Wavelet analysis of well-logging data from oil source rock, Egret Member, offshore eastern Canada
Wavelet analysis of well-logging data from oil source rock, Egret Member, offshore eastern Canada
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DOI：
10.1306/8626bf15-173b-11d7-8645000102c1865d
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发表时间：
2000-10
期刊：
影响因子：
3.5
通讯作者：
A. Prokoph;F. Agterberg
中科院分区：
文献类型：
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作者：
A. Prokoph;F. Agterberg
小波分析是一种用于自动检测和区分突变不连续性（即，断层、不整合面）、旋回性以及通过转换与深度相关的沉积信号（即，伽马射线）转换成不同深度间隔处的波长。本文应用小波分析方法，以高分辨率评价沉积盆地中生油岩的时空分布，并估算其聚集速率。该方法被应用到16伽马射线测井从侏罗纪白鹭成员（油源岩继承55米至227米厚），加拿大东部近海。小波分析检测到的优势伽马射线周期波长从2.8米（盆地西缘）到24米（盆地东部）。主要γ射线周期的比值与米兰科维奇谱（约400、100、40、20 k.y.）气候旋回是控制白鹭组沉积旋回性的重要因素。主要波长可能代表~100 k. y。偏心率，累积时间约为190万年。对于具有19个连续的2.8 m伽马射线周期并给出~600 k. y的累积时间的地层完整剖面，对于只有6个周期的不完全连续。多达四个不连续性出现在伽马测井旋回性和分离白鹭成员到亚单位。我们将不连续面解释为不整合面或断层，并解释为与具有低石油潜力的沉积物有关。白鹭段地层完整性与有机碳总量和非烃源岩段厚度递减相关，相关系数分别为r = 0.8和r =-0.76。
Wavelet analysis is a sensitive method for automatically detecting and distinguishing abrupt discontinuities (i.e., faults, unconformities), cyclicity, and gradual changes in sedimentation rate by transforming depth-related sedimentary signals (i.e., gamma-rays) into wavelengths at distinct depth intervals. We used wavelet analysis for evaluation of the spatio-temporal distribution of oil source rocks and for estimating accumulation rates in a sedimentary basin having high resolution. The method was applied to 16 gamma-ray logs from the Jurassic Egret Member (an oil-source rock succession 55 m to 227 m in thickness), offshore eastern Canada. Dominant gamma-ray cycles having wavelengths varying from 2.8 m (western margin of the basin) to 24 m (eastern part of the basin) have been detected by wavelet analysis. The coincidence of the ratio of predominant gamma-ray cycles with the ratio of Milankovitch spectra (about 400, 100, 40, 20 k.y.) suggests that climatic cycles are an important factor controlling sedimentary cyclicity in the Egret Member. Dominant wavelengths likely represent ~100 k.y. eccentricity, giving accumulation times of ~1.9 m.y. for stratigraphically complete sections having 19 successive 2.8 m gamma-ray cycles and giving accumulation times of ~600 k.y. for incomplete successions having only 6 cycles. Up to four discontinuities occur in gamma-ray log cyclicity and separate the Egret Member into subunits. We interpret the discontinuities as unconformities or faults and as related to sediments having low petroleum potential. The stratigraphic completeness of the Egret Member is correlated to total mass of organic carbon and decreasing thickness of non-source rock intervals, having correlation coefficients of r = 0.8 and r = -0.76, respectively.