Linnan Sag Sand Four Upper Sequence Stratigraphy And Sedimentary Facies Research

The Linnan low-laying which is on the westward of JiYang Depression, is the hypo-grade tectonic cell of Huimin sag. In north of the low-laying the tectonic zone of Lin-Shang fault assembles abundant oil and gas, meanwhile the igneous rock structure and the southern slope of the Low-laying also formed industrial oil and gas field. Along with the oil and gas prospecting, the chance of exploring big and middling structural oil and gas reservoirs becomes less and less. Therefore the empresses of prospecting turn from big and middling constructional oil and gas reservoirs to medium and little sized structural-lithologic subtle reservoirs.The E2S4 of Linnan low-laying mainly develops clastic volcanic and a suit of siltstone and fine sandstone\ mudstone interbeds which is shore shallow lake sedimentary facies. People wonder whether there is good source rocks sediment in the pass.This paper studies on the sequence of stratigraphic frame, the characters of facies marks, facies types and distribution rules of facies by the relevant data of cores, well-log and seismic data on the basis of the sequence of stratigraphy and sedimentary.Under the guide of the theory of sequence stratigraphy and basing on the characters of T-R cyclic sequence stratigrapy combining the sedimentary characters and seismic data, the boundaries of tracts and sequence are recognized in the upper member of E2S4 low-laying. The top boundary of the sequence is corresponding to the T6'seismic reflection, and the bottom is corresponding to the T6 seismic reflection. The upper E2S4 of Linnan low-laying is divided into a 3rd order sequence contains lake transgression and lake regression tracts. This type of sequence is called T-R cyclic sequence.There are delta, fan delta and alluvial fan in the upper member of Shasi(E2S4) of Linnan low-laying by the relevant data such as cores, well-log data, log data and geochemistry data.The research on the sediment evolution is conducted in the sequence of stratigaphic frame. The development of stratigraphy in the upper member of Shasi(E2S4) of Linnan low-laying reflects the sedimentary characters of shallow-water and broad basin during the privilege period of faulted lake basin. During the sedimentary period of the upper member of Shasi(E2S4), the main material resource came from south,north and west. During the privilege period of the upper member of Shasi which is mentioned lake transgression tracts, the basin developmented river-delta sedimentary systems, flood-overflow sedimentary systems and shallow lake-lake bar sedimentary system. During the middle period of the upper member of Shasi which is mentioned lake regression tracts, the basin developments delta sedimentary system in the south, north and west as the result of wet weather and the well-contributed material resources. During the same period, it developmented shallow-lake and lake-beach-bar sedimentary systems in the other region of the basin and semi-deep-lake sedimentary system near the center of the basin.