摘要
火山岩储层预测难度较大,尤其在低勘探程度地区,在缺乏岩心资料的情况下,通常利用地震相识别及划分、地震常规属性提取、相干分析等方法识别火山岩,但受制于地震资料品质,往往需要大量的井资料进行约束。为此,使用改进的小波变换方法分频重构处理地震信号以提高地震资料品质,通过地震相、模型正演、地震属性分析、地震层切片综合研究准噶尔盆地东部木垒凹陷上石炭统巴三段古火山发育特征,获得以下认识:(1)当分频重构频率低于优势频段的频率时,能量降低,分辨率较低;当分频重构频率高于优势频段的频率时,子波能量也会逐渐降低,并且过高的重构频率也会降低信噪比。(2)理想火山模型正演分析发现:地震反射特征表现为火山顶部强反射、火山锥内部弱反射,由于岩性变化,向两侧同相轴振幅逐渐增强;火山锥两侧地层向中心存在超覆现象,且远离火山锥地层逐渐稳定;火山通道具有内部短轴假象。(3)均方根振幅属性对近火山口的火山碎屑岩敏感,分频重构后表现为低均方根振幅值,杂乱丘状相主要代表的近火山口的火山碎屑岩是有利储层之一。(4)火山岩沿北东向两个条带呈串珠状发育,具有"北密南疏"的特点,并预测了3个火山岩储层有利发育区。
It is very difficult to predict volcanic rock reservoirs,especially in low-exploration areas with very few core and well data.Volcanic rocks are usually identified with seismic facies,seismic attributes and coherent analysis.However a large amount of well data is needed to constrain seismic data due to its quality limited.To overcome this difficulty,we utilize an improved wavelet transform for seismic data reconstruction based on frequency division to improve seismic data quality,and predict ancient volcanic distribution characteristics with seismic facies,forward modeling,seismic attributes,and seismic slices.This approach is used to predict volcanic rocks in Mulei Sag,Junggar Basin.The following understandings are obtained:(1)When the frequency of the division reconstruction is lower than the dominant frequency,the energy is reduced and the resolution is low.When the frequency of the division reconstruction is higher than the dominant frequency,the energy will gradually decrease,and much higher frequency will harm the signal-to-noise ratio;(2)Based on volcanic rock forward modeling,ancient volcanic tops show strong reflection,and inner cones show weak reflection.Due to lithologic changes,the amplitude on cone sides increases gradually.The strata on volcanic cone sides overlap to the center.Volcanic channels have internal short axis seeming;(3)RMS amplitude attributes which show low values are very sensitive to pyroclastic rocks near ancient craters.Pyroclastic rock mainly represented by messy mounds,is one of the favorable reservoirs;(4)Volcanic rocks are distributed along two NNE stripes and they are more in the north and less in the south.Finally,three favorable volcanic reservoir zones are predicted based on our study.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2018年第4期805-816,共12页
Oil Geophysical Prospecting
关键词
古火山
模型正演
火山岩储层预测
改进小波变换
分频重构
木垒凹陷
准噶尔盆地
ancient volcanic
forward modeling
volcanic reservoir prediction
improved wavelet transform
frequency division reconstruction
Mulei Sag
Junggar Basin
