Transport Characteristics Of Oil And Water In Micro-scale Porous Media

With the continuously development of economic society, oil resources has become theimportant support and the strategy guarantee, which are promoting the development ofnational economy, political and military power and comprehensive national strength. Thelow permeability reservoir is defined as the permeability of porous media which lower than50milli-Darcy in field of the petroleum development. The typical characteristic of lowpermeability and ultra-low permeability reservoirs has TPG in our country. They are shownnon-darcy flow. For a long time, because of the existence of the threshold pressure gradient(TPG), the mathematical model of liquid flow in low permeability reservoirs is difficult todescribe this kind of flow. There is not an ideal model until now. In this paper, the TPG arestudied. The main contents are as follows:First of all, based on the boundary stick layer model of a micro-channel, a new liquidflow model was derived for low permeability reservoirs in this paper. First the no movementliquid layer close to the solid surface is defined as the boundary stick layer which regardedas the negative slip length, used the exponential function of the height of the boundary sticklayer to the pressure drop gradient, the formulae of liquid velocity and the flow rate of around channel were derived; Then the model of liquid flows in low permeability reservoirswas gotten based on the capillaries model. Finally, the flow models were tested by examplesand shown how to get the flow characteristics of a low permeability reservoir. The newnonlinear model of liquid flows has a clear physical definition, and can be easily used todescribe liquid flows in low permeability media.Secondly, there is no TPG on the whole of low permeability reservoir, but in less localpressure gradient can be thought of to PTPG exists. Based on the experimental data ofdifferent power fitting, we can compare the1to the power exponential function fitting isrelatively accurate.Thirdly, after introducing the concept of relative permeability, the single phase modelare generalized to multiphase system, we can get multiphase nonlinear flow model. Throughtwo-phase flow experiment and theoretical model of the low permeability core, we analyzedthe relationship of the oil phase and water phase static boundary layer thickness andpermeability, water saturation and oil-water viscosity ratio.