Experimental Study On Water Flooding In Low Permeability Reservoirs In XL Block

XL block is a typical low permeability reservoir,with strong reservoir heterogeneity,poor fluid passing capacity and large seepage resistance,and fluid no longer follows Darcy's law of seepage when flowing in the reservoir.Therefore,it is difficult to control the movement law of water drive front and the change law of recovery percentage.In this paper,the influence of reservoir plane heterogeneity and interlayer heterogeneity on water flooding law is studied by designing and making a model of pouring natural cores with electrodes and pressure measuring points,and changing core collocation and injection conditions.The experimental study on water flooding law of series cores shows that:(1)The whole movement law of water drive front remains unchanged in different permeability ranges.The larger the permeability range is,the smaller the PV number of relatively high permeability cores is,and the larger the difference between PV numbers of high permeability cores and low permeability cores is,the more obvious the difference increases.(2)After the cores are connected in series,the final recovery degree of the cores near the injection end increases,while the recovery end decreases.(3)In the heterogeneous series core experiment,when the water drive reaches the low permeability core,the water drive front curve rises to some extent.With the backward movement of low permeability core,the PV number of water breakthrough increases,and the final recovery degree increases.Experimental study on water flooding law in parallel cores shows that:(1)The whole movement law of water flooding front is unchanged in different permeability ranges.The larger the permeability range is,the smaller the PV number of relatively high permeability cores is,and the difference between PV numbers of high permeability cores and low permeability cores gradually increases,and the increasing range of PV number difference is more obvious.(2)After the cores are connected in parallel,the final recovery degree of relatively high permeability cores does not change obviously,while that of relatively low permeability cores decreases obviously.Relative to high permeability cores,the final recovery degree is relatively high,and the greater the permeability range,the more obvious the difference between the final recovery degree of high and low permeability cores.When the permeability is extremely poor,the relatively low permeability core does not produce liquid.(3)When the properties of relatively high permeability cores are similar,the greater the permeability range,the lower the overall recovery degree of parallel connection,and the overall recovery degree is mainly affected by the recovery degree of relatively high permeability cores.(4)The increase of displacement speed will not change the change rule of overall recovery degree of parallel cores,and the increase of final recovery degree of relatively low permeability cores is more obvious.The increase of displacement speed will improve the overall final recovery degree of parallel cores,narrow the gap between the final recovery degree of high and low permeability cores,and make the relatively low permeability cores that no longer produce liquid produce liquid again.