The Study On Reservoir Sedimentology Of Paleogene In The Liuxi-Hejian Area Of Raoyang Sag

In this paper, directed by sequence stratigraphy, sedimentology and reservoir geology, starting with stratigraphic classification and correlation, Paleogene is divided into 10 third grade sequences with 21 system tracts in the research area. By taking full advantage of the core, drilling, logging and seismic data, it is shown that the main sedimentary facies are fluvial facies,braided river deltas, lakes, alluvial fans and fan deltas in Paleogene of this area, and it can be further divided into subdivided into 15 subfacies and nearly 50 microfacies, among them, the main microfacies of the area are braided channel, underwater distributary channel, mouth bar, sheet sand, channel fill, diara, flood-plain and beach bar, and detailedly summarize all kinds of subfacies and microfacies identifier on rock type, colour, texture, sedimentary structures, rhythmicity, logging and seismic. In addition, the paper systematically study the plane distribution of sedimentary facies and sandstones in different 3-order sequences and system tracts, and it is shown that the main reservoir bodies in Paleogene of the area include the sandbodies in the delta front and the river sandbodies of fluvial facies as well as beach-bar sandstone in the shallow lake.According to plenty of thin section, casting lamella and scanning electron microscope, petrologic characterishcs, physical properties and the pore types of different genetic type reservoir bodies are systematically studied, and it is shown that reservoir sandstone has medium and somewhat low compositional maturity and medium textural maturity; in Shahejie Formation reservoir primarily belongs to low porosity and low permeability,secondly medium porosity and low permeability or low porosity and extra-low permeability, reservoir primarily belongs to middle-high porosity and middle-high permeability in Dongying Formation, few low porosity and low permeability; pore type in the resevoir of the area includes primary intergranular pores, rudimental intergranular pores and intergranular dissolved pore, intragranular dissolved pore, moldic pore, intercrystalline pore and fracture formed by corrosion. Reservoir is mainly influenced by tectonic, deposition and diagenesis. Tectonics controls the development of depositional systems macroscopically, and then control the distribution of sandstone, different sand body types developed in different tectonic positions. At the same range of depth, the reservoir property are basically controlled by sedimentary facies zones, usually, the favorable reservoir mainly distributed in the channel sandbodies and diaras of the fluvial facies, the sandbodies of distributary channel and river mouth dam of braided river deltas. The influence in squeezingaction shows that porosity decreases 0.75% for each additional 100 meters in the range of 0～4000m. Cementaction have strong damaging effect on reservoir properties in the range of 2500～3500m. Dissolution plays a leading role in improving sandstone reservoir quality of deep reservoirs in the range of 2800～4000m.