Permian High Resolution Sequence Stratigraphy Of The Southern Section Of The Western Ordos Basin

The Southern area of Western Margin of Ordos Basin, the Permian formation is coal measure strata, developed many kinds of sedimentation type and distributed in many areas.The result indicated that this area is going to be important district for gas prospecting in the Ordos Basin because of its perfect play. But low degree of prospecting, the exploration activity of study area didn't make a breakthrough to this day. Obviously gas accumulation and pay bed are controlled by sedimentary derivation and the distribution of sedarenite in which distributary channel of delta plain and delta front valley, therefore it is significant to research the characteristic of distribution of sedarenite and channel sand by high resolution sequence stratigraphy.This study bases on the research of sedimentary system and consider the boundary surface as constraint condition, to analysis deleveling by using outcrop ,drill sample, well logging and seismic.Through analyzing structure type of short term datum level cycle and the changing of A/S, the author studied the characteristic of middle term datum level and matching of successions of high resolution sequence stratigraphy.According mid-term datum level as formation units to establish high-resolution sequence stratigraphy and sum up the feature of deposit sand-fillings by analyzing of short-term datum level. Through analyzing of the sedimentary derivation, author discuss the characteristic of sedimentary facies under the high-resolution sequence stratigraphy.Basing on above research, Some opinions and results obtained as follow:1. The Permian formation of study area is composed by clastic coastal deposit, deltaic deposit and lacustrine deposit.2. Analyzing structure type of short term datum level cycle, the study area existthree main types which are up-deeping asymmetry(A), symmetry (C) and up-shallowing asymmetry(D).The mid-term datum level include seven types which are fast rise, slowly rise, falling to low point—fast rise, upward—downward, rise to high point—falling, quickly falling. 3. The Permian formation is divided into four long-term cycle, nine mid-term cycle, several short-term cycle.4. The differently characteristic sand body are grow in vary mid-term cycle5. Under sedimentary derivation from Southern and Northern control, the sedimentary facies extend from Northern to Southern...