Changes in rock permeability near-wellbore due to operational loads


The paper presents the results of studies of changes in the permeability of rocks in the bottom hole zone of wells in the process of oil production. Using the exponential equation for predicting the permeability of the rock with a change in reservoir pressure based on the data of well test data, an improved model is proposed. The developed model takes into account operational conditions that lead to a change in the structure of the rock matrix and oil degassing as a result of a reservoir pressure decrease. The proposed model includes empirical parameters. The model describes the hysteresis of the rock permeability for oil during the subsequent decrease and increase in reservoir pressure. For the model under consideration, the average change (decrease) in the permeability at the wellbore with an increase and subsequent decrease in the load is 30% of the initial value. Using the proposed model, numerical hydrodynamic calculations of the change in the time of oil production with a change in pressure were carried out. The lower the reservoir pressure, the longer the period of oil production. A significant decrease in reservoir pressure at the initial stages of oil production and its subsequent production leads to an increase in the terms of the development of recoverable oil reserves.