The influence of technological fluids filtrates on well productivity decrease is considered. There was established that natural residual water saturation of a layer changing due to filtrate penetration. It is determined that the technogenically modified residual water saturation consists of strongly bound (adsorbed) water saturation and conditionally mobile (capillary-jammed) water saturation. Such a structure of residual water saturation leads to changes in its values during well operation.
There suggested the models of residual water saturation changing under the action of a pressure gradient. The effects of a complex impact of jammed residual oil saturation and blocking of near wellbore part of formation as a result of colmatation on the values of the relative phase permeability are analyzed. The models taking into account the effect of these changes on the values of the relative phase permeability are proposed. There was developed a design model for taking into account the influence of a complex formation damage mechanism in near well-bore zones on well productivity. Analytic expressions for wells productivity in layers with an altered near wellbore zone are obtained.
The analysis of the obtained analytical solutions indicates a significant influence of considered factors on well productivity. The proposed solutions will make it possible to choose the way of action on near-wellbore zone adequately to its structure, to evaluate its efficiency, and to choose the optimal radius and intensity of the impact. The obtained results of the influence of jammed fluids will allow to estimate the productivity losses of the wells after putting them into operation after stopping.
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