电化学采油及其作用机理综述

A discussion on the electrochemical recovery method and its mechanism.

电化学采油方法是依据直流电场和电化学助剂在地层孔隙中引起的电化学、电动力学作用而提高采收率的新方法，在低渗油藏及注水后期的中、高渗油藏的开采中具有广阔的应用前景。论述了电化学采油的４种作用机理，即电渗效应、地层细组分的电化学聚结及粘土矿物的变化作用、电解及其产物的作用、润湿性的改善作用。在外电场作用下，油水的电渗效应使油水流动状态得到调整；地层细组分由细变粗，渗透率提高，油流阻力减小；电解碱液和气体进入油层，降低了油水界面张力，阻滞了水流；岩石润湿性受电场及电解产物影响而发生变化。这些过程的综合效应促使含水率下降，油产量增大，采收率提高。

The electrochemical recovery approach is a new method for improving oil production and enhancing oil recovery which is based on the process of electrochemical and electrodynamic reaction within the porous medium of a reservoir under the application of direct electrical field and injection of electrochemical reagent. It has a wide foreground to apply in low permeability sandstone reservoirs as well as in medium or high permeability reservoirs at the late stage of waterflooding. In this paper, four mechanisms of the electrochemical recovery methods are discussed: the effect of electroosmosis, the electrochemical aggregation action of tiny contents and the construction change of clay minerals in oil bearing, the effect of electrolysis and electrolytic products and the improve of wettability.When a direct electrical field is applied to oil bearing formations, flow characteristics of oil and water are adjusted by the effect of electroosmosis and permeability is increased and the resistance to fluids flow is decreased by the electrochemical aggregation of tiny contents in oil bearing layers. Electrolytic alkaline and gases enter into the oil bearing formation to decrease the surface tensions and water flow rate. Moreover, rock wettability may be affected and changed by the action of electrical field applied and electrolytic products. The comprehensive effect of all these changes leads to the decrease of water cut and increase of oil production and recovery.