Practice of High-density 3D Seismic Exploration in Tight Oil Exploration in G Area of Central Sichuan

Abstract

The Oil reservoir in Jurassic of Sichuan Basin is tight, thin, high heterogeneity, complex sand distribution and well-developed micro-fault etc., whose difference of buried depth is up to 2000m from south to north. The vertical and lateral resolution of conventional seismic exploration is too low to predict reservoir clearly, which restrains further development of close oil exploitation in central of Sichuan Basin. Lots of examples shows that high density acquisition is able to improve the description ability of seismic data, In G area of Sichuan Basin, a high-density, high-fold, small-cell, full-azimuthal 3D acquisition has been tested, which is the first mountainous high-density seismic exploration in China. In view of mass data and difficult geological target, a processing technique series including auto-first-break-picking, pre-stack noise suppression, robust surface consistent deconvolution, pre-stack time migration in OVT (Offset Vector Tile) field is applied to obtain high quality image. Analysis of multiple geological target results revealed that, the high-density data has fair higher signal-to-noise ratio, much wider bandwidth with more information, much better vertical and lateral resolution, which increased the identification of sand boundary, predication of thin reservoir, discrimination of micro-fault and fracture, recognition of sub geological features. It is well provided that high-density 3D seismic exploration has vast application future in close oil exploitation.