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加拿大及世界其它各地的大量重油油藏均为薄边际型油藏 ,不适于用热采方法 ,非混相气驱是提高这类油藏原油采收率的最好方法。本文对注CO2 、产出气及烟道气这三种气体提高重油采收率的适用性和效果进行了评价 ,对实验室研究结果进行了讨论。实验室研究包括压力 /体积 /温度 (PVT)研究和岩心驱替试验。被研究的气体为烟道气 (N2 中含摩尔浓度 1 5%的CO2 )、产出气 (CH4中含摩尔浓度1 5%的CO2 )和纯CO2 。试验所用重油采自位于加拿大萨斯喀彻温Lloydminster地区的Senlac油藏。PVT研究表明 ,通过注气开采Senlac重油的主要机理是降低原油粘度。纯CO2 为最佳开采剂 ,其次是产出气。岩心驱替结果证实了这些发现。然而 ,产出气和烟道气也是很有效的驱替剂 ,在注烟道气或产出气中产出的油主要是两个竞争机理———由N2 或CH4产生的游离气机理和由CO2 产生的溶解机理的综合作用的结果。后者在CO2 驱中起主要作用。
A large number of heavy oil reservoirs in Canada and other parts of the world are all thin marginal reservoirs, which are not suitable for thermal recovery methods. Non-heterogeneous gas flooding is the best way to increase oil recovery of such reservoirs. In this paper, the applicability and effect of enhancing the recovery rate of heavy oil by injection of CO2, produced gas and flue gas are evaluated. The results of laboratory research are also discussed. Laboratory studies include pressure / volume / temperature (PVT) studies and core flood tests. The gases studied were flue gas (15% molar CO2 in N2), produced gas (15% molar CO2 in CH4) and pure CO2. The heavy oil used in the test was collected from the Senlac reservoir in Lloydminster, Saskatchewan, Canada. PVT research shows that the main mechanism for the recovery of Senlac heavy oil by gas injection is to reduce the viscosity of crude oil. Pure CO2 is the best extraction agent, followed by production gas. Core flooding results confirm these findings. However, produced gas and flue gas are also very effective displacing agents. The oil produced in flue gas or produced gas is mainly composed of two competing mechanisms --- the free gas mechanism generated by N2 or CH4 and The result of the combined effect of the dissolution mechanism by CO2. The latter plays a major role in CO2 flooding.