Abstract: Quality Dolomite Reservoir of exposure shallow shoal in back reef and the exposure reef flat has developed on
the platform edge of Changxing Formation in Yuanba Area in Sichuan Basin. By observation and description to hundreds of
meters drilling core and more than one thousand cast pieces sections of more than 20 wells drilling，we discover many reservoir
space type. The major reservoir space types are the dolomite intercrystalline pore，organism coelom pore，framework pore，
the biological intergranular porosity and dissolved pore or break，etc. The advantage reservoir spaces of the quality dolomite
reservoir Changxing Formation in Yuanba Area in Sichuan Basin，are the biological dissolved pores，and the secondary origin
porosities and cavities related to biology. The minority of secondary pores are formed directly by dolomitization，dissolution
and recrystallization etc，while the majority from biological pore. The biological pore are controlled by sedimentary context
and constructional diagenesis besides internal cause，such as mineral composition，architecture，conformation，ect. The development
of biology and dissolved pore are one of the main control factors for the quality Dolomite Reservoir in the exposure
shallow shoal in back reef and the exposure reef flat on the platform edge of Changxing Formation in Yuanba Area.

Key words: biological pores, charateristics, controlling factor, Changxing Formation, Yuanba Area