| Based on the basic geological works and the analysis of conflict between invest and output in Yuan 214 Area of Jiyuan Oilfield, the data and graphic from normal and advanced experiment such as casting thin sections, scanning electron microscope(SEM), X-ray, porosity, permeability, oil-water relative permeability, nuclear magnetic resonance(NMR) and real sandstone micro-model experiment combined with production performances data in oilfield were adopted to study the microscopic percolation characteristics quantitatively and qualitatively. The main results achieved are as follows:1.The upper of Chang-2 Formation was suffered with uneven denudation and high in east and low in west with some low amplitude nose-like structures. The reservoir sandbody mainly in meandering river delta plain.2.The rock types in research area are mainly grey and light grey fine arkose and the dominated cements are kaolinite, chlorite, ferrocalcite and ankerite which content are 5.0%, 3.0%,2.8% and 1.2% respectively. The reservoir were determined to low porosity and ultra-low permeability because of the high density of physical property, higher-permeability regions were developed locally. The average of porosity and permeability are 14.5%? 5.7×10-3um2, respectively. The average facial porosity are 7.2%, including prime pore structures are intergranular pores(5.3%) and feldspar dissolved pores(1.5%), followed with few intracrystalline pores and microfractures.3.The reservoir was strongly reformed by compaction, cementation and dissolution lead to various types of diagenesis minerals. The original porosity are 38.2%, the decrement caused by compaction and cementation are 28.3% and 21.0% respectively, and increment related to dissolution is 10.2% during the A of middle diagenesis phase.4.The diagenetic facies are divided into five types, which based on diagenesis types, characteristics and parameters, plus the application of SPSS statistics software to carry out clustering analysis.5.Reasonable diagenetic facies pattern can represent microscopic structures and seepage features effectively by analyzing oil-water relative permeability experiment combined with production performances.6.The average of movable fluid saturation is 52.01% and reservoir quality are type ?-? mainly. The shape of NMR T2 spectrum curves are bimodal pattern before centrifugation and turn into unimodal after that. This indicates that the similarity between different size of reservoir space do not represent similar movable fluid content in pore space, and it's a positive correlation between remainder potential-digging ability and the amount of residual movable fluid in original intergranular.7.The initial oil saturation, oil-water displacement efficiency and remaining oil saturation are 37.69%,32.54% and 26.24% respectively. Proper partition of diagenetic facies unit by means of physical property, multiple of oil-water displacement, seepage channel and displacement pressure indicate that it can represent the quality of reservoir effectively, namely, it reflect oil and water seepage characteristics, oil displacement efficiency, occurrence and producing degree of remaining oil.8.Utilize oil-water relative permeability experiment, NMR and real sandstone micro-model experiment, combined with real production performances in oilfield, the results show that diagenesis and evolution can influence the microscopic structures and percolation characteristics which be characterized quantitatively, and then provide reasonable, scientific and effective guidance to oilfield increase dependable crude oil... |
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