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摘要
The fluid permeability describes the flow characteristics of rock, which is an important parameter in the evaluation of reservoirs and prediction of oil and gas production. The fluid permeability can be measured when brine solution flow in pores and has physical and chemical effects with clays which adhere to or coat the grains. The measurement conditions of fluid permeability are similar to the actual conditions of shale sandstone reservoirs, so this parameter is considered to be better expression of the flow characteristics of shale sandstone reservoirs. However, there are few evaluation models of fluid permeability reported, and the existing models cannot reveal the relationship between fluid permeability and salinity of solution. To address this issue, this paper presents a model for fluid permeability calculation. In this study, based on the assumption-that the shaly sand can be simplified as a capillary tubes model, a expression of fluid permeability in terms of the surface area, tortuosity of throat, total porosity, and bound water porosity of clay is deduced. In addition, according to the physics volume model, the relationship of bound water porosity of clay to cation exchange capacity and salinity of solution is derived. Finally, by means of introducing the bound water porosity of clay to the expression of fluid permeability, a theoretical model of fluid permeability in terms of total porosity, cation exchange capacity, salinity of solution, surface area, and tortuosity of throat is deduced. The theoretical model and two sets of experimental data of fluid permeability show that the fluid permeability decreases with the increasing cation exchange capacity, and increases with the growing salinity of solution. However, in the application of the model of fluid permeability, it is difficult to calculate the parameters of the surface area and tortuosity of throat. So the application of the theoretical model to calculate the fluid permeability is limited. Based on the analysis of the models of fluid permeability and air permeability, a transformation model of fluid permeability and air permeability is established. Then, with the help of the transformation model, a new method for calculating fluid permeability is suggested. In order to verify the accuracy of the transformation model of fluid permeability and air permeability, two sets of experimental data are used to calculate fluid permeability. Comparison of the calculated fluid permeability and core measured fluid permeability shows that the calculated fluid permeability matches fairly well with core measured results, which indicates that the transformation Model in this study is credible.
- 出版日期2015-10
- 单位西南石油大学; 中国石油大学（北京）
