关键词: 碎屑岩, 储集层, 孔隙结构, 数学模型, 孔隙度, 渗透率

Abstract: The physical properties and the pore structure of a clastic sedimentary rock are affected by the size and the sorting of the grains, and the models of packing types, i. e, structure model. In this paper how the sorting of grains, one of the important sedimentary environment indexes, affects the type of pore structure model is studied. Five basic structure models have been presented mathematically and geologically according to the sorting of the grain sizes and their relative contents. They are unimodel, floated-bimodel, infilled-bimodel,floated-trimodel and infilled-trimodel. The bimodel and trimodel exist not only in conglomeratic sendstone but also in conventional sandstones. however, the conditions to form different models are dif ferent, and their lithology and pore structure are presented in the photographs attached. Finally, the equations for calculating the porosity and permeability in different structure models have been given. Main results of this study are: l)the porosity is affected only by the packing type(packed angle)in unimodel,while by relative contents of different grains also the bimodels and trimodels; 2) the permeability is affected by packing type, grain size and their relative contents. The mathematic models presented in this paper can be used to predict the structure models in different sedimentary environments to estimate their porosity and permeability,and the size of pores and throats etc., and other parameters of pore structure also.