界面消失技术确定注CO2驱油混相条件

Determination of miscibility conditions by vanishing interfacial tension between CO2 and crude oil

关键词:  CO₂  界面张力  驱油  混相  最小混相压力 

Key words:  carbon dioxide  interfacial tension  oil displacement  miscible phase  minimum miscibility pressure

摘要:

重新回收温室气体CO₂注入地层原油进行混相驱油是实现CO₂封存和利用的主要途径之一,但其最小混相压力(MMP)被认为是该技术的一个关键参数。采用悬滴法测定了CO₂和4种不同地层原油之间的界面张力,并直观地确定了4种不同地层原油注CO₂驱油的MMP分别为:24.12 MPa、24.81 MPa、26.87 MPa和31.69 MPa。同时,采用多项式外延法确定各自的MMP,对比发现外延法确定的MMP误差均在3.0%以内,且MMP越高,误差越小。该实验表明,采用界面消失技术确定MMP具有操作简单、耗时少、成本低、准确度高等特点。 

Abstract:

Injecting recovered CO₂ from fuel gases into the reservoir crude oil at or near the condition of miscibility is one of the main methods to realize CO₂ sequestration and utilization. Minimum miscibility pressure (MMP) is often considered as a key parameter for the design of a gas injection project. In this paper, the interfacial tension between CO₂ and four kinds of reservoir crude oil were measured by the pendant drop method at stratum temperature, and the MMPs for the four kinds of reservoir crude oil were determined directly with visually observed miscibility appearance as 24.12 MPa, 24.81 MPa, 26.87 MPa and 31.69 MPa, respectively. At the same time, the polynomial extrapolation method was also used to determine their MMPs. The results showed that the error of MMPs determined by polynomial extrapolation method was within 3%, and corresponding to lower error value at higher MMP. It indicated that MMP determined by vanishing interfacial tension had the advances of low error and cost, convenience and easy operation.