Abstract:

There are four facies belts developed in Changxing Formation inWubaiti area, including intraplatformtrough （deep water basin）, platform slope, platform margin reef flat and open platform. The platform marginal facies of continental shelf around intraplatform trough developed well. It is across entire eastern Sichuan and extends hundreds of kilometers, and it is the most important facies for seeking reef gas reservoir. The platformmargin reef in Wubaiti area can be divided into five subfacies, including reef base, reef core, reef crest, reef front and reef behind, amongwhich reef core and reef crest are the most favorable subfacies for the reservoir development. The reservoir rocks are mainly dolomite of reef and shoal facies and grain dolomite. Hummocky disorder reflection and chimney effect in seismic profile can be used to effectively predict reef reservoir. Dolomitization and dissolution are not only the key factors for controlling the forming of reef gas reservoir, but also the basis for forming high quality reef reservoir. The fracture raises the porosity and permeability of reservoir.

Key words: facies-constrained modeling, stochastic modeling, reservoir description, Yanchang Oilfield