Based on detailed observation of cores

thin sections and analysis of seismic data

this paper studied the high frequency sequence

sedimentary facies

reservoir types and diagenesis of the biohermal reservoiors in the Changxing Formation in Yuanba area

the Sichuan Basin

analyzed the architecture of the biohermal reservoir and the factors controlling its development

and formulated its development models.The results show that the bioherms in the Changxing Formation were favorable facies and were developed mainly on platform margin of the SQ2.Vertically

the bioherms consist of two distinct reef cycles.Laterally they are in asymmetrical distribution featuring in "early in the east and later in the west".The quality biohermal reservoirs are dominated by dissolved dolomite with low porosity and moderate-low permeability and mainly occur in reef caps of the upper fourth-order sequences

and feature in typical "double layer reservoirs architecture".Meteoric dissolution and dolomitization in the early diagentic stage were the most important constructive diagenesis in the Changing Formation.A comprehensive analysis indicates that the biohermal facies controlled by high-frequency sequence is the foundation of reservoir development

and also is the key factor controlling penecontemporaneous meteoric dissolution and dolomitization of the bioherms in Changxing Fm.Burial dissolution

burial dolomitization and fracturing further improve the physical properties of reservoir rocks.The development model of the biohermal reservoirs in the Changxing Fm of Yuanba area is ‘lithofacies-controlling reservoir

early formation and late reformation’.