Abstract: To establish a sequence stratigraphic framework for the middle-lower Ordovician Yingshan Formation on an open-to-restricted carbonate platform in the Shunbei Area of the Tarim Basin,and to investigate how sequence stratigraphy controls favorable reservoirs and to build reservoir models,outcrop,core,well-logging and seismic data were used, third-order sequence boundaries were identified.Upon this,INPEFA(Integrated Prediction Error Filter Analysis)well logging cycle and Dmey wavelet transform were applied to Th/U ratio log curves.Combined with Fischer diagram methods,fourth-order sequences were produced,which enabled classification of reservoir types and characteristics,analysis of their reservoir-control effects,and determination of reservoir development patterns under multiple factors.In the study area,two third-order sequences(SQ1-SQ2)and four fourth-order sequences(YSQ1-YSQ4)were identified.Based on fracture characteristics and depositional context, sequence SQ1 contained more thin interbedded tuffaceous limestone layers and higher dolomite content than SQ2,making it more prone to bed fracturing and reservoir development.Within the fourth-order sequences(YSQ1-YSQ4),four bottom-top reservoir types were identified:fracture reservoirs associated with the main fault,dolomite reservoirs formed by burial or hydrothermal processes,limestone fracture reservoirs controlled by secondary faults,and karst(dissolution-cavity)reservoirs closely linked to penecontemporaneous processes.This study provides a theoretical basis for high-frequency sequence stratigraphy controls reservoirs and clarifies directions for predicting favorable reservoirs.

Key words: the Shunbei Area, Yingshan Formation, natural gamma-ray spectrometry logging, sequence stratigraphic division, reservoir development model