大同煤田边缘相侵入岩测井响应及地震预测方法研究

Logging Response and Seismic Prediction of Marginal Facies Intrusive Rock in Datong Coalfield

侵入岩对大同盆地北部石炭-二叠纪煤炭资源破坏严重,制约了特大型矿井的高效、安全开采。为此,基于钻井取芯、巷道揭露和测井等资料,首先厘清了中心相和边缘相不同蚀变程度侵入岩的测井响应特征。针对强蚀变边缘相侵入岩与煤层顶、底板围岩物性波阻抗差异小,地震预测困难的问题,进一步研究并应用了振幅类、频率类和构造类地震属性解释技术,提出了以瞬时频率为主,构造属性为辅的侵入岩地震预测方法。钻孔对比结果表明:边缘相区残存煤厚度变薄是导致煤层反射波频率增大的主要原因。地震预测的总误判率约9.1%,揭露侵入岩的钻孔预测准确率约93.7%,实现了边缘相侵入岩分布的地震精细预测。

Intrusive rocks have seriously damaged Carboniferous and Permian coal resources in the northern Datong basin,which restricts the mining efficiency and safety of ultra large mines.Therefore,based on the data of drilling coring,roadway exposing and well logging,the logging response characteristics of intrusive rocks with different alteration degrees of central and marginal facies are firstly clarified.In view of the difficulty of seismic prediction due to the small difference in impedance between the heavily altered marginal facies intrusive rocks and the coal seam surrounding rocks,the seismic attribute interpretation techniques of amplitude,frequency and structure are studied and applied.A seismic prediction method of intrusive rock based on instantaneous frequency and supplemented by structural properties is proposed.The results of borehole data show that the thinning of residual coal thickness is the main reason for the increasing frequencyof the reflected wave of coal seam.The total error rate of seismic prediction is about 9.1%,and the accuracy of borehole of revealing intrusive rocks is about 93.7%,which realizes the fine prediction of the distribution of marginal facies intrusive rocks.