Synsedementary Faulting And Its Controls On Depositional Systems Of Paleogene In Liaozhong Depression

Liaozhong depression, in the the Liaodong Bay area of northeast of Bohai Sea, elongated strip, is a secondary structural units of the Bohai Sea.The sedimentary structures plays an important control role of sediment filling and sediment deposits in the exhibition.Therefore, seeking rock-stratum and stratigraphic traps by studying the synsedimentary faulting and the control role of the deposition system will be of great theoretical and practical significance.In this paper, through the integrated application the theory and methods of Sedimentology, Sequence Stratigraphy, Tectonic Stratigraphy, Basin Analysis, and taking advantage of the rich seismic reflection data, core, well loggings and other geophysical and geological datum from oilfield, starting with the basin development of stratum and areal structural evolution, and based on developmental characteristics of third-grade interface, then establish third-grade chrono-stratigraphic sequence framework of the research area. The paleogene in the research area can be divided into 4 second-grade sequences and 10 third-grade sequences.There are 3 major faults nearly to NE direction in research area, no.2 fault of Liaodong, no.1 fault of Liaozhong and no.1 fault of Liaoxi. With the reactions of no.2 fault of Liaodong and no.1 fault of Liaozhong, the steep slope of in Liaozhong depression developed in a number of en echelon arrangement of the tensile fault. Dongying Formation in the region has obvious erosion and overlap the top of the same phenomenon sedimentary faults, the length from several kilometers to hundreds of kilometers, and the plane branch complex with the geese rows. In order to investigate the synsedimentary faults, this paper uses two methods to discuss this problem, which include net growth index and fault activity rate.Faulting slope-break zone play the control roles to sequence development on the main roles that sedimentary slopes and constraints on the super-band, major sand distributed systems distribution and sequence, and control in sand thickness changes, and structural - lithologic or stratigraphic traps with the development of a controlling role in the distribution. HST and TST mainly distribute above slope-break zone and LST develops below slope-break zone. Both sides of the larger long-term activity faults limit the Liaozhong depression. Particularly, the long-term activities no.1 fault of Liaozhong in the east side of Liaozhong depression, which plays an important control role to depression, easily lead to sand accumulation. Therefore, it is beneficial to oil and gas accumulation zonesCombined with logging curve shape, core lithofacies and seismic facies of a comprehensive analysis, from development of reservoir conditions, identifying the main dispersion and deposition of sand system types, divided into a steep slope near the source of fan or braided river delta, the gentle slope or a vertical far-source rivers delta, lacustrine fan system, shallow lake - beach bar system, deep lake deposition shale facies. And the establishment of basin filling, reservoir, cap growth mode, and finally made a favorable reservoir facies. Therefore, oil and gas exploration breakthrough in the basin to provide a theoretical basis.