低渗透油藏CO2泡沫驱室内评价及数值模拟研究

Indoor evaluation and numerical simulation research of CO2 foam flooding in low permeability reservoirs

关键词:  低渗透裂缝性油藏  泡沫封堵  提高采收率  泡沫驱  数值模拟

Key words:  low-permeability fractured reservoir  foam plugging  enhanced oil recovery  foam flooding  numerical simulation

摘要:

腰英台油田CO₂驱油先导试验中,CO₂过早气窜,降低了波及体积,影响区块产能。采用岩心切割技术制作了低渗透裂缝性岩心模型,通过室内实验,研究了CO₂泡沫在低渗透裂缝性岩心中的封堵能力以及水驱或气驱后CO₂泡沫驱提高采收率的效果。基于数值模拟方法,分析了泡沫中各组分的作用机制以及泡沫调驱提高低渗透裂缝性油藏采收率机理。研究表明,CO₂泡沫能增加流体在裂缝中的流动阻力,有效降低驱替液流度,阻力因子在46~80之间；泡沫在裂缝中存在启动压力,它将影响泡沫在初始阶段的流动。对于水驱和气驱之后采用泡沫驱的岩心,采收率分别增加了26%和35%,揭示了泡沫在裂缝与基质间形成的横向压差是提高低渗透裂缝性油藏采收率的机理。

Abstract:

CO₂ channeling occurred too early in the pilot test of CO₂ flooding in Yaoyingtai oil field, which decreased its sweeping volume and production capacity. Low permeability fractured core models were generated by core cutting technique. Based on indoor experiments, the foam blocking ability and flooding performance were measured by core flooding experimental apparatus and EOR results of foam displacement following water and gas flooding were conducted. The mechanisms of different components in foam and EOR performance in low permeability fractured reservoirs were analyzed by numerical simulation. The results showed that foam could increase fluid flow resistance in the fracture, reduce liquid motility effectively and resistance factors were between 46 and 80; there was a foam apparent viscosity in the fracture that had an impact on the initial flow of foam. For the oil saturated fractured cores flooded by water and gas, oil recovery was increased by 26% and 35% respectively, and the mechanism of CO₂ foam EOR in low permeability fractured reservoirs was the transverse pressure between facture and matrix.