| This paper take the low permeability and tight gas sandstone reservoir of He 8 fomation in the southeastern Sulige area of ordos basin as the research object.Many advanced experimental research methods have been used such as analysis experiments as sandstone thin section identification, casting thin section, scanning electronic microscope, high pressure mercury injection, constant velocity mercury injection and nuclear magnetic resonance (NMR) to analyse and study the basic geological characteristics,sandbody distribution, microscopic pore structure characteristics and microscopic filtration characteristics of He 8 fomation in the southeastern Sulige area of ordos basin.Fully combining above analysis with flow unit to analyse the macro and micro characteristics of different types of reservoir flow units.Finally combining all kinds of experimental results to select the superiority reservoir distribution and prediction research in the study area of He 8 formation, Which get the following conclusions:(1) The study area of He 8 reservoir belongs to the relatively stable delta front subfacies deposition,which mainly develop the underwater distributary channel and distributary bay microfacies. He 8 reservoir can be divided into 4 small layers such as He 8x2,He 8x1 He 8s2,He 8s1,and the sandbody size reduces in turn.(2) He 8 reservoir builds a total of 14 sections from horizontal and longitudinal level.Horizontal profile is in the direction of east-west and its distribution direction is vertical to the channel. Longitudinal profile is in the direction of south-north and its distribution direction is the same as the channel.the quality degree of the sandbody connectivity is influenced by river swing.The thickness of the sandbody in different wells and layers has larger difference. The sandbody development of He 8x2 is the best, and He 8x1,He 8s2,He 8s1 is worse in turn.(3) The division of flow units of He 8 reservoir in the study area mainly select six parameters such as effective thickness, porosity, permeability, flow zone index (FZI), gas saturation eatl,which is based on the comprehensive and quantitative analysis of reservoir evaluation.Each small layer is divided into E, G, M, P classes according to the cluster analysis method,At the same time we established the discrimination and regression equation of the each flow unit.(4) The studies to the main reservoir of each flow unit of He 8x2 and He 8x1,which is using high-pressure mercury injection, constant speed mercury injection, gas water phase permeability and nuclear magnetic resonance (NMR), have shown that:E class flow unit reservoir has higher gas phase relative permeability. Two phase seepage area is wider. The gas water disturbance degree is weaker.And the property of G class flow unit reservoir is relatively poorer than E class. M class is the worst. (P class don’t do the research)(5) Through the analysis of reservoir characteristics and refer to the result of the division to the flow units at the same time, the reservoir in the study area is divided into four categories. E type of reservoir has better pore permeability. The pore throat radius is bigger,and movable fluid saturation is higher, which is the best reservoirs in the study area. G type of reservoir has good pore permeability,The pore throat radius is big and the movable fluid saturation is high, which is as the study area has good reservoir. M class reservoir mainly packages around the E and G reservoir. Pore structure connectivity and movable fluid saturation is mediμm,which is mediμm reservoir in the research area. P type reservoir is less well developed. The physical properties is the worst.The pore throat radius is the minimμm and movable fluid saturation is the lowest, which is the worst reservoir in the study area. |
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