利用稳定泥岩段层速度建立高精度剩余层速度场

High-precision residual interval velocity field construction with stable mudstone interval velocity

高精度剩余层速度的求取需要解决两方面的问题:一是建立高精度的层速度场,二是建立高精度的正常压实速度场。为此,提出了一种精确求取剩余层速度场的新方法。基于模型层析法求取层速度,结合井震速度标定和空间网格化加密,精确求取层速度场;然后基于已钻井稳定纯泥岩段的层速度,拟合求取正常压实速度场,并对层速度场进行压实校正,得到能预测岩性的高精度剩余层速度场。研究结果表明,在基于模型层析法得到高精度层速度场的基础上,利用稳定纯泥岩段层速度拟合的正常压实速度值更符合研究区不同年代实际地层,能够从层速度场中筛选出更多的岩性信息,提高砂体预测的精度。该方法在二连盆地SH凹陷得到有效应用,成功预测了目标区砂体的分布,为该区井位部署及相似地质条件地区的砂体预测提供了新的思路。

High-precision residual interval velocity field construction needs to solve two problems: building both a high-precision interval velocity field and a high precision normal compaction velocity field. So we propose in this paper a new method to exactly calculate the residual interval velocity field. First we calculate interval velocity based on the model tomographic method. Then we obtain an accurate interval velocity field by the calibration between well velocity and seismic velocity, and 3D space grids. After that we calculate normal compaction velocity field based on fitting stable pure mudstone interval velocity from drilling data. Finally, with the compaction correction on interval velocity field, we get the exact residual interval velocity field which allows us to predict the lithology. Our research results show that normal compaction velocity values we get by fitting stable pure mudstone section are very close to real situation after the high precision of interval velocity field is established based on model tomographic method. Consequently, we can pick out more and smaller sand body from interval velocity field, and improve reservoir prediction. The proposed method is effectively applied in SH Depression, Erlian Basin, and we have successfully predicted the reservoir distribution, and propose well deployment for the future drilling. © 2016, Editorial Department OIL GEOPHYSICAL PROSPECTING. All right reserved.