A Study On Pore Structure Of E₁f₃ Low Permeability Reservoir In South Shanian And Huazhuang Area Gaoyou Depression

With the the techniques of casting section, SEM, pore image, high pressure mercury penetration, rate-controlled mercury penetration, NMR, relative permeability, water/oil displacement experiment, and rock and mineral analysis, the thesis makes a thorough research, focusing on reservior's pore structure character, the initial oil saturation and microscopes filtration characteristics controlled by it, and the impact of sediment and diagenesis on pore structure character, into the low permeable reservoir of south Shanian and Huazhuang area which is studied. The conclusions go as following:(1) The main pore types of the reservoir in the region of interest are dissolution pores between grains and in grains, primary pores are fewer, and intercrystal pores and microcracks can be seen by chance; the main throat type is point, lamellar and curved lamellar are next, the connectivity of interporosity is poor, between partial pores there are not throats, and the throats' coordinate number is low; pore throat combination display as mesopore- fine throat and micropore- fine throat.(2) In terms of the impact of pore throat characteristic parameter on physical property, the parameters which make more effect on E₁f₃ reservoir in the region of interest are as following: coefficient of sorting, mean value, relative GF, maximum throat radius, medium radius and mean throat radius. The bigger the coefficient of sorting, the wiser the throat radius sizes, the smaller the mean value and the binger relative GF get, the better the reservoir's pore structure and the physical property.(3) Oil/water transition zone of the principal producing formation in the region of interest is thick, and the depth of the water/oil contact planes changes in a large scope because of the pore structure and strong heterogeneity, as a consequence, the contours of oil saturation are not parallel to structural contour; Not only is the initial oil saturation controlled by tectonic setting, but also it is affected by differences of the lithology , the physical property and pore structure resulting from the sedimentation and the diagenesis.(4) The movable liquid's saturation of E₁f₃ reservoir in the region of interest is low, because it is controlled mainly by grain size, pore surface to volume ratio, pore type and clay mineral content and attitude, and so on.(5) The results of oil/water displacement experiments demonstrate that different models because of the diversity in lithology , physical property and pore structure display differently in the process of saturating oil; especially for some models with argillous stripe there are high permeability argillous, which impacts obviously on course of saturing oil; oil/water displacement modes of the model mainly include the uniform patterns, finger-like patterns and chicken wire patterns; the irreducible oil of the model mainly includes the oil film and the bypassing irreducible oil.(6) E₁f₃ reservoirs' physical property in the region of interest is controlled mainly by sedimentation and diagenesis. The compositional maturity of E₁f₃ reservoirs in the region of interest is middle or low, and the texture maturity is low. High content of cement and fine grain grade is the main reason of the low permeability of in the region of interest; and the denudation controls the production of secondary pore.