Experimental Research of Remaining Oil Distribution for Inverted Nine-Sport Pattern and Infill Well Pattern

The remaining oil distribution in heavy oil reservoir with the unconsolidated sandstone before and after infilling of the inverted nine-spot well pattern was complicated. To better understand the variation of flow field and remaining oil distribution of inverted nine-sport pattern and infill well pattern, the physical experiments were examined using a three-dimensional physical model. The physical simulation experiment of water displacing oil was conducted with the self-developed high pressure–temperature experiment device. For inverted nine-sport pattern, the remaining oil was distributed in the area between injection-production wells and edge region on a flat surface. In vertical, the remaining oil was distributed in the top area of composite reverse and positive rhythm reservoir and in the middle area of composite positive and reverse rhythm reservoir. For infill well pattern, the remaining oil was distributed in the area between production wells on a flat surface. In vertical, the remaining oil was distributed in the area of poor physical property with weak water flooding. Simultaneously, the enhanced recovery efficiency was about 11% by transforming the inverted nine-sport pattern into row injection-production well pattern and the final recovery efficiency was 27.27%. The results can provide reference for tapping the remaining oil and recovery calibration of unconsolidated sand heavy oil reservoir.