Automatic tracing of reservoir's sedimentary microfacies is to predict automatically the distribution and boundaries of sedimentary microfacies and draw facies map by using computer technologies based on interwell stratigraphic classification and correlation and analysis of sedimentary microfacies. It is carried out in 5 steps including coordinate transform of well positions

gridding

interpolation

superposition

search of boundaries and drawing sedimentary microfacies map. The key of this method is to determine the distributions of different sedimentary microfacies by spatial interpolation and "worm" interpolation

and create a map of sedimentary microfacies belts through superposing these microfacies distributions."Worm"interpolation

unlike conventional interpolation methods

is an intelligent method that mimic human to analyze zonal distribution of sedimentary microfacies based on geologic rules. The MFBTS (Micro-Facies Belt Tracing System)software

developed according to the above mentioned principles

provides a tool for analyzing and tracing rapidly the distribution of reservoirs and sedimentary microfacies. Application of this technique in Putaohua oilfield in Songliao Bsasin shows that the map of sedimentary microfacies created by MFBTS is basically consistent with that drawn by hands.