | 241.9 | 6.2 | 2.5 | 6.8 | 4.7 | 1 | |
7.7 | 108.1 | 287.6 | 241.9 | 6.2 | 2.8 | 10.6 | 4.1 | 1 | |
7.7 | 100.5 | 244.7 | 222.7 | 4.6 | 3.3 | 11.9 | 7.0 | 1 | |
7.7 | 98.6 | 244.7 | 222.7 | 4.6 | 2.2 | 6.1 | 6.4 | 1 | |
石英闪长玢岩 | 9.7 | 147.2 | 2301.8 | 1237.4 | 3.2 | 3.5 | 1.6 | 14.1 | 2 |
9.9 | 161.8 | 2167.1 | 1348.2 | 3.5 | 3.4 | 4.8 | 3.5 | 2 | |
9.8 | 178.8 | 2117.9 | 1385.7 | 3.6 | 3.2 | 2.8 | 12.7 | 2 | |
9.7 | 140.8 | 1988.1 | 1495.9 | 3.4 | 3.9 | 2.6 | 4.8 | 2 | |
9.9 | 148.5 | 1899.8 | 1514.2 | 3.3 | 3.8 | 14.4 | 0.5 | 2 | |
9.8 | 157.6 | 1783.3 | 1548.3 | 3.2 | 1.5 | 14.7 | 6.4 | 2 | |
9.9 | 161.9 | 1745.4 | 1622.9 | 3.2 | 4.7 | 11.8 | 2.1 | 2 | |
9.8 | 210.4 | 1717.8 | 1686.4 | 3.1 | 1.9 | 3.2 | 15.0 | 2 | |
9.8 | 134.5 | 1699.8 | 1828.1 | 3.1 | 3.9 | 13.1 | 5.7 | 2 | |
9.8 | 171.4 | 1691.3 | 1910.7 | 3.0 | 5.4 | 25.6 | 5.8 | 2 |
本次岩性识别网络训练共使用角岩测井数据1 010组,石英二长斑岩测井数据1 043组,石英闪长玢岩测井数据1 016组,其中取各岩性数据组中的70%作为训练样本,剩下的30%作为测试样本。
根据本次实验数据的混淆矩阵统计(表3),利用CNN进行岩性识别的准确率为97.94%。
表3 CNN网络岩性预测混淆矩阵
Table 3
真实类别 | 预测类别 | |||
---|---|---|---|---|
角岩 | 石英二长斑岩 | 石英闪长玢岩 | 总计 | |
角岩 | 296 | 2 | 2 | 300 |
石英二长斑岩 | 0 | 306 | 3 | 309 |
石英闪长玢岩 | 7 | 5 | 300 | 312 |
总计 | 303 | 313 | 305 | 921 |
4 普朗铜矿裂隙特征分析
金属矿地层的裂缝或裂隙展布信息对于矿体分布、矿体开发具有意义,而双侧向测井的深、浅电阻率数据差异程度可以较好地反映地层裂隙的发育情况。Sibbit裂缝开度模型[14]针对的是水平裂缝和垂直裂缝,利用双侧向测井资料计算裂隙开度,本文采用Sibbit模型计算普朗铜矿地层的裂隙参数、分析裂隙类型。
裂隙发育地层的电阻率变化主要受裂隙产状、裂隙张开度和泥浆侵入深度的影响。裂隙按其倾角大小一般分为3类:低角度缝(0°~30°),倾斜裂缝(30°~60°)和高角度缝(>60°)。通常在高阻背景下,高角度缝的深、浅双侧向电阻率特征表现为正异常,即RD>RS;低角度缝则表现为负异常,即RD<RS。而对于判断裂隙倾角类型,可将Y值的大小作为判断依据。Y值的计算公式为
式中:RD、RS分别为深侧向、浅侧向电阻率。
双侧向测井资料除了可以用来判断裂隙倾角范围外,还可以用来计算裂隙开度。
低角度缝裂隙开度:
高角度缝裂隙开度:
式中:Wl、Wh分别表示低角度、高角度裂隙开度;Rm为泥浆滤液电阻率;Rb表示无裂缝基岩电阻率;h表示双侧向测井仪器主电流厚度,m;d1表示双侧向浅探测深度,d2表示双侧向深探测深度;r表示井眼半径。
图6
表4 Y值判断裂隙类型统计
Table 4
Y值范围 | 裂隙类型 | 倾角范 围/(°) | 判断 点数 | 判断正 确点数 | 判断正 确率/% |
---|---|---|---|---|---|
Y≤0.3 | 低角度缝 | 0~30 | 20 | 14 | 70.0 |
0.3<Y≤0.5 | 倾斜裂缝 | 30~60 | 15 | 13 | 86.7 |
Y>0.5 | 高角度缝 | 60~90 | 22 | 19 | 86.4 |
表5 ZK18XX含矿脉体倾角数据
Table 5
倾角范围/(°) | 频数/条 | 占比/% |
---|---|---|
0~15 | 3 | 0.76 |
15~30 | 31 | 7.81 |
30~45 | 56 | 14.11 |
45~60 | 65 | 16.37 |
60~75 | 143 | 36.02 |
75~90 | 99 | 24.94 |
总计 | 397 | 100 |
图7
图8
5 结论和认识
通过对普朗铜矿钻孔的测井数据采集和综合解释评价,结合钻孔编录、部分岩心样品测试资料开展了综合应用研究,取得如下认识:
1)开展测井资料综合评价对于普朗铜矿的矿体特征识别、矿体开发具有意义;采用卷积神经网络进行地层岩性识别具有效果,准确率为97.94%。
2)石英二长斑岩地层的充电率(极化率)相对偏高,角岩地层、石英闪长玢岩地层的充电率(极化率)相对偏低。角岩地层的深侧向电阻率相对较高,石英闪长玢岩地层、石英二长斑岩地层依次相对偏低。充电率(极化率)越高,电阻率相对偏低;电阻率高,充电率(极化率)会偏低。Cu品位高相应的地层电阻率会降低。角岩地层的自然伽马数值相对高一些,即放射性强度相对高,石英闪长玢岩地层、石英二长斑岩地层的放射性强度相对偏低。
3)利用双侧向测井数据计算地层的裂隙参数、分析裂隙类型。普朗铜矿存在较多高角度裂隙发育,特别在裂隙发育层段或者较为破碎的层段,电阻率降低明显。相对来说,石英二长斑岩地层裂隙特别是高角度缝较为发育,石英闪长玢岩地层会存在几米厚的裂隙不太发育的层段。
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基于支持向量机与地球物理测井资料的煤体结构识别方法
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The coal structure identification method based on support vector machine and geophysical logging data
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Use of spectral gamma ray as a lithology guide for fault rocks: A case study from the Wenchuan Earthquake Fault Scientific Drilling project Borehole 4 (WFSD-4)
[J].
DOI:S0969-8043(17)30025-8
URL
PMID:28688249
[本文引用: 1]
The main purpose of the Wenchuan Earthquake Fault Scientific drilling project (WFSD) was to produce an in-depth borehole into the Yingxiu-Beichuan (YBF) and Anxian-Guanxian faults in order to gain a much better understanding of the physical and chemical properties as well as the mechanical faulting involved. Five boreholes, namely WFSD-1, WFSD-2, WFSD-3P, WFSD-3 and WFSD-4, were drilled during the project entirety. This study, therefore, presents first-hand WFSD-4 data on the lithology (original rocks) and fault rocks that have been obtained from the WFSD project. In an attempt to determine the physical properties and the clay minerals of the lithology and fault rocks, this study analyzed the spectral gamma ray logs (Total gamma ray, Potassium, Thorium and Uranium) recorded in WFSD-4 borehole on the Northern segment of the YBF. The obtained results are presented as cross-plots and statistical multi log analysis. Both lithology and fault rocks show a variability of spectral gamma ray (SGR) logs responses and clay minerals. This study has shown the capabilities of the SGR logs for well-logging of earthquake faults and proves that SGR logs together with others logs in combination with drill hole core description is a useful method of lithology and fault rocks characterization.Copyright © 2017 Elsevier Ltd. All rights reserved.
Deep learning of rock images for intelligent lithology identification
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Application of convolutional neural network in lithology identification
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Characteristics and metallogenic model of the Pulang super large porphyry copper deposit in Yunnan, China
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西南”三江”格咱岛弧斑岩成矿系统
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The dual laterolog response in fractured rocks
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