Diagenesis And Its Impact On The Reservoir Quality Of Deep Reservoir From Paleogene In Huimin Depression

Huimin depression contains abundant hydrocarbon resources. But from the year 2000, the deep zone reservoir haven't made a breakthrough because of the lack of research intension, and the superficial degree of understanding. The article based on the observation of core, and the sufficiently use of core, seismic, well logging, and test data, to proceed sedimentary facie research. Based on the classify of sedimentary facie, make use of thin section, SEM, X-ray diffraction, and etc., we research on lithological characteristics, characteristics of diagenesis and reservoir quality, generalizing a series of diagenesis types and its effect to the reservoir quality, and evaluate different reservoir.The main diagenetic processes that have affected the sandstones include compaction, cementation and dissolution. Authigenic minerals consist mostly of calcite, feldspar, quartz and mineral clays. The major diagenetic evolution stage in Huimin Sag is mesodiagenesis A. The reservoir of Kongdian Formation in center uplift and Linnan Depression is in mesodiagenesis B. According to diagenetic facies, the reservoir can be divided into five types: compaction and packing action, dissolution of ductile grain, carbonate cemetation, silica cementation, and kaolinite cementation.The sandstones in study area are mostly arkose to lithic arkose. Thin section porosity was divided into five categories, including: intergranular pores, intragranular dissolution pores, mold pores, oversized pores, micropores and fissures. According to types of pores and throats, pore structure can be divided into five groups. Porosity and permeability is low in Kongdian Formation, high in the third Member of Shahejie Formation. Porosity and permeability have a positive correlation to burial depth, capillary pressure and connected pore channel radius.The effect of diagenesis on reservoir quality includes compaction, cementation and dissolution. The forth two can decrease the porosity of reservoir. Dissolution can raise the porosity of reservoir. The result of quantitative analysis proved that the relative importance of compaction and cementation is different in different areas. In Linnan Depression, Xinyang Depression, Hepan Area and Qianguan Area, compaction has a great affection to the physical property of reservoir; in Shanghe Area, the decline of porosity is chiefly caused by cementation; in Ycheng Area, compaction and cementation are both weak. Dissolution raised the porosity by 0.3%～10% in the region of studied area.According to the research on diagenetic evolution, distribution of reservoir, evolutionary rules, types of pore structure and local distribution of depositional system, reservoir are evaluated, and the results are as below: reservoir in center uplift and most of Linnan Depression belong toⅣ;Ⅱ～III in Yucheng Area,Ⅱin the west of Huimin Depression, Wuli Uplift and the head of Luxi Uplift, andⅠin Qianguantun area of South slope belt.