摘要
采用数据驱动的方式,提出了一种基于随机森林机器学习算法训练出含气饱和度地震预测方法,并将该方法应用于中国西部复杂天然气藏中,分别对单井资料和二维地震资料进行了含气饱和度预测与分析。研究结果表明:(1)抽取井旁道纵波速度、横波速度和密度3个弹性参数叠前地震反演结果作为基本特征变量样本,引入边界合成少数类过采样技术对基本特征变量样本和对应的含气饱和度样本进行平衡化处理;利用扩展弹性阻抗结合数学变换自动生成一系列的扩展变量;再利用随机森林对特征变量进行含气饱和度预测重要性排名,并优选重要性较高的特征变量进行含气饱和度随机森林训练。(2)该方法大幅减少了特征变量提取和优选的人工工作量,且有效减少了信息冗余以及因含气饱和度样本不平衡导致的训练偏倚问题,有效增强了随机森林算法在含气饱和度地震预测方面的能力。(3)实际单井应用中预测的含气饱和度与测井解释的含气饱和度的相关系数可达0.9855;在二维地震资料应用中,该方法比基于常规未平衡化的11个弹性参数作为随机森林输入预测出的含气饱和度精度更高。
A data-driven approach was proposed to predict gas saturation based on random forests machine learning algorithm.This method was applied to predict and analyze gas saturation in a complex natural gas reservoir in western China from single well data and two-dimensional seismic data respectively.The results show that:(1)The method extracts the pre-stack seismic inversion results of three elastic parameters from the uphole trace(compres-sional wave velocity,shear wave velocity,and density)from well log data as basic feature variables.It employs the boundary synthetic minority oversampling technique to balance the basic feature variables and corresponding gas saturation samples,generates a series of extended variables by combining the extended elastic impedance with mathematical transformations,and then uses random forests to rank the importance of the feature variables for gas saturation prediction,finally selects feature variables with higher importance for gas saturation random forests training.(2)This method significantly reduces the manual workload for feature variables extraction and selection,effectively reduces information redundancy and training bias caused by imbalanced gas saturation samples,and effectively enhances the capability of the random forests algorithm in predicting gas saturation.(3)In practical applications,the predicted gas saturation using this method shows a high correlation coefficient of 0.9855 with the gas saturation by log interpretation.In the case of two-dimensional data,it achieves higher accuracy in gas saturation prediction compared to using 11 conventional unbalanced elastic parameters as inputs for random forests.
作者
桂金咏
李胜军
高建虎
刘炳杨
郭欣
GUI Jinyong;LI Shengjun;GAO Jianhu;LIU Bingyang;GUO Xin(PetroChina Research Institute of Petroleum Exploration and Development-Northwest,Lanzhou 730020,China)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2024年第2期65-75,共11页
Lithologic Reservoirs
基金
中国石油天然气股份公司前瞻性基础性重大科技项目“复杂气藏地震识别与预测技术研究”(编号:2021DJ0606)
中国石油直属院所基础研究和战略储备技术研究基金项目“孔、渗、饱多参数联合智能化地震反演技术研究”(编号:2022D-XB01)联合资助。
关键词
含气饱和度
随机森林
纵波速度
横波速度
密度
特征变量
不平衡数据
机器学习
气层预测
地震预测
gas saturation
random forests
compressional wave velocity
shear wave velocity
density
feature variable
imbalance data
machine learning
gas layer prediction
seismic prediction
