频谱分析在含煤地层沉积旋回分析中的应用

Spectrum Analysis Applied to Sedimentary Cycle Analysis of Coal Measures

为了建立测井曲线与含煤地层段沉积旋回的关系,以川东须家河组五段地层为例,利用测井曲线频谱分析方法对自然伽玛测井曲线进行分析,认为该区地层沉积旋回发育主要受米兰科维奇旋回控制,各频点所对应的厚度比值与米兰科维奇旋回比值存在很好的一致性,其中偏心率周期引起的地层旋回厚度变化范围为10.16～14.25 m;地轴倾角周期引起的地层旋回厚度变化范围为2.96～5.01 m;岁差周期引起的地层旋回厚度变化范围为1.55～2.43 m。该区煤层和炭质泥岩沉积旋回厚度11～14 m,其发育受控于时间为123 ka的偏心率周期,因此,频谱分析方法适合含煤地层段沉积旋回的分析。

In order to establish a relationship between the logging curve and sedimentary cycle of coal measares, taking No. 5 section of Xujiahe Formation in the east Sichuan Province as a case, the logging curve spectrum analysis method was applied to analyze the natural gamma ray curve. The analysis held that the sedimentary cycle development of the strata in the area was mainly controlled by the Milanko- vitch cycles. There was a good consistency between the thickness ratio and the Milankovitch cycles ratio and the strata cycle thickness vari- ation scope occurred by the eccentric ratio period was 10. 16- 14, 25 m. The strata cycle thickness variation scope occurred by the earth＇s axis inclination period was 2.96 ~ 5.01 m. The strata cycle thickness variation scope occurred by the precession period was 1.55 ~ 2.43 m. The sedimentary cycle thickness of the seam and carbonaceous mudstone in the area was ranging from 11- 14 m and the development controlled by the eccentric ratio period with a time of 123 ka. Therefore the spectrum analysis method could be applied to the analysis on the sedimentary cycle of the coal measures section.