井震联合煤系沉积微相及其演化特征预测

Prediction of coal measures sedimentary microfacies and their evolution characteristics by well-to-seismic integration

为实现对聚煤前后沉积微相及其演化特征的精细预测,运用井震联合方式,以地质统计学和平面差值算法为工具,利用基于地层切片的属性解释技术,以层序内砂地比信息作为沉积微相的表征参数,建立敏感属性与岩性、沉积微相的对应关系,对鄂尔多斯盆地东缘沙曲地区山西组3+4#煤层聚煤前后沉积微相及其演化特征进行精细预测。结果表明:研究区山西组可以划分为两个中期基准面旋回和若干短期基准面旋回,而中期基准面旋回是井震统一尺度研究的基础;平均反射强度和最大波峰属性可以作为聚煤前最优属性组合,弧长和最大波谷属性可以作为聚煤后最优属性组合;山西组3+4#煤层聚煤前为下三角洲平原沉积环境,聚煤后为上三角洲平原沉积环境。

In order to realize the fine prediction of sedimentary microfaeies and their evolution characteristics before and after coal accumulation, a well-to-seismic integration method was adopted, the geostatistics and planar difference algorithm were used as a tool. Using the gttribute interpretation technique based on stratigraphic slices, the relationships between the sensitivity and the lithology and sedimentary microfacies were established by using the sandstone ratio information in succession of strata as the characterization parameters of the sedimentary microfacies. The sedimentary microfacies and their evolution characteristics of the 3q-4＇＊ coal seam in Shanxi Formation of the Shaqu area in the east of the Ordos Basin were predicted finely. The results showed that the Shanxi Formation in the study area could be divided into two medium-term base-level cycles and several short-term base- level cycles, while the medium-term base-level cycle was the basis for the study of the unified scale of the well-to-seismic integration. The average reflection strength and the maximum peak amplitude attributes could be used as combination of optimal attrib- utes before coal accumulation, the arc length-and maximum trough amplitude attributes could be used as combination of optimal attributes after coal＇accumulation. The No. 3＋4^# coal seam in Shanxi Formation was in lower delta plain sedimentary environ- ment before the coal accumulation and in upper delta plain sedimentary environment after coal accumulation.