Abstract:

In order to study sequence stratigraphic framework and source-reservoir-caprock assemblage of Upper Triassic Yanchang Formation in western Nanliang area, this paper studied the sequence boundary types, the characteristics of sequence stratigraphic framework, and the relationship between long-term base-level cycle and source-reservoir caprock assemblage by the theory and approach of high resolution sequence stratigraphy. The result shows that five third-order sequence boundaries are identified, the Yanchang Formation consist of four long-term and one super-long term base-level cycles. The source-reservoir-caprock assemblage has close relation to the long-term base-level cycle. The sand bodies of delta plain distributary channel and front underwater distributary channel developed in the early middle stage of the uprising periods and middle-late stage of subsiding periods are high quality reservoir, the turbidite sand bodies developed in the middle-late stage of the uprising periods and early-middle stage of subsiding periods are potential reservoir, and the lacustrine shale and carbon mudstone developed in the surrounding of transforming interface of uprising to subsiding of the long-term base-level cycle. The Yanchang Formation developed three types of source-reservoir-caprock assemblage, including upper-sourcing and lower-reservoir type and lower-sourcing and upper reservoir type and self-sourcing and self-reservoir type.

Key words: extra-highwater cut stage, liquid-oil ratio, water drive curve, forecastingmodel