摘要
在陆源碎屑岩地层的沉积记录中,测井曲线上一个砂泥岩旋回可以采用正弦波进行描述,测井曲线幅度的高低反映旋回粒度大小的变化,旋回波长则是度量旋回厚度的标尺。本研究表明,测井曲线变化幅度与其平均值之差计算的累积残差曲线,是识别沉积体系、判别旋回层序界面的一个有效图解方法。根据数值模拟实验,证实对于任意一个级次的旋回复合波系,累积残差曲线的正半波和负半波曲线分别对应低频旋回的向上变细和向上变粗的沉积序列,正半波和负半波曲线的转换点位置对应旋回层序界面的深度。同时,引进测井曲线的频谱分析和滤波方法,可以划分沉积旋回的级别,进而研究沉积旋回变化形式的驱动机制。文中以柴达木盆地东部地区仙3井为例,根据测井数据计算的累积残差曲线,说明了划分低频和高频旋回层序的方法和流程,讨论了旋回幅度、波长变化与沉积环境和沉积速率的关系。
The rhythmic sandstone and mudstone cycles are common lithologic units in terrigenous stratigraphic system. Wireline log curves of sandstone and mudstone cycles can be described in term of sinusoidal waves in depth domains. Amplitude variations of wellline logs reflect grain sizes in a sedimentary cycle,and wavelength changes are a measure scale to mark cyclic thickness. The cumulative residual curves from average amplitude variations of well logs are introduced and demonstrated as a valid graphical method to define depositional regime transformation and check boundary surfaces of cyclic sequences. The numerical simulation results shows the positive half waves and negative half waves of cumulative residual curves are respectively corresponding to coarsening-upward and fining-upward sedimentary successions in low frequency cyclic sequences in a well interval. Transform points of positive half waves and negative half waves are calibrated to boundary surface depth of cyclic sequences. The spectral analysis and filter methods are adopted to divide cyclic sequence hierarchy and then discuss depositional mechanism. The GR log data from Xian Well 3 of Qaidam Basin as a case,cumulative residual curves are calculated and constructed on well log data.The low and high frequency cyclic sequences are distinguished and its procedure and methods are illustrated in detail.The significance and interpretation of amplitudes and wavelength changes of sedimentary cycles is discussed in this paper.
出处
《沉积学报》
CAS
CSCD
北大核心
2015年第5期855-864,共10页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(批准号:40972084)
教育部博士点基金项目(编号:20105122110013)联合资助
关键词
沉积旋回
叠置形式
频率
幅度
波形分析
旋回层序
sedimentary cycle
stacking pattern
frequency
amplitude
waveform analysis
cyclic sequence
