Evaluation on plugging capability and practical adaptability of controllable self-aggregating colloidal particles in an ultra-low permeability heterogeneous reservoir
This paper studied the plugging capability of controllable self-aggregating(CSA)colloidal particles to channeling paths in an ultra-low permeability heterogeneous oil reservoir as well as the influence of different injection volumes of CSA colloidal particles on reservoir development effects. Specifically,the synthetic homogeneous columnar cores and heterogeneous plate cores were used to perform a percolation experiment of plugging control and water displacement as well as simulation experiment of plugging control and production by natural energy. On the basis of the independently developed experimental devices for oil reservoirs that have an edge and bottom water and are produced by natural energy,the similari? ty simulation of the practical production characteristics of a target reservoir was achieved in the laboratory. Moreover,we clarified the effect of the injection volume of CSA colloidal particles on controlling water channeling,the increasing oil production,maintaining reservoir pressure,enhanced oil recovery,and matrix remaining oil activation. The results show that the CSA colloidal particles with an average particle diameter of 0.5 μm have both good injectability and high plugging capa?bility under the target reservoir conditions. The increase in the injection volume of CSA colloidal particles is conducive to controlling water channeling,improving sweep efficiency of the low-permeability matrix,increasing the oil production rate, and reducing the releasing rate of reservoir pressure. Moreover,it has a profound effect on prolonging the stable production period of an oil well and enhancing reservoir recovery. However,when the injection volume exceeds a certain critical value,the continuous injection does not significantly improve the reservoir production performance. For the target reservoir,the laboratory results reveal that the appropriate injection volume is 0.3 PVc(PVc represents the pore volume of the channeling path),and at this injection volume,the recovery can reach 32.43%. Therefore,an effective plugging control technology for an ultra-low permeability heterogeneous reservoir should provide both suitable plugging agents and an appropriate injection volume.