Application of the new vanishing interfacial tension technique to evaluate miscibility conditions for the Terra Nova Offshore Project
Application of the new vanishing interfacial tension technique to evaluate miscibility conditions for the Terra Nova Offshore Project
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DOI：
10.1016/s0920-4105(02)00246-2
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发表时间：
2002-08
影响因子：
--
通讯作者：
Dandina N Rao;J.I Lee
中科院分区：
文献类型：
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作者：
Dandina N Rao;J.I Lee
Terra Nova油池是加拿大东海岸大浅滩发现的第二大油池，目前正在开发中。作为石油采收工艺选择标准的一部分，使用最近开发的界面张力消失 (VIT) 技术确定了 Terra Nova 石油与海上生产设施中各种富集水平天然气的混溶条件。 VIT 技术基于这样的概念：当气相和原油相接近混溶点时，储层温度下气相和原油相之间的界面张力必须降至零。混溶时界面张力为零的概念又基于一个公认的事实，即当相之间的界面变得彼此混溶时，它们之间的界面必须消失。因此，最小混溶压力（MMP）和最小混溶成分（MMC）可以通过测量作为压力和气体成分函数的油气界面张力来精确确定，直至测量技术允许的最低界面张力，然后将数据外推至零界面张力。本文详细介绍了这种新的 VIT 技术及其针对细管测试的评估，并讨论了其在 Terra Nova 气体注入方案中的应用。使用计算机轴对称液滴形状分析（ADSA）技术在储层条件下获得的界面张力数据呈现为压力、气体成分和油气接触模式（首次接触或平衡）的函数。除了在接近零界面张力点时提供混溶性的视觉证据外，VIT 技术速度很快，因为它可以在大约 2-3 天内完成 MMP 和 MMC 的实验测定，而细管技术需要 4-6 周。
Terra Nova oil pool is the second largest oil pool discovered in the Grand Banks of the Canadian East Coast and is under development. As a part of the oil recovery process selection criteria, miscibility conditions were determined for Terra Nova oil with various enrichment levels of gas available from the offshore production facilities using the recently developed vanishing interfacial tension (VIT) technique. The VIT technique is based on the concept that the interfacial tension between the gas and crude oil phases at reservoir temperature must reduce to zero as these two phases approach the point of miscibility. The concept of zero-interfacial tension at miscibility is, in turn, based on the well-accepted fact that the interface between the phases must vanish, as they become miscible with one another. Thus, the minimum miscibility pressure (MMP) and minimum miscibility composition (MMC) can be determined precisely by measuring gas–oil interfacial tension as a function of pressure and gas composition, down to as low an interfacial tension as the measurement technique allows, and then extrapolating the data to zero-interfacial tension. This paper presents the details of this new VIT technique and its evaluation against slim-tube tests, and discusses its application to the Terra Nova gas injection scheme. The interfacial tension data obtained at reservoir conditions using the computerized axisymmetric drop shape analysis (ADSA) technique are presented as a function of pressure, gas composition, and the mode of gas–oil contact (first-contact or equilibrium). In addition to providing visual evidence of miscibility as the point of zero-interfacial tension is approached, the VIT technique is rapid in that it enables the experimental determination of MMP and MMC within about 2–3 days as against 4–6 weeks required by the slim-tube technique.