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Heterogeneous equation systems in a pair of coupled co-ordinate systems are solved by a finite element method. The specific physical application studied is the effect of temperature on single-well chemical tracer (SWCT) tests to measure residual oil saturation (volume fraction of immobile oil phase) remaining after waterflooding of an oil reservoir. Since temperature effects are caused by injecting cooler surface fluid down a well into a warm reservoir, the vertical temperature profile in the wellbore as well as the temperature distribution in the porous oil-bearing layer must be considered. The entire system is modelled to account for the different transport mechanisms. However, it is expedient to divide the connected geometrical region into two model domains. The equations for each submodel are expressed in an appropriate set of co-ordinates. The variational formulation of each model is then discussed. A significant temperature effect on the estimation of residual oil saturation occurs when the radial temperature and concentration wave propagation speeds in the porous formation are about the same. In this case the temperature gradient is located across the chemical tracer bank, causing the chemical reaction rate to vary radially. The temperature effects are demonstrated for two actual field tests in complex reservoirs. 相似文献
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Based on the stochastic resonance theory, a new single-well potential stochastic resonance algorithm (SSR) to improve the signal-to-noise ratio (SNR) is presented. In the new algorithm, stochastic resonance takes place in a single-well potential driven only by the noise. The effect on the proposed algorithm is discussed. By using simulated and experimental data sets, it is proven that the signal-to-noise ratio (SNR) of the weak signal can be greatly enhanced by this method. The new single-well potential stochastic resonance algorithm (SSR) may be a promising tool to extend instrumental linear range and to improve the accuracy of trace analysis. The research enlarges the application scope of single-well potential to nonlinear signal processing. 相似文献
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