致密砂岩孔隙中气水分布规律可视化实验

Visual Test of Gas-Water Distribution in Tight Sandstone Pores

为深入研究气水两相渗流在储层岩石孔隙中形成封闭气和残余水的机理,采用3D打印技术和玻璃刻蚀技术制作了2种具有气藏岩石孔喉结构特征的微流控芯片和1种裂缝-孔隙模型,并研制了一种人造微观可视化模型,进行气水两相驱替实验,观察水驱气和气驱水过程中气水分布情况。结果表明:水驱气和气驱水过程中气水在孔喉中分布规律相反;在水侵过程中,因卡断和绕流作用会形成封闭气,盲端、角隅和不连通孔隙等处也会形成封闭气,当盲端朝向与水流方向夹角为锐角时,盲端中滞留气可被部分采出;在裂缝-孔隙模型中,裂缝、“十型”和“H型”孔道是水驱过程中形成封闭气的主要原因;气驱水过程中,卡断、绕流和“A型”孔道是形成残余水的主要原因。研究多孔介质中气水流动的微观渗流机理有助于了解气藏成藏机理及水驱气时气藏的开发特性,可为定量分析实验现象提供较为准确的图像及数据资料,对于提高气藏开发效果的技术决策具有重要参考价值。

In order to further explore the mechanisms of pent-up gas and residual water during gas-water two-phase fluid flow in reservoir rock pores,two microflow chips with gas reservoir rock pore-throat structure and a fracture-pore model were prepared by 3D printing technology and glass etching technology.An artificial microscopic visualization model was developed to conduct gas-water two-phase displacement experiments to observe the gas-water distribution during water-flooding and gas-flooding.Result indicates that the water-flooding and gas-flooding show inverse gas-water distribution patterns in pores.Breaking and bypassing will lead to pent-up water during water invasion process.Blind end,corner and disconnected pore also result in pent-up water.When the blind end orientation shows an acute angle with the water flow direction,the retained gas in the blind end can be partially recovered.In the fracture-pore model,the fracture,“Cross-type”and“H-type”pores mainly result in retained gas.The breaking,bypassing and“A-type”pore mainly lead to residual water.The study of gas-water microscopic flow mechanism in porous media is favorable to understanding the gas accumulation mechanism and water-flooding development performance,which can also supply more accurate images and data for quantitative experiment analysis.This research could provide certain reference for the technical decision to improve gas reservoir development performance.