歧口凹陷西斜坡沙一段薄储层预测

Thin-layer reservoir prediction in the lower ESj of the western ramp of Qikou depression

关键词:  歧口凹陷  沙河街组  薄储层  岩相  生物碎屑灰岩  地震有色反演  储层预测

Key words:  Qikou depression  Shahejie formation  thin-layer reservoir  lithofacies  bioclastic limestone  seismic colored inversion  reservoir prediction

摘要:

歧口凹陷西斜坡沙一下亚段的地震反射同相轴是复杂岩性的综合地震响应，不具备等时性，不能利用追踪地 震同相轴和常规反演方法预测储层分布。针对该地区沙一下亚段储层单层厚度薄、横向岩相变化快的特点,首先采 用沉积旋回分析法将所研究的目的层划分出3个五级高频旋回层序,并归纳了岩相序列模式;再利用有色反演沿层 切片法，检测出薄互层地层中高波阻抗体的形态及其在时间域上的变化;最后以岩相序列模式分析法解释反演结 果,实现了五级高频旋回层序内的岩相重构,最终预测出该地区沙一下亚段厚度为3 ~9 m的生物碎屑灰岩薄储层的 平面分布，达到了储层分布预测的目的。研究表明，对于薄层、多种高波阻抗岩性共存的地层,应用地质-地球物理信 息的岩相重构方法可以减少地震储层预测中的多解性风险。

Abstract:

The seismic reflection event of the lower Es, member in the western ramp of Qikou depression is a sort of comprehensive seismic response in complex lithology. Due to its poor isochronous properties, the reservoirs distribution cannot be predicted by technology of seismic reflection event and traditional inversion. According to the features of thin layer and quick changes in spatial of bioclastic limestone in the western ramp of Qikou depression, the lower Es, member of Shahejie formation was divided into three high frequency sequences cycles of fifth-order by sedimentary cycle analysis. Its sedimentary patterns in vertical sequence were concluded. Then, the continuous change of high impedance body in time-domain was detected by colored inversion amplitude map technique. Finally, large-scale li thofacies of every fifth-order cycle are reconstructed with the combination of geological and geophysical information on the guidance of sedimentary patterns，and the distribution of bio-clastic limestone in the layers with thickness of 3 ~ 9 m was predicted. The method of multi-information lithofacies reconstruction can lessen the risk of reservoir prediction effectively.