Numerical study of the water channeling problem in fractured thick oil reservoir

Abstract

For the fractured thick oil reservoir of LiaoHe oilfield, water channeling controlling is the key issue of the enhanced oil recorvery in next stage. A high-speed numerical method is proposed in this work and is used in the study of the cause of water channeling and how to control water channeling. Water saturation is updated by calculating the pressure balance of adjacent grid so that pressure solving in each step is not needed. The method is more concise than streamline method for the non-necessity of streamline calculation. Moreover, it is 30 times faster than the traditional IMPES method with comparable precision. Specific to the complex geologic body and horizontal well network, by the investigation of the controlling factors of water channeling, two dimensionless number, Ⅱ g and Ⅱ ex are defined to represent the ratio of gravity-driven flow vs. production flow and the ratio of fracture-matrix exchange flow vs. production flow. The influences of Ⅱ g and Ⅱ ex on water channeling are studied numerically. A zone chart of the strength of water channeling, which depends on Ⅱ g and Ⅱ ex , is obtained. The variation tendency of water channeling with Ⅱ g and Ⅱ ex is analyzed. The result of the research has guiding significance for enhanced oil recorvery of LiaoHe oilfield.