Abstract:

In order to analyze the fracture characteristics, the origin mechanism and the controlling factors of Triassic sand reservoir in Dongpu sag, the techniques of field outcrop section observation, core overview, sample analysis, conventional logging, imaging logging, NMR logging, and rock mechanics experiment, and so on, were applied to study the fractures of Triassic sand reservoir in Wenmingzhai area. The research showed that there were three kinds of structure fractures as NNE, NE and nearly EW. The fracture trend was nearly parallel or perpendicular to the main faults. Fractures following tectonic highs appeared like belt. There were mainly high angle fractures (60°-90°), then low angle ones (30°-50°). They were mutually interlaced and formed the fracture network systems. Core analysis and porosity logging showed that the fracture porosity was 2.60%-3.20%, and the tectonic stress field was the external factor which controlled fracture growth in reservoir, while the reservoir lithology, the sand reservoir thickness, the rock mechanics nature were the internal ones.

Key words: Dongpu sag, Triassic, fracture, origin mechanism of fracture, reservoir, tectonic