The molecular diffusion of an oil-gas system is a key factor to determine the mass transfer rate. The actual mass transfer between oil and gas is an unsteady-state process. In this paper, the diffusion coefficients of the N 2 -rich gas-crude oil, CO 2 -rich gas-crude oil, and CH 4 -rich gas-crude oil systems were determined at 60 °C and 20 MPa by the mutual diffusion model developed. Results of the coefficient measurements show obvious transit characteristics of the gas-oil diffusion processes. Both the required equilibrium time and the diffusion rate depend on not only the diffusion gas but also the diffusion system. The diffusion gas concentration affects the diffusion coefficients slightly.

No abstract

In porous media, fluid flows through mesh structure made up of micro-braided capillary. Its flow state is similar to the flow in capillary. For Non-Newtonian fluid, we considered viscosity changes with shear strain rate (transformed to pressure difference) in reservoir simulator. It directly uses rhelogical relationship measured by viscometers, but it doesn't consider flow factor in micro-pore. Therefore for Non-Newtonian fluid we educed viscosity transfer relationship between macro- viscosity (viscometer rhelogical formula) and apparent viscosity (flow in capillary), it can be used in reservoir simulator, and it can reflect the difference between micro-flow and the normal flow. 1. Introduction Nowadays, most oilfields use the Non-Newtonian fluid typal displacement fluid to displace oil. The seepage of the displacement fluid in the reservoir, it is the seeping in the mesh structure made up of micro-braided capillary in porous media. The flow modality is similar to that in capillary. In reservoir simulation software, we directly use the flowage relationship measured by viscometer to simulate the Non-Newtonian seeping in mesh structure made up of micro-braided capillary in porous media. To the Non-Newtonian fluid, we use the apparent viscosity of the fluid flow in the capillary to replace the relationship of the ordinary macroscopic viscosity of the Non-Newtonian fluid (fluid meter flowage formula). It is much easier to understand the difference features of the seepage of Non-Newtonian fluid and the common fluid flow using this formula. And more accurate results will be gotten by using this formula in reservoir simulation. 2. Preparation of the experimental apparatus Seepage features of Non-Newtonian fluid are not only in connection with the rheological properties of Non-Newtonian fluid, but also in connection with the pore configuration features of the rock which is the medium. In rotary rheometre the Non-Newtonian fluid is subject to the shearing stress, but it cannot simulate the affects like machine cutting and stretching etc. of the micron sized pores. (Fig 1). The rotary rheometre has other limitations in measuring rheological properties of the disperse system (emulsion) and the results related to the viscoelastic behavior and astatization of thermodynamics of the emulsion. For the effective measurement in the rheological measuring of the emulsion, lower rate of shearing is generally used. Therefore, the classical measurement of rheological property can't meet the request of this research. Independently designed a rheological properties /seepage features association measuring system to well observe and research the issue of Non-Newtonian fluid seepage features in the porous medium. (Fig 2). This system then separately makes the capillary rheometerand and the core sample transfusion system functional; also may makes the association measure functional. The capillary rheometer (capillary tube) is formed by the rheometer mold mouth and the system which determines differential pressure Delta P and the speed of flow Q, the capillary tube cross section area assumes the circular. In the actually operation establishes the pressure (or differential pressure) value Delta P, determines the speed of flow Q which produced in the operation, or establishes speed of flow Q, determines pressure Delta P. This way enables it to become the best model of the porous medium transfusion to establish relations rheological propertyless survey model.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn porous media, fluid flows through mesh structure made up of micro-braided capillary. Its flow state is similar to the flow in capillary. For Non-Newtonian fluid, we considered viscosity changes with shear strain rate (transformed to pressure difference) in reservoir simulator. It directly uses rhelogical relationship measured by viscometers, but it doesn't consider flow factor in micro-pore. Therefore for Non-Newtonian fluid we educed viscosity transfer relationship between macro-viscosity (viscometer rhelogical formula) and apparent viscosity (flow in capillary), it can be used in reservoir simulator, and it can reflect the difference between micro-flow and the normal flow.