Study On The Stratigraphic Division And Correlation And Sedimentary Environment Of Ordovician In Nanpu Depression Of Jidong Oil Field

Jidong oil field, which is located in the north of Huanghua depression of Bohai bay basin, is a fault basin formed in Mesozoic and Cenozoic Era where the oil and gas were abundant. In which the Ordovician system and the thickness of its sedimentary cover developed well. For a long time, the stratigraphic correlation of Lower Paleozoic Erathem, especially the Ordovician system between different structural units, was the difficulty in the area, which effected Oil and gas exploration.Using the stratigraphic theory and the high-resolution sequence stratigraphic methods, this dissertation focused on the stratigraphic division and correlation and Sedimentary Environment of Ordovician, which was the key and difficult problem in the Ordovician sedimentary carbonate stratigraphy.Based on synthesizing of the predecessors'data, observing and analyzing the core of lithology, construing the paleontological data and interpreting the seismic data, the main conclusions of the article are as following:1. According to the latest conodont data, the Ordovician stratigraphic sequence was revised, and the accuracy of the stratigraphic division and correlation was increased. All of these laid the foundation for the analysis of the sedimentary environment and paleogeography.2. Based on the analysis of the lithology and the well log of the area in detailed, the sedimentary sequences and the various sedimentary cycles of Ordovician were recorgnized in seven wells. Ordovician in the study area was divided into six sequences, and the regional correlation was carried out.3. In the basis of observation on large amound of core, including the characteristics of lithology, sedimentary structures, fossil features, sedimentary facies analysis of each single well were completed. The sedimentary facies model of Ordovician of study area was set up ,which was a mainly carbonate tidal flat and ramp model. The main sedimantary features of the facies were summaried in detailed.4. Thoughtout the correlation of the different wells and seismic calibration, a Ordovician sequence stratigraphic framework in the study area was set up, which revealed the change of Ordovician sedimentary sequence of the study area with the temporal and spatial variation. The Ordovician paleogeographic framework of the area was reconstruction using the distribution and evolution of sedimentary system.