The Study On The Micro-pore Structure And Percolation Characteristics Of Yanchang Formation Chang6Reservoir In Huaqing Area

The micro-pore structure of the Low permeability reservoir was heterogeneity, the law of the oil-water percolation was complicated. In this paper, testing methods of casting thin sections, SEM, X-ray diffraction, high pressure Hg injection, contant-speed mercury injection, oil-water relative permeability, experimental results of oil-water displacement in microscopic model of real sandstone and nuclear magnetic resonance and so on were used to study the paper. It was started from the point of diagenetic phase, deeply analyze the micro-pore structure and its permeability characteristics of the different types of diagenetic phases. Finally, combined with the data of performance to analyze and summarize the law of the different types of diagenetic phases. By studying deeply, the following results were got:1. The results of the heavy mineral assemblages, light mineral assemblages and quartz cathodoluminescence characteristics showed, there existed two source that were northeast and southwest2. The diagenetic phase of chang6reservior of the study area, the hydromica cementation-integranular pore and feldspar dissolution diagenetic phase, feldspar dissolution and hydromica cementation-integranular pore phase, feldspar dissolution and chlorite cementation-integranular pore phase, the hydromica cementation and feldspar dissolution diagenetic phase, he hydromica cementation phase and the carbonate cementation phase.3. The features of microscopic pore structures of various types of diagenetic phases were different. And the relation between the pore-throat ratio and coordination number with mercury injection saturation and mercury withdrawal efficiency had a good correspondence. That is, the smaller the pore-throat ratio was, the greater the coordination number was, and the greater the mercury injection saturation and mercury withdrawal efficiency were, such as the hydromica cementation-integranular pore and feldspar dissolution diagenetic facies; otherwise, the greater the pore-throat ratio was, the smaller the coordination number was, and the smaller the mercury injection saturation and mercury withdrawal efficiency were, such as the feldspar dissolution and chlorite cementation-integranular pore.4. The results of the contant-speed mercury injection showed that:the throat radius of Class Two was the largest and the pore-throat ratio was the smallest, the throat radius of Class Three was smaller and the pore-throat ratio was bigger, the throat radius of Class Four was the smallest and the pore-throat ratio was biggest.5. The results of the oil-water relative permeability, nuclear magnetic resonance and water flooding experiment showed that:the pore-throat ratio of the he hydromica cementation-integranular pore and feldspar dissolution diagenetic phase was smaller, its pore structure was better, and the oil displacement efficiency was higher; the pore-throat ratio of the feldspar dissolution and chlorite cementation-integranular pore phase was bigger, the pore structure was woser, and the oil displacement efficiency was lower.6. By comparing the distribution map of the pore radius and throat radius and the T2spectra distribution map of the NMR experiment, the results showed that The fluid in the pore and the throat composite the movable fluid, which had nothing to do with the spatial location, only has relation with the radius. The common radius of the effective volume of the pore and throat of the NMR movable fluid was that corresponding to the T2relaxation in NMR.7. The features of microscopic pore structures and production performance of various types of diagenetic phases were different. Hydromica cementation-integranular pore and feldspar dissolution diagenetic facies’s pore-throat ratio was low and coordination number was also big, so the daily fluid production of initial pilot development was low, the moisture content was low and stable, the period of stable yield was the longest, the feldspar dissolution and chlorite cementation-integranular pore diagenetic facies’s pore-throat ratio was hign and coordination number was small, so the daily fluid production of initial pilot development was hign, the moisture content was high and unstable, the period of stable yield was shorter.