岩性油气藏 ›› 2026, Vol. 38 ›› Issue (5): 159–169.doi: 10.12108/yxyqc.20260515

• 地质勘探 • 上一篇    下一篇

基于混合随机森林的煤岩气储层孔隙度地震智能预测方法——以鄂尔多斯盆地米脂北地区石炭系本溪组8#煤为例

赵森(), 陈胜(), 李新豫, 杜文辉, 王秀姣, 杨昊, 李艳东, 代春萌   

  1. 中国石油勘探开发研究院北京 100083
  • 收稿日期:2026-03-12 修回日期:2026-04-17 出版日期:2026-09-01 发布日期:2026-09-04
  • 第一作者:赵森(2002—),男,中国石油勘探开发研究院在读硕士研究生,研究方向为智能储层预测。地址:(100083)北京市海淀区学院路20号。Email:1581808972@qq.com
  • 通信作者: 陈胜
  • 基金资助:
    深地国家科技重大专项课题“氦气勘查评价关键技术及装备”(2025ZD1010504)

Intelligent seismic prediction method for porosity of coal rock gas reservoirs based on hybrid random forest: A case study of Carboniferous Benxi Formation 8# coal in northern Mizhi area, Ordos Basin

ZHAO Sen(), CHEN Sheng(), LI Xinyu, DU Wenhui, WANG Xiujiao, YANG Hao, LI Yandong, DAI Chunmeng   

  1. Research Institute of Petroleum Exploration & Development, Beijing 100083, China
  • Received:2026-03-12 Revised:2026-04-17 Online:2026-09-01 Published:2026-09-04
  • Contact: CHEN Sheng E-mail:1581808972@qq.com;cs69@petrochina.com.cn

摘要:

针对鄂尔多斯盆地米脂北地区石炭系本溪组8#煤常规方法对高孔隙度储层刻画精度不足的问题,基于斯皮尔曼相关分析优选敏感地震属性,构建低冗余输入特征集,提出了一种“分类—回归”两阶段协同的混合随机森林孔隙度预测方法,将该方法与6种常规方法进行了对比。研究结果表明:①混合随机森林孔隙度预测方法利用带类别平衡的分类器识别无效值,输出对应概率;在回归器训练中引入孔隙度分段样本权重,将低、中、高孔隙度区间的权重纳入优化;通过概率加权机制对预测结果进行自适应调整,在非储层段抑制背景值虚高、在储层段保持回归精度。②混合随机森林盲井预测孔隙度决定系数R2为0.864 4,显著优于单属性回归(0.720 4)、多属性线性回归(0.766 5)、XGBoost(0.717 5)、常规随机森林(0.791 0)及SMOTE+随机森林(0.771 3);该方法低孔背景段预测结果偏差为0.416 4%,较常规随机森林(0.829 8%)和XGBoost(0.881 6%)明显降低,有效抑制了背景值虚高;在“甜点”段(孔隙度 ≥ 6%)预测平均绝对误差为0.703 8%。③连井剖面和平面预测结果表明,该方法在储层横向连续性、“甜点”带识别及背景区控制方面均优于对比方法,能够准确刻画本溪组8#煤孔隙度平面展布特征。

关键词: 混合随机森林算法, 煤岩气储层, 孔隙度预测, 智能物探, 三维地震, 本溪组8#煤, 米脂北地区, 鄂尔多斯盆地

Abstract:

To address the problem that conventional methods are insufficient for accurately characterizing high‑porosity reservoirs in Carboniferous Benxi Formation 8# coal in northern Mizhi area of Ordos Basin, a “classification‑regression” two‑stage collaborative hybrid random forest porosity prediction method was proposed by selecting sensitive seismic attributes based on Spearman rank correlation analysis, and constructing a low‑redundancy input feature set. It was then compared with six conventional methods. The results show that:(1) The hybrid random forest porosity prediction method uses a class‑balanced classifier to identify invalid va-lues and output their probabilities, introduces porosity‑segmented sample weights into the regressor training to incorporate weights of low‑, medium‑, and high‑porosity intervals into optimization, and adaptively adjusts the predictions through a probability‑weighted mechanism, which suppresses false high‑porosity anomalies in non‑reservoir sections while maintaining regression accuracy in reservoir sections. (2) On the blind well test set, determination coefficient(R2)of the hybrid random forest porosity predictions is 0.864 4, which significantly outperforms single‑attribute regression (0.720 4), multi‑attribute linear regression (0.766 5), XGBoost (0.717 5), conventional random forest (0.791 0), and SMOTE + random forest (0.771 3). In the low‑porosity background interval, the bias of the proposed method is only 0.416 4%, markedly lower than that of conventional random forest (0.829 8%) and XGBoost (0.881 6%), effectively suppressing false high‑porosity anomalies. In the sweet‑spot interval (porosity ≥ 6%), it also maintains a high prediction accuracy with an MAE of 0.703 8%. (3) Well‑tie profiles and planar prediction results demonstrate that the proposed method outperforms the compared methods in lateral reservoir continuity, sweet‑spot identification, and background control, and can accurately delineate the planar distribution characteristics of porosity of Benxi Formation 8# coal.

Key words: hybrid random forest algorithm, coal rock gas reservoir, porosity prediction, intelligent geophysical prospecting, 3D seismic, Benxi Formation 8# coal, northern Mizhi area, Ordos Basin

中图分类号: 

  • TE311

图1

鄂尔多斯盆地米脂北地区构造图(a)及上石炭统本溪组—下二叠统山西组岩性地层综合柱状图(b)"

图2

随机森林模型原理图"

图3

混合随机森林孔隙度预测模型流程"

表1

混合随机森林孔隙度预测模型中采用的地震属性名称"

属性
种类
属性名称
基础
属性
振幅包络(Amplitude Envelope)、瞬时相位(Instantaneous
Phase)、瞬时频率(Instantaneous Frequency)
导数
属性
一阶导数(Derivative)、二阶导数(Second Derivative)
积分
属性
导数瞬时振幅(Derivative Instantaneous Amplitude)、
积分(Integrate)
频率
属性
积分绝对值(Integrate Absolute Amplitude)、主频(Dominant Frequency)、平均频率(Average Frequency)、振幅
加权频率(Amplitude Weighted Frequency)
相位
属性
正交迹(Quadrature Trace)、余弦瞬时相位(Cosine Instantaneous Phase)、振幅加权相位(Amplitude Weighted Phase)、振幅加权余弦相位(Amplitude Weighted Cosine Phase)
极性
属性
视极性(Apparent Polarity)
滤波
属性
基础滤波(Filter)、5~10 Hz滤波(Filter 5-10 Hz)、15~
20 Hz滤波(Filter 15-20 Hz)、25~30 Hz滤波(Filter 25-30 Hz)、35~40 Hz滤波(Filter 35-40 Hz)、45~50 Hz滤波(Filter 45-50 Hz)、55~60 Hz滤波(Filter 55-60 Hz)
复合
属性
二阶导数瞬时振幅(Second Derivative Instantaneous
Amplitude)

图4

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤及围岩测井解释孔隙度分布直方图"

图5

鄂尔多斯盆地米脂北地区40口井石炭系本溪组8#煤平均孔隙度统计"

图6

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤孔隙度与特征参数相关性热力图"

图7

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤孔隙度-优选特征参数交会图 注:ρ为斯皮尔曼相关系数。"

图8

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤优选特征参数连井剖面"

表2

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤混合随机森林孔隙度预测模型中超参数取值设定"

超参数 参数搜索
范围
分类器
最佳
参数
回归器
最佳
参数
决策树数量 10~500 30 180
单棵决策树的最大深度 1~50、None 16 16
节点分裂所需最小样本数 1~10 2 2
叶节点所需最小样本数 1~10 1 1
单棵树在节点分裂时最大特征参数数量 None, sqrt, log2,1 sqrt 1

表3

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤混合随机森林孔隙度预测模型中孔隙度权重及分段阈值设定"

超参数 搜索范围 最佳参数
低孔段权重 1~10 8
中孔段权重 1~10 2
高孔段权重 1~10 8
低孔、中孔分界/% 2~4 2
中孔、高孔分界/% 6~10 10

图9

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤混合随机森林孔隙度预测模型中网格化搜索评分分布"

图10

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤混合随机森林孔隙度预测模型中特征参数重要性得分对比"

图11

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤多方法预测盲井孔隙度效果对比"

表4

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤多方法预测孔隙度误差对比"

方法 整体平均
绝对
误差/%
非“甜点”
段平均
绝对误差/%
非“甜点”
段平均
偏差/%
“甜点”段平均绝对误差/% 整体
R2
单属性回归 1.243 6 1.343 4 0.703 3 0.732 8 0.720 4
多属性回归 1.252 3 1.364 7 0.670 1 0.677 1 0.766 5
XGBoost 1.177 5 1.251 2 0.881 6 0.800 4 0.717 5
随机森林 0.995 9 1.049 1 0.829 8 0.723 6 0.791 0
SMOTE_RF 1.021 3 1.073 7 0.859 9 0.753 4 0.771 3
混合随机森林 0.791 4 0.808 5 0.416 4 0.703 8 0.864 4

图12

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤多方法预测孔隙度连井剖面效果对比"

图13

鄂尔多斯盆地米脂北地区石炭系本溪组8#煤随机森林(a)、混合随机森林(b)预测孔隙度平面分布"

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