初始孔隙度对泡沫排砂解堵效果的影响试验研究

Experimental Study on the Effect of Initial Porosity on Foam Assisted Sand Discharge and Plug Removal

为研究泡沫排砂解堵的适应性,首次设计了氮气泡沫解堵试验设备。其中,井筒容器可模拟井筒的沉砂效果,此外,为了能够提供充足的泡沫,特设了油藏缓冲容器。为了模拟初始孔隙度对泡沫排砂解堵效果的影响,采用控制压实压力及PVA薄膜包裹的技术,首次获取了5块初始孔隙度各异的可出砂岩心。完成了泡沫排砂解堵试验,发现排砂后岩心的孔隙度和渗透率皆有增加,证明了氮气泡沫排砂解堵作为一种储层伤害修复方式十分有效。定义了渗透率及孔隙度恢复系数,发现在相同的排砂条件下,初始孔隙度越高,排砂后其孔隙度和渗透率的恢复程度越高。在相同的排砂条件下,出砂量随着初始孔隙度的增加而增加。当初始孔隙度达到20%,粒径为148μm的游离砂排出量剧增。当岩心孔隙度超过22%后,出砂量急剧增加。

An experiment apparatus of Foam Assisted Sand Discharge and Plug Removal is designed.There is a wellbore vessel which can stimulate the effect of sand setting.And a reservoir vessel is designed to supply enough foam.Five pieces of artificial cores,which are permeability contrastive and sand producible,are made firstly based on the technology of pressure control and PVS membrane wrapping.The experimental results show that foam can enhance the porosity and permeability significantly and it is an effective way to treat formation damage.Recovery factors of the permeability and porosity are defined in this paper.The higher the initial porosity,the bigger recovery factors of the permeability and porosity and the more produced sand quantity.Produced sand quantity increases dramatically when the initial porosity gets 22%.Sand production with size in 148μm increase substantially when the initial porosity gets 20%.