Study on sedimentary microfacies of lower Youshashan formation in Wunan area

Through the massive core samples, the loginformation analysis, as well as the key well entire section oil well logging-sedimentary facies division, combined with the region deposition background and the systematic analy sis, sedimentary facies, sub-facies, and microfacies model developed in Wunan area lower Youshashan formation has been determined. Which developed delta front-shore shal low lake subfacies, and divided eight main micro facies types: underwater distributary channel, underwater distrib utary interchannel, river mouth bar, sandbar-sheet sand, front delta slime, beach slime, beach, dam. Among which beach dam, river mouth dam are main type of studied area. Based on this, the research was carried on various oil layer sedimentary facies planar distribution rule and the analysis of deposition faces evolution rule provides the important geo logical basis for the oil-field development.