Abstract:

Both domestic and abroad petroleum production demonstrate that carbonate inner platform shoals have been the most important targets for hydrocarbon exploration. But domestic researches on the creation and development of inner platform shoal reservoirs are relatively inadequate, the authors provide a new typical case of inner-platform shoals concerning Xiaohaizi Formation of Late Carboniferous in Bamai region, Tarim basin. Based on the integrative investigation of outcrops, cores, thin sections, logs, and seismic data, it is found that inner platform buildup is composed of fusulinid bioclastic, algal oncoid, and bioclastic and superficial oolitic, and sand shoals, and thereby deduced that these shoals formed in inner ramp micro-paleo-uplift environment under the global transgression setting, and controlled by tectonic deformation and sea level change. Also it is inferred that most high-quality reservoir rocks occur vertically in the lower part of Xiaohaizi Formation, and that horizontally the excellent reservoir rocks (reservoir rock typeⅠ) extend from the northeastern well Bt 8 to the southwestern corresponding to the highest relief in the open-marine inner platform paleoenvironment，and the good reservoir rocks (reservoir rock typeⅡ) appear scatteredly corresponding to the higher relief. Ultimately, it is concluded that the formation and distribution of high-quality inner platform shoal reservoirs are primarily influenced by openmarine inner platform shoal sedimentation and the early diagenesis.

Key words: carbonate inner platform shoals, reservoirs, sequence stratigraphy, diagenesis, Xiaohaizi Formation, Bamai region, Tarim basin, carbonates