Abstract: Based on the characteristics and evolutionary variation of platform margin and intra-platform reef-shoal reservoirs in the Upper Ordovician Lianglitage Formation in the western Tarim Basin, data on rock core, thin slices, logging, and geochemical analysis were used to compare and analyze the differences in the basic characteristics, diagenesis, and pore evolution of the two reservoirs. A reservoir development model and proposed corresponding exploration strategies are established. In terms of the reservoir characteristics, the reservoir space of the platform margin reef-shoal reservoir shows the coexistence of fabricselective and non-fabric-selective characteristics. The reservoir is vertically stacked in multiple layers and is laterally aligned. The reservoir space of the intra-platform reef-shoal is in the form of non-fabric selective fracture-holes, mainly distributes in the middle and lower parts. Its vertical thickness and lateral continuity are lower than those of the platform margin. The evolution and distribution of high-quality reservoirs in the platform margin are controlled by penecontemporaneous meteoric dissolution, early diagenesis near-surface karstification, and burial dissolution, whereas the intra-platform reservoirs are controlled by fractures and burial karstification. In terms of exploration strategies for platform margin reef-shoal reservoirs, priority should be given to the three-stage karst and tectonic rupture superimposed development zone. For intra-platform reservoirs, attention should be paid to the jointly controlled zones of fault and burial dissolution.

Key words: reservoir characteristics, reservoir variation, platform margin, open platform, carbonate rock, reef-shoal, western Tarim Basin, Lianglitage Formation